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LEED v4
Healthcare
Energy and Atmosphere
Minimum energy performance

LEED CREDIT

Healthcare-v4 EAp2: Minimum Energy Performance Required

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© Copyright U.S. Green Building Council, Inc. All rights reserved.

Intent

To reduce the environmental and economic harms of excessive energy use by achieving a minimum level of energy efficiency for the building and its systems.

Requirements

Option 1. Whole-building energy simulation

Demonstrate an improvement of 5% for new construction, 3% for major renovations, or 2% for core and shell projects in the proposed building performance rating compared with the baseline building performance rating. Calculate the baseline building performance according to ANSI/ASHRAE/IESNA Standard 90.1–2010, Appendix G, with errata (or a USGBC-approved equivalent standard for projects outside the U.S.), using a simulation model.

Projects must meet the minimum percentage savings before taking credit for renewable energy systems.

The proposed design must meet the following criteria:

Document the energy modeling input assumptions for unregulated loads. Unregulated loads should be modeled accurately to reflect the actual expected energy consumption of the building.

If unregulated loads are not identical for both the baseline and the proposed building performance rating, and the simulation program cannot accurately model the savings, follow the exceptional calculation method (ANSI/ASHRAE/IESNA Standard 90.1–2010, G2.5). Alternatively, use the COMNET Modeling Guidelines and Procedures to document measures that reduce unregulated loads.

OR

Option 2. Prescriptive compliance: ASHRAE 50% Advanced Energy Design Guide

Comply with the mandatory and prescriptive provisions of ANSI/ASHRAE/IESNA Standard 90.1–2010, with errata (or a USGBC-approved equivalent standard for projects outside the U.S.).

Comply with the HVAC and service water heating requirements, including equipment efficiency, economizers, ventilation, and ducts and dampers, in Chapter 4, Design Strategies and Recommendations by Climate Zone, for the appropriate ASHRAE 50% Advanced Energy Design Guide and climate zone:

  • ASHRAE 50% Advanced Energy Design Guide for Small to Medium Office Buildings, for office buildings smaller than 100,000 square feet (9 290 square meters);
  • ASHRAE 50% Advanced Energy Design Guide for Medium to Large Box Retail Buildings, for retail buildings with 20,000 to 100,000 square feet (1 860 to 9 290 square meters);
  • ASHRAE 50% Advanced Energy Design Guide for K–12 School Buildings; or
  • ASHRAE 50% Advanced Energy Design Guide for Large Hospitals. Over 100,000 square feet (9 290 square meters)

For projects outside the U.S., consult ASHRAE/ASHRAE/IESNA Standard 90.1–2010, Appendixes B and D, to determine the appropriate climate zone.

OR

Option 3. Prescriptive compliance: Advanced BuildingsTM Core PerformanceTM Guide

Comply with the mandatory and prescriptive provisions of ANSI/ASHRAE/IESNA Standard 90.1-2010, with errata (or USGBC approved equivalent standard for projects outside the U.S.).

Comply with Section 1: Design Process Strategies, Section 2: Core Performance Requirements, and the following three strategies from Section 3: Enhanced Performance Strategies, as applicable. Where standards conflict, follow the more stringent of the two. For projects outside the U.S., consult ANSI/ASHRAE/IESNA Standard 90.1-2010, Appendixes B and D, to determine the appropriate climate zone.

3.5 Supply Air Temperature Reset (VAV)
3.9 Premium Economizer Performance
3.10 Variable Speed Control

To be eligible for Option 3, the project must be less than 100,000 square feet (9 290 square meters).

Note: Healthcare, Warehouse or Laboratory projects are ineligible for Option 3.

Alternative Compliance Paths (ACPs)

Canada ACP - NECB

Projects in Canada may instead demonstrate a percentage improvement in the proposed building performance rating compared with the baseline according to the National Energy Code for Buildings (NECB) 2011. The same percentage cost improvement in energy performance is required to meet the Prerequisite, and the same points for cost percentage improvement in energy performance are applicable for the Credit.

The following conditions (where applicable) must be met. Note that unless otherwise noted, CanQUEST (the Canadian energy modelling software based on eQUEST that performs NECB 2011 compliance runs) does not implement many of these conditions correctly and would require corresponding modifications to the Reference case.

  1. Comply with mandatory requirements of ASHRAE 90.1-2010
  2. ASHRAE 90.1-2010 mandatory requirements must be met, in addition to the performance path limitations referenced in the NECB 2011 Sections 3.4.1.2, 5.4.1.2 and 6.4.1.2. In cases where ASHRAE and the NECBC reference requirements concerning the same item, the more stringent requirement shall be adhered to.

    The following exceptions apply:

  • ASHRAE 90.1-2010 mandatory items 6.4.3.9, 9.4.1.2b, 9.4.1.4, 9.4.1.5, 9.4.3
  • Apply fenestration area convention similar to ASHRAE 90.1-2010
  • Maintain the same FWR (as defined by NECB, including doors) for the Reference as exists in the Proposed Design, up to the prescribed maximum. If the Proposed Design’s FWR exceeds the prescribed FWR, scale down the fenestrations in the Reference case accordingly.

  • Apply skylight area convention similar to ASHRAE 90.1-2010
  • Maintain the same SRR for the Reference as exists in the Proposed Design, up to the prescribed 5% maximum. If the Proposed Design’s SRR exceeds 5%, scale down the skylights in the Reference case accordingly.

  • Model proposed and reference outside air similar to ASHRAE 90.1-2010
  • Proposed and reference (baseline) outside air rates shall be modeled as per ASHRAE 90.1 – 2010 (G3.1.2.6).

  • Apply ASHRAE kitchen exhaust demand ventilation requirements
  • Provide for the same demand ventilation requirements as described in ASHRAE Appendix G3.1.1.d.

  • Apply ASHRAE’s chiller heat recovery requirements
  • Provide for the same chiller heat recovery requirements as applies to ASHRAE.

  • Apply supply air temperature reset controlled based on warmest zone
  • Reset the minimum supply air temperature to satisfy the cooling requirements of the warmest zone, as stipulated in NECB Section 5.2.8.8. Note that this control setting is already corrected in CanQUEST for the Reference case.

  • Account for uninsulated structural penetrations if they exceed 2% of net wall area
  • The 2% allowance may be applied, but based on the net opaque wall area, not the entire building envelope area.

  • Follow ASHRAE/LEED rules for renovations to existing buildings
  • Model existing components consistent with ASHRAE and LEED provisions.

  • Account for all anticipated energy use in building
  • Fully account for all energy end-uses in the energy performance modelling.

  • DES Systems are to be modeled according to Option 1, Path 1 or Option 1, Path 2 as indicated in the LEED v4 Reference Guide
  • The following exceptions apply:

    • Option 1, Path 1 - Do not apply ASHRAE 90.1-2010 requirements for purchased heating and cooling. Under this ACP, purchased heating and cooling (as applicable) are modeled as cost-neutral in the baseline and proposed case. Local rates for purchased heating (fossil fuel based) and cooling are used to establish the purchased heating and cooling costs. The energy model's scope accounts for only downstream equipment, plus purchased heating and cooling. NECB clause 8.4.3.6 does not apply for LEED projects.
    • Model baseline systems in accordance with NECB requirements, with DX coils replaced with chilled water coils if purchased cooling is present and fossil-fired furnaces replaced with hot water