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LEED v2009
Core & Shell
Energy and Atmosphere
Minimum Energy Performance

LEED CREDIT

CS-2009 EAp2: Minimum Energy Performance Required

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Intent

To establish the minimum level of energy efficiency for the proposed building and systems to reduce environmental and economic impacts associated with excessive energy use.

Requirements

Projects that register on or after April 8, 2016 and are subject to the four point mandatory minimum, demonstrate a 14% improvement for new buildings, or a 10% improvement for major renovations to existing buildings.
Option 1. Whole building energy simulation
Demonstrate a 10% improvement in the proposed building performance rating for new buildings, or a 5% improvement in the proposed building performance rating for major renovations to existing buildings, compared with the baseline building performance rating. Calculate the baseline building performance rating according to the building performance rating method in Appendix G of ANSI/ASHRAE/IESNA Standard 90.1-2007 (with errata but without addenda1) using a computer simulation model for the whole building project. Projects outside the U.S. may use a USGBC approved equivalent standard2. Appendix G of Standard 90.1-2007 requires that the energy analysis done for the building performance rating method include all energy costs associated with the building project. To achieve points using this credit, the proposed design must meet the following criteria:
  • Comply with the mandatory provisions (Sections 5.4, 6.4, 7.4, 8.4, 9.4 and 10.4) in Standard 90.1-2007 (with errata but without addenda1) or USGBC approved equivalent.
  • Inclusion of all the energy costs within and associated with the building project.
  • Compare against a baseline building that complies with Appendix G of Standard 90.1-2007 (with errata but without addenda1) or USGBC approved equivalent. The default process energy cost is 25% of the total energy cost for the baseline building. If the building’s process energy cost is less than 25% of the baseline building energy cost, the LEED submittal must include documentation substantiating that process energy inputs are appropriate.
For the purpose of this analysis, process energy is considered to include, but is not limited to, office and general miscellaneous equipment, computers, elevators and escalators,kitchen cooking and refrigeration, laundry washing and drying, lighting exempt from the lighting power allowance (e.g., lighting integral to medical equipment) and other (e.g., waterfall pumps). Regulated (non-process) energy includes lighting (for the interior, parking garage, surface parking, façade, or building grounds, etc. except as noted above), heating, ventilation and air conditioning (HVAC) (for space heating, space cooling, fans, pumps, toilet exhaust, parking garage ventilation, kitchen hood exhaust, etc.), and service water heating for domestic or space heating purposes. Process loads must be identical for both the baseline building performance rating and the proposed building performance rating. However, project teams may follow the exceptional calculation method (ANSI/ASHRAE/IESNA Standard 90.1-2007 G2.5) or USGBC approved equivalent to document measures that reduce process loads. Documentation of process load energy savings must include a list of the assumptions made for both the base and the proposed design, and theoretical or empirical information supporting these assumptions. Projects in California may use Title 24-2005, Part 6 in place of ANSI/ASHRAE/IESNA Standard 90.1-2007 for Option 1.

OR

Option 2 is not an eligible compliance option for projects that registered on or after April 8, 2016.
Option 2. Prescriptive compliance path: ASHRAE Advanced Energy Design Guide
Comply with the prescriptive measures of the ASHRAE Advanced Energy Design Guide appropriate to the project scope, outlined below. Project teams must comply with all applicable criteria as established in the Advanced Energy Design Guide for the climate zone in which the building is located. Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.
Path 1. ASHRAE Advanced Energy Design Guide for Small Office Buildings 2004
The building must meet the following requirements:
  • Less than 20,000 square feet (1,800 square meters).
  • Office occupancy.
Path 2. ASHRAE Advanced Energy Design Guide for Small Retail Buildings 2006
The building must meet the following requirements:
  • Less than 20,000 square feet (1,800 square meters).
  • Retail occupancy.
Path 3. ASHRAE Advanced Energy Design Guide for Small Warehouses and Self Storage Buildings 2008
The building must meet the following requirements:
  • Less than 50,000 square feet (4,600 square meters).
  • Warehouse or self-storage occupancy.

OR

Option 3 is not an eligible compliance option for projects that registered on or after April 8, 2016.
Option 3. Prescriptive compliance path: Advanced Buildings™ Core Performance™ Guide
Comply with the prescriptive measures identified in the Advanced Buildings™ Core Performance™ Guide developed by the New Buildings Institute. The building must meet the following requirements:
  • Less than 100,000 square feet (9,300 square meters).
  • Comply with Section 1: Design Process Strategies, and Section 2: Core Performance Requirements.
  • Health care, warehouse and laboratory projects are ineligible for this path.
Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.

OR

Option 4. Brazil compliance path: PBE Edifica

Projects in Brazil that are certified at the “A” level under the Regulation for Energy Efficiency Labeling (PBE Edifica) program for all attributes (Envelope, Lighting, HVAC) achieve this prerequisite. The following building types cannot achieve this prerequisite using this option: Healthcare, Data Centers, Manufacturing Facilities, Warehouses, and Laboratories.

1Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.

2 Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1-2007 if it is approved by USGBC as an equivalent standard using the process identified in the LEED 2009 Green Building Design and Construction Global ACP Reference Guide Supplement.

Pilot ACPs Available

The following pilot alternative compliance path is available for this prerequisite. See the pilot credit library for more information. EApc95: Alternative Energy Performance Metric ACP
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Frequently asked questions

Can mezzanines open to floors below be excluded from the energy model?

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How do I provide a zip code for an international location?

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For a project outside the U.S., how do I determine the climate zone?

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For a project outside the U.S., how do I determine the Target Finder score?

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Do hotel rooms need automatic light shut-off control?

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How commonly are the 90.1 mandatory compliance forms submitted as part of EAp2/EAc1?

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The Section 9 space-by-space method does not include residential space types. What should I use?

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Can the Passive House Planning Package (PHPP) be used to energy model for LEED?

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Is it acceptable to model a split-type AC with inverter technology compressor as a heat pump, like modeling VRF?

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Can the Trace 700 'LEED Energy Performance Summary Report' by uploaded to LEED Online in lieu of the Section 1.4 tables spreadsheet?

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A portion of our building envelope is historic. Can we exclude it from our model?

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Which baseline HVAC system do I use if my building has no heating or air conditioning?

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For an existing building, do I need to rotate the model?

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Our project has a diesel backup generator. Should we include it in our energy model?

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Our project has a large process load—75%. Despite our efforts to make an efficient HVAC design, the cost savings are minimal. What can we do to earn this prerequisite and be eligible for LEED certification? Is there any flexibility in how we model the process load?

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Can SHGC be higher in the proposed than in the baseline model?

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Our process load is higher than 25%. Do we have to justify that?

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Do I need to justify the electrical and fuel rates I am using in my model?

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Our local code references ASHRAE 90.1-2010. Should I use that for my documentation, or 90.1-2007?

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Can I claim exterior lighting savings for canopy lighting even though a baseline model cannot include shading elements?

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The project is built on a site with existing exterior lighting installed. How should this be accounted for?

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Addenda

1/1/2015Updated: 3/29/2018
Regional ACP
Description of change:
Add the following new option after Option 3:

"OR

OPTION 4. Brazil Compliance Path: PBE Edifica

Projects in Brazil that are certified at the “A” level under the Regulation for Energy Efficiency Labeling (PBE Edifica) program for all attributes (Envelope, Lighting, HVAC) achieve this prerequisite. The following building types cannot achieve this prerequisite using this option: Healthcare, Data Centers, Manufacturing Facilities, Warehouses, and Laboratories"
Campus Applicable
No
Internationally Applicable:
Yes
7/1/2015Updated: 10/2/2015
Global ACP
Description of change:
Add the following at the end of the section, prior to the heading for Section 6:

For an expanded reference of international locations, ASHRAE 169-2013 Table A-5 (Canada) or Table A-6 (International) may be consulted. ASHRAE 169-2013 subdivides Climate Zone 1 into two climate zones (Climate Zone 1 and Climate Zone 0). Locations listed in ASHRAE 169-2013 in Climate Zone 1 and Climate Zone 0 should be considered Climate Zone 1 under ASHRAE 90.1-2010.
Campus Applicable
No
Internationally Applicable:
Yes
2/1/2010Updated: 2/14/2015
Rating System Correction
Description of change:
Below the box, insert the following text as a footnote:?Project teams wishing to use ASHRAE approved addenda for thepurposes of this credit may do so at their discretion. Addenda mustbe applied consistently across all LEED credits.
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add, "or USGBC approved equivalent." to the end of the first bullet.
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Change "(10,000 square meters)" to "(9,300 square meters)"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Delete the box that states, "This OPTION is not available to Projects outside the U.S."
Campus Applicable
No
Internationally Applicable:
Yes
2/1/2010Updated: 2/14/2015
Reference Guide Correction
Description of change:
In the first line of the fourth paragraph, replace "tare" with "are" so the text becomes "Within each section are mandatory..."
Campus Applicable
No
Internationally Applicable:
No
10/1/2012Updated: 2/14/2015
Global ACP
Description of change:
Replace the definition of " baseline building performance" with "Baseline building performance is the annual energy cost for a building design, used as a baseline for comparison with above-standard design."
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Change "(2,000 square meters)" to "(1,800 square meters)".
Campus Applicable
No
Internationally Applicable:
Yes
2/2/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Remove the third and fourth bullet of the section:
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add footnote 2, "Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1-2007 if it is approved by USGBC as an equivalent standard using the process located at www.usgbc.org/leedisglobal."
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Delete the box that states "This OPTION is not available to Projects outside the U.S."
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Remove "energy cost budget or" so that the paragraph reads, "Project teams must meet the minimum efficiency requirements for system components listed in ASHRAE 90.1-2007, Tables 6.8.1A-G, even if using the performance-based compliance method."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add, "or USGBC approved equivalent." to the end of the first sentence in the third bullet.
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add "Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone." to the end of the option.
Campus Applicable
No
Internationally Applicable:
Yes
2/2/2011Updated: 2/14/2015
Rating System Correction
Description of change:
Remove the third and fourth bullet of the section:
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add "Projects outside the U.S. may use a USGBC approved equivalent standard2." to the end of the second paragraph.
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Change "(2,000 square meters)" to "(1,800 square meters)".
Campus Applicable
No
Internationally Applicable:
Yes
2/1/2010Updated: 2/14/2015
Reference Guide Correction
Description of change:
Below the box, insert the following text as a footnote:?Project teams wishing to use ASHRAE approved addenda for thepurposes of this credit may do so at their discretion. Addenda mustbe applied consistently across all LEED credits.
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Change "(5,000 square meters)" to "(4,600 square meters)"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add "Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone." to the end of the first paragraph.
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Remove paragraph (begins with "The energy cost budget method...")
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add: "or USGBC approved equivalent" after "(ANSI/ASHRAE/IESNA Standard 90.1-2007 G2.5)" in the paragraph beginning with "For this credit, process loads...".
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Delete the Alternative Compliance Path for Projects Outside the U.S. box.
Campus Applicable
No
Internationally Applicable:
Yes
7/1/2015
LEED Interpretation
Inquiry:

Is there an adjusted point scale and minimum point threshold where applicable for LEED v2009 projects using ASHRAE 90.1-2010?

Ruling:

**July 1, 2016 update:This ruling has been revised to address the LEED 2009 minimum point requirement released 4/8/2016.**

Yes, LEED v2009 projects that demonstrate compliance using ASHRAE 90.1-2010 may utilize the adjusted point scale as shown in the Related Resource "ASHRAE 90.1-2010 Adjusted Point Scale for LEED v2009 Projects", subject to the following limitations:

• All mandatory provisions associated with ASHRAE 90.1-2010 (or an approved alternative standard) must be met in order for the project to use this compliance path.
• The ID+C thresholds shown are only relevant for projects using the Alternative Compliance Path described in LEED Interpretation 10412 that replaces the LEED 2009 requirements for EAp2, EAc1.1, EAc1.2, EAc1.3, and EAc1.4 with a Performance compliance path. All other ID&C projects would use the standard points available from EAc1.1 through EAc1.4 to comply with the 4-point minimum requirements.
• The CS 2009 EAp2-c1 ACP (http://www.usgbc.org/resources/cs-2009-eap2-c1-acp) may not be used in conjunction with this ASHRAE 90.1-2010 ACP. The project team must either use ASHRAE 90.1-2007 Appendix G with the CS 2009 EAp2-c1 ACP or use ASHRAE 90.1-2010 Appendix G without the CS 2009 EAp2-c1 ACP.

For projects that register on or after April 8th, 2016 and are subject to the mandatory Optimize Energy Performance point minimum:
If the project complies with all LEED v4 Minimum Energy Performance requirements for the relevant LEED v4 rating system, the project shall be considered to satisfy the LEED 2009 EA Prerequisite: Minimum Energy Performance mandatory minimum EAc1 points requirements (applicable for projects registered on or after April 8th, 2016), regardless of number of points achieved when applying this LEED Interpretation. The points documented under EAc1: Optimize Energy Performance shall be as shown in the ASHRAE 90.1-2010 Adjusted Points Scale for LEED v2009 for projects following the Performance Path, and zero for projects following a Prescriptive path.

Campus Applicable
No
Internationally Applicable:
Yes
9/10/2007
LEED Interpretation
Inquiry:

The SRA Arlington Consolidation design development phase started in February of 2005. The owner asked that the project be designed per the LEED-CI criteria and an early analysis of the project checklist indicated a possible Silver Certification. The LEED-CI checklist was discussed at our weekly project meetings from February 2005 until May 2005, when our CD\'s were Issued for Bid on 5/13/2005. In February 2005, the current LEED-CI checklist was Version 2, which referenced the ASHRAE 90.1-2001 criteria. We continued to review the LEED-CI criteria, and completed our CD\'s as stated above utilizing the 2001 criteria. Up unitl this time, we anticipated a paper submittal to USGBC. The LEED Online website was introduced at GreenBuild in Atlanta in November 2005, however USGBC wrestled with numerous technical challenges and did not go live until the Spring of 2006. (We know this because we attempted several times to access the website to begin entering our data the early part of 2006.) The project was bid and then sat dormant until the base building progressed to a point when the interiors portion of the work could start, per the lease, in January 2006. Also, in late summer/early fall 2005 there was significant concern on the part of the interiors team that the base building was not hitting critical milestone dates, thus providing the tenant an escape clause included in the lease - effectively cancelling the construction of interiors portion of the project. Due to these delays and uncertainty, the project was not registered with USGBC until 1/26/2006. We are asking for relief or a variance from the USGBC regarding the ASHRAE 90.1 standard, specifically that due to the timing of our design phase and CD\'s (5/13/05) versus the release of LEED-CI Version 2 on 5/25/05 that we be allowed to use ASHRAE 90.1 - 2001 criteria and not ASHRAE 90.1 - 2004. Obviously, without this prerequisite we will not be able to continue completing the submittal for this project.

Ruling:

Projects must adhere to the requirements of the version in effect at the time of the project\'s registration. No exceptions can be made. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
11/11/2008
LEED Interpretation
Inquiry:

The tenant\'s fitout design complies with most of the requirements of EA P2 however due to local design standards and the clients operational process requirements there are 2 clauses that we are not able to achieve and as such will require a waiver for : ASHRAE 90-1 2004 Clause 6.5.4 Hydronic System Design and Control As part of the Client\'s global network the fitout for the above project includes a data centre/ main communications room (MCR). The cooling load associated with the MCR is served by a number of chilled water units connected to 2no tenant packaged air cooled chiller. Due to the constant nature of the process load associated with the MCR room it is not proposed to install Variable speed drives to the pumps. The heat load associated with the servers contained within the MCR room is maintained at close to 100% due to the international nature of the network that the system serves and as such it is operated 24/7. The introduction of Variable Speed pumping to this system (as required to comply with ASHRAE 90.1 -2004 clause (6.5.4.1 Hydronic Variable Flow Systems) would therefore not achieve any energy saving and as such is not proposed to be installed. The client is willing to install them if necessary however does not understand how the procurement, manufacture, installation and maintenance issues associated with the additional equipment increases the sustainability of the project, given the very limited scope for VSDs to reduce energy use. Furthermore the additional complexity of Variable Speed Drives within such a critical process system adds further risk to the client business. ASHRAE 90.1-2004 allows exemption to clause 6.5.4.1 where a reduced "flow is less than the minimum flow required by the equipment manufacturer for the proper operation of the equipment served by the system" we believe that we qualify for this exemption as the client\'s critical system would be affected by any reduction in chilled water flow. As such it is proposed to install the pumps as a constant volume system albeit fitted with high efficiency motors which when combined with high efficiency air cooled chillers which exceed the minimum set out in ASHRAE 90.1-2004 (table 6.8.1C) produce an energy efficient solution which does not compromise the clients operational requirements. Further to this the application of temperature reset on the chilled water system (clause 6.5.4.3) would also be detrimental to the clients critical systems as such we believe that the system is exempt under the relevant exemption clause within the standard. ASHRAE 90-1 2004 Clause 8.4.1 Voltage Drop The local design standards require the voltage drop across the system to be sized as a maximum of 4% with 3.5% being from the feeder conductors and 0.5% from the branch circuits. The ASHRAE standard calls for a maximum voltage drop at design of 5% with 2% being from the feeder conductors and 3% from the branch circuits. As such the local design standard calls for a smaller voltage drop across the system, relative to the ASHRAE standard, but with a different split between sections. The project is therefore looking for a credit interpretation regarding this issue on the basis of the local design standards being lower on a total system basis, albeit with a different percentage split across the system.

Ruling:

The applicant is requesting a waiver from the provisions of ASHRAE 90.1-2004 Mandatory Requirements as they pertain to the data-center portion of the project. As per section 2.3, sub-section (C), requirements of ASHRAE 90.1-2004 do not apply to process requirements provided it meets the following criteria: 1. Equipment is primarily dedicated to process loads (50% or more of the flow is supplying process loads). 2. Exemption applies only to EAp2 and not EAc1 Regarding the issue of voltage drop, the project team should use the requirements of the local governing code. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
4/1/2012
LEED Interpretation
Inquiry:

The project consists of a consumer products manufacturing facility.The energy intensive manufacturing process exceeds an estimated 90% of the facility\'s total energy load. The Project Client has developed a new manufacturing process which consumes approximately 15% less energy per produced than the previous generation process.The new proprietary process has recently been installed at a similar facility and energy reduction has been demonstrated. Since industrial energy for manufacturing is not covered by ASHRAE 90.1-2007 and the building cannot be accurately modeled using the Appendix G method, project team is seeking to establish and obtain approval of an alternative compliance path.Following the Appendix G procedure would be very challenging because there are so many interacting process and non-process systems. Artificially segregating the systems in the model would not reflect energy consumption patterns accurately. Focusing on non-process components that represent less than 10% of the total energy consumption would not demonstrate the majority of the facility\'s energy savings. Manufacturing process improvements targeted at the other 90% of energy usage have a much greater impact on the entire facility\'s energy consumption. Instead of creating an energy model, baseline and proposed energy consumption will be compared by utilizing an Energy Consumption Index (ECI), which is recognized by the Association of Energy Engineers as an accepted methodology for calculating energy consumption in a manufacturing facility. The Project Client has tabulated historical overall site energy data and production at an existing facility which uses only the previous generation manufacturing platform and is also tabulating data from a site with new generation equipment. The energy data from both of these plants is not sub-metered between process and building loads because there is little economic benefit to meter the small building-only loads. An alternative compliance path will be established using the overall site ECI. Please verify that the following method may be used for determining the entire facility\'s energy cost savings.PROPOSED COMPLIANCE PATH:1. Baseline Building:The existing baseline site

Ruling:

Using the Energy Consumption Index instead of ASHRAE 90.1-2007 Appendix G to determine the annual cost savings of the building is not acceptable. The manufacturing process(es) should be calculated using the Exceptional Calculation methodology. A narrative should describe all Baseline and Proposed case assumptions included for this measure, and the calculation methodology used to determine the project savings. The narrative and energy savings should be reported separately from efficiency measures in the template Section 1.7. Additionally, documentation should be provided to verify that the manufacturing process is not standard practice for a similar newly constructed facility by including a recently published document, a utility incentive program that incentivizes the new process, or by documenting the systems used to perform the same function in other newly constructed facilities. While it is acceptable to use monitored data from a similar facility (constructed within the last five years) to document these exceptional calculation savings using a per product or per pound metric, sufficient information must be provided to document the nature of the efficiency improvements made, and to confirm that the data has been normalized appropriately. Specific product names are not required, and the specific details of the manufacturing process are not required; however, the description of the efficiency improvements to the manufacturing process must be adequate to allow the reviewer to confirm that improvements in energy consumption are tied to improved equipment or controls efficiency, and are not associated with decreases in building square footage, differing project locations, local climate data, quantity of shifts operating per day, etc. Any process energy differences related to local climate or weather (such as refrigeration energy, boiler energy, etc.) should be accounted for in the data normalization process, and the method used for normalizing must be clearly indicated. Ensure the same utility rate is used for the proposed case, baseline case, and exceptional calculation. Additionally, all mandatory requirements of ASHRAE 90.1-2007 must be met."

Campus Applicable
No
Internationally Applicable:
No
7/1/2012
LEED Interpretation
Inquiry:

This LEED Interpretation pertains to the requirement to limit voltage drop for Energy & Atmosphere Prerequisite 2 for Minimum Energy Performance. The current limit is posing a significant hardship to tall buildings relative to satisfying the mandatory requirements of ASHRAE Standard 90.1-2007 (also applicable in 90.1-2010), referenced in the prerequisite.

Specifically, the requirement in Standard 90.1 to limit voltage drop to not greater that 2% for electrical feeders and 3% for branch circuits (section 8.4.1) has proven to be problematic for large projects which often contain feeders of extended length. By comparison, the National Electric Code does not explicitly regulate voltage drop, but suggests model Code language that limits either electrical feeder or branch circuit voltage drop to 3%, with the combined voltage drop of both feeders and branch circuits when added together not to exceed 5%.

This may appear to be a minor difference, However, when applied to long copper electrical feeders which are present in tall buildings, this absolute constraint from Standard 90.1 on the feeder voltage drop (of 2%) results in a significant increase in the required quantity of copper conductors and associated conduit.

As an example of a higher density regions attempting to resolve this issue, the New York City Electrical Code has adopted the National Electric Code model language as mandatory for all buildings and also included an exception for residential occupancies within buildings to limit electrical feeder voltage drop to 4%, and the combined voltage drop of both feeders and branch circuits to not more than 5%.

This change is in recognition of the inherently short branch circuit lengths in typical NYC apartments, and is based on measured testing results which indicate that voltage drop is often negligible due to the conservative feeder and circuit sizing requirements mandated by other aspects of the Code. Thus, for residential buildings the allowable voltage drop of 4% is twice the allowable voltage drop of 2% as required in 90.1. Depending upon the length and capacity of a particular feeder, this difference can equate to a 3X variance in the required quantity of copper conductors and conduit, with a significant associated cost premium.

The magnitude of the cost premium to satisfy the 90.1 criteria in tall buildings, as compared with New York City Code requirements, can be equal to the total of all of the other cost premiums (hard and soft) associated with achieving LEED certification (at the Silver or Gold level) for a medium to large project in New York City.

In order to resolve this issue, we are proposing an alternate compliance path that we believe would meet the intent of the prerequisite, while at the same time preventing cost prohibitive use of significant amounts of additional copper.

Voltage drop is literally the loss of electrical energy (converted to heat) within a building, therefore regulating voltage drop is no different than regulating the energy efficiency of any electricity consuming device in a building (such as light fixtures or HVAC motors).

Several approaches could be implemented within the LEED rating system to address this disproportionate prescriptive requirement of Standard 90.1. A simple and straight forward approach would be to allow buildings utilizing Appendix G energy modeling as the LEED energy compliance path to include voltage drop as a regulated parameter within both the Energy Cost Budget and Design Energy Cost models. Under this approach, the 90.1 criteria (2% for feeders and 3% for branch circuits) would included in the Energy Cost Budget model, but the Design Energy Cost model would be allowed to include the actual voltage drop that will be implemented in the project design.

This approach would achieve the direct intent of the voltage drop requirement of Standard 90.1 in regulating the energy efficiency of power distribution systems, but through the inherent trade-off methodology of Appendix G would allow projects the flexibility to eliminate a disproportionate cost premium that is otherwise incurred by a prescriptive requirement.

Ruling:

The proposed alternative compliance path for meeting the mandatory requirement of ASHRAE 90.1-2007/2010 Section 8.4, Voltage Drop Limitation, allowing voltage drop as a regulated parameter within the energy models, is not acceptable; however, a simplified alternative compliance path can be approved. As noted in the Formal Inquiry, code requirements and guidelines allow flexibility in meeting voltage drop guidance in feeders and branches as long as the overall voltage drop from service entrance to the worst-case connection is within limits. For the purposes of this prerequisite, the mandatory provision of ASHRAE 90.1-2007/2010 Section 8.4 will be met as long as the total voltage drop does not exceed 5%. Internationally applicable.

Campus Applicable
No
Internationally Applicable:
No
5/27/2008
LEED Interpretation
Inquiry:

Energy & Atmosphere, Prerequisite 2.0 Minimum Energy Performance. More specifically, we need an interpretation of 2004 Ashrae 90.1 Standard Section 9.6.1 on whether or not we are allowed to trade interior lighting power allowances between spaces in different buildings when the buildings are on the same tract of land and operated by the same owner. Our interpretation of the 2004 Ashrae 90.1 Standard Section 9.6.1 is that we can trade interior lighting power allowances between spaces in different buildings when using the Space-by-Space Method of Calculating Interior Lighting Power Allowance for this project. This interpretation arises from the fact that we have multiple buildings on the same tract of land that will be operated by the same entity, the Federal Government. If we can make this interpretation, we can meet the Standard. If not, some buildings on their own will not meet the Standard.

Ruling:

The applicant is requesting clarification regarding the application of ASHRAE 90.1-2004 section 9.6.1. Each building in a multiple building project must comply separately with the requirements of EA prerequisite 2. Therefore projects may not trade interior lighting power allowances between different buildings. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
5/9/2011
LEED Interpretation
Inquiry:

For a data center with 10% office space, verify that exception G3.1.1 (b) from ASHRAE 90.1 can be applied to the server rooms and that server power can be omitted from the model.

Ruling:

The exception applies, but the energy cannot be omitted from the model. The applicant may use the server power to demonstrate energy reduction in this process load using Exceptional Calculations as per section G 2.5. Applicable internationally.

Campus Applicable
No
Internationally Applicable:
Yes
7/30/2009
LEED Interpretation
Inquiry:

The project is a greenhouse-exhibit-office space complex located in urban Denver, CO that serves as a horticulture production facility for the regional botanic gardens. Since the project consists largely of greenhouse space, the project team would like confirmation of baseline assumptions in this process-load dominated space. In addition, modeling limitations exist within the EnergyPlus simulation software for simulating evaporative cooling. The project team would like to confirm acceptance of the analysis method proposed for overcoming the software limitations. Greenhouse Baseline Characteristics In the CIR dated 4/30/2008 concerning energy use in greenhouses, the ruling clearly states that any conditioned space that is used primarily to support plant growth should be modeled as a process space and all characterizations for the space, its space conditioning equipment, and controls should be the same in the baseline and the proposed-design energy model. Therefore, in order to demonstrate efficiency improvements for these end-uses, the project team must follow an exceptional calculation method (ECM) that compares standard design practice to design improvements. The design team desires to demonstrate design improvements in three areas as outlined below. 1) The greenhouse proposed design includes high performance glazing. The project team has found standard design practice for glazing selection for greenhouses to include single-pane clear glass. The team would like to confirm that this is an acceptable baseline for the analysis. 2) The greenhouse design includes an automated shading system to decrease solar heat gain and radiative heat loss in the space. The project team would like to confirm that a greenhouse design without a shading system is an appropriate baseline. 3) The greenhouse design includes an automated natural ventilation system controlled by space and ambient temperature sensors. The ventilation system releases heat from the upper-most portion of the greenhouse when the space temperature exceeds the set-point temperature during mild ambient conditions. The project team believes that automated natural ventilation controls are not part of standard design practice and should be excluded from the baseline greenhouse. The team would like to confirm this baseline condition. Evaporative Cooler Controls Implementation of evaporative cooling systems with EnergyPlus is problematic as active control of evaporative cooling can not occur in conjunction with system or zone heating controls. If there is a need for evaporative cooling, the system operates. Otherwise, the system is off and no heating can be provided at the system or zone level. The EnergyPlus development team has been made aware of these issues but the fix is not foreseen for the near future. This problem results in heating zone loads not being met in the greenhouses. The project team proposes the following solution to work around this evaporative cooling modeling limitation. The solution implemented by the energy analyst is to schedule the evaporative cooling on/off for each hour in the year (8760 schedule), based upon the cooling and heating set points and achieved zone temperatures. Establishing the schedule is an iterative process. However because the evaporative-cooler on-schedule is specified at an hourly time step (and not smaller), the zone temperature for some hours falls below the set point. To minimize these occurrences, the evaporative coolers were shut off when they overcooled the space. But in doing so, this increased the number of hours that loads were not met in the space to be beyond 300 hours. Since this is a process space, the baseline model and proposed design models were treated similarly. Is it acceptable to exceed the 300 hour loads-out-of-range limit due to this simulation software limitation?

Ruling:

The applicant is asking two questions. It appears, based on the description provided, that the greenhouse portion of the project is correctly identified as process space and the associated energy use should be considered process load. The first question asked requests confirmation that exceptional calculation baselines they are proposing are acceptable. The proposed baselines sound reasonable, but further supporting documentation will need to be provided to verify that the baseline used does in fact represent the industry standard. As seen in a similar CIR dated 1/16/2009, the following information must be provided to show process energy savings via the Exceptional Calculation method: 1. Detailed narrative description of the greenhouse system or process for which credit is taken 2. Detailed narrative and back up data for determining the baseline energy consumption 3. Narratives and cutsheets of the proposed new equipment clearly highlighting the efficiency metric for each piece of equipment for which credit is claimed. The second question asks for clarification if the HVAC systems serving the greenhouse area can be exempt from the 300 unmet load hour requirements. The applicant states that the baseline and proposed systems are treated similarly given the process use of the space. Any credits for process energy savings should be claimed through Section 1.7 - Exceptional Calculation Methodology (ECM). Thus, it is understood that Evaporative coolers will not be modeled in the baseline and intermediate proposed case. As such, the 300 hours unmet load hour exemption is not granted for this scenario. When Evaporative Coolers are modeled for ECM, provide sufficient documentation to demonstrate that the unmet load hours in the other conditioned areas do not exceed 300 hours. The 300 unmet load hours exemption is granted for the greenhouse area, however, the LEED submission will require a full narrative explaining how the system was modeled and why the unmet load hours exceed the baseline. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
10/1/2012
LEED Interpretation
Inquiry:

The goal of EAp2 is to establish the minimum level of energy efficiency for the proposed building and systems to reduce environmental and economic impacts associated with excessive energy use. Introduction The project is a Core and Shell building in Germany with leasable space for office and retail tenants. The Whole Building Simulation has been prepared in accordance with ANSI/ASHRAE/IESNA Standard 90.1-2007 (ASHRAE 90.1). For larger retail stores, vestibules and revolving doors are unusual entrances for contemporary retail buildings in Germany and would place a disadvantage on the marketability of the tenant spaces. In lieu of vestibules, air curtains are planned for the high traffic entrances to the retail areas to prevent infiltration and improve energy performance. Project Approach The design team would like to propose an alternative compliance path for the Mandatory Provision of ASHRAE 90.1 Section 5.4.3.4 that requires vestibules or revolving doors for entrance spaces greater than 3000 sq ft. This will apply mainly to tenant retail areas. For all entrances requiring vestibules as per ASHRAE 90.1, it is planned to utilize air curtains. Note that the local Codes do not mandate vestibules and they are uncommon for German retail stores. The latest version of the International Green Construction Code, IgCC 2012, approves the use of air curtains as a substitute for the vestibules required by the current International Energy Conservation Code (IECC). Per Section 605.1.2.3 of IgCC, Where a building entrance is required to be protected with a vestibule in accordance with the IECC, an air curtain tested in accordance with ANSI/AMCA 220 is permitted to be used as an alternative to separate conditioned space from the exterior. Air curtains were approved as a substitute for vestibules in the IgCC because they were determined to prevent infiltration and heat loss equally or more effectively than vestibules. The study Air Curtains: A Proven Alternative to Vestibule Design by Berner International utilized computational fluid dynamics (CFD) modeling to demonstrate that air curtains used with automatic doors at building entrances are 10% more energy efficient than vestibules. For entrances with high traffic such as the case for retail, air curtains were calculated to reduce space heat loss by as much as 20-40% compared to standard vestibules. The IECC currently does not include air curtains as an alternative to vestibules, but this measure will be considered by code committees next year. Yet, air curtains are already approved as an acceptable alternative by the IgCC, which can be considered the first step in the approval process for the next version of the IECC. In addition, the USGBC refers to the IgCC as a new code baseline for greener building construction that is complementary to LEED, per USGBC Press Release. Air curtains have been used as an acceptable energy conservation measure to achieve EAc1 points. Approving air curtains as an alternative to vestibules at building entrances meets the intent of EAp2 and ASHRAE 90.1-2007 Section 5.4.3.4, with the added benefit of potentially improved energy performance. Additionally, retail buildings pursuing LEED would not be disadvantaged by losing leasable tenant space or reducing green space as a result of an increased building footprint and by adding further restrictions to building owners trying to find retail tenants in a highly competitive market. For the areas listed in ASHRAE 90.1-2007 Section 5.4.3.4 that would require vestibules, the project team will submit the following: 1. Drawings with locations of air curtains at main entrances 2. Air curtain manufacturer and model number The air curtains will also be commissioned as part of EAp1, Fundamental Commissioning, and EAc3, Enhanced Commissioning, if part of developer scope. Please verify that the above approach is acceptable to satisfy the requirements of LEED-NC/CS 2009 EAp2 for a project in Germany.

Ruling:

The use of air curtains instead of vestibules as an alternative method to meet ASHRAE 90.1 Section 5.4.3.4 is not acceptable. Projects may wish to seek an Interpretation directly from ASHRAE in regard to this matter. In general, USGBC will uphold an ASHRAE interpretation. Applicable Internationally; Germany.

Campus Applicable
No
Internationally Applicable:
Yes
4/2/2014
LEED Interpretation
Inquiry:

Clarification is requested regarding whether garage demand control ventilation may be modeled for credit. Garage Ventilation is not addressed by ASHRAE 90.1 – 2007, Appendix G, therefore if savings is claimed it must be modeled as an Exceptional Calculation Measure (ECM). Garage demand control ventilation is increasingly becoming standard practice in newly constructed buildings. In order to take credit for this measure as an ECM, it must be demonstrated that the proposed design goes beyond standard practice.

Ruling:

ECMs must be approved by the Rating Authority. As the Rating Authority for LEED projects, the GBCI will accept an ECM for garage demand control ventilation under the following circumstances:
1) Baseline case shall meet the requirements of ASHRAE 90.1-2010, Section 6.4.3.4.5 Enclosed Parking Garage Ventilation. Baseline fan volume shall be based on the minimum required ASHRAE 62.1 parking ventilation rates of 0.75 cfm / square foot. Baseline system fan power shall be calculated at 0.3 watts per CFM.

2) Proposed case shall reflect the actual design. Evidence shall be provided documenting that demand control ventilation strategies are sufficient to automatically detect contaminant levels of concern in parking garages (for example, Carbon Monoxide, Particulates, VOCs, etc. and NO2) and modulate airflow such that contaminant levels are maintained below specified contaminant concentration as identified in ASHRAE 62.1-2010 Addendum d. Evidence shall also be provided that contaminant sensors are placed in space in an appropriate manner for detection of contaminant in question, included in the building commissioning plan upon installation, and then calibrated yearly following installation.

The contaminants of concern that must be monitored may be limited to CO if a narrative is provided justifying how the controls will also help to limit NO2, VOCs and PM2.5 concentrations. The narrative should address how the parking garage minimum exhaust flow rate and/or the minimum fan run time (if applicable) are maintained, and provide clarification that other contaminant levels are expected to remain low based on that design. Note that NO2 would also be expected to be monitored in garages where more than 20% of the vehicles are anticipated to be diesel-fueled.

Note: though it does not need to be addressed specifically in the narrative, the project team must confirm compliance of all ASHRAE 62.1 mandatory measures, including the measure addressing “Buildings with Attached Parking Garages” requiring limitation of vehicular exhaust into adjacent spaces. .

3) If other activities occur in the garage area, the ventilation for these uses shall be in addition to garage vehicle ventilation.

4) Proposed case shall be modeled such that a minimum air flow of 0.05 cfm/square foot is maintained.

5) A narrative shall describe all Baseline and Proposed case assumptions included for this measure, and the calculation methodology used to determine the projected savings. The narrative and energy savings should be reported separately from the other efficiency measures in the LEED Form.

6) No more than a 75% fan energy savings shall be claimed for this measure.

UPDATED on 01/05/18 for rating system version applicability and in Section (2) to clarify that not all contaminants of concern must be continuously monitored.

Campus Applicable
No
Internationally Applicable:
Yes
8/26/2008
LEED Interpretation
Inquiry:

This project consists of the rehabilitation of a one-story brick warehouse in downtown Phoenix, Arizona, built by the Arizona Hardware Supply Company in 1930. It has been determined to be eligible for listing on the National Register of Historic Places, and formal listing is anticipated following review and approval by the National Park Service (NPS). The building will be rehabilitated in accordance with the Secretary of the Interior\'s Standards for Historic Preservation. Plans are being reviewed by the Arizona State Historic Preservation Office (SHPO). The warehouse will be converted into a commercial office housing about 40 people, and may be the first project in Phoenix to combine LEED-NC certification with the Federal Rehabilitation Tax Credits. Existing brick walls are of double wythe construction, 8 inches in nominal thickness, with original bricks set in a common bond pattern. Consistent with the Secretary of the Interior\'s Standards for Rehabilitation, changes to the building that would alter the historic character, both inside and outside, are not recommended by the SHPO and NPS. Therefore, the addition of insulation to the interior or exterior walls is prohibited since it would alter one of the main "character-defining features" of this building. The ground floor level and surface of the concrete floor are also subject to the constraints of the SHPO/NPS requirements. The only proposed alterations to the building envelope are the addition of storm windows, with insulated glass placed on the interior of the window opening to provide thermal efficiency, and providing insulation to a value of R-30 for a roof that has never been insulated. EAp2 requires this renovation project to comply with ASHRAE 90.1 2004 Sections 5-10 and EAc1 requires that the project secure 2 points, or a 7% improvement over the same ASHRAE standards. While we anticipate meeting the mandatory and prescriptive requirements listed in Sections 6-10, we are unable to meet the requirements in Section 5: Building Envelope. ASHRAE 90.1-2004 Section 4.2.1.3 lists exceptions to compliance with Sections 5-10 for "a building that has been specifically designated as historically significant by the adopting authority or is listed in \'The National Register of Historic Places,\' or has been determined to be eligible for listing by the US Secretary of the Interior need not comply with these requirements." In a Credit Interpretation Ruling dated 5/27/2008, a brick warehouse project similar to this one, also being renovated to meet the Secretary of the Interior\'s standards, and reviewed by the applicable SHPO, and the NPS, was granted permission "to exclude those components that cannot be upgraded to meet the mandatory and prescriptive requirements due to the standards of the Secretary of the Interior and of the National Park Service from demonstrating compliance" in order to comply with LEED Energy and Atmosphere requirements. With this in mind, will this project be allowed to meet EA Prerequisite 2 without securing two points under EAc1, considering that ASHRAE 90.1-2004 exempts the project from meeting the requirements, owing to its historical significance?

Ruling:

The project team is requesting a variance from meeting the mandatory and prescriptive requirements of ASHRAE 90.1-2004 under EAp2, specifically Section 5-10. The project team is also requesting a variance from meeting the mandatory achievement of 2 points under EAc1 (achieving a 7% energy cost savings for an existing building renovation). For EAp2, the cited exemption for meeting the requirements of Section 5-10 of ASHRAE 90.1-2004 applies to this project, provided that the project receives the designation, listing, or eligibility that is required by the exception. For EAc1, there are other efficiency measures that can and should be pursued to meet the minimum target of 7% in energy cost savings for existing building renovations. As the opportunity to pursue other energy saving measures exists for this project, the request for variance is denied.

Campus Applicable
No
Internationally Applicable:
No
5/9/2011
LEED Interpretation
Inquiry:

In consideration of EAp2, are plug-in type occupancy sensors acceptable to control task lights?

Ruling:

The proposed task lighting controls are acceptable. Although ASHRAE 90.1-2004 Section 9.4.1.1 does not list an exemption for task lighting, the context of this section implies that the requirement applies only to general lighting. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
3/11/2003
LEED Interpretation
Inquiry:

ASHRAE 90.1 does not allow credit for air leakage reduction. However, it does indicate that windows are allowed to have 1 cfm per square foot air leakage (at 0.30" water.) The windows we are using in this project are very high performance, with significantly lower air leakage rates. The manufacturer has supplied test results indicating the tested air leakage rate. Further, we are using a blower door and infra-red camera simultaneously to locate and seal any air leaks in the window system that result from installation. We propose to take credit for this air leakage reduction, with the following methodology:The tested air leakage rate at 0.30" can be established for the windows as installed, based on manufacturer\'s data, and for the base case windows based on ASHRAE 90.1. Both these values will be extrapolated to expected winter heating season air leakage rate, using the LBL correlation for blower door test data. We have run two blower door tests, and will use the most recent (during which most of the air leakage has been taken care of) test data to establish the relationship between the air leakage rate at 0.30" static pressure (75 Pa) and the average heating season air leakage rate, which is calculated at the building pressure established by the LBL correlation, which is based, in part, on the exposure of the building to wind. In this case exposure is significant, as the building is fully exposed on the west side of the building to windows ranging from south to west to north. We then propose to run the base case building, in the energy modeling, using TRACE, with the air leakage rate for the windows established in the above manner. The building as built would be modeled with zero air leakage rate. Preliminary estimates indicate that the difference in overall extrapolate natural air leakage rates in 0.04 air changes per hour, at typical heating season winter conditions. Blower door guided air leakage reduction: A significant effort at air sealing is part of the energy saving strategy for this building. With the location noted above, air leakage reduction is particularly important. Two blower door tests with simultaneous infrared scanning, have been completed. The first identified a number of areas that were not complete as designed. Most of these were completed by the time of the second test, and a number of areas were identified during the second test that, in my opinion, would not have subsequently been air sealed had this procedure not been in place. A list of further items was developed from this second air leakage test, and this list has been circulated by the GC to responsible parties, who will sign off when they have completed the items. When those items are complete, a third, and hopefully final, blower test will be conducted.We propose to take credit in our energy calculations for the air leakage reduction between the second and third blower door tests, using the LBL correlation to extrapolate to typical heating and cooling season air leakage rates, as described in number 2 above. The extrapolated seasonal air leakage rate reduction would be applied to the base case building. For example, if the extrapolated air leakage reduction were 0.1 heating season air changes per hour from blower door test #2 to test #3, we would assign 0.1 ACH to the base case building and zero air leakage to the building as built.We feel that this third round of testing and air leakage reduction is well beyond typical attention paid to air leakage, that air leakage control is particularly important in this very cold (7700 degree-day) climate and at this exposed site, and that we have demonstrated a method using accepted principals to quantify the savings. Blower door test results and LBL correlation spreadsheets for each test would be provided as part of the submission. We would also submit the list of items to be air sealed as part of the final air leakage reduction package. Windows and air leakage reduction together: We propose to add the two air leakage reductions - from window improvements and blower-door-guided air leakage reduction. For example, if the blower-door-guided heating season air leakage rate reduction were 0.1 ACH and the window air leakage reduction were 0.04 ACH, the base case building would be modeled at 0.14 ACH and the building as built at 0.0 ACH.)

Ruling:

**Updated 7/1/2015 with applicability to corresponding EAp2 prerequisites.
Advanced air sealing is a strategy that can lead to measurable energy savings, particularly in cold climates. Although this measure is outside the scope of ASHRAE 90.1 modeling protocol, you may be able to make a case for the significance of this strategy in improving energy performance. However, this will require clear and thorough documentation in order to be considered under the requirements of this credit. The following guidelines are provided to help strengthen your approach:(1) Provide manufacturer\'s air leakage test results that use the same testing protocol as that by which ASHRAE identified the baseline for window air leakage.(2) Use a typical infiltration rate as a baseline, and reduce it by the amount of improvement you can document or estimate from the air sealing strategies employed. Do not use zero infiltration in the model, as this is not a realistic assumption. A zero infiltration strategy would over-emphasize the percentage of overall energy use reduction represented by infiltration improvements.(3) Include required fresh air ventilation rates (per ASHRAE 62) in both the proposed and baseline model results.(4) Provide clear documentation of air sealing strategies and blower door test results, corrected for wind and temperature effects, to clarify anticipated air sealing performance.(5) Provide documentation which clarifies the percentage of energy savings attributed to the air sealing strategy, as opposed to other energy performance measures incorporated into the building. Applicable Internationally.

**Updated January 1, 2014
Advanced air sealing is a strategy that can lead to measurable energy savings, particularly in cold climates, though its effectiveness is especially dependent on the quality of construction and cannot easily be predicted during the design phase. Recognizing this, the ASHRAE 90.1 committee developed Addendum ag to Standard 90.1-2010, which establishes guidelines for claiming energy savings that result from reduced infiltration in Appendix G. The approved change allows credit only for buildings that complete envelope pressurization testing in accordance with ASTM E779. The appendix establishes a baseline air leakage rate of 0.40 cfm/ft2 (2.03 L/s•m2) at 0.3 in. wc (75 Pa) pressure differential compared to the measured leakage results in the proposed building.
Projects wishing to claim energy savings from advanced air sealing may do so given they meet the following requirements:
1. Utilize Addendum ag to Standard 90.1-2010 to document savings.
2. Provide clear documentation of air sealing strategies and air leakage results from ASTM E779-10 Standard Test Method for Determining Air Leakage Rate by Fan Pressurization, including confirmation that all testing criteria defined in the standard have been met.
3. Provide documentation that clarifies how energy savings from reduced air leakage has been estimated from the ASTM E779 test results and identifies the percentage of energy savings attributed to the air sealing strategy, as opposed to other energy performance measures incorporated into the building.

Campus Applicable
No
Internationally Applicable:
Yes
12/2/2006
LEED Interpretation
Inquiry:

We are seeking a variance for the parking garage HVAC system. Our project is located in Teton Village, Wyoming. Teton Village receives an average snowfall of 185 inches/year. As snowy cars use the garage during the winter, we\'re concerned snow and ice will accumulate in the garage causing a life safety issue. We feel a Snow/Ice melt system is necessary for this space. The following are extracts from ASHRAE 90.1-2004 and ASHRAE Application- ASHRAE HVAC Prescriptive Requirement "Radiant heaters complying with 6.5.8.1 are used to heat unenclosed space". ASHRAE 6.5.8.1 states "Radiant heating shall be used when heating is required for unenclosed spaces". ASHRAE 90.1-2004 states that a Radiant Heating System shall transfer heat primarily (greater than 50%) by infrared radiation. ASHRAE 6.4.3.7 states that Snow/ Ice Melting systems shall include automatic controls capable of shutting off the systems when the pavement temperature is above 50

Ruling:

The floor radiant system and associated controls you are proposing is acceptable as a snow melt system for the garage as an unenclosed space under ASHRAE 90.1-2004. Radiant heat systems emit low-temperature infrared radiation, whether they operate at 80 F or 300 F. The ASHRAE Application Guide is referring to a specific technology, infrared radiators, and not necessarily requiring their use as radiant heaters. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
7/2/2018
LEED Interpretation
Inquiry:

Our project is subject to ASHRAE Standard 90.1-2013 for code compliance. To pursue Option 1: Whole Building Simulation, is there a methodology for documenting additional energy performance for LEED v4 projects regulated by ASHRAE Standard 90.1-2013?

Ruling:

Yes, projects applying Option 1: Whole Building Simulation, and regulated by ASHRAE Standard 90.1-2013 may document additional energy performance improvement under LEED v4 EA credit Optimize Energy Performance as described below. The Appendix G modeling method must be used for the LEED submission, even if the Energy Cost Budget method is used to document local code compliance.

Projects may calculate the Equivalent ASHRAE 90.1-2010 Performance improvement as:
Equivalent performance Improvement = % better than ASHRAE 90.1-2013 + Additional Percent Savings

Where Additional Percent Savings is shown in Table 1:

Table 1: Additional Percent Savings for ASHRAE 90.1-2013

Project Type1 Additional Percent Savings
NC-Office 5%
NC-Retail (except restaurant/grocery) 5%
NC-School 6%
NC-Health Care 3%
NC-Restaurant / Grocery 3%
NC-Hospitality 5%
NC-Warehouse 1%
NC-Multifamily 3%
NC-All Other 2%
CS-Office 3%
CS-Retail (except restaurant/grocery) 3%
CS-School 6%
CS-Health Care 1%
CS-Restaurant / Grocery 2%
CS-Hospitality 3%
CS-Warehouse 0%
CS-Multifamily 1%
CS-All Other 1%
CI-Office 3%
CI-Retail (except restaurant/grocery) 4%
CI-School 6%
CI-Health Care 2%
CI-Restaurant / Grocery 3%
CI-Hospitality 4%
CI-Warehouse 0%
CI-Multifamily 1%
CI-All Other 2%

1 Mixed use buildings shall use the weighted average Additional Percent Savings based on the gross enclosed floor area associated with each building type. Unfinished spaces not submitted in the CS rating system shall use the CS values. Data center space must always be considered “All Other”.

Campus Applicable
No
Internationally Applicable:
No
2/3/2009
LEED Interpretation
Inquiry:

We would like clarification as to whether EA p2 can be demonstrated and EA credit 1 points achieved based on centrally managed lighting wattage limits. Specifically, we would like to know if the wattage limits set by the DALI (Digital Addressable Lighting Interface) system, which allows maximum wattage limits to be programmed into all fixtures, can be used to show credit compliance. Our project, the fit-out of an office space, would like to utilize these controls in order to provide exceptional energy efficiency, individual occupant control including individual fixture dimming in the open office space, as well as to control these lamps with IR occupancy sensors, photo sensors, and programmable time clocks for additional energy savings. The system also includes facility maintenance reporting of lamp and ballast status and energy usage monitoring and trend logging and could include demand response interface with BMS if desired, though not part of this project. While setting the maximum allowable wattage on the DALI system absolutely limits the amount of wattage able to be drawn by the fixtures and this limit is not something that can be over-ridden by building occupants, it is not clear if computer based controls are allowed by ASHRAE 90.1 or the LEED Rating System. It is standard practice for LEED projects to utilize reduced ballast factors or physical wattage limiters as a means to claim energy efficiency from a fixture. The dimmable DALI system and efficient T-5 linear fluorescent lamps proposed by our project cannot utilize fluorescent ballasts with a reduced ballast factor, but the equivalent energy savings can be seen by capping the fixture wattage when setting up the space\'s lighting controls. The alternative to this approach would be to utilize fewer fixtures and produce more light from each, but then the individual workstation controllability provided by the DALI system is negated because individual fixtures are shared by multiple workstations. We would like verification that it is OK to use the maximum allowable wattage set in the DALI system to compare to the AHSRAE lighting power density. The building owner will provide a signed note stating that the wattage limits will not be altered (and won\'t need to be as the lighting levels are designed to be completely sufficient with the 70% wattage limits proposed). This is consistent with the LEED Core and Shell energy modeling requirements that allow reduced lighting power densities if included in the lease agreement (a written confirmation that these levels will be met). Consistent with ASHRAE and the LEED Reference Guides, we will assume the highest wattage lamps acceptable in the fixtures and follow all other ASHRAE guidelines.

Ruling:

The applicant is requesting verification regarding the applicability of electronically controlled lighting wattage limits by using a Digital Addressable Lighting Interface (DALI) system. The proposed approach is an acceptable means of lighting power reduction provided the overall maximum Lighting Power Density is maintained at or below ASHRAE 90.1 specifications. The commissioning authority (CxA) must confirm that the wattage limits used to document credit achievement for EAc1 are programmed correctly as part of the fundamental commissioning activities performed to achieve EAp1. Additionally, the project team should provide documentation to verify the wattage limits (e.g., cutsheets, specifications, etc.) when documenting compliance for EAc1. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011
LEED Interpretation
Inquiry:

As 90.1-2007 is essentially a compilation of addenda, we assume it may be treated in the way outlined in the footnote to EA prerequisite 2, "Project teams wishing to use ASHRAE approved addenda for the purposes of this credit may do so at their discretion. Addenda must be applied consistently across all LEED credits." However, between 2004 and 2007 Appendix G was modified in some ways without addenda being published or approved, and these modifications were made official only by inclusion in the 2007 version. We further assume that we can use these modifications, as long as we use ALL the modifications in the 2007 Appendix G and referenced sections of 90.1, similar to the guidance on addenda noted above. Is this correct?

Ruling:

For LEED v2.x Rating Systems, where ASHRAE 90.1-2004 is the referenced standard, it is acceptable to use ASHRAE 90.1-2007 Appendix G in place of ASHRAE 90.1-2004 Appendix G if the energy simulation follows the language of 2007 Appendix G in its entirety, though the project must only meet the prescriptive requirements listed in 2004. Projects that want to use 90.1-2007 in its entirety may do so as well. Applicable internationally.

Campus Applicable
No
Internationally Applicable:
Yes
10/1/2015
LEED Interpretation
Inquiry:

Can the baseline model for refrigerated facilities be determined based on the IARW/IACSC Energy Modeling Guideline for Cold Storage and Refrigerated Warehouse Facilities as an exceptional calculation methodology under Appendix G?

Ruling:

Yes, project teams may use the IARW/IACSC Energy Modeling Guideline for Cold Storage and Refrigerated Warehouse Facilities as an exceptional calculation methodology when ASHRAE 90.1-2010 is used for compliance with EA Prerequisite Minimum Energy Performance. This guideline may not be used when an equivalent code is used for compliance unless approved by a project-specific Credit Interpretation Ruling. The following additional requirements apply:
1. Refrigerant type may not be used as an efficiency measure.
2. Table 1.4 must be completed for both the portions of the building complying with the IARW/IACSC Guideline as well as those following the standard ASHRAE 90.1 Appendix G requirements
3. If ASHRAE 62.1-2010 Addendum L is applied using the IARW/IACSC Guideline, it must be applied consistently throughout the project submittal.
4. Projects applying the IARW/IACSC Guideline may apply LEED Interpretation 10237 in order to claim energy savings for refrigeration equipment efficiency as an exceptional calculation methodology.

Internationally applicable as follows: The guidance applies to compliance paths using ASHRAE standards and cannot be applied to projects using an equivalent local code. Project teams wishing to apply this to an equivalent local code must obtain approval through a project-specific credit interpretation ruling.

This ruling supersedes the following LEED Interpretations: LI 5178, LI 2301, and LI 2026.

Campus Applicable
Yes
Internationally Applicable:
Yes
8/13/2007
LEED Interpretation
Inquiry:

The project is a 3,000 square foot 1-story new office building. The requirements of this prerequisite are to comply with the mandatory provisions (sections 5.4, 6.4, 7.4, 8.4, 9.4, and 10.4) of ASHRAE/IESNA Standard 90.1-2004 and the prescriptive requirements (sections 5.5, 6.5, 7.5, and 9.5) of ASHRAE/IESNA Standard 90.1-2004. ASHRAE/IESNA Standard 90.1 2004 Section 8.4.1.1 states "Feeder conductors shall be sized for a maximum voltage drop of 2% at design load." The exception we would like to take is as follows: We meet all the other requirements of this prerequisite for minimum energy efficiency requirements. Our design is approximately a 2.9% voltage drop, which meets the latest edition of the National Electric Code 215-2(A)(2) FPN#2 which allows between 3-5% voltage drop. The cable size is parallel 500 MCM. To meet the 2% requirement, the cable size would be increased to parallel 750 MCM. This is a significant cost increase to the project without gaining any energy savings. Will the 2.9% voltage drop be acceptable to use?

Ruling:

The project is requesting a relaxed voltage drop requirement for feeder conductors. ASHRAE/IESNA Standard 90.1-2004 is the referenced standard for EAp2 for LEED. The purpose of this standard is to provide minimum requirements for the energy-efficient design of buildings except low-rise residential buildings. This Standard is explicit in the requirement as stated in Section 8.4.1.1: "Feeder conductors shall be sized for a maximum voltage drop of 2% at design load." The fundamental purpose of the National Electrical Code (Section 90.1(A) and (B)) is to provide for practical safeguarding of persons and property, and contains provisions that are necessary for safety. In keeping with the purpose of the ASHRAE/IESNA Standard 90.1-2004, its requirements are more stringent than the allowances in the National Electrical Code. Therefore, the project must meet the requirement per Section 8.4.1.1 of the Standard in order to comply with this prerequisite. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
1/4/2016
LEED Interpretation
Inquiry:

Where the local code does not require vestibules or allows alternatives, can the project team take a penalty for not including vestibules in the design model?

Ruling:

Yes, in locations where the local code does not require vestibules or revolving doors the project team may choose one of the two options below. Additionally, all projects using this method must provide a narrative explaining how infiltration and exfiltration of air through building entries is addressed in the design.

1. Manual subtraction of the energy cost savings associated with vestibules as conservatively estimated by PNNL-20026 “Energy Saving Impact of ASHRAE 90.1 Vestibule Requirements: Modeling of Air Infiltration through Door Openings”. Refer to the Related Resource “Default Deduction for Vestibules” for the specific percentage subtraction required based on project type and climate zone.
2. Provide detailed exceptional calculation method calculations with each step of the calculation clearly described and in alignment with the analysis performed in PNNL-20026, but specific to the project building. Document the additional energy consumption of the project building associated with removing the vestibules from the project. No credit will be given for the use of air curtains when using this approach. A sensitivity analysis related to the number of occupants entering on an hourly basis would need to be justified. The narrative would also need to justify that the simulation software is capable of addressing the conditions required for the calculation. (Software with a well-mixed air assumption would not be able to apply this modeling approach).

***Update 11/9/20: This ruling is now applicable to LEED v4.1 BD+C and ID+C projects.

Campus Applicable
No
Internationally Applicable:
Yes
4/10/2007
LEED Interpretation
Inquiry:

Background: This project is using underfloor air distribution (UFAD) as the main HVAC system. Passive floor-mounted swirl-type diffusers (manually operated by the occupants for interior "cooling-only" zones. They will not be controlled via thermostats. The perimeter zones will be served by UFAD fan powered units (with electric heat for heating) and will be controlled via space mounted thermostats. The prerequisite requires compliance with ASHRAE 90.1-2004, section 6.4. Section 6.4.3.1.1 states: "The supply of heating and cooling energy to each zone shall be individually controlled by thermostatic controls responding to temperature within the zone". Question: Does the use of passive floor mounted diffusers in the UFAD system and controlled as described above meet the requirements of ASHRAE 90.1-2004, section 6.4.3.1.1 and this prerequisite?

Ruling:

The project team is requesting clarification regarding the requirement for zone-specific thermostat controls in order to meet the requirements of section 6.4.3.1.1 of ASHRAE 90.1-2004 for EAp2. The interior spaces of the project receive cooling air through in-floor swirl-diffusers that are occupant controlled, but there is no zone-specific thermostat control. In this case, the design meets the intent of the ASHRAE 90.1 requirement. Ultimately the temperatures in these spaces are maintained in a similar approach to a VAV box, by regulating air flow. The occupants control this airflow based on personal comfort levels, and are effectively the controls system (similar to operable windows in a naturally ventilated and cooled space). Provided that the system meets the rest of the requirements of section 6.4 (especially 6.4.3.2.1-Automatic shut-down), and thus does not supply unneeded cold air during unoccupied hours, the design appears to meet the intent of ASHRAE 90.1 and LEED-NC 2.2- EAp2. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
4/1/2012
LEED Interpretation
Inquiry:

We request a ruling regarding building ventilation and its impact on EAp2/EAc1. The question is two-fold: (1) Will USGBC/GBCI allow credit for a design that increases ventilation effectiveness other than Displacement Ventilation (a noted exception for PDV now exists in ASHRAE 62.1-2010), and, (2) will USGBC/GBCI allow credit for reduced ventilation by decoupling the outdoor air from the multi-zone VAV system, which requires increased ventilation rates to ensure the appropriate airflow is reaching all of the zones? Project Design Information:The project is a multi-story office space undergoing a major renovation. In accordance with ASHRAE Standard 90.1-2007 Appendix G, the baseline system is System 8. Ventilation is handled by VAV air handling units, thus requiring multi-zone calculations. Due to elevated terminal heating temperature, zone air distribution effectiveness (Ez) is 0.8.Similarly, the proposed system will employ a VAV system, but with decoupled constant-volume ventilation, thus foregoing multi-zone calculations and reducing outdoor air. Ventilation is room neutral resulting in an Ez of 1.0.Referenced Standards/Guidelines/Research:Ez factors and ventilation rates are determined from ASHRAE Standard 62.1-2007 Tables 6-2 and 6-1, respectively.ASHRAE Standard 90.1-2007 Appendix G Section G.3.1.2.8 Design Airflow Rates states:(D)esign supply airflow rates for the baseline building design shall be based on supply-air-to-room-air temperature difference of 20°F

This exceeds the 15°F limit from Table 6-2. ASHRAE 62.1-2007 User’s Manual (page 6-27) instructs to use the worst case factor, which is the heating Ez of 0.8.

ASHRAE Standard 90.1-2007 Appendix G Section G.3.1.2.5 Ventilation states:

(V)ventilation rates shall be the same for the proposed and baseline building designs.

Reviewing the User’s Manual for this section adds:

(V)ventilation can be a major contributor to building energy consumption, but it is not considered an opportunity for energy savings... (V)ventilation is energy neutral as far as tradeoffs are concerned.

Spare a recent exemption for using PDV to reduce outdoor air rates via an allowable manipulation of Ez, no other exemptions exist. Yet, ASHRAE research recognizes the advantages of decoupling ventilation in its ability to reduce ventilation volume and therefore energy costs. From Jeong, J.W., et. al, ASHRAE Transactions 2003, Volume 109, Part 2:

“All-air [VAV] systems are widely used in many types of buildings, [even though] these common systems have several significant deficiencies. …(T)he multiple spaces method must be used to increase the [OA fraction... This increase… may add significantly to energy consumption and operating cost…

“The challenge of conforming to [ASHRAE Standard 62] in an energy efficient manner can be met with a dedicated outdoor air system (DOAS)… The DOAS provides 100% of the required ventilation air at constant volume”

In addition, EPA’s Technical Report PNNL-18774 (Strategies for 50% Energy Savings in Medium Office Buildings) recognized DOAS as a primary energy savings strategy using the previous research by ASHRAE noted above as support and justification.

Conclusions:
It is clear that, as written, the ventilation volumes should be the same in both models. But we respectfully ask the LEED® Reviewer to provide us feedback on whether this makes sense for the current LEED® Rating Systems. It appears the rules are evolving (ex. Displacement Ventilation) as technologies and techniques evolve. And yet full credit for decoupled ventilation systems doesn’t currently exist and therefore may discourage designers and owner from investing in a system that often has higher first cost. We recommend and endorse this investment because of the excellent returns both in terms of dollars saved and carbon emissions reduced. We ask for your ruling to create an exception that allows credit for increased ventilation effectiveness and reduced ventilation rates (compared to multi-zone VAV systems) using a DOAS.

Ruling:

Credit cannot be taken for ventilation effectiveness in systems other than displacement ventilation, such as a dedicated outdoor air unit, using an Ez of 1.0 in the proposed case, with an Ez of 0.8 for the baseline case (VAV system).Addendum bj to ASHRAE 90.1-2007 states that the Baseline Case ventilation airflow rates can be calculated using an Ez value of 1.0 only if the Proposed Case Ez value is greater than 1.0. The project team may not take credit unless the Proposed Case Ez value is greater than 1.0, because 90.1 does not set a Baseline Case standard for that scenario. Equivalent to ASHRAE 90.1 may be used.

Campus Applicable
No
Internationally Applicable:
No
10/1/2013
LEED Interpretation
Inquiry:

For buildings with high unregulated energy loads, is it acceptable to show compliance with EA prerequisite: Minimum Energy Performance by considering the unregulated load separately from the ASHRAE 90.1 energy model?

Ruling:

**Updated 7/01/2016 to address the LEED 2009 4-point minimum requirement.

For buildings where unregulated loads account for more than 60% of project energy cost, the following alternative compliance path may be followed:
1. Create an energy model that includes all loads (regulated and unregulated), then remove the unregulated loads from the model through post-processing and demonstrate that the project meets the minimum performance required for EAp2, or the 4-point minimum requirement for projects registered after April 8th, 2016 (e.g. 18% for LEED-NC).
2. Demonstrate that the proposed unregulated loads are 5% more efficient than the industry standard baseline or company average production efficiency using the one of the three ECM approaches outlined below.
3. In addition to the standard documentation required for EAp2, submit calculations showing energy model results with all loads (regulated and unregulated) included and all documentation necessary to demonstrate the 5% process energy improvement.
This alternative compliance path can only be used to demonstrate compliance with the EAp2 Minimum Energy Performance requirement, and in lieu of the four-point minimum requirement for projects registered after April 8th, 2016. Points for EAc1 must be determined with 100% of the unregulated load included in the energy model.
Document ECMs using one of the following three methods:
1. For ECMs listed in the Interpretation database:
- Calculate the annual energy cost savings using the procedure listed in the database
- Enter the calculated savings into section 1.7 of the EAp2 form
- Reference the LEED Interpretation number and upload the required documentation

2. For projects establishing a new baseline technology as the industry standard, submit exceptional calculations and at least one of the following:
- List of three facilities built in the last five years that use the baseline technology
- Current utility incentive programs for new construction that establish the baseline
- Published studies justifying the baseline technology as standard practice

3. For projects with proprietary manufacturing processes, demonstrate that the production process is more efficient than the company’s average production efficiency:
- Identify at least three facilities built in the last five years that manufacture the product
- Calculate the process’ past average Energy Consumption Index (ECI) in units of energy per product manufactured to establish the baseline production efficiency
- Provide the new process’ estimated ECI, anticipated production level, and an explanation of how these numbers were determined
- Calculate the annual production process energy cost savings using the baseline ECI, proposed ECI, and anticipated production level

Campus Applicable
Yes
Internationally Applicable:
Yes
4/25/2008
LEED Interpretation
Inquiry:

We are working on a multi use facility with a full kitchen for restaurant style serving of the employees. There is nothing in the ASHRAE 90.1-2004 standard that defines the baseline energy for a restaurant and kitchen equipment. The owner is investing significant funds in highly efficient kitchen equipment and would like to take credit for the energy savings related to the kitchen. How do we define the baseline energy and calculate the ASHRAE savings to be incorporated in our energy calculations?

Ruling:

The project team is requesting guidance on defining a baseline for restaurant and kitchen equipment as well as instruction on how to take credit for using efficient equipment in the proposed design. The LEED-NCv2.2 Reference Guide states that project teams may follow the Exceptional Calculation Method (ECM) (ASHRAE 90.1-2004 G2.5) to document measures that reduce process loads. Please refer to the Standard for more information on the ECM methodology. The CIR dated 8/07/2007 also offers guidance on ECMs for process loads. An appropriate baseline for restaurant and kitchen equipment may be created using the energy rates for various equipment found in the 2005 ASHRAE Handbook - Fundamentals, Chapter 30, Table 5 in conjunction with an appropriate equipment schedule. Please comply with the documentation requirements laid out in ASHRAE 90.1-2004 G2.5 for the Exceptional Calculation Method. Another resource for determining the appropriate baseline for restaurant and kitchen equipment is the LEED for Retail Rating Systems. These can be found on the USGBC website. An informed determination can only be provided during LEED certification review if the requirements ASHRAE 90.1 Section G2.5 guidance are satisfied (i.e., provide theoretical and empirical information verifying accuracy). Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
5/21/2009
LEED Interpretation
Inquiry:

The following request is regarding three glass garage roll-up doors that are proposed for this Rescue Station Apparatus Bay. Due to tight site conditions and a shared apparatus exit drive path; it is important safety requirement that glass doors be provided that allow for a line of sight to the adjacent, existing fire station. Exiting dispatched Rescue trucks must have full view of the vehicles in the parking lot and other exiting fire apparatus that both share the common travel pathway. The space is heated and ventilated but not mechanically cooled. This is a garage for the storage of vehicles and will not be heated to the same level as the main building. A total of six 12ft wide by 14ft high, roll-up doors are to be provided; three of the proposed doors, used for entrance, are to be a highly insulated product. In order to provide the required high visibility for the exiting emergency vehicles the three, exit roll-up fire apparatus doors are proposed to be aluminum framed glass doors with a solid bottom panel. No aluminum and glass garage door had been tested to the standards required (NFRC and/or DASMA105) according to review with installers, manufacturers and the Door and Access Systems Manufacturers Association. We are requesting an exemption from the rating requirements for these exit garage doors for the following reasons: 1. Glass doors are required to provide visibility for exiting Rescue Apparatus. 2. No testing data is available for glass roll up doors. 3. The rear doors are highly insulated and we believe the average of all six doors is sufficient to pass the thermal requirements.

Ruling:

The project team is requesting clarification regarding being granted an exemption for meeting the standards for the exit garage doors of their Rescue Apparatus Bay. The reasons provided for exempting the doors from the testing requirement is that no testing data is available for glass roll up doors. This is acceptable given the special circumstances of this case, because these doors are located in a garage which is an unoccupied space, and they open to the outdoors rather than to an occupied space. The project submittal should provide information justifying why NFRC 400 air leakage testing is not feasible for the doors in question as well as photographs/drawings of the tight site conditions to demonstrate that glass doors must be used for safety reasons. In order for the project to exempt the manufactured doors from the requirements, the following criteria must be met: 1. The doors required are unavailable are certified to meet the NFRC 400 requirements. 2. The manufactured doors exempted open directly to spaces less than 3,000 square feet of building area. 3. At least 85% of the doors for the project meet the Door air leakage labeling requirements.

Campus Applicable
No
Internationally Applicable:
No
10/1/2012
LEED Interpretation
Inquiry:

Many projects in Europe are connected to highly efficient district energy systems. However, the EAp2/EAc1 Option 2 guidance provided in the "Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 - Design & Construction" (DESv2) document is not well-suited for the complex interconnected district energy systems with multiple fuel sources that are common in Europe. Many European countries already make use of the Primary Energy Factor (PEF) as a means of evaluating district energy performance and building energy performance. Is there an alternative compliance path available to document EAp2/EAc1 credit for the district energy system using the Primary Energy Factor in lieu of the DESv2 Option 2 compliance path?

Ruling:

An alternative EAp2/EAc1 compliance path is available to document the energy performance for complex interconnected district energy systems in Europe using the Primary Energy Factor and the greenhouse gas emissions associated with these systems. The Sweden Green Building Council developed an approved method, "Treatment of European District Energy Systems in LEED" (available November 1, 2012), which may be used in lieu of EAp2 Option 2 of the "Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 - Design & Construction" guidance. This compliance path is currently available for projects located in Europe only. Note: The "Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 - Design & Construction" (DESv2) is Optional Guidance for LEED 2009 projects. However, project teams that use the guidance must apply all relevant portions of the guidance. The alternative compliance path outlined in the "Treatment of European District Energy Systems in LEED" may only be used to replace Option 2 of the EAp2/EAc1 Energy Modeling Path defined in the DES v2 guidance. Project teams that opt to use the "Treatment of European District Energy Systems in LEED" method must comply with all other applicable requirements of the DES v2 guidance such as those defined for EA Credit 3, EA Credit 4, EA Credit 5, etc. Applicable Internationally; only for projects located in the Europe region.

Campus Applicable
No
Internationally Applicable:
Yes
7/1/2014
LEED Interpretation
Inquiry:

There is significant confusion, and seemingly contradictory LEED Interpretations on the required methodology for addressing “purchased” on-site renewable energy, and/or purchased biofuel that is not considered on-site renewable energy within the LEED energy model. For renewable fuels meeting the requirements of Addendum 100001081 (November 1, 2011) or other purchased renewable fuels, how should purchased on-site renewable energy be treated in the LEED energy model? How should purchased bio-fuels (meaning it I not fossil fuel but is used in a similar manner to bio-fuel) be treated in the energy model?

Ruling:

For any on-site renewable fuel source that is purchased (such as qualifying wood pellets, etc.), or for biofuels not qualifying as on-site renewable fuel sources that are purchased, the actual energy costs associated with the purchased energy must be modeled in EA Prerequisite 2: Minimum Energy Performance and EA Credit 1: Optimize Energy Performance, and the renewable fuel source may not be modeled as "free", since it is a purchased energy source.

For non-traditional fuel sources (such as wood pellets) that are unregulated within ASHRAE 90.1, use the actual cost of the fuel, and provide documentation to substantiate the cost for the non-traditional fuel source. The same rates are to be used for the baseline and proposed buildings, with the following exception: If the fuel source is available at a discounted cost because it would otherwise be sent to the landfill or similarly disposed of, the project team may use local rates for the fuel for the baseline case and actual rates for the proposed case, as long as documentation is provided substantiating the difference in rates, and substantiating that the fuel source would otherwise be disposed of.

When these non-traditional fuel sources are used for heating the building, the proposed case heating source must be the same as the baseline case for systems using the non-traditional fuel source, and the project team must use fossil fuel efficiencies for the Baseline systems, or provide evidence justifying that the baseline efficiencies represent standard practice for a similar, newly constructed project with the same fuel source.

Updated 8/7/17 for rating system applicability.

Campus Applicable
Yes
Internationally Applicable:
Yes
8/27/2008
LEED Interpretation
Inquiry:

The Natural Sciences Complex is a new three story 51,884 square foot, L-shaped building. The building includes college level science laboratories, laboratory support rooms, faculty offices, classrooms, and study areas. The HVAC system serving the laboratory wing of the building includes a single packaged VAV air handler with hot water reheat coils, a run-around heat recovery loop and a variable volume general exhaust system. In addition, laboratory spaces requiring fume hood exhaust are equipped with variable volume exhaust air devices mounted directly on top of fume hoods. The office wing is naturally ventilated and it is heated by a hydronic heating system. There are five classrooms that have mixed mode ventilation system and they are heated and cooled through the radiant slab. There are sixteen chemical fume hoods, and twelve chemical flow benches located in ten laboratories. Laboratory support rooms contain several storage cabinets that require continuous ventilation. Total fume hood exhaust rate is 11,600 cfm, and total exhaust rate of chemical flow benches is 2,100 cfm. Designed minimum ventilation rate for spaces containing chemicals is four ACH, as recommended by NFPA Standard 45. The same standard prohibits recirculation of chemicals originating from the laboratories. Since the 24,150 square feet laboratory wing contains only a few small spaces without chemicals (total floor area 450 square feet), the packaged air handler serving this area is 100% outside air system. This efficiently utilizes heat recovery system, reduces fan energy, and eliminates need for return air duct. The laboratory spaces are load driven. Total supply and exhaust flow rates for laboratory wing are 38,000 cfm and 33,000 cfm respectively. Following the requirements of the ASHRAE Standard 90.1-2004, Appendix G, Section G 3.1.1, based on usage, number of floors, conditioned floor area and heating source, our baseline model is a constant volume packaged single zone air conditioner with DX cooling coils and fossil fuel furnace. This type of system is assigned to each thermal zone. There is no thermal zone in the baseline model that has supply air capacity of 5,000 cfm or greater, and exhaust air energy recovery was not modeled in the baseline building according to Section G 3.1.2.10. This produced considerable energy savings due to the huge amount of outside air and the requirements for continuous ventilation of the laboratory spaces even during unoccupied hours. Since a large portion of our energy savings is the result of adding heat recovery to our system, we wanted to verify that we have correctly interpreted that the ASHRAE Standard does not require heat recovery in the baseline model for our building. Please advise if this modeling strategy is acceptable by USGBC.

Ruling:

The applicant requests confirmation that their modeling approach that excludes exhaust heat recovery from the baseline case due to baseline case system size is an acceptable modeling approach. This modeling approach is acceptable. The language of Section G3.1.2.10 with regards to system design airflow and outside air percentage refers to baseline case systems, not to proposed systems. As indicated above, the baseline case systems for the laboratory spaces all have air flow less than 5,000 cfm. Therefore, based on the description above, energy recovery would likely not be required in the baseline case systems serving the laboratory spaces. Please note that thermal blocks must have airflow less than 5,000 cfm for any thermal block where energy recovery is modeled for credit, and the size of the thermal block may not be manipulated to reflect a smaller thermal block than would typically be modeled just to avoid the prescriptive requirement for energy recovery.

Campus Applicable
No
Internationally Applicable:
No
5/9/2011
LEED Interpretation
Inquiry:

Can the project team use the ASHRAE 90.1 2007 energy model as the baseline for both EA Prerequisite 2 and EA Credit 1 in LEED v2.2?

Ruling:

If the project team is following the point thresholds from LEED v2.2 the direction outlined in the credit interpretation request is acceptable. Note: this ruling does not apply to Core and Shell projects. Note: this ruling does not apply to Core and Shell projects. Applicable internationally.

Campus Applicable
No
Internationally Applicable:
Yes
1/1/2014
LEED Interpretation
Inquiry:

ASHRAE Interpretation “ASHRAE/IES IC 90.1-2007-14” states that the baseline pump power cited in Section G3.1.3.10 was developed as 22 W/gpm total for all baseline chilled water pumps. Is this applicable for LEED projects?

Ruling:

ASHRAE Interpretations are considered applicable for all LEED projects using the referenced ASHRAE Standard, regardless of LEED registrations date, since ASHRAE Interpretations are considered to be clarifications of the ASHRAE standards only. However, in consideration of the long-standing GBCI review approach that allowed 22 W/gpm for each Baseline chilled water pump, this ASHRAE Interpretation which states that “the baseline pump power in Section G3.1.3.10 was developed as 22 W/gpm, and is the total wattage allowed for all cooling system pumps,” shall be mandatory only for projects registered after the publication date of this LEED Interpretation.
For projects registered after the date of this LEED Interpretation, the total Baseline chilled water system pump power shall be 22 W/gpm per ASHRAE 90.1-2007 Section G3.1.3.10; and the Baseline pump power shall be evenly distributed between the Baseline primary and secondary chilled water pumps. Alternatively, if the proposed case has primary/secondary chilled water pumps, the Baseline pump power may be distributed between the Baseline primary and secondary pumps consistent with the proposed design.

Campus Applicable
No
Internationally Applicable:
Yes
12/2/2006
LEED Interpretation
Inquiry:

There are two main components to this CIR with regards to the prerequisite (envelope / simplified approach with HVAC) detailed as follows: Maximum U-factor and SGHF requirements for the building envelope The majority of the building is naturally ventilated and only the three following areas are being air conditioned:- a) Room 1: Room 1 is air conditioned via an air cooled split package unit system consisting of an outdoor condensing/compressor unit coupled to an indoor air handling unit with a direct expansion cooling coil. The cooled air is distributed to the room via a network of insulated galvanized steel ductwork with ceiling mounted diffusers. b) Room 2: Room 2 is air conditioned via an air cooled variable refrigerant package unit system consisting of an outdoor inverter condensing/compressor unit coupled to a few indoor concealed ducted fan coil units. The cooled air is distributed to the room via a network of insulated galvanized steel ductwork with ceiling mounted diffusers. c) Area 3: The office and meeting rooms are air conditioned via an air cooled variable refrigerant package unit system consisting of an outdoor inverter condensing/compressor unit coupled to a few indoor concealed ducted fan coil units. The cooled air is distributed to the room via a network of insulated galvanized steel ductwork with ceiling mounted diffusers. With regards to the maximum U-factor and SGHF requirements on the building envelope it is suggested we apply only to parts of the envelope separating the air conditioned space with the outdoor space. We also understand there are some requirements for the envelope elements that are adjacent to the \'unconditioned space\' in the Semi-heated column of ASHRAE 90.1-2004 section 5.5.2 and figure 5-5 that we will need to be in compliance with. Simplified Approach Option for HVAC System Instead of complying with the mandatory provision of Section 6.4 of ASHRAE Std 90.1 - 2004, we propose the above mentioned approach based on Section 6.3 of the same standard. The standard allows building with gross floor area less than 2,300 m2 to follow this approach. Although the proposed building gross floor area is approximately 8,300 m2, the air conditioned area in this building is only approximately 1,230 m2. In addition, the proposed air conditioning system as described in Issue 1 (a), (b) and (c) is fairly simple system. Will this suggested building envelope and simplified HVAC System approach be acceptable?

Ruling:

To demonstrate compliance with ASHRAE 90.1-2004 using the prescriptive or trade-off approach, only those areas that are heated or cooled per section 2.2.(a) of the standard must comply with the envelope requirements. As for compliance with the HVAC section 6, the gross floor area of your project is greater than the 25,000 ft2 maximum required by section 6.3.1(b). Gross floor area represents the entire building floor area, not just the gross conditioned floor area. The HVAC systems must comply with the mandatory requirements in section 6.4. Note that the building systems must also meet the requirements of section 7, 8 and 9.

Campus Applicable
No
Internationally Applicable:
No
10/1/2013
LEED Interpretation
Inquiry:

What is considered “hybrid” heating?

Ruling:

**Update 1.11.2019: LI is applicable to LEED v4 projects.

Clarification is requested regarding when a building heat source in Table G3.1.1A should be identified as "Fossil/Electric Hybrid" versus "Electric".

The ASHRAE 90.1-2007 User's Manual states that a fossil/electric hybrid source "refers to a system with any combination of fossil and electric heat, and the baseline system for this is a fossil fuel system". Therefore, the predominant heating type for the building shall be determined based on the percentage of building area served by Electric-only heating versus “Fossil Fuel” and/or “Fossil/Electric Hybrid” heating. The heating source for any building space would be considered “Fossil Fuel/Electric Hybrid” if the space is heated by any combination of fossil fuel and electricity. This includes backup heating, heating of ventilation air serving the space, or preheating, But does not include emergency backup heat sources. The predominant heating type for the building shall be determined based on the percentage of building area served by Electric-only heating versus “Fossil Fuel” and/or “Fossil/Electric Hybrid” heating. (Note: Emergency back-up heating refers to heating that runs when the primary system fails or needs to be shut off in an emergency, and does not refer to a backup system which may be used to provide additional capacity as needed.)

Exception: ASHRAE 90.1 Section G3.1.1 Exception (a) stipulates additional system type(s) for non-predominant conditions (i.e. residential/non-residential or heating source) if those conditions apply to more than 20,000 square feet of conditioned floor area.

EXAMPLES OF BASELINE HEATING SOURCE DETERMINATION:
The Baseline heat source from Table G3.1.1A for the following Proposed Case system types would be fossil fuel since the proposed system design includes a combination of fossil and electric heat serving the same space for the majority of the building:
1. Variable air volume system with gas furnace preheat and electric reheat
2. Packaged terminal heat pumps with outside air tempered by fossil fuel furnace
3. Water source heat pumps with fossil fuel boiler
4. Ground source heat pumps with backup fossil fuel boiler
5. Residential condominium units with packaged terminal heat pumps, that have any amount of ventilation air provided to the space from air handling unit(s) where the supply air is tempered with fossil fuel.

The following buildings would be modeled with an electric heat source for the Baseline Case since the heating source serving the majority of spaces is electric-only:
1. 90,000 square feet is conditioned by a variable air volume system with electric reheat, and 10,000 square feet is conditioned with fossil fuel furnaces
2. 50,000 square feet is conditioned by electric heat pump systems. 15,000 square feet is conditioned with fossil fuel radiant heaters.

The following buildings would be modeled with an additional system type with a different Baseline heating source in accordance with Section G3.1.1 Exception (a):
1. 90,000 square feet is conditioned by a variable air volume system with electric reheat, and 20,000 square feet is conditioned with Packaged DX systems with fossil fuel furnaces. In this case, the 90,000 square feet of area would be modeled with an electric heat source in the Baseline Case (System Type #6 - Packaged VAV with Electric PFP Boxes), and the 20,000 square feet of area would be modeled with a fossil fuel heat source in the Baseline Case (System Type #3 - Packaged Single Zone AC with fossil fuel furnace).
2. 50,000 square feet is conditioned by water source heat pumps with a fossil fuel boiler, and 25,000 square feet is conditioned by electric heat pumps. In this case, the 50,000 square feet of area would be modeled with a fossil fuel heat source in the Baseline Case (System Type #5 - Packaged VAV with hot water reheat), and the 25,000 square feet of area would be modeled with an electric heat source in the Baseline Case (System Type #4 - Packaged Single Zone Heat Pump).

Campus Applicable
No
Internationally Applicable:
Yes
11/11/2008
LEED Interpretation
Inquiry:

The prerequisites requirements are to design the building project to comply with both- the mandatory provisions (Sections 5.4, 6.4, 7.4, 8.4, 9.4 and 10.4) of ASHRAE/IESNA Standard 90.1-2004 (without amendments); and the prescriptive requirements (Sections 5.5, 6.5, 7.5 and 9.5) or performance requirements (Section 11) of ASHRAE/IESNA Standard 90.1-2004 (without amendments). The project consists on installations for a public park, they are: an exterior amphitheater, one administrative office, exhibition space and a refreshment stand. The project is designed 100% "off-grid" with Photovoltaic (PV) renewable energy source completely, that means that there will be no electrical consumption from fossil fuels. A battery bank will provide the back up power. The project is 100% naturally ventilated. There is no mechanical ventilation and it will be operated accordingly. The ASHRAE\'s Mandatory provisions in Section 5: Building Envelope will not be met completely, outside air infiltration will be promoted, all windows will be opened during operation hours. The walls are designed to be permanently permeable to outside air. Accordingly, thermal transmission will not be possible to achieve in some of the spaces. Section 6: HVAC, will not be contemplated for being outside of the project\'s scope. Section 7: Water heating for service water will be designed with solar thermal water heaters. Therefore water heating in this project is contemplated as no electrical consumption. Section 8, 9 and 10 will be completely contemplated. Because of project\'s scope, complete compliance with ASHRAE would be incoherent. But being a 100% renewable energy, \'off grid\' project, its design is streamlined for energy efficiency, and obliged to operate as intended, as it will be demonstrated. Therefore we think we will meet outstandingly the EA Prerequisite 2 and EA Credit 1 intents, even if deviating from ASHRAE\'s provisions and requirements. Is our assumption correct?

Ruling:

The project team is requesting variance on meeting the mandatory and prescriptive requirements of ASHRAE 90.1-2004, given that this project is a public park with some structures, all of which will be naturally ventilated. Section 5.2.1 - Compliance, of the ASHRAE 90.1-2004 states: "For the appropriate climate, space-conditioning category, and class of construction, the building envelope shall comply with 5.1, General; 5.4, Mandatory Provisions; 5.7, Submittals; and 5.8, Product Information and Installation Requirements; and either..." (It goes on to state Section 5.5 (Prescriptive Building Envelope Option) or Section 5.6 (Building Envelope Trade-Off option) as the compliance paths - however LEED only allows for Section 5.5 as the compliance path). Section 5.1.2 - Space-Conditioning Categories, Sub-Section 5.1.2.3, of ASHRAE 90.1-2004 provides further guidance on this, stating that: "In climate zones 3 through 8, a space may be designated as either semiheated or unconditioned only if approved by the building official." (See definitions in ASHRAE 90.1-2004 for italicized terms, including "building official".) (Note that it is not clear from the request, as to whether this project is indeed in climate zones 3 through 8.) On the prescriptive building envelope requirements, assuming that this designation will be approved, given this situation; the project team can follow Section 5.5.2 of the ASHRAE 90.1-2004 which states: "If a building contains any semiheated space or unconditioned space, then the semi-exterior building envelope shall comply with the requirements for semiheated space in Tables 5.5-1 through 5.5-8 for the appropriate climate." The project team may interpret this requirement to apply only to parts of the building envelope that are not designed to be permeable to outside air, as long as supporting documentation to this effect is provided. On the mandatory provisions (Section 5.4), subject to the space-conditioning category designation being approved by the building official; and provided ALL of the structures are indeed naturally ventilated/conditioned (including the administrative office, exhibition space and refreshment stand); it is acceptable to exclude requirements for Section 5.4.3 - Air Leakage for this project. Please provide sufficient documentation to demonstrate that this is indeed the case, when submitting for certification/review. Sections 5.4.1 and 5.4.2 would fall under the purview of Section 5.5.2 as quoted above. Furthermore, this should be accompanied by a letter of undertaking by the responsible party that in the event that alterations are made to the structures under the scope of this certification that would affect it\'s energy performance in the future, these alterations will comply with the requirements of this prerequisite. The project must also include occupied interior space in order to be eligible for certification. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
5/9/2011
LEED Interpretation
Inquiry:

For a fine art museum pursuing EAp2, is it acceptable to use the systems and recommendations described in the ASHRAE HVAC Applications 2007 Handbook as the baseline in cases where Appendix G does not adequately describe a typical preservation area?

Ruling:

The outlined approach is acceptable. Applicable internationally.

Campus Applicable
No
Internationally Applicable:
Yes
10/1/2013
LEED Interpretation
Inquiry:

A centrifugal chiller, manufactured in Brazil, is specified for the project. The chiller is not AHRI certified and there is no laboratory in Brazil that can do this test. Since there is no laboratory in Brazil that can do this test, to comply with section 6.4.1.4 Verification of Equipment Efficiencies of ASHRAE 90.1-2007 Standard, would the equipment fall under option d (if no certification program exists for a covered product, the equipment efficiency ratings shall be supported by data furnished by the manufacturer)? Can this equipment be used in the project?

Ruling:

A supplier’s claims regarding energy efficiency would not be considered sufficient to document compliance with EA Prerequisite 2 (Minimum Energy Performance) and EA Credit 1 (Optimize Energy Performance) for a centrifugal HVAC unit that has not been tested and certified by a 3rd party in accordance with AHRI Standard 550-590. However, if the project team can provide documentation that the efficiency has been tested by a third party using an equivalent standard for HVAC efficiency, this testing would be sufficient in lieu of the AHRI Standard 550-990 testing. Any differences in test conditions and the resulting adjustments to the efficiency values claimed in the energy model would need to be described in the project submittal documentation. Alternatively, the project team may use the supplier’s claims regarding energy efficiency if the commissioning scope of work includes field testing of the equipment efficiency for the range of full- and part-load design conditions under which the building will operate; any adjustments related to altitude, etc. must be accounted for in the commissioning testing. In this case, the energy modeling documentation must include details about the commissioning functional testing method to confirm the performance of the chiller at full and part load operation. If the LEED submittal is provided as a split design / construction phase submittal, and the commissioning agent determines that the equipment efficiency does not meet or exceed the efficiency values claimed by the supplier, the energy documentation must be resubmitted at the construction phase with the values measured by the commissioning agent.

Campus Applicable
No
Internationally Applicable:
Yes
6/13/2007
LEED Interpretation
Inquiry:

We are in the process of submitting a Laboratory for LEED certification. The building contains a two-story, 6650 square foot Electromagnetic Compatibility (EMC) Laboratory which houses several shielded enclosures. Experiments are performed in and around the shielded enclosures that are very sensitive to electromagnetic interference (EMF). To minimize EMF issues, a two-tiered lighting scheme was developed. Tier 1 consists of thirty-one (31) industrial high bay luminaires, containing 1000 watt incandescent lamps, which are to be operated when experiments are running because they are EMF neutral. Tier 2 consists of thirty (30) industrial high bay luminaires containing 400 watt metal halide lamps (455 watts with ballast) which are to be operated for maintenance and general illumination when experiments are not running for higher efficiency. The space also contains 1200 watts of accent lighting. The lighting power density (LPD) of Tier 1 is 4.7 watts per square foot. The LPD of Tier 2 is 2.1 watts per square foot. Even if we take into account the Exception to 9.2.4 in ASHRAE 90.1-1999: "if two or more independently operated lighting systems in a space are capable of being controlled to prevent simultaneous user operation, the installed interior power shall be based solely on the lighting system with the highest wattage", the 4.7 watts per square foot in this space still far exceeds the 1.8 watts per square foot prescribed in the space-by-space method for laboratories. Because of the highly specialized nature of the EMC Laboratory and the fact that incandescent lamps sources had to be deployed, we feel that the LPD requirements stipulated in ASHRAE 90.1-1999 cannot be achieved. Therefore, we are asking to exclude the EMC Laboratory from our lighting power allowance calculations.

Ruling:

The applicant is seeking a waiver to exclude the EMC Laboratory from their lighting power allowance calculations. Based on the narrative, it would be appropriate to consider the lighting systems that are required only during the experiments as a process load. The lighting that is used for maintenance and general illumination and when experiments are not running needs to be accounted for. However, even this LPD is higher than stipulated. Please note that if the project is targeting EAc1, the applicant must include the larger lighting power density on the appropriate schedule to generate accurate equipment sizing scenarios.

Campus Applicable
No
Internationally Applicable:
No
7/2/2018
LEED Interpretation
Inquiry:

Our project is located in California. To pursue Option 1: Whole Building Simulation, is there a methodology for documenting additional energy performance for LEED v4 projects regulated by Title 24-2016?

Ruling:

Project Type1
Additional Percent Savings

NC-Office
7%

NC-Retail (except restaurant/grocery)
8%

NC-School
7%

NC-Health Care
0%

NC-Restaurant/Grocery
0%

NC-Hospitality
8%

NC-Warehouse
0%

NC-Multifamily
8%

NC-All Other
0%

CS-Office
5%

CS-Retail (except restaurant/grocery)
7%

CS-School
5%

CS-Health Care
0%

CS-Restaurant/Grocery
0%

CS-Hospitality
7%

CS-Warehouse
0%

CS-Multifamily
7%

CS-All Other
0%

CI-Office
6%

CI-Retail (except restaurant/grocery)
7%

CI-School
6%

CI-Health Care
0%

CI-Restaurant/Grocery
0%

CI-Hospitality
7%

CI-Warehouse
0%

CI-Multifamily
7%

CI-All Other
0%

Campus Applicable
No
Internationally Applicable:
No
3/11/2009
LEED Interpretation
Inquiry:

We have 108 heat pump PTAC\'s that meet the efficiency requirements of EA prerequisite 2 credit. Due to application requirements, we need to also have 2 vertical heat pump PTAC units. The 2 vertical heat pump PTAC units do not meet the efficiency requirements of EA prerequisite 2 credit. Efficiencies are below: 108 units at EER of 12.8, EA prerequisite 2 requires 11.3 2 units at EER of 9.6, EA prerequisite 2 requires 11.3 The 2 units that don\'t meet the efficiency requirement are similar in capacity to the other 108 units. These units need to be ducted however and they do not offer a ducted unit with the high efficiency option. These units were added to meet building code needs. With only 2 out of 110 total units not meeting efficiency requirements, the average efficiency of the 110 units (all similar in capacity) easily exceeds the minimum requirements. Is it okay to have these 2 units out of 110 total?

Ruling:

The project team has furnished further details explaining that in trying to meet building code requirements to provide heating and cooling to the corridors with outside air, and due to the peculiar configuration of the building, it was unable to use minimum efficiency ducted PTACs for 2% of the building\'s cooling capacity for two corridors of the building. It also states that ducted PTACs were not available in a higher efficiency option. Per LEED-CI Reference Guide, all equipment components must meet the mandatory, minimum efficiency requirements as listed in ASHRAE Standard 90.1-2004 Tables 6.8.1A-G. Utilizing the mean efficiency of all equipment in a system is not listed as an acceptable method of satisfying this requirement in ASHRAE Standard 90.1-2004. The PTACs (even those that are ducted) must be rated at the rating conditions specified in ARI 310/380 and 95

Campus Applicable
No
Internationally Applicable:
No
11/1/2011
LEED Interpretation
Inquiry:

Table G3.1.1A lists two possible categories for the building heating source: (1) Fossil fuel, fossil/electric hybrid, & purchased heat; (2) Electric and other. In cases where the proposed building design includes both a natural gas heating source and an electric heating source, when should the heat source in Table G3.1.1A be identified as "Fossil/Electric Hybrid" versus "Electric"?

Ruling:

Clarification is requested regarding when a building heat source in Table G3.1.1A should be identified as "Fossil/Electric Hybrid" versus "Electric". The ASHRAE 90.1-2007 User\'s Manual states that a fossil/electric hybrid source "refers to a system with any combination of fossil and electric heat, and the baseline system for this is a fossil fuel system". Therefore, the heating source for the proposed building would be considered "Fossil Fuel" or "Fossil/Electric Hybrid" if the building uses any fossil fuel source for space heating (including backup heating or preheating), and the baseline building heat source would be fossil fuel.Exception: ASHRAE 90.1 Section G3.1.1 Exception (a) stipulates additional system type(s) for non-predominant conditions (i.e. residential/non-residential or heating source) if those conditions apply to more than 20,000 square feet of conditioned floor area. EXAMPLES OF BASELINE HEATING SOURCE DETERMINATION: The Baseline heat source from Table G3.1.1A for the following Proposed Case system types would be fossil fuel since the proposed system design includes a combination of fossil and electric heat: 1. Variable air volume system with gas furnace preheat and electric reheat2. Packaged terminal heat pumps with outside air tempered by fossil fuel furnace3. Water source heat pumps with fossil fuel boiler4. Ground source heat pumps with backup fossil fuel boiler5. 90,000 square feet is conditioned by a variable air volume system with electric reheat, and 10,000 square feet is conditioned with fossil fuel furnacesThe following buildings would be modeled with an additional system type with a different Baseline heating source in accordance with Section G3.1.1 Exception (a):1. 90,000 square feet is conditioned by a variable air volume system with electric reheat, and 20,000 square feet is conditioned with Packaged DX systems with fossil fuel furnaces. In this case, the 90,000 square feet of area would be modeled with an electric heat source in the Baseline Case (System Type #6 - Packaged VAV with Electric PFP Boxes), and the 20,000 square feet of area would be modeled with a fossil fuel heat source in the Baseline Case (System Type #3 - Packaged Single Zone AC with fossil fuel furnace).2. 50,000 square feet is conditioned by water source heat pumps with a fossil fuel boiler, and 25,000 square feet is conditioned by electric heat pumps. In this case, the 50,000 square feet of area would be modeled with a fossil fuel heat source in the Baseline Case (System Type #5 - Packaged VAV with hot water reheat), and the 25,000 square feet of area would be modeled with an electric heat source in the Baseline Case (System Type #4 - Packaged Single Zone Heat Pump). Applicable internationally.

Campus Applicable
No
Internationally Applicable:
Yes
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Intent

To establish the minimum level of energy efficiency for the proposed building and systems to reduce environmental and economic impacts associated with excessive energy use.

Requirements

Projects that register on or after April 8, 2016 and are subject to the four point mandatory minimum, demonstrate a 14% improvement for new buildings, or a 10% improvement for major renovations to existing buildings.
Option 1. Whole building energy simulation
Demonstrate a 10% improvement in the proposed building performance rating for new buildings, or a 5% improvement in the proposed building performance rating for major renovations to existing buildings, compared with the baseline building performance rating. Calculate the baseline building performance rating according to the building performance rating method in Appendix G of ANSI/ASHRAE/IESNA Standard 90.1-2007 (with errata but without addenda1) using a computer simulation model for the whole building project. Projects outside the U.S. may use a USGBC approved equivalent standard2. Appendix G of Standard 90.1-2007 requires that the energy analysis done for the building performance rating method include all energy costs associated with the building project. To achieve points using this credit, the proposed design must meet the following criteria:
  • Comply with the mandatory provisions (Sections 5.4, 6.4, 7.4, 8.4, 9.4 and 10.4) in Standard 90.1-2007 (with errata but without addenda1) or USGBC approved equivalent.
  • Inclusion of all the energy costs within and associated with the building project.
  • Compare against a baseline building that complies with Appendix G of Standard 90.1-2007 (with errata but without addenda1) or USGBC approved equivalent. The default process energy cost is 25% of the total energy cost for the baseline building. If the building’s process energy cost is less than 25% of the baseline building energy cost, the LEED submittal must include documentation substantiating that process energy inputs are appropriate.
For the purpose of this analysis, process energy is considered to include, but is not limited to, office and general miscellaneous equipment, computers, elevators and escalators,kitchen cooking and refrigeration, laundry washing and drying, lighting exempt from the lighting power allowance (e.g., lighting integral to medical equipment) and other (e.g., waterfall pumps). Regulated (non-process) energy includes lighting (for the interior, parking garage, surface parking, façade, or building grounds, etc. except as noted above), heating, ventilation and air conditioning (HVAC) (for space heating, space cooling, fans, pumps, toilet exhaust, parking garage ventilation, kitchen hood exhaust, etc.), and service water heating for domestic or space heating purposes. Process loads must be identical for both the baseline building performance rating and the proposed building performance rating. However, project teams may follow the exceptional calculation method (ANSI/ASHRAE/IESNA Standard 90.1-2007 G2.5) or USGBC approved equivalent to document measures that reduce process loads. Documentation of process load energy savings must include a list of the assumptions made for both the base and the proposed design, and theoretical or empirical information supporting these assumptions. Projects in California may use Title 24-2005, Part 6 in place of ANSI/ASHRAE/IESNA Standard 90.1-2007 for Option 1.

OR

Option 2 is not an eligible compliance option for projects that registered on or after April 8, 2016.
Option 2. Prescriptive compliance path: ASHRAE Advanced Energy Design Guide
Comply with the prescriptive measures of the ASHRAE Advanced Energy Design Guide appropriate to the project scope, outlined below. Project teams must comply with all applicable criteria as established in the Advanced Energy Design Guide for the climate zone in which the building is located. Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.
Path 1. ASHRAE Advanced Energy Design Guide for Small Office Buildings 2004
The building must meet the following requirements:
  • Less than 20,000 square feet (1,800 square meters).
  • Office occupancy.
Path 2. ASHRAE Advanced Energy Design Guide for Small Retail Buildings 2006
The building must meet the following requirements:
  • Less than 20,000 square feet (1,800 square meters).
  • Retail occupancy.
Path 3. ASHRAE Advanced Energy Design Guide for Small Warehouses and Self Storage Buildings 2008
The building must meet the following requirements:
  • Less than 50,000 square feet (4,600 square meters).
  • Warehouse or self-storage occupancy.

OR

Option 3 is not an eligible compliance option for projects that registered on or after April 8, 2016.
Option 3. Prescriptive compliance path: Advanced Buildings™ Core Performance™ Guide
Comply with the prescriptive measures identified in the Advanced Buildings™ Core Performance™ Guide developed by the New Buildings Institute. The building must meet the following requirements:
  • Less than 100,000 square feet (9,300 square meters).
  • Comply with Section 1: Design Process Strategies, and Section 2: Core Performance Requirements.
  • Health care, warehouse and laboratory projects are ineligible for this path.
Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.

OR

Option 4. Brazil compliance path: PBE Edifica

Projects in Brazil that are certified at the “A” level under the Regulation for Energy Efficiency Labeling (PBE Edifica) program for all attributes (Envelope, Lighting, HVAC) achieve this prerequisite. The following building types cannot achieve this prerequisite using this option: Healthcare, Data Centers, Manufacturing Facilities, Warehouses, and Laboratories.

1Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.

2 Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1-2007 if it is approved by USGBC as an equivalent standard using the process identified in the LEED 2009 Green Building Design and Construction Global ACP Reference Guide Supplement.

Pilot ACPs Available

The following pilot alternative compliance path is available for this prerequisite. See the pilot credit library for more information. EApc95: Alternative Energy Performance Metric ACP

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Which baseline HVAC system do I use if my building has no heating or air conditioning?

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For an existing building, do I need to rotate the model?

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Our project has a diesel backup generator. Should we include it in our energy model?

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Our project has a large process load—75%. Despite our efforts to make an efficient HVAC design, the cost savings are minimal. What can we do to earn this prerequisite and be eligible for LEED certification? Is there any flexibility in how we model the process load?

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Can SHGC be higher in the proposed than in the baseline model?

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Our process load is higher than 25%. Do we have to justify that?

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Do I need to justify the electrical and fuel rates I am using in my model?

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Our local code references ASHRAE 90.1-2010. Should I use that for my documentation, or 90.1-2007?

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Can I claim exterior lighting savings for canopy lighting even though a baseline model cannot include shading elements?

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The project is built on a site with existing exterior lighting installed. How should this be accounted for?

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1/1/2015Updated: 3/29/2018
Regional ACP
Description of change:
Add the following new option after Option 3:

"OR

OPTION 4. Brazil Compliance Path: PBE Edifica

Projects in Brazil that are certified at the “A” level under the Regulation for Energy Efficiency Labeling (PBE Edifica) program for all attributes (Envelope, Lighting, HVAC) achieve this prerequisite. The following building types cannot achieve this prerequisite using this option: Healthcare, Data Centers, Manufacturing Facilities, Warehouses, and Laboratories"
Campus Applicable
No
Internationally Applicable:
Yes
7/1/2015Updated: 10/2/2015
Global ACP
Description of change:
Add the following at the end of the section, prior to the heading for Section 6:

For an expanded reference of international locations, ASHRAE 169-2013 Table A-5 (Canada) or Table A-6 (International) may be consulted. ASHRAE 169-2013 subdivides Climate Zone 1 into two climate zones (Climate Zone 1 and Climate Zone 0). Locations listed in ASHRAE 169-2013 in Climate Zone 1 and Climate Zone 0 should be considered Climate Zone 1 under ASHRAE 90.1-2010.
Campus Applicable
No
Internationally Applicable:
Yes
2/1/2010Updated: 2/14/2015
Rating System Correction
Description of change:
Below the box, insert the following text as a footnote:?Project teams wishing to use ASHRAE approved addenda for thepurposes of this credit may do so at their discretion. Addenda mustbe applied consistently across all LEED credits.
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add, "or USGBC approved equivalent." to the end of the first bullet.
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Change "(10,000 square meters)" to "(9,300 square meters)"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Delete the box that states, "This OPTION is not available to Projects outside the U.S."
Campus Applicable
No
Internationally Applicable:
Yes
2/1/2010Updated: 2/14/2015
Reference Guide Correction
Description of change:
In the first line of the fourth paragraph, replace "tare" with "are" so the text becomes "Within each section are mandatory..."
Campus Applicable
No
Internationally Applicable:
No
10/1/2012Updated: 2/14/2015
Global ACP
Description of change:
Replace the definition of " baseline building performance" with "Baseline building performance is the annual energy cost for a building design, used as a baseline for comparison with above-standard design."
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Change "(2,000 square meters)" to "(1,800 square meters)".
Campus Applicable
No
Internationally Applicable:
Yes
2/2/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Remove the third and fourth bullet of the section:
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add footnote 2, "Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1-2007 if it is approved by USGBC as an equivalent standard using the process located at www.usgbc.org/leedisglobal."
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Delete the box that states "This OPTION is not available to Projects outside the U.S."
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Remove "energy cost budget or" so that the paragraph reads, "Project teams must meet the minimum efficiency requirements for system components listed in ASHRAE 90.1-2007, Tables 6.8.1A-G, even if using the performance-based compliance method."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add, "or USGBC approved equivalent." to the end of the first sentence in the third bullet.
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add "Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone." to the end of the option.
Campus Applicable
No
Internationally Applicable:
Yes
2/2/2011Updated: 2/14/2015
Rating System Correction
Description of change:
Remove the third and fourth bullet of the section:
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add "Projects outside the U.S. may use a USGBC approved equivalent standard2." to the end of the second paragraph.
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Change "(2,000 square meters)" to "(1,800 square meters)".
Campus Applicable
No
Internationally Applicable:
Yes
2/1/2010Updated: 2/14/2015
Reference Guide Correction
Description of change:
Below the box, insert the following text as a footnote:?Project teams wishing to use ASHRAE approved addenda for thepurposes of this credit may do so at their discretion. Addenda mustbe applied consistently across all LEED credits.
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Change "(5,000 square meters)" to "(4,600 square meters)"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add "Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone." to the end of the first paragraph.
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Remove paragraph (begins with "The energy cost budget method...")
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add: "or USGBC approved equivalent" after "(ANSI/ASHRAE/IESNA Standard 90.1-2007 G2.5)" in the paragraph beginning with "For this credit, process loads...".
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Delete the Alternative Compliance Path for Projects Outside the U.S. box.
Campus Applicable
No
Internationally Applicable:
Yes
7/1/2015
LEED Interpretation
Inquiry:

Is there an adjusted point scale and minimum point threshold where applicable for LEED v2009 projects using ASHRAE 90.1-2010?

Ruling:

**July 1, 2016 update:This ruling has been revised to address the LEED 2009 minimum point requirement released 4/8/2016.**

Yes, LEED v2009 projects that demonstrate compliance using ASHRAE 90.1-2010 may utilize the adjusted point scale as shown in the Related Resource "ASHRAE 90.1-2010 Adjusted Point Scale for LEED v2009 Projects", subject to the following limitations:

• All mandatory provisions associated with ASHRAE 90.1-2010 (or an approved alternative standard) must be met in order for the project to use this compliance path.
• The ID+C thresholds shown are only relevant for projects using the Alternative Compliance Path described in LEED Interpretation 10412 that replaces the LEED 2009 requirements for EAp2, EAc1.1, EAc1.2, EAc1.3, and EAc1.4 with a Performance compliance path. All other ID&C projects would use the standard points available from EAc1.1 through EAc1.4 to comply with the 4-point minimum requirements.
• The CS 2009 EAp2-c1 ACP (http://www.usgbc.org/resources/cs-2009-eap2-c1-acp) may not be used in conjunction with this ASHRAE 90.1-2010 ACP. The project team must either use ASHRAE 90.1-2007 Appendix G with the CS 2009 EAp2-c1 ACP or use ASHRAE 90.1-2010 Appendix G without the CS 2009 EAp2-c1 ACP.

For projects that register on or after April 8th, 2016 and are subject to the mandatory Optimize Energy Performance point minimum:
If the project complies with all LEED v4 Minimum Energy Performance requirements for the relevant LEED v4 rating system, the project shall be considered to satisfy the LEED 2009 EA Prerequisite: Minimum Energy Performance mandatory minimum EAc1 points requirements (applicable for projects registered on or after April 8th, 2016), regardless of number of points achieved when applying this LEED Interpretation. The points documented under EAc1: Optimize Energy Performance shall be as shown in the ASHRAE 90.1-2010 Adjusted Points Scale for LEED v2009 for projects following the Performance Path, and zero for projects following a Prescriptive path.

Campus Applicable
No
Internationally Applicable:
Yes
9/10/2007
LEED Interpretation
Inquiry:

The SRA Arlington Consolidation design development phase started in February of 2005. The owner asked that the project be designed per the LEED-CI criteria and an early analysis of the project checklist indicated a possible Silver Certification. The LEED-CI checklist was discussed at our weekly project meetings from February 2005 until May 2005, when our CD\'s were Issued for Bid on 5/13/2005. In February 2005, the current LEED-CI checklist was Version 2, which referenced the ASHRAE 90.1-2001 criteria. We continued to review the LEED-CI criteria, and completed our CD\'s as stated above utilizing the 2001 criteria. Up unitl this time, we anticipated a paper submittal to USGBC. The LEED Online website was introduced at GreenBuild in Atlanta in November 2005, however USGBC wrestled with numerous technical challenges and did not go live until the Spring of 2006. (We know this because we attempted several times to access the website to begin entering our data the early part of 2006.) The project was bid and then sat dormant until the base building progressed to a point when the interiors portion of the work could start, per the lease, in January 2006. Also, in late summer/early fall 2005 there was significant concern on the part of the interiors team that the base building was not hitting critical milestone dates, thus providing the tenant an escape clause included in the lease - effectively cancelling the construction of interiors portion of the project. Due to these delays and uncertainty, the project was not registered with USGBC until 1/26/2006. We are asking for relief or a variance from the USGBC regarding the ASHRAE 90.1 standard, specifically that due to the timing of our design phase and CD\'s (5/13/05) versus the release of LEED-CI Version 2 on 5/25/05 that we be allowed to use ASHRAE 90.1 - 2001 criteria and not ASHRAE 90.1 - 2004. Obviously, without this prerequisite we will not be able to continue completing the submittal for this project.

Ruling:

Projects must adhere to the requirements of the version in effect at the time of the project\'s registration. No exceptions can be made. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
11/11/2008
LEED Interpretation
Inquiry:

The tenant\'s fitout design complies with most of the requirements of EA P2 however due to local design standards and the clients operational process requirements there are 2 clauses that we are not able to achieve and as such will require a waiver for : ASHRAE 90-1 2004 Clause 6.5.4 Hydronic System Design and Control As part of the Client\'s global network the fitout for the above project includes a data centre/ main communications room (MCR). The cooling load associated with the MCR is served by a number of chilled water units connected to 2no tenant packaged air cooled chiller. Due to the constant nature of the process load associated with the MCR room it is not proposed to install Variable speed drives to the pumps. The heat load associated with the servers contained within the MCR room is maintained at close to 100% due to the international nature of the network that the system serves and as such it is operated 24/7. The introduction of Variable Speed pumping to this system (as required to comply with ASHRAE 90.1 -2004 clause (6.5.4.1 Hydronic Variable Flow Systems) would therefore not achieve any energy saving and as such is not proposed to be installed. The client is willing to install them if necessary however does not understand how the procurement, manufacture, installation and maintenance issues associated with the additional equipment increases the sustainability of the project, given the very limited scope for VSDs to reduce energy use. Furthermore the additional complexity of Variable Speed Drives within such a critical process system adds further risk to the client business. ASHRAE 90.1-2004 allows exemption to clause 6.5.4.1 where a reduced "flow is less than the minimum flow required by the equipment manufacturer for the proper operation of the equipment served by the system" we believe that we qualify for this exemption as the client\'s critical system would be affected by any reduction in chilled water flow. As such it is proposed to install the pumps as a constant volume system albeit fitted with high efficiency motors which when combined with high efficiency air cooled chillers which exceed the minimum set out in ASHRAE 90.1-2004 (table 6.8.1C) produce an energy efficient solution which does not compromise the clients operational requirements. Further to this the application of temperature reset on the chilled water system (clause 6.5.4.3) would also be detrimental to the clients critical systems as such we believe that the system is exempt under the relevant exemption clause within the standard. ASHRAE 90-1 2004 Clause 8.4.1 Voltage Drop The local design standards require the voltage drop across the system to be sized as a maximum of 4% with 3.5% being from the feeder conductors and 0.5% from the branch circuits. The ASHRAE standard calls for a maximum voltage drop at design of 5% with 2% being from the feeder conductors and 3% from the branch circuits. As such the local design standard calls for a smaller voltage drop across the system, relative to the ASHRAE standard, but with a different split between sections. The project is therefore looking for a credit interpretation regarding this issue on the basis of the local design standards being lower on a total system basis, albeit with a different percentage split across the system.

Ruling:

The applicant is requesting a waiver from the provisions of ASHRAE 90.1-2004 Mandatory Requirements as they pertain to the data-center portion of the project. As per section 2.3, sub-section (C), requirements of ASHRAE 90.1-2004 do not apply to process requirements provided it meets the following criteria: 1. Equipment is primarily dedicated to process loads (50% or more of the flow is supplying process loads). 2. Exemption applies only to EAp2 and not EAc1 Regarding the issue of voltage drop, the project team should use the requirements of the local governing code. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
4/1/2012
LEED Interpretation
Inquiry:

The project consists of a consumer products manufacturing facility.The energy intensive manufacturing process exceeds an estimated 90% of the facility\'s total energy load. The Project Client has developed a new manufacturing process which consumes approximately 15% less energy per produced than the previous generation process.The new proprietary process has recently been installed at a similar facility and energy reduction has been demonstrated. Since industrial energy for manufacturing is not covered by ASHRAE 90.1-2007 and the building cannot be accurately modeled using the Appendix G method, project team is seeking to establish and obtain approval of an alternative compliance path.Following the Appendix G procedure would be very challenging because there are so many interacting process and non-process systems. Artificially segregating the systems in the model would not reflect energy consumption patterns accurately. Focusing on non-process components that represent less than 10% of the total energy consumption would not demonstrate the majority of the facility\'s energy savings. Manufacturing process improvements targeted at the other 90% of energy usage have a much greater impact on the entire facility\'s energy consumption. Instead of creating an energy model, baseline and proposed energy consumption will be compared by utilizing an Energy Consumption Index (ECI), which is recognized by the Association of Energy Engineers as an accepted methodology for calculating energy consumption in a manufacturing facility. The Project Client has tabulated historical overall site energy data and production at an existing facility which uses only the previous generation manufacturing platform and is also tabulating data from a site with new generation equipment. The energy data from both of these plants is not sub-metered between process and building loads because there is little economic benefit to meter the small building-only loads. An alternative compliance path will be established using the overall site ECI. Please verify that the following method may be used for determining the entire facility\'s energy cost savings.PROPOSED COMPLIANCE PATH:1. Baseline Building:The existing baseline site

Ruling:

Using the Energy Consumption Index instead of ASHRAE 90.1-2007 Appendix G to determine the annual cost savings of the building is not acceptable. The manufacturing process(es) should be calculated using the Exceptional Calculation methodology. A narrative should describe all Baseline and Proposed case assumptions included for this measure, and the calculation methodology used to determine the project savings. The narrative and energy savings should be reported separately from efficiency measures in the template Section 1.7. Additionally, documentation should be provided to verify that the manufacturing process is not standard practice for a similar newly constructed facility by including a recently published document, a utility incentive program that incentivizes the new process, or by documenting the systems used to perform the same function in other newly constructed facilities. While it is acceptable to use monitored data from a similar facility (constructed within the last five years) to document these exceptional calculation savings using a per product or per pound metric, sufficient information must be provided to document the nature of the efficiency improvements made, and to confirm that the data has been normalized appropriately. Specific product names are not required, and the specific details of the manufacturing process are not required; however, the description of the efficiency improvements to the manufacturing process must be adequate to allow the reviewer to confirm that improvements in energy consumption are tied to improved equipment or controls efficiency, and are not associated with decreases in building square footage, differing project locations, local climate data, quantity of shifts operating per day, etc. Any process energy differences related to local climate or weather (such as refrigeration energy, boiler energy, etc.) should be accounted for in the data normalization process, and the method used for normalizing must be clearly indicated. Ensure the same utility rate is used for the proposed case, baseline case, and exceptional calculation. Additionally, all mandatory requirements of ASHRAE 90.1-2007 must be met."

Campus Applicable
No
Internationally Applicable:
No
7/1/2012
LEED Interpretation
Inquiry:

This LEED Interpretation pertains to the requirement to limit voltage drop for Energy & Atmosphere Prerequisite 2 for Minimum Energy Performance. The current limit is posing a significant hardship to tall buildings relative to satisfying the mandatory requirements of ASHRAE Standard 90.1-2007 (also applicable in 90.1-2010), referenced in the prerequisite.

Specifically, the requirement in Standard 90.1 to limit voltage drop to not greater that 2% for electrical feeders and 3% for branch circuits (section 8.4.1) has proven to be problematic for large projects which often contain feeders of extended length. By comparison, the National Electric Code does not explicitly regulate voltage drop, but suggests model Code language that limits either electrical feeder or branch circuit voltage drop to 3%, with the combined voltage drop of both feeders and branch circuits when added together not to exceed 5%.

This may appear to be a minor difference, However, when applied to long copper electrical feeders which are present in tall buildings, this absolute constraint from Standard 90.1 on the feeder voltage drop (of 2%) results in a significant increase in the required quantity of copper conductors and associated conduit.

As an example of a higher density regions attempting to resolve this issue, the New York City Electrical Code has adopted the National Electric Code model language as mandatory for all buildings and also included an exception for residential occupancies within buildings to limit electrical feeder voltage drop to 4%, and the combined voltage drop of both feeders and branch circuits to not more than 5%.

This change is in recognition of the inherently short branch circuit lengths in typical NYC apartments, and is based on measured testing results which indicate that voltage drop is often negligible due to the conservative feeder and circuit sizing requirements mandated by other aspects of the Code. Thus, for residential buildings the allowable voltage drop of 4% is twice the allowable voltage drop of 2% as required in 90.1. Depending upon the length and capacity of a particular feeder, this difference can equate to a 3X variance in the required quantity of copper conductors and conduit, with a significant associated cost premium.

The magnitude of the cost premium to satisfy the 90.1 criteria in tall buildings, as compared with New York City Code requirements, can be equal to the total of all of the other cost premiums (hard and soft) associated with achieving LEED certification (at the Silver or Gold level) for a medium to large project in New York City.

In order to resolve this issue, we are proposing an alternate compliance path that we believe would meet the intent of the prerequisite, while at the same time preventing cost prohibitive use of significant amounts of additional copper.

Voltage drop is literally the loss of electrical energy (converted to heat) within a building, therefore regulating voltage drop is no different than regulating the energy efficiency of any electricity consuming device in a building (such as light fixtures or HVAC motors).

Several approaches could be implemented within the LEED rating system to address this disproportionate prescriptive requirement of Standard 90.1. A simple and straight forward approach would be to allow buildings utilizing Appendix G energy modeling as the LEED energy compliance path to include voltage drop as a regulated parameter within both the Energy Cost Budget and Design Energy Cost models. Under this approach, the 90.1 criteria (2% for feeders and 3% for branch circuits) would included in the Energy Cost Budget model, but the Design Energy Cost model would be allowed to include the actual voltage drop that will be implemented in the project design.

This approach would achieve the direct intent of the voltage drop requirement of Standard 90.1 in regulating the energy efficiency of power distribution systems, but through the inherent trade-off methodology of Appendix G would allow projects the flexibility to eliminate a disproportionate cost premium that is otherwise incurred by a prescriptive requirement.

Ruling:

The proposed alternative compliance path for meeting the mandatory requirement of ASHRAE 90.1-2007/2010 Section 8.4, Voltage Drop Limitation, allowing voltage drop as a regulated parameter within the energy models, is not acceptable; however, a simplified alternative compliance path can be approved. As noted in the Formal Inquiry, code requirements and guidelines allow flexibility in meeting voltage drop guidance in feeders and branches as long as the overall voltage drop from service entrance to the worst-case connection is within limits. For the purposes of this prerequisite, the mandatory provision of ASHRAE 90.1-2007/2010 Section 8.4 will be met as long as the total voltage drop does not exceed 5%. Internationally applicable.

Campus Applicable
No
Internationally Applicable:
No
5/27/2008
LEED Interpretation
Inquiry:

Energy & Atmosphere, Prerequisite 2.0 Minimum Energy Performance. More specifically, we need an interpretation of 2004 Ashrae 90.1 Standard Section 9.6.1 on whether or not we are allowed to trade interior lighting power allowances between spaces in different buildings when the buildings are on the same tract of land and operated by the same owner. Our interpretation of the 2004 Ashrae 90.1 Standard Section 9.6.1 is that we can trade interior lighting power allowances between spaces in different buildings when using the Space-by-Space Method of Calculating Interior Lighting Power Allowance for this project. This interpretation arises from the fact that we have multiple buildings on the same tract of land that will be operated by the same entity, the Federal Government. If we can make this interpretation, we can meet the Standard. If not, some buildings on their own will not meet the Standard.

Ruling:

The applicant is requesting clarification regarding the application of ASHRAE 90.1-2004 section 9.6.1. Each building in a multiple building project must comply separately with the requirements of EA prerequisite 2. Therefore projects may not trade interior lighting power allowances between different buildings. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
5/9/2011
LEED Interpretation
Inquiry:

For a data center with 10% office space, verify that exception G3.1.1 (b) from ASHRAE 90.1 can be applied to the server rooms and that server power can be omitted from the model.

Ruling:

The exception applies, but the energy cannot be omitted from the model. The applicant may use the server power to demonstrate energy reduction in this process load using Exceptional Calculations as per section G 2.5. Applicable internationally.

Campus Applicable
No
Internationally Applicable:
Yes
7/30/2009
LEED Interpretation
Inquiry:

The project is a greenhouse-exhibit-office space complex located in urban Denver, CO that serves as a horticulture production facility for the regional botanic gardens. Since the project consists largely of greenhouse space, the project team would like confirmation of baseline assumptions in this process-load dominated space. In addition, modeling limitations exist within the EnergyPlus simulation software for simulating evaporative cooling. The project team would like to confirm acceptance of the analysis method proposed for overcoming the software limitations. Greenhouse Baseline Characteristics In the CIR dated 4/30/2008 concerning energy use in greenhouses, the ruling clearly states that any conditioned space that is used primarily to support plant growth should be modeled as a process space and all characterizations for the space, its space conditioning equipment, and controls should be the same in the baseline and the proposed-design energy model. Therefore, in order to demonstrate efficiency improvements for these end-uses, the project team must follow an exceptional calculation method (ECM) that compares standard design practice to design improvements. The design team desires to demonstrate design improvements in three areas as outlined below. 1) The greenhouse proposed design includes high performance glazing. The project team has found standard design practice for glazing selection for greenhouses to include single-pane clear glass. The team would like to confirm that this is an acceptable baseline for the analysis. 2) The greenhouse design includes an automated shading system to decrease solar heat gain and radiative heat loss in the space. The project team would like to confirm that a greenhouse design without a shading system is an appropriate baseline. 3) The greenhouse design includes an automated natural ventilation system controlled by space and ambient temperature sensors. The ventilation system releases heat from the upper-most portion of the greenhouse when the space temperature exceeds the set-point temperature during mild ambient conditions. The project team believes that automated natural ventilation controls are not part of standard design practice and should be excluded from the baseline greenhouse. The team would like to confirm this baseline condition. Evaporative Cooler Controls Implementation of evaporative cooling systems with EnergyPlus is problematic as active control of evaporative cooling can not occur in conjunction with system or zone heating controls. If there is a need for evaporative cooling, the system operates. Otherwise, the system is off and no heating can be provided at the system or zone level. The EnergyPlus development team has been made aware of these issues but the fix is not foreseen for the near future. This problem results in heating zone loads not being met in the greenhouses. The project team proposes the following solution to work around this evaporative cooling modeling limitation. The solution implemented by the energy analyst is to schedule the evaporative cooling on/off for each hour in the year (8760 schedule), based upon the cooling and heating set points and achieved zone temperatures. Establishing the schedule is an iterative process. However because the evaporative-cooler on-schedule is specified at an hourly time step (and not smaller), the zone temperature for some hours falls below the set point. To minimize these occurrences, the evaporative coolers were shut off when they overcooled the space. But in doing so, this increased the number of hours that loads were not met in the space to be beyond 300 hours. Since this is a process space, the baseline model and proposed design models were treated similarly. Is it acceptable to exceed the 300 hour loads-out-of-range limit due to this simulation software limitation?

Ruling:

The applicant is asking two questions. It appears, based on the description provided, that the greenhouse portion of the project is correctly identified as process space and the associated energy use should be considered process load. The first question asked requests confirmation that exceptional calculation baselines they are proposing are acceptable. The proposed baselines sound reasonable, but further supporting documentation will need to be provided to verify that the baseline used does in fact represent the industry standard. As seen in a similar CIR dated 1/16/2009, the following information must be provided to show process energy savings via the Exceptional Calculation method: 1. Detailed narrative description of the greenhouse system or process for which credit is taken 2. Detailed narrative and back up data for determining the baseline energy consumption 3. Narratives and cutsheets of the proposed new equipment clearly highlighting the efficiency metric for each piece of equipment for which credit is claimed. The second question asks for clarification if the HVAC systems serving the greenhouse area can be exempt from the 300 unmet load hour requirements. The applicant states that the baseline and proposed systems are treated similarly given the process use of the space. Any credits for process energy savings should be claimed through Section 1.7 - Exceptional Calculation Methodology (ECM). Thus, it is understood that Evaporative coolers will not be modeled in the baseline and intermediate proposed case. As such, the 300 hours unmet load hour exemption is not granted for this scenario. When Evaporative Coolers are modeled for ECM, provide sufficient documentation to demonstrate that the unmet load hours in the other conditioned areas do not exceed 300 hours. The 300 unmet load hours exemption is granted for the greenhouse area, however, the LEED submission will require a full narrative explaining how the system was modeled and why the unmet load hours exceed the baseline. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
10/1/2012
LEED Interpretation
Inquiry:

The goal of EAp2 is to establish the minimum level of energy efficiency for the proposed building and systems to reduce environmental and economic impacts associated with excessive energy use. Introduction The project is a Core and Shell building in Germany with leasable space for office and retail tenants. The Whole Building Simulation has been prepared in accordance with ANSI/ASHRAE/IESNA Standard 90.1-2007 (ASHRAE 90.1). For larger retail stores, vestibules and revolving doors are unusual entrances for contemporary retail buildings in Germany and would place a disadvantage on the marketability of the tenant spaces. In lieu of vestibules, air curtains are planned for the high traffic entrances to the retail areas to prevent infiltration and improve energy performance. Project Approach The design team would like to propose an alternative compliance path for the Mandatory Provision of ASHRAE 90.1 Section 5.4.3.4 that requires vestibules or revolving doors for entrance spaces greater than 3000 sq ft. This will apply mainly to tenant retail areas. For all entrances requiring vestibules as per ASHRAE 90.1, it is planned to utilize air curtains. Note that the local Codes do not mandate vestibules and they are uncommon for German retail stores. The latest version of the International Green Construction Code, IgCC 2012, approves the use of air curtains as a substitute for the vestibules required by the current International Energy Conservation Code (IECC). Per Section 605.1.2.3 of IgCC, Where a building entrance is required to be protected with a vestibule in accordance with the IECC, an air curtain tested in accordance with ANSI/AMCA 220 is permitted to be used as an alternative to separate conditioned space from the exterior. Air curtains were approved as a substitute for vestibules in the IgCC because they were determined to prevent infiltration and heat loss equally or more effectively than vestibules. The study Air Curtains: A Proven Alternative to Vestibule Design by Berner International utilized computational fluid dynamics (CFD) modeling to demonstrate that air curtains used with automatic doors at building entrances are 10% more energy efficient than vestibules. For entrances with high traffic such as the case for retail, air curtains were calculated to reduce space heat loss by as much as 20-40% compared to standard vestibules. The IECC currently does not include air curtains as an alternative to vestibules, but this measure will be considered by code committees next year. Yet, air curtains are already approved as an acceptable alternative by the IgCC, which can be considered the first step in the approval process for the next version of the IECC. In addition, the USGBC refers to the IgCC as a new code baseline for greener building construction that is complementary to LEED, per USGBC Press Release. Air curtains have been used as an acceptable energy conservation measure to achieve EAc1 points. Approving air curtains as an alternative to vestibules at building entrances meets the intent of EAp2 and ASHRAE 90.1-2007 Section 5.4.3.4, with the added benefit of potentially improved energy performance. Additionally, retail buildings pursuing LEED would not be disadvantaged by losing leasable tenant space or reducing green space as a result of an increased building footprint and by adding further restrictions to building owners trying to find retail tenants in a highly competitive market. For the areas listed in ASHRAE 90.1-2007 Section 5.4.3.4 that would require vestibules, the project team will submit the following: 1. Drawings with locations of air curtains at main entrances 2. Air curtain manufacturer and model number The air curtains will also be commissioned as part of EAp1, Fundamental Commissioning, and EAc3, Enhanced Commissioning, if part of developer scope. Please verify that the above approach is acceptable to satisfy the requirements of LEED-NC/CS 2009 EAp2 for a project in Germany.

Ruling:

The use of air curtains instead of vestibules as an alternative method to meet ASHRAE 90.1 Section 5.4.3.4 is not acceptable. Projects may wish to seek an Interpretation directly from ASHRAE in regard to this matter. In general, USGBC will uphold an ASHRAE interpretation. Applicable Internationally; Germany.

Campus Applicable
No
Internationally Applicable:
Yes
4/2/2014
LEED Interpretation
Inquiry:

Clarification is requested regarding whether garage demand control ventilation may be modeled for credit. Garage Ventilation is not addressed by ASHRAE 90.1 – 2007, Appendix G, therefore if savings is claimed it must be modeled as an Exceptional Calculation Measure (ECM). Garage demand control ventilation is increasingly becoming standard practice in newly constructed buildings. In order to take credit for this measure as an ECM, it must be demonstrated that the proposed design goes beyond standard practice.

Ruling:

ECMs must be approved by the Rating Authority. As the Rating Authority for LEED projects, the GBCI will accept an ECM for garage demand control ventilation under the following circumstances:
1) Baseline case shall meet the requirements of ASHRAE 90.1-2010, Section 6.4.3.4.5 Enclosed Parking Garage Ventilation. Baseline fan volume shall be based on the minimum required ASHRAE 62.1 parking ventilation rates of 0.75 cfm / square foot. Baseline system fan power shall be calculated at 0.3 watts per CFM.

2) Proposed case shall reflect the actual design. Evidence shall be provided documenting that demand control ventilation strategies are sufficient to automatically detect contaminant levels of concern in parking garages (for example, Carbon Monoxide, Particulates, VOCs, etc. and NO2) and modulate airflow such that contaminant levels are maintained below specified contaminant concentration as identified in ASHRAE 62.1-2010 Addendum d. Evidence shall also be provided that contaminant sensors are placed in space in an appropriate manner for detection of contaminant in question, included in the building commissioning plan upon installation, and then calibrated yearly following installation.

The contaminants of concern that must be monitored may be limited to CO if a narrative is provided justifying how the controls will also help to limit NO2, VOCs and PM2.5 concentrations. The narrative should address how the parking garage minimum exhaust flow rate and/or the minimum fan run time (if applicable) are maintained, and provide clarification that other contaminant levels are expected to remain low based on that design. Note that NO2 would also be expected to be monitored in garages where more than 20% of the vehicles are anticipated to be diesel-fueled.

Note: though it does not need to be addressed specifically in the narrative, the project team must confirm compliance of all ASHRAE 62.1 mandatory measures, including the measure addressing “Buildings with Attached Parking Garages” requiring limitation of vehicular exhaust into adjacent spaces. .

3) If other activities occur in the garage area, the ventilation for these uses shall be in addition to garage vehicle ventilation.

4) Proposed case shall be modeled such that a minimum air flow of 0.05 cfm/square foot is maintained.

5) A narrative shall describe all Baseline and Proposed case assumptions included for this measure, and the calculation methodology used to determine the projected savings. The narrative and energy savings should be reported separately from the other efficiency measures in the LEED Form.

6) No more than a 75% fan energy savings shall be claimed for this measure.

UPDATED on 01/05/18 for rating system version applicability and in Section (2) to clarify that not all contaminants of concern must be continuously monitored.

Campus Applicable
No
Internationally Applicable:
Yes
8/26/2008
LEED Interpretation
Inquiry:

This project consists of the rehabilitation of a one-story brick warehouse in downtown Phoenix, Arizona, built by the Arizona Hardware Supply Company in 1930. It has been determined to be eligible for listing on the National Register of Historic Places, and formal listing is anticipated following review and approval by the National Park Service (NPS). The building will be rehabilitated in accordance with the Secretary of the Interior\'s Standards for Historic Preservation. Plans are being reviewed by the Arizona State Historic Preservation Office (SHPO). The warehouse will be converted into a commercial office housing about 40 people, and may be the first project in Phoenix to combine LEED-NC certification with the Federal Rehabilitation Tax Credits. Existing brick walls are of double wythe construction, 8 inches in nominal thickness, with original bricks set in a common bond pattern. Consistent with the Secretary of the Interior\'s Standards for Rehabilitation, changes to the building that would alter the historic character, both inside and outside, are not recommended by the SHPO and NPS. Therefore, the addition of insulation to the interior or exterior walls is prohibited since it would alter one of the main "character-defining features" of this building. The ground floor level and surface of the concrete floor are also subject to the constraints of the SHPO/NPS requirements. The only proposed alterations to the building envelope are the addition of storm windows, with insulated glass placed on the interior of the window opening to provide thermal efficiency, and providing insulation to a value of R-30 for a roof that has never been insulated. EAp2 requires this renovation project to comply with ASHRAE 90.1 2004 Sections 5-10 and EAc1 requires that the project secure 2 points, or a 7% improvement over the same ASHRAE standards. While we anticipate meeting the mandatory and prescriptive requirements listed in Sections 6-10, we are unable to meet the requirements in Section 5: Building Envelope. ASHRAE 90.1-2004 Section 4.2.1.3 lists exceptions to compliance with Sections 5-10 for "a building that has been specifically designated as historically significant by the adopting authority or is listed in \'The National Register of Historic Places,\' or has been determined to be eligible for listing by the US Secretary of the Interior need not comply with these requirements." In a Credit Interpretation Ruling dated 5/27/2008, a brick warehouse project similar to this one, also being renovated to meet the Secretary of the Interior\'s standards, and reviewed by the applicable SHPO, and the NPS, was granted permission "to exclude those components that cannot be upgraded to meet the mandatory and prescriptive requirements due to the standards of the Secretary of the Interior and of the National Park Service from demonstrating compliance" in order to comply with LEED Energy and Atmosphere requirements. With this in mind, will this project be allowed to meet EA Prerequisite 2 without securing two points under EAc1, considering that ASHRAE 90.1-2004 exempts the project from meeting the requirements, owing to its historical significance?

Ruling:

The project team is requesting a variance from meeting the mandatory and prescriptive requirements of ASHRAE 90.1-2004 under EAp2, specifically Section 5-10. The project team is also requesting a variance from meeting the mandatory achievement of 2 points under EAc1 (achieving a 7% energy cost savings for an existing building renovation). For EAp2, the cited exemption for meeting the requirements of Section 5-10 of ASHRAE 90.1-2004 applies to this project, provided that the project receives the designation, listing, or eligibility that is required by the exception. For EAc1, there are other efficiency measures that can and should be pursued to meet the minimum target of 7% in energy cost savings for existing building renovations. As the opportunity to pursue other energy saving measures exists for this project, the request for variance is denied.

Campus Applicable
No
Internationally Applicable:
No
5/9/2011
LEED Interpretation
Inquiry:

In consideration of EAp2, are plug-in type occupancy sensors acceptable to control task lights?

Ruling:

The proposed task lighting controls are acceptable. Although ASHRAE 90.1-2004 Section 9.4.1.1 does not list an exemption for task lighting, the context of this section implies that the requirement applies only to general lighting. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
3/11/2003
LEED Interpretation
Inquiry:

ASHRAE 90.1 does not allow credit for air leakage reduction. However, it does indicate that windows are allowed to have 1 cfm per square foot air leakage (at 0.30" water.) The windows we are using in this project are very high performance, with significantly lower air leakage rates. The manufacturer has supplied test results indicating the tested air leakage rate. Further, we are using a blower door and infra-red camera simultaneously to locate and seal any air leaks in the window system that result from installation. We propose to take credit for this air leakage reduction, with the following methodology:The tested air leakage rate at 0.30" can be established for the windows as installed, based on manufacturer\'s data, and for the base case windows based on ASHRAE 90.1. Both these values will be extrapolated to expected winter heating season air leakage rate, using the LBL correlation for blower door test data. We have run two blower door tests, and will use the most recent (during which most of the air leakage has been taken care of) test data to establish the relationship between the air leakage rate at 0.30" static pressure (75 Pa) and the average heating season air leakage rate, which is calculated at the building pressure established by the LBL correlation, which is based, in part, on the exposure of the building to wind. In this case exposure is significant, as the building is fully exposed on the west side of the building to windows ranging from south to west to north. We then propose to run the base case building, in the energy modeling, using TRACE, with the air leakage rate for the windows established in the above manner. The building as built would be modeled with zero air leakage rate. Preliminary estimates indicate that the difference in overall extrapolate natural air leakage rates in 0.04 air changes per hour, at typical heating season winter conditions. Blower door guided air leakage reduction: A significant effort at air sealing is part of the energy saving strategy for this building. With the location noted above, air leakage reduction is particularly important. Two blower door tests with simultaneous infrared scanning, have been completed. The first identified a number of areas that were not complete as designed. Most of these were completed by the time of the second test, and a number of areas were identified during the second test that, in my opinion, would not have subsequently been air sealed had this procedure not been in place. A list of further items was developed from this second air leakage test, and this list has been circulated by the GC to responsible parties, who will sign off when they have completed the items. When those items are complete, a third, and hopefully final, blower test will be conducted.We propose to take credit in our energy calculations for the air leakage reduction between the second and third blower door tests, using the LBL correlation to extrapolate to typical heating and cooling season air leakage rates, as described in number 2 above. The extrapolated seasonal air leakage rate reduction would be applied to the base case building. For example, if the extrapolated air leakage reduction were 0.1 heating season air changes per hour from blower door test #2 to test #3, we would assign 0.1 ACH to the base case building and zero air leakage to the building as built.We feel that this third round of testing and air leakage reduction is well beyond typical attention paid to air leakage, that air leakage control is particularly important in this very cold (7700 degree-day) climate and at this exposed site, and that we have demonstrated a method using accepted principals to quantify the savings. Blower door test results and LBL correlation spreadsheets for each test would be provided as part of the submission. We would also submit the list of items to be air sealed as part of the final air leakage reduction package. Windows and air leakage reduction together: We propose to add the two air leakage reductions - from window improvements and blower-door-guided air leakage reduction. For example, if the blower-door-guided heating season air leakage rate reduction were 0.1 ACH and the window air leakage reduction were 0.04 ACH, the base case building would be modeled at 0.14 ACH and the building as built at 0.0 ACH.)

Ruling:

**Updated 7/1/2015 with applicability to corresponding EAp2 prerequisites.
Advanced air sealing is a strategy that can lead to measurable energy savings, particularly in cold climates. Although this measure is outside the scope of ASHRAE 90.1 modeling protocol, you may be able to make a case for the significance of this strategy in improving energy performance. However, this will require clear and thorough documentation in order to be considered under the requirements of this credit. The following guidelines are provided to help strengthen your approach:(1) Provide manufacturer\'s air leakage test results that use the same testing protocol as that by which ASHRAE identified the baseline for window air leakage.(2) Use a typical infiltration rate as a baseline, and reduce it by the amount of improvement you can document or estimate from the air sealing strategies employed. Do not use zero infiltration in the model, as this is not a realistic assumption. A zero infiltration strategy would over-emphasize the percentage of overall energy use reduction represented by infiltration improvements.(3) Include required fresh air ventilation rates (per ASHRAE 62) in both the proposed and baseline model results.(4) Provide clear documentation of air sealing strategies and blower door test results, corrected for wind and temperature effects, to clarify anticipated air sealing performance.(5) Provide documentation which clarifies the percentage of energy savings attributed to the air sealing strategy, as opposed to other energy performance measures incorporated into the building. Applicable Internationally.

**Updated January 1, 2014
Advanced air sealing is a strategy that can lead to measurable energy savings, particularly in cold climates, though its effectiveness is especially dependent on the quality of construction and cannot easily be predicted during the design phase. Recognizing this, the ASHRAE 90.1 committee developed Addendum ag to Standard 90.1-2010, which establishes guidelines for claiming energy savings that result from reduced infiltration in Appendix G. The approved change allows credit only for buildings that complete envelope pressurization testing in accordance with ASTM E779. The appendix establishes a baseline air leakage rate of 0.40 cfm/ft2 (2.03 L/s•m2) at 0.3 in. wc (75 Pa) pressure differential compared to the measured leakage results in the proposed building.
Projects wishing to claim energy savings from advanced air sealing may do so given they meet the following requirements:
1. Utilize Addendum ag to Standard 90.1-2010 to document savings.
2. Provide clear documentation of air sealing strategies and air leakage results from ASTM E779-10 Standard Test Method for Determining Air Leakage Rate by Fan Pressurization, including confirmation that all testing criteria defined in the standard have been met.
3. Provide documentation that clarifies how energy savings from reduced air leakage has been estimated from the ASTM E779 test results and identifies the percentage of energy savings attributed to the air sealing strategy, as opposed to other energy performance measures incorporated into the building.

Campus Applicable
No
Internationally Applicable:
Yes
12/2/2006
LEED Interpretation
Inquiry:

We are seeking a variance for the parking garage HVAC system. Our project is located in Teton Village, Wyoming. Teton Village receives an average snowfall of 185 inches/year. As snowy cars use the garage during the winter, we\'re concerned snow and ice will accumulate in the garage causing a life safety issue. We feel a Snow/Ice melt system is necessary for this space. The following are extracts from ASHRAE 90.1-2004 and ASHRAE Application- ASHRAE HVAC Prescriptive Requirement "Radiant heaters complying with 6.5.8.1 are used to heat unenclosed space". ASHRAE 6.5.8.1 states "Radiant heating shall be used when heating is required for unenclosed spaces". ASHRAE 90.1-2004 states that a Radiant Heating System shall transfer heat primarily (greater than 50%) by infrared radiation. ASHRAE 6.4.3.7 states that Snow/ Ice Melting systems shall include automatic controls capable of shutting off the systems when the pavement temperature is above 50

Ruling:

The floor radiant system and associated controls you are proposing is acceptable as a snow melt system for the garage as an unenclosed space under ASHRAE 90.1-2004. Radiant heat systems emit low-temperature infrared radiation, whether they operate at 80 F or 300 F. The ASHRAE Application Guide is referring to a specific technology, infrared radiators, and not necessarily requiring their use as radiant heaters. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
7/2/2018
LEED Interpretation
Inquiry:

Our project is subject to ASHRAE Standard 90.1-2013 for code compliance. To pursue Option 1: Whole Building Simulation, is there a methodology for documenting additional energy performance for LEED v4 projects regulated by ASHRAE Standard 90.1-2013?

Ruling:

Yes, projects applying Option 1: Whole Building Simulation, and regulated by ASHRAE Standard 90.1-2013 may document additional energy performance improvement under LEED v4 EA credit Optimize Energy Performance as described below. The Appendix G modeling method must be used for the LEED submission, even if the Energy Cost Budget method is used to document local code compliance.

Projects may calculate the Equivalent ASHRAE 90.1-2010 Performance improvement as:
Equivalent performance Improvement = % better than ASHRAE 90.1-2013 + Additional Percent Savings

Where Additional Percent Savings is shown in Table 1:

Table 1: Additional Percent Savings for ASHRAE 90.1-2013

Project Type1 Additional Percent Savings
NC-Office 5%
NC-Retail (except restaurant/grocery) 5%
NC-School 6%
NC-Health Care 3%
NC-Restaurant / Grocery 3%
NC-Hospitality 5%
NC-Warehouse 1%
NC-Multifamily 3%
NC-All Other 2%
CS-Office 3%
CS-Retail (except restaurant/grocery) 3%
CS-School 6%
CS-Health Care 1%
CS-Restaurant / Grocery 2%
CS-Hospitality 3%
CS-Warehouse 0%
CS-Multifamily 1%
CS-All Other 1%
CI-Office 3%
CI-Retail (except restaurant/grocery) 4%
CI-School 6%
CI-Health Care 2%
CI-Restaurant / Grocery 3%
CI-Hospitality 4%
CI-Warehouse 0%
CI-Multifamily 1%
CI-All Other 2%

1 Mixed use buildings shall use the weighted average Additional Percent Savings based on the gross enclosed floor area associated with each building type. Unfinished spaces not submitted in the CS rating system shall use the CS values. Data center space must always be considered “All Other”.

Campus Applicable
No
Internationally Applicable:
No
2/3/2009
LEED Interpretation
Inquiry:

We would like clarification as to whether EA p2 can be demonstrated and EA credit 1 points achieved based on centrally managed lighting wattage limits. Specifically, we would like to know if the wattage limits set by the DALI (Digital Addressable Lighting Interface) system, which allows maximum wattage limits to be programmed into all fixtures, can be used to show credit compliance. Our project, the fit-out of an office space, would like to utilize these controls in order to provide exceptional energy efficiency, individual occupant control including individual fixture dimming in the open office space, as well as to control these lamps with IR occupancy sensors, photo sensors, and programmable time clocks for additional energy savings. The system also includes facility maintenance reporting of lamp and ballast status and energy usage monitoring and trend logging and could include demand response interface with BMS if desired, though not part of this project. While setting the maximum allowable wattage on the DALI system absolutely limits the amount of wattage able to be drawn by the fixtures and this limit is not something that can be over-ridden by building occupants, it is not clear if computer based controls are allowed by ASHRAE 90.1 or the LEED Rating System. It is standard practice for LEED projects to utilize reduced ballast factors or physical wattage limiters as a means to claim energy efficiency from a fixture. The dimmable DALI system and efficient T-5 linear fluorescent lamps proposed by our project cannot utilize fluorescent ballasts with a reduced ballast factor, but the equivalent energy savings can be seen by capping the fixture wattage when setting up the space\'s lighting controls. The alternative to this approach would be to utilize fewer fixtures and produce more light from each, but then the individual workstation controllability provided by the DALI system is negated because individual fixtures are shared by multiple workstations. We would like verification that it is OK to use the maximum allowable wattage set in the DALI system to compare to the AHSRAE lighting power density. The building owner will provide a signed note stating that the wattage limits will not be altered (and won\'t need to be as the lighting levels are designed to be completely sufficient with the 70% wattage limits proposed). This is consistent with the LEED Core and Shell energy modeling requirements that allow reduced lighting power densities if included in the lease agreement (a written confirmation that these levels will be met). Consistent with ASHRAE and the LEED Reference Guides, we will assume the highest wattage lamps acceptable in the fixtures and follow all other ASHRAE guidelines.

Ruling:

The applicant is requesting verification regarding the applicability of electronically controlled lighting wattage limits by using a Digital Addressable Lighting Interface (DALI) system. The proposed approach is an acceptable means of lighting power reduction provided the overall maximum Lighting Power Density is maintained at or below ASHRAE 90.1 specifications. The commissioning authority (CxA) must confirm that the wattage limits used to document credit achievement for EAc1 are programmed correctly as part of the fundamental commissioning activities performed to achieve EAp1. Additionally, the project team should provide documentation to verify the wattage limits (e.g., cutsheets, specifications, etc.) when documenting compliance for EAc1. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011
LEED Interpretation
Inquiry:

As 90.1-2007 is essentially a compilation of addenda, we assume it may be treated in the way outlined in the footnote to EA prerequisite 2, "Project teams wishing to use ASHRAE approved addenda for the purposes of this credit may do so at their discretion. Addenda must be applied consistently across all LEED credits." However, between 2004 and 2007 Appendix G was modified in some ways without addenda being published or approved, and these modifications were made official only by inclusion in the 2007 version. We further assume that we can use these modifications, as long as we use ALL the modifications in the 2007 Appendix G and referenced sections of 90.1, similar to the guidance on addenda noted above. Is this correct?

Ruling:

For LEED v2.x Rating Systems, where ASHRAE 90.1-2004 is the referenced standard, it is acceptable to use ASHRAE 90.1-2007 Appendix G in place of ASHRAE 90.1-2004 Appendix G if the energy simulation follows the language of 2007 Appendix G in its entirety, though the project must only meet the prescriptive requirements listed in 2004. Projects that want to use 90.1-2007 in its entirety may do so as well. Applicable internationally.

Campus Applicable
No
Internationally Applicable:
Yes
10/1/2015
LEED Interpretation
Inquiry:

Can the baseline model for refrigerated facilities be determined based on the IARW/IACSC Energy Modeling Guideline for Cold Storage and Refrigerated Warehouse Facilities as an exceptional calculation methodology under Appendix G?

Ruling:

Yes, project teams may use the IARW/IACSC Energy Modeling Guideline for Cold Storage and Refrigerated Warehouse Facilities as an exceptional calculation methodology when ASHRAE 90.1-2010 is used for compliance with EA Prerequisite Minimum Energy Performance. This guideline may not be used when an equivalent code is used for compliance unless approved by a project-specific Credit Interpretation Ruling. The following additional requirements apply:
1. Refrigerant type may not be used as an efficiency measure.
2. Table 1.4 must be completed for both the portions of the building complying with the IARW/IACSC Guideline as well as those following the standard ASHRAE 90.1 Appendix G requirements
3. If ASHRAE 62.1-2010 Addendum L is applied using the IARW/IACSC Guideline, it must be applied consistently throughout the project submittal.
4. Projects applying the IARW/IACSC Guideline may apply LEED Interpretation 10237 in order to claim energy savings for refrigeration equipment efficiency as an exceptional calculation methodology.

Internationally applicable as follows: The guidance applies to compliance paths using ASHRAE standards and cannot be applied to projects using an equivalent local code. Project teams wishing to apply this to an equivalent local code must obtain approval through a project-specific credit interpretation ruling.

This ruling supersedes the following LEED Interpretations: LI 5178, LI 2301, and LI 2026.

Campus Applicable
Yes
Internationally Applicable:
Yes
8/13/2007
LEED Interpretation
Inquiry:

The project is a 3,000 square foot 1-story new office building. The requirements of this prerequisite are to comply with the mandatory provisions (sections 5.4, 6.4, 7.4, 8.4, 9.4, and 10.4) of ASHRAE/IESNA Standard 90.1-2004 and the prescriptive requirements (sections 5.5, 6.5, 7.5, and 9.5) of ASHRAE/IESNA Standard 90.1-2004. ASHRAE/IESNA Standard 90.1 2004 Section 8.4.1.1 states "Feeder conductors shall be sized for a maximum voltage drop of 2% at design load." The exception we would like to take is as follows: We meet all the other requirements of this prerequisite for minimum energy efficiency requirements. Our design is approximately a 2.9% voltage drop, which meets the latest edition of the National Electric Code 215-2(A)(2) FPN#2 which allows between 3-5% voltage drop. The cable size is parallel 500 MCM. To meet the 2% requirement, the cable size would be increased to parallel 750 MCM. This is a significant cost increase to the project without gaining any energy savings. Will the 2.9% voltage drop be acceptable to use?

Ruling:

The project is requesting a relaxed voltage drop requirement for feeder conductors. ASHRAE/IESNA Standard 90.1-2004 is the referenced standard for EAp2 for LEED. The purpose of this standard is to provide minimum requirements for the energy-efficient design of buildings except low-rise residential buildings. This Standard is explicit in the requirement as stated in Section 8.4.1.1: "Feeder conductors shall be sized for a maximum voltage drop of 2% at design load." The fundamental purpose of the National Electrical Code (Section 90.1(A) and (B)) is to provide for practical safeguarding of persons and property, and contains provisions that are necessary for safety. In keeping with the purpose of the ASHRAE/IESNA Standard 90.1-2004, its requirements are more stringent than the allowances in the National Electrical Code. Therefore, the project must meet the requirement per Section 8.4.1.1 of the Standard in order to comply with this prerequisite. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
1/4/2016
LEED Interpretation
Inquiry:

Where the local code does not require vestibules or allows alternatives, can the project team take a penalty for not including vestibules in the design model?

Ruling:

Yes, in locations where the local code does not require vestibules or revolving doors the project team may choose one of the two options below. Additionally, all projects using this method must provide a narrative explaining how infiltration and exfiltration of air through building entries is addressed in the design.

1. Manual subtraction of the energy cost savings associated with vestibules as conservatively estimated by PNNL-20026 “Energy Saving Impact of ASHRAE 90.1 Vestibule Requirements: Modeling of Air Infiltration through Door Openings”. Refer to the Related Resource “Default Deduction for Vestibules” for the specific percentage subtraction required based on project type and climate zone.
2. Provide detailed exceptional calculation method calculations with each step of the calculation clearly described and in alignment with the analysis performed in PNNL-20026, but specific to the project building. Document the additional energy consumption of the project building associated with removing the vestibules from the project. No credit will be given for the use of air curtains when using this approach. A sensitivity analysis related to the number of occupants entering on an hourly basis would need to be justified. The narrative would also need to justify that the simulation software is capable of addressing the conditions required for the calculation. (Software with a well-mixed air assumption would not be able to apply this modeling approach).

***Update 11/9/20: This ruling is now applicable to LEED v4.1 BD+C and ID+C projects.

Campus Applicable
No
Internationally Applicable:
Yes
4/10/2007
LEED Interpretation
Inquiry:

Background: This project is using underfloor air distribution (UFAD) as the main HVAC system. Passive floor-mounted swirl-type diffusers (manually operated by the occupants for interior "cooling-only" zones. They will not be controlled via thermostats. The perimeter zones will be served by UFAD fan powered units (with electric heat for heating) and will be controlled via space mounted thermostats. The prerequisite requires compliance with ASHRAE 90.1-2004, section 6.4. Section 6.4.3.1.1 states: "The supply of heating and cooling energy to each zone shall be individually controlled by thermostatic controls responding to temperature within the zone". Question: Does the use of passive floor mounted diffusers in the UFAD system and controlled as described above meet the requirements of ASHRAE 90.1-2004, section 6.4.3.1.1 and this prerequisite?

Ruling:

The project team is requesting clarification regarding the requirement for zone-specific thermostat controls in order to meet the requirements of section 6.4.3.1.1 of ASHRAE 90.1-2004 for EAp2. The interior spaces of the project receive cooling air through in-floor swirl-diffusers that are occupant controlled, but there is no zone-specific thermostat control. In this case, the design meets the intent of the ASHRAE 90.1 requirement. Ultimately the temperatures in these spaces are maintained in a similar approach to a VAV box, by regulating air flow. The occupants control this airflow based on personal comfort levels, and are effectively the controls system (similar to operable windows in a naturally ventilated and cooled space). Provided that the system meets the rest of the requirements of section 6.4 (especially 6.4.3.2.1-Automatic shut-down), and thus does not supply unneeded cold air during unoccupied hours, the design appears to meet the intent of ASHRAE 90.1 and LEED-NC 2.2- EAp2. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
4/1/2012
LEED Interpretation
Inquiry:

We request a ruling regarding building ventilation and its impact on EAp2/EAc1. The question is two-fold: (1) Will USGBC/GBCI allow credit for a design that increases ventilation effectiveness other than Displacement Ventilation (a noted exception for PDV now exists in ASHRAE 62.1-2010), and, (2) will USGBC/GBCI allow credit for reduced ventilation by decoupling the outdoor air from the multi-zone VAV system, which requires increased ventilation rates to ensure the appropriate airflow is reaching all of the zones? Project Design Information:The project is a multi-story office space undergoing a major renovation. In accordance with ASHRAE Standard 90.1-2007 Appendix G, the baseline system is System 8. Ventilation is handled by VAV air handling units, thus requiring multi-zone calculations. Due to elevated terminal heating temperature, zone air distribution effectiveness (Ez) is 0.8.Similarly, the proposed system will employ a VAV system, but with decoupled constant-volume ventilation, thus foregoing multi-zone calculations and reducing outdoor air. Ventilation is room neutral resulting in an Ez of 1.0.Referenced Standards/Guidelines/Research:Ez factors and ventilation rates are determined from ASHRAE Standard 62.1-2007 Tables 6-2 and 6-1, respectively.ASHRAE Standard 90.1-2007 Appendix G Section G.3.1.2.8 Design Airflow Rates states:(D)esign supply airflow rates for the baseline building design shall be based on supply-air-to-room-air temperature difference of 20°F

This exceeds the 15°F limit from Table 6-2. ASHRAE 62.1-2007 User’s Manual (page 6-27) instructs to use the worst case factor, which is the heating Ez of 0.8.

ASHRAE Standard 90.1-2007 Appendix G Section G.3.1.2.5 Ventilation states:

(V)ventilation rates shall be the same for the proposed and baseline building designs.

Reviewing the User’s Manual for this section adds:

(V)ventilation can be a major contributor to building energy consumption, but it is not considered an opportunity for energy savings... (V)ventilation is energy neutral as far as tradeoffs are concerned.

Spare a recent exemption for using PDV to reduce outdoor air rates via an allowable manipulation of Ez, no other exemptions exist. Yet, ASHRAE research recognizes the advantages of decoupling ventilation in its ability to reduce ventilation volume and therefore energy costs. From Jeong, J.W., et. al, ASHRAE Transactions 2003, Volume 109, Part 2:

“All-air [VAV] systems are widely used in many types of buildings, [even though] these common systems have several significant deficiencies. …(T)he multiple spaces method must be used to increase the [OA fraction... This increase… may add significantly to energy consumption and operating cost…

“The challenge of conforming to [ASHRAE Standard 62] in an energy efficient manner can be met with a dedicated outdoor air system (DOAS)… The DOAS provides 100% of the required ventilation air at constant volume”

In addition, EPA’s Technical Report PNNL-18774 (Strategies for 50% Energy Savings in Medium Office Buildings) recognized DOAS as a primary energy savings strategy using the previous research by ASHRAE noted above as support and justification.

Conclusions:
It is clear that, as written, the ventilation volumes should be the same in both models. But we respectfully ask the LEED® Reviewer to provide us feedback on whether this makes sense for the current LEED® Rating Systems. It appears the rules are evolving (ex. Displacement Ventilation) as technologies and techniques evolve. And yet full credit for decoupled ventilation systems doesn’t currently exist and therefore may discourage designers and owner from investing in a system that often has higher first cost. We recommend and endorse this investment because of the excellent returns both in terms of dollars saved and carbon emissions reduced. We ask for your ruling to create an exception that allows credit for increased ventilation effectiveness and reduced ventilation rates (compared to multi-zone VAV systems) using a DOAS.

Ruling:

Credit cannot be taken for ventilation effectiveness in systems other than displacement ventilation, such as a dedicated outdoor air unit, using an Ez of 1.0 in the proposed case, with an Ez of 0.8 for the baseline case (VAV system).Addendum bj to ASHRAE 90.1-2007 states that the Baseline Case ventilation airflow rates can be calculated using an Ez value of 1.0 only if the Proposed Case Ez value is greater than 1.0. The project team may not take credit unless the Proposed Case Ez value is greater than 1.0, because 90.1 does not set a Baseline Case standard for that scenario. Equivalent to ASHRAE 90.1 may be used.

Campus Applicable
No
Internationally Applicable:
No
10/1/2013
LEED Interpretation
Inquiry:

For buildings with high unregulated energy loads, is it acceptable to show compliance with EA prerequisite: Minimum Energy Performance by considering the unregulated load separately from the ASHRAE 90.1 energy model?

Ruling:

**Updated 7/01/2016 to address the LEED 2009 4-point minimum requirement.

For buildings where unregulated loads account for more than 60% of project energy cost, the following alternative compliance path may be followed:
1. Create an energy model that includes all loads (regulated and unregulated), then remove the unregulated loads from the model through post-processing and demonstrate that the project meets the minimum performance required for EAp2, or the 4-point minimum requirement for projects registered after April 8th, 2016 (e.g. 18% for LEED-NC).
2. Demonstrate that the proposed unregulated loads are 5% more efficient than the industry standard baseline or company average production efficiency using the one of the three ECM approaches outlined below.
3. In addition to the standard documentation required for EAp2, submit calculations showing energy model results with all loads (regulated and unregulated) included and all documentation necessary to demonstrate the 5% process energy improvement.
This alternative compliance path can only be used to demonstrate compliance with the EAp2 Minimum Energy Performance requirement, and in lieu of the four-point minimum requirement for projects registered after April 8th, 2016. Points for EAc1 must be determined with 100% of the unregulated load included in the energy model.
Document ECMs using one of the following three methods:
1. For ECMs listed in the Interpretation database:
- Calculate the annual energy cost savings using the procedure listed in the database
- Enter the calculated savings into section 1.7 of the EAp2 form
- Reference the LEED Interpretation number and upload the required documentation

2. For projects establishing a new baseline technology as the industry standard, submit exceptional calculations and at least one of the following:
- List of three facilities built in the last five years that use the baseline technology
- Current utility incentive programs for new construction that establish the baseline
- Published studies justifying the baseline technology as standard practice

3. For projects with proprietary manufacturing processes, demonstrate that the production process is more efficient than the company’s average production efficiency:
- Identify at least three facilities built in the last five years that manufacture the product
- Calculate the process’ past average Energy Consumption Index (ECI) in units of energy per product manufactured to establish the baseline production efficiency
- Provide the new process’ estimated ECI, anticipated production level, and an explanation of how these numbers were determined
- Calculate the annual production process energy cost savings using the baseline ECI, proposed ECI, and anticipated production level

Campus Applicable
Yes
Internationally Applicable:
Yes
4/25/2008
LEED Interpretation
Inquiry:

We are working on a multi use facility with a full kitchen for restaurant style serving of the employees. There is nothing in the ASHRAE 90.1-2004 standard that defines the baseline energy for a restaurant and kitchen equipment. The owner is investing significant funds in highly efficient kitchen equipment and would like to take credit for the energy savings related to the kitchen. How do we define the baseline energy and calculate the ASHRAE savings to be incorporated in our energy calculations?

Ruling:

The project team is requesting guidance on defining a baseline for restaurant and kitchen equipment as well as instruction on how to take credit for using efficient equipment in the proposed design. The LEED-NCv2.2 Reference Guide states that project teams may follow the Exceptional Calculation Method (ECM) (ASHRAE 90.1-2004 G2.5) to document measures that reduce process loads. Please refer to the Standard for more information on the ECM methodology. The CIR dated 8/07/2007 also offers guidance on ECMs for process loads. An appropriate baseline for restaurant and kitchen equipment may be created using the energy rates for various equipment found in the 2005 ASHRAE Handbook - Fundamentals, Chapter 30, Table 5 in conjunction with an appropriate equipment schedule. Please comply with the documentation requirements laid out in ASHRAE 90.1-2004 G2.5 for the Exceptional Calculation Method. Another resource for determining the appropriate baseline for restaurant and kitchen equipment is the LEED for Retail Rating Systems. These can be found on the USGBC website. An informed determination can only be provided during LEED certification review if the requirements ASHRAE 90.1 Section G2.5 guidance are satisfied (i.e., provide theoretical and empirical information verifying accuracy). Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
5/21/2009
LEED Interpretation
Inquiry:

The following request is regarding three glass garage roll-up doors that are proposed for this Rescue Station Apparatus Bay. Due to tight site conditions and a shared apparatus exit drive path; it is important safety requirement that glass doors be provided that allow for a line of sight to the adjacent, existing fire station. Exiting dispatched Rescue trucks must have full view of the vehicles in the parking lot and other exiting fire apparatus that both share the common travel pathway. The space is heated and ventilated but not mechanically cooled. This is a garage for the storage of vehicles and will not be heated to the same level as the main building. A total of six 12ft wide by 14ft high, roll-up doors are to be provided; three of the proposed doors, used for entrance, are to be a highly insulated product. In order to provide the required high visibility for the exiting emergency vehicles the three, exit roll-up fire apparatus doors are proposed to be aluminum framed glass doors with a solid bottom panel. No aluminum and glass garage door had been tested to the standards required (NFRC and/or DASMA105) according to review with installers, manufacturers and the Door and Access Systems Manufacturers Association. We are requesting an exemption from the rating requirements for these exit garage doors for the following reasons: 1. Glass doors are required to provide visibility for exiting Rescue Apparatus. 2. No testing data is available for glass roll up doors. 3. The rear doors are highly insulated and we believe the average of all six doors is sufficient to pass the thermal requirements.

Ruling:

The project team is requesting clarification regarding being granted an exemption for meeting the standards for the exit garage doors of their Rescue Apparatus Bay. The reasons provided for exempting the doors from the testing requirement is that no testing data is available for glass roll up doors. This is acceptable given the special circumstances of this case, because these doors are located in a garage which is an unoccupied space, and they open to the outdoors rather than to an occupied space. The project submittal should provide information justifying why NFRC 400 air leakage testing is not feasible for the doors in question as well as photographs/drawings of the tight site conditions to demonstrate that glass doors must be used for safety reasons. In order for the project to exempt the manufactured doors from the requirements, the following criteria must be met: 1. The doors required are unavailable are certified to meet the NFRC 400 requirements. 2. The manufactured doors exempted open directly to spaces less than 3,000 square feet of building area. 3. At least 85% of the doors for the project meet the Door air leakage labeling requirements.

Campus Applicable
No
Internationally Applicable:
No
10/1/2012
LEED Interpretation
Inquiry:

Many projects in Europe are connected to highly efficient district energy systems. However, the EAp2/EAc1 Option 2 guidance provided in the "Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 - Design & Construction" (DESv2) document is not well-suited for the complex interconnected district energy systems with multiple fuel sources that are common in Europe. Many European countries already make use of the Primary Energy Factor (PEF) as a means of evaluating district energy performance and building energy performance. Is there an alternative compliance path available to document EAp2/EAc1 credit for the district energy system using the Primary Energy Factor in lieu of the DESv2 Option 2 compliance path?

Ruling:

An alternative EAp2/EAc1 compliance path is available to document the energy performance for complex interconnected district energy systems in Europe using the Primary Energy Factor and the greenhouse gas emissions associated with these systems. The Sweden Green Building Council developed an approved method, "Treatment of European District Energy Systems in LEED" (available November 1, 2012), which may be used in lieu of EAp2 Option 2 of the "Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 - Design & Construction" guidance. This compliance path is currently available for projects located in Europe only. Note: The "Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 - Design & Construction" (DESv2) is Optional Guidance for LEED 2009 projects. However, project teams that use the guidance must apply all relevant portions of the guidance. The alternative compliance path outlined in the "Treatment of European District Energy Systems in LEED" may only be used to replace Option 2 of the EAp2/EAc1 Energy Modeling Path defined in the DES v2 guidance. Project teams that opt to use the "Treatment of European District Energy Systems in LEED" method must comply with all other applicable requirements of the DES v2 guidance such as those defined for EA Credit 3, EA Credit 4, EA Credit 5, etc. Applicable Internationally; only for projects located in the Europe region.

Campus Applicable
No
Internationally Applicable:
Yes
7/1/2014
LEED Interpretation
Inquiry:

There is significant confusion, and seemingly contradictory LEED Interpretations on the required methodology for addressing “purchased” on-site renewable energy, and/or purchased biofuel that is not considered on-site renewable energy within the LEED energy model. For renewable fuels meeting the requirements of Addendum 100001081 (November 1, 2011) or other purchased renewable fuels, how should purchased on-site renewable energy be treated in the LEED energy model? How should purchased bio-fuels (meaning it I not fossil fuel but is used in a similar manner to bio-fuel) be treated in the energy model?

Ruling:

For any on-site renewable fuel source that is purchased (such as qualifying wood pellets, etc.), or for biofuels not qualifying as on-site renewable fuel sources that are purchased, the actual energy costs associated with the purchased energy must be modeled in EA Prerequisite 2: Minimum Energy Performance and EA Credit 1: Optimize Energy Performance, and the renewable fuel source may not be modeled as "free", since it is a purchased energy source.

For non-traditional fuel sources (such as wood pellets) that are unregulated within ASHRAE 90.1, use the actual cost of the fuel, and provide documentation to substantiate the cost for the non-traditional fuel source. The same rates are to be used for the baseline and proposed buildings, with the following exception: If the fuel source is available at a discounted cost because it would otherwise be sent to the landfill or similarly disposed of, the project team may use local rates for the fuel for the baseline case and actual rates for the proposed case, as long as documentation is provided substantiating the difference in rates, and substantiating that the fuel source would otherwise be disposed of.

When these non-traditional fuel sources are used for heating the building, the proposed case heating source must be the same as the baseline case for systems using the non-traditional fuel source, and the project team must use fossil fuel efficiencies for the Baseline systems, or provide evidence justifying that the baseline efficiencies represent standard practice for a similar, newly constructed project with the same fuel source.

Updated 8/7/17 for rating system applicability.

Campus Applicable
Yes
Internationally Applicable:
Yes
8/27/2008
LEED Interpretation
Inquiry:

The Natural Sciences Complex is a new three story 51,884 square foot, L-shaped building. The building includes college level science laboratories, laboratory support rooms, faculty offices, classrooms, and study areas. The HVAC system serving the laboratory wing of the building includes a single packaged VAV air handler with hot water reheat coils, a run-around heat recovery loop and a variable volume general exhaust system. In addition, laboratory spaces requiring fume hood exhaust are equipped with variable volume exhaust air devices mounted directly on top of fume hoods. The office wing is naturally ventilated and it is heated by a hydronic heating system. There are five classrooms that have mixed mode ventilation system and they are heated and cooled through the radiant slab. There are sixteen chemical fume hoods, and twelve chemical flow benches located in ten laboratories. Laboratory support rooms contain several storage cabinets that require continuous ventilation. Total fume hood exhaust rate is 11,600 cfm, and total exhaust rate of chemical flow benches is 2,100 cfm. Designed minimum ventilation rate for spaces containing chemicals is four ACH, as recommended by NFPA Standard 45. The same standard prohibits recirculation of chemicals originating from the laboratories. Since the 24,150 square feet laboratory wing contains only a few small spaces without chemicals (total floor area 450 square feet), the packaged air handler serving this area is 100% outside air system. This efficiently utilizes heat recovery system, reduces fan energy, and eliminates need for return air duct. The laboratory spaces are load driven. Total supply and exhaust flow rates for laboratory wing are 38,000 cfm and 33,000 cfm respectively. Following the requirements of the ASHRAE Standard 90.1-2004, Appendix G, Section G 3.1.1, based on usage, number of floors, conditioned floor area and heating source, our baseline model is a constant volume packaged single zone air conditioner with DX cooling coils and fossil fuel furnace. This type of system is assigned to each thermal zone. There is no thermal zone in the baseline model that has supply air capacity of 5,000 cfm or greater, and exhaust air energy recovery was not modeled in the baseline building according to Section G 3.1.2.10. This produced considerable energy savings due to the huge amount of outside air and the requirements for continuous ventilation of the laboratory spaces even during unoccupied hours. Since a large portion of our energy savings is the result of adding heat recovery to our system, we wanted to verify that we have correctly interpreted that the ASHRAE Standard does not require heat recovery in the baseline model for our building. Please advise if this modeling strategy is acceptable by USGBC.

Ruling:

The applicant requests confirmation that their modeling approach that excludes exhaust heat recovery from the baseline case due to baseline case system size is an acceptable modeling approach. This modeling approach is acceptable. The language of Section G3.1.2.10 with regards to system design airflow and outside air percentage refers to baseline case systems, not to proposed systems. As indicated above, the baseline case systems for the laboratory spaces all have air flow less than 5,000 cfm. Therefore, based on the description above, energy recovery would likely not be required in the baseline case systems serving the laboratory spaces. Please note that thermal blocks must have airflow less than 5,000 cfm for any thermal block where energy recovery is modeled for credit, and the size of the thermal block may not be manipulated to reflect a smaller thermal block than would typically be modeled just to avoid the prescriptive requirement for energy recovery.

Campus Applicable
No
Internationally Applicable:
No
5/9/2011
LEED Interpretation
Inquiry:

Can the project team use the ASHRAE 90.1 2007 energy model as the baseline for both EA Prerequisite 2 and EA Credit 1 in LEED v2.2?

Ruling:

If the project team is following the point thresholds from LEED v2.2 the direction outlined in the credit interpretation request is acceptable. Note: this ruling does not apply to Core and Shell projects. Note: this ruling does not apply to Core and Shell projects. Applicable internationally.

Campus Applicable
No
Internationally Applicable:
Yes
1/1/2014
LEED Interpretation
Inquiry:

ASHRAE Interpretation “ASHRAE/IES IC 90.1-2007-14” states that the baseline pump power cited in Section G3.1.3.10 was developed as 22 W/gpm total for all baseline chilled water pumps. Is this applicable for LEED projects?

Ruling:

ASHRAE Interpretations are considered applicable for all LEED projects using the referenced ASHRAE Standard, regardless of LEED registrations date, since ASHRAE Interpretations are considered to be clarifications of the ASHRAE standards only. However, in consideration of the long-standing GBCI review approach that allowed 22 W/gpm for each Baseline chilled water pump, this ASHRAE Interpretation which states that “the baseline pump power in Section G3.1.3.10 was developed as 22 W/gpm, and is the total wattage allowed for all cooling system pumps,” shall be mandatory only for projects registered after the publication date of this LEED Interpretation.
For projects registered after the date of this LEED Interpretation, the total Baseline chilled water system pump power shall be 22 W/gpm per ASHRAE 90.1-2007 Section G3.1.3.10; and the Baseline pump power shall be evenly distributed between the Baseline primary and secondary chilled water pumps. Alternatively, if the proposed case has primary/secondary chilled water pumps, the Baseline pump power may be distributed between the Baseline primary and secondary pumps consistent with the proposed design.

Campus Applicable
No
Internationally Applicable:
Yes
12/2/2006
LEED Interpretation
Inquiry:

There are two main components to this CIR with regards to the prerequisite (envelope / simplified approach with HVAC) detailed as follows: Maximum U-factor and SGHF requirements for the building envelope The majority of the building is naturally ventilated and only the three following areas are being air conditioned:- a) Room 1: Room 1 is air conditioned via an air cooled split package unit system consisting of an outdoor condensing/compressor unit coupled to an indoor air handling unit with a direct expansion cooling coil. The cooled air is distributed to the room via a network of insulated galvanized steel ductwork with ceiling mounted diffusers. b) Room 2: Room 2 is air conditioned via an air cooled variable refrigerant package unit system consisting of an outdoor inverter condensing/compressor unit coupled to a few indoor concealed ducted fan coil units. The cooled air is distributed to the room via a network of insulated galvanized steel ductwork with ceiling mounted diffusers. c) Area 3: The office and meeting rooms are air conditioned via an air cooled variable refrigerant package unit system consisting of an outdoor inverter condensing/compressor unit coupled to a few indoor concealed ducted fan coil units. The cooled air is distributed to the room via a network of insulated galvanized steel ductwork with ceiling mounted diffusers. With regards to the maximum U-factor and SGHF requirements on the building envelope it is suggested we apply only to parts of the envelope separating the air conditioned space with the outdoor space. We also understand there are some requirements for the envelope elements that are adjacent to the \'unconditioned space\' in the Semi-heated column of ASHRAE 90.1-2004 section 5.5.2 and figure 5-5 that we will need to be in compliance with. Simplified Approach Option for HVAC System Instead of complying with the mandatory provision of Section 6.4 of ASHRAE Std 90.1 - 2004, we propose the above mentioned approach based on Section 6.3 of the same standard. The standard allows building with gross floor area less than 2,300 m2 to follow this approach. Although the proposed building gross floor area is approximately 8,300 m2, the air conditioned area in this building is only approximately 1,230 m2. In addition, the proposed air conditioning system as described in Issue 1 (a), (b) and (c) is fairly simple system. Will this suggested building envelope and simplified HVAC System approach be acceptable?

Ruling:

To demonstrate compliance with ASHRAE 90.1-2004 using the prescriptive or trade-off approach, only those areas that are heated or cooled per section 2.2.(a) of the standard must comply with the envelope requirements. As for compliance with the HVAC section 6, the gross floor area of your project is greater than the 25,000 ft2 maximum required by section 6.3.1(b). Gross floor area represents the entire building floor area, not just the gross conditioned floor area. The HVAC systems must comply with the mandatory requirements in section 6.4. Note that the building systems must also meet the requirements of section 7, 8 and 9.

Campus Applicable
No
Internationally Applicable:
No
10/1/2013
LEED Interpretation
Inquiry:

What is considered “hybrid” heating?

Ruling:

**Update 1.11.2019: LI is applicable to LEED v4 projects.

Clarification is requested regarding when a building heat source in Table G3.1.1A should be identified as "Fossil/Electric Hybrid" versus "Electric".

The ASHRAE 90.1-2007 User's Manual states that a fossil/electric hybrid source "refers to a system with any combination of fossil and electric heat, and the baseline system for this is a fossil fuel system". Therefore, the predominant heating type for the building shall be determined based on the percentage of building area served by Electric-only heating versus “Fossil Fuel” and/or “Fossil/Electric Hybrid” heating. The heating source for any building space would be considered “Fossil Fuel/Electric Hybrid” if the space is heated by any combination of fossil fuel and electricity. This includes backup heating, heating of ventilation air serving the space, or preheating, But does not include emergency backup heat sources. The predominant heating type for the building shall be determined based on the percentage of building area served by Electric-only heating versus “Fossil Fuel” and/or “Fossil/Electric Hybrid” heating. (Note: Emergency back-up heating refers to heating that runs when the primary system fails or needs to be shut off in an emergency, and does not refer to a backup system which may be used to provide additional capacity as needed.)

Exception: ASHRAE 90.1 Section G3.1.1 Exception (a) stipulates additional system type(s) for non-predominant conditions (i.e. residential/non-residential or heating source) if those conditions apply to more than 20,000 square feet of conditioned floor area.

EXAMPLES OF BASELINE HEATING SOURCE DETERMINATION:
The Baseline heat source from Table G3.1.1A for the following Proposed Case system types would be fossil fuel since the proposed system design includes a combination of fossil and electric heat serving the same space for the majority of the building:
1. Variable air volume system with gas furnace preheat and electric reheat
2. Packaged terminal heat pumps with outside air tempered by fossil fuel furnace
3. Water source heat pumps with fossil fuel boiler
4. Ground source heat pumps with backup fossil fuel boiler
5. Residential condominium units with packaged terminal heat pumps, that have any amount of ventilation air provided to the space from air handling unit(s) where the supply air is tempered with fossil fuel.

The following buildings would be modeled with an electric heat source for the Baseline Case since the heating source serving the majority of spaces is electric-only:
1. 90,000 square feet is conditioned by a variable air volume system with electric reheat, and 10,000 square feet is conditioned with fossil fuel furnaces
2. 50,000 square feet is conditioned by electric heat pump systems. 15,000 square feet is conditioned with fossil fuel radiant heaters.

The following buildings would be modeled with an additional system type with a different Baseline heating source in accordance with Section G3.1.1 Exception (a):
1. 90,000 square feet is conditioned by a variable air volume system with electric reheat, and 20,000 square feet is conditioned with Packaged DX systems with fossil fuel furnaces. In this case, the 90,000 square feet of area would be modeled with an electric heat source in the Baseline Case (System Type #6 - Packaged VAV with Electric PFP Boxes), and the 20,000 square feet of area would be modeled with a fossil fuel heat source in the Baseline Case (System Type #3 - Packaged Single Zone AC with fossil fuel furnace).
2. 50,000 square feet is conditioned by water source heat pumps with a fossil fuel boiler, and 25,000 square feet is conditioned by electric heat pumps. In this case, the 50,000 square feet of area would be modeled with a fossil fuel heat source in the Baseline Case (System Type #5 - Packaged VAV with hot water reheat), and the 25,000 square feet of area would be modeled with an electric heat source in the Baseline Case (System Type #4 - Packaged Single Zone Heat Pump).

Campus Applicable
No
Internationally Applicable:
Yes
11/11/2008
LEED Interpretation
Inquiry:

The prerequisites requirements are to design the building project to comply with both- the mandatory provisions (Sections 5.4, 6.4, 7.4, 8.4, 9.4 and 10.4) of ASHRAE/IESNA Standard 90.1-2004 (without amendments); and the prescriptive requirements (Sections 5.5, 6.5, 7.5 and 9.5) or performance requirements (Section 11) of ASHRAE/IESNA Standard 90.1-2004 (without amendments). The project consists on installations for a public park, they are: an exterior amphitheater, one administrative office, exhibition space and a refreshment stand. The project is designed 100% "off-grid" with Photovoltaic (PV) renewable energy source completely, that means that there will be no electrical consumption from fossil fuels. A battery bank will provide the back up power. The project is 100% naturally ventilated. There is no mechanical ventilation and it will be operated accordingly. The ASHRAE\'s Mandatory provisions in Section 5: Building Envelope will not be met completely, outside air infiltration will be promoted, all windows will be opened during operation hours. The walls are designed to be permanently permeable to outside air. Accordingly, thermal transmission will not be possible to achieve in some of the spaces. Section 6: HVAC, will not be contemplated for being outside of the project\'s scope. Section 7: Water heating for service water will be designed with solar thermal water heaters. Therefore water heating in this project is contemplated as no electrical consumption. Section 8, 9 and 10 will be completely contemplated. Because of project\'s scope, complete compliance with ASHRAE would be incoherent. But being a 100% renewable energy, \'off grid\' project, its design is streamlined for energy efficiency, and obliged to operate as intended, as it will be demonstrated. Therefore we think we will meet outstandingly the EA Prerequisite 2 and EA Credit 1 intents, even if deviating from ASHRAE\'s provisions and requirements. Is our assumption correct?

Ruling:

The project team is requesting variance on meeting the mandatory and prescriptive requirements of ASHRAE 90.1-2004, given that this project is a public park with some structures, all of which will be naturally ventilated. Section 5.2.1 - Compliance, of the ASHRAE 90.1-2004 states: "For the appropriate climate, space-conditioning category, and class of construction, the building envelope shall comply with 5.1, General; 5.4, Mandatory Provisions; 5.7, Submittals; and 5.8, Product Information and Installation Requirements; and either..." (It goes on to state Section 5.5 (Prescriptive Building Envelope Option) or Section 5.6 (Building Envelope Trade-Off option) as the compliance paths - however LEED only allows for Section 5.5 as the compliance path). Section 5.1.2 - Space-Conditioning Categories, Sub-Section 5.1.2.3, of ASHRAE 90.1-2004 provides further guidance on this, stating that: "In climate zones 3 through 8, a space may be designated as either semiheated or unconditioned only if approved by the building official." (See definitions in ASHRAE 90.1-2004 for italicized terms, including "building official".) (Note that it is not clear from the request, as to whether this project is indeed in climate zones 3 through 8.) On the prescriptive building envelope requirements, assuming that this designation will be approved, given this situation; the project team can follow Section 5.5.2 of the ASHRAE 90.1-2004 which states: "If a building contains any semiheated space or unconditioned space, then the semi-exterior building envelope shall comply with the requirements for semiheated space in Tables 5.5-1 through 5.5-8 for the appropriate climate." The project team may interpret this requirement to apply only to parts of the building envelope that are not designed to be permeable to outside air, as long as supporting documentation to this effect is provided. On the mandatory provisions (Section 5.4), subject to the space-conditioning category designation being approved by the building official; and provided ALL of the structures are indeed naturally ventilated/conditioned (including the administrative office, exhibition space and refreshment stand); it is acceptable to exclude requirements for Section 5.4.3 - Air Leakage for this project. Please provide sufficient documentation to demonstrate that this is indeed the case, when submitting for certification/review. Sections 5.4.1 and 5.4.2 would fall under the purview of Section 5.5.2 as quoted above. Furthermore, this should be accompanied by a letter of undertaking by the responsible party that in the event that alterations are made to the structures under the scope of this certification that would affect it\'s energy performance in the future, these alterations will comply with the requirements of this prerequisite. The project must also include occupied interior space in order to be eligible for certification. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
5/9/2011
LEED Interpretation
Inquiry:

For a fine art museum pursuing EAp2, is it acceptable to use the systems and recommendations described in the ASHRAE HVAC Applications 2007 Handbook as the baseline in cases where Appendix G does not adequately describe a typical preservation area?

Ruling:

The outlined approach is acceptable. Applicable internationally.

Campus Applicable
No
Internationally Applicable:
Yes
10/1/2013
LEED Interpretation
Inquiry:

A centrifugal chiller, manufactured in Brazil, is specified for the project. The chiller is not AHRI certified and there is no laboratory in Brazil that can do this test. Since there is no laboratory in Brazil that can do this test, to comply with section 6.4.1.4 Verification of Equipment Efficiencies of ASHRAE 90.1-2007 Standard, would the equipment fall under option d (if no certification program exists for a covered product, the equipment efficiency ratings shall be supported by data furnished by the manufacturer)? Can this equipment be used in the project?

Ruling:

A supplier’s claims regarding energy efficiency would not be considered sufficient to document compliance with EA Prerequisite 2 (Minimum Energy Performance) and EA Credit 1 (Optimize Energy Performance) for a centrifugal HVAC unit that has not been tested and certified by a 3rd party in accordance with AHRI Standard 550-590. However, if the project team can provide documentation that the efficiency has been tested by a third party using an equivalent standard for HVAC efficiency, this testing would be sufficient in lieu of the AHRI Standard 550-990 testing. Any differences in test conditions and the resulting adjustments to the efficiency values claimed in the energy model would need to be described in the project submittal documentation. Alternatively, the project team may use the supplier’s claims regarding energy efficiency if the commissioning scope of work includes field testing of the equipment efficiency for the range of full- and part-load design conditions under which the building will operate; any adjustments related to altitude, etc. must be accounted for in the commissioning testing. In this case, the energy modeling documentation must include details about the commissioning functional testing method to confirm the performance of the chiller at full and part load operation. If the LEED submittal is provided as a split design / construction phase submittal, and the commissioning agent determines that the equipment efficiency does not meet or exceed the efficiency values claimed by the supplier, the energy documentation must be resubmitted at the construction phase with the values measured by the commissioning agent.

Campus Applicable
No
Internationally Applicable:
Yes
6/13/2007
LEED Interpretation
Inquiry:

We are in the process of submitting a Laboratory for LEED certification. The building contains a two-story, 6650 square foot Electromagnetic Compatibility (EMC) Laboratory which houses several shielded enclosures. Experiments are performed in and around the shielded enclosures that are very sensitive to electromagnetic interference (EMF). To minimize EMF issues, a two-tiered lighting scheme was developed. Tier 1 consists of thirty-one (31) industrial high bay luminaires, containing 1000 watt incandescent lamps, which are to be operated when experiments are running because they are EMF neutral. Tier 2 consists of thirty (30) industrial high bay luminaires containing 400 watt metal halide lamps (455 watts with ballast) which are to be operated for maintenance and general illumination when experiments are not running for higher efficiency. The space also contains 1200 watts of accent lighting. The lighting power density (LPD) of Tier 1 is 4.7 watts per square foot. The LPD of Tier 2 is 2.1 watts per square foot. Even if we take into account the Exception to 9.2.4 in ASHRAE 90.1-1999: "if two or more independently operated lighting systems in a space are capable of being controlled to prevent simultaneous user operation, the installed interior power shall be based solely on the lighting system with the highest wattage", the 4.7 watts per square foot in this space still far exceeds the 1.8 watts per square foot prescribed in the space-by-space method for laboratories. Because of the highly specialized nature of the EMC Laboratory and the fact that incandescent lamps sources had to be deployed, we feel that the LPD requirements stipulated in ASHRAE 90.1-1999 cannot be achieved. Therefore, we are asking to exclude the EMC Laboratory from our lighting power allowance calculations.

Ruling:

The applicant is seeking a waiver to exclude the EMC Laboratory from their lighting power allowance calculations. Based on the narrative, it would be appropriate to consider the lighting systems that are required only during the experiments as a process load. The lighting that is used for maintenance and general illumination and when experiments are not running needs to be accounted for. However, even this LPD is higher than stipulated. Please note that if the project is targeting EAc1, the applicant must include the larger lighting power density on the appropriate schedule to generate accurate equipment sizing scenarios.

Campus Applicable
No
Internationally Applicable:
No
7/2/2018
LEED Interpretation
Inquiry:

Our project is located in California. To pursue Option 1: Whole Building Simulation, is there a methodology for documenting additional energy performance for LEED v4 projects regulated by Title 24-2016?

Ruling:

Project Type1
Additional Percent Savings

NC-Office
7%

NC-Retail (except restaurant/grocery)
8%

NC-School
7%

NC-Health Care
0%

NC-Restaurant/Grocery
0%

NC-Hospitality
8%

NC-Warehouse
0%

NC-Multifamily
8%

NC-All Other
0%

CS-Office
5%

CS-Retail (except restaurant/grocery)
7%

CS-School
5%

CS-Health Care
0%

CS-Restaurant/Grocery
0%

CS-Hospitality
7%

CS-Warehouse
0%

CS-Multifamily
7%

CS-All Other
0%

CI-Office
6%

CI-Retail (except restaurant/grocery)
7%

CI-School
6%

CI-Health Care
0%

CI-Restaurant/Grocery
0%

CI-Hospitality
7%

CI-Warehouse
0%

CI-Multifamily
7%

CI-All Other
0%

Campus Applicable
No
Internationally Applicable:
No
3/11/2009
LEED Interpretation
Inquiry:

We have 108 heat pump PTAC\'s that meet the efficiency requirements of EA prerequisite 2 credit. Due to application requirements, we need to also have 2 vertical heat pump PTAC units. The 2 vertical heat pump PTAC units do not meet the efficiency requirements of EA prerequisite 2 credit. Efficiencies are below: 108 units at EER of 12.8, EA prerequisite 2 requires 11.3 2 units at EER of 9.6, EA prerequisite 2 requires 11.3 The 2 units that don\'t meet the efficiency requirement are similar in capacity to the other 108 units. These units need to be ducted however and they do not offer a ducted unit with the high efficiency option. These units were added to meet building code needs. With only 2 out of 110 total units not meeting efficiency requirements, the average efficiency of the 110 units (all similar in capacity) easily exceeds the minimum requirements. Is it okay to have these 2 units out of 110 total?

Ruling:

The project team has furnished further details explaining that in trying to meet building code requirements to provide heating and cooling to the corridors with outside air, and due to the peculiar configuration of the building, it was unable to use minimum efficiency ducted PTACs for 2% of the building\'s cooling capacity for two corridors of the building. It also states that ducted PTACs were not available in a higher efficiency option. Per LEED-CI Reference Guide, all equipment components must meet the mandatory, minimum efficiency requirements as listed in ASHRAE Standard 90.1-2004 Tables 6.8.1A-G. Utilizing the mean efficiency of all equipment in a system is not listed as an acceptable method of satisfying this requirement in ASHRAE Standard 90.1-2004. The PTACs (even those that are ducted) must be rated at the rating conditions specified in ARI 310/380 and 95

Campus Applicable
No
Internationally Applicable:
No
11/1/2011
LEED Interpretation
Inquiry:

Table G3.1.1A lists two possible categories for the building heating source: (1) Fossil fuel, fossil/electric hybrid, & purchased heat; (2) Electric and other. In cases where the proposed building design includes both a natural gas heating source and an electric heating source, when should the heat source in Table G3.1.1A be identified as "Fossil/Electric Hybrid" versus "Electric"?

Ruling:

Clarification is requested regarding when a building heat source in Table G3.1.1A should be identified as "Fossil/Electric Hybrid" versus "Electric". The ASHRAE 90.1-2007 User\'s Manual states that a fossil/electric hybrid source "refers to a system with any combination of fossil and electric heat, and the baseline system for this is a fossil fuel system". Therefore, the heating source for the proposed building would be considered "Fossil Fuel" or "Fossil/Electric Hybrid" if the building uses any fossil fuel source for space heating (including backup heating or preheating), and the baseline building heat source would be fossil fuel.Exception: ASHRAE 90.1 Section G3.1.1 Exception (a) stipulates additional system type(s) for non-predominant conditions (i.e. residential/non-residential or heating source) if those conditions apply to more than 20,000 square feet of conditioned floor area. EXAMPLES OF BASELINE HEATING SOURCE DETERMINATION: The Baseline heat source from Table G3.1.1A for the following Proposed Case system types would be fossil fuel since the proposed system design includes a combination of fossil and electric heat: 1. Variable air volume system with gas furnace preheat and electric reheat2. Packaged terminal heat pumps with outside air tempered by fossil fuel furnace3. Water source heat pumps with fossil fuel boiler4. Ground source heat pumps with backup fossil fuel boiler5. 90,000 square feet is conditioned by a variable air volume system with electric reheat, and 10,000 square feet is conditioned with fossil fuel furnacesThe following buildings would be modeled with an additional system type with a different Baseline heating source in accordance with Section G3.1.1 Exception (a):1. 90,000 square feet is conditioned by a variable air volume system with electric reheat, and 20,000 square feet is conditioned with Packaged DX systems with fossil fuel furnaces. In this case, the 90,000 square feet of area would be modeled with an electric heat source in the Baseline Case (System Type #6 - Packaged VAV with Electric PFP Boxes), and the 20,000 square feet of area would be modeled with a fossil fuel heat source in the Baseline Case (System Type #3 - Packaged Single Zone AC with fossil fuel furnace).2. 50,000 square feet is conditioned by water source heat pumps with a fossil fuel boiler, and 25,000 square feet is conditioned by electric heat pumps. In this case, the 50,000 square feet of area would be modeled with a fossil fuel heat source in the Baseline Case (System Type #5 - Packaged VAV with hot water reheat), and the 25,000 square feet of area would be modeled with an electric heat source in the Baseline Case (System Type #4 - Packaged Single Zone Heat Pump). Applicable internationally.

Campus Applicable
No
Internationally Applicable:
Yes

LEEDuser expert

Marcus Sheffer

7group / Energy Opportunities
LEED Fellow

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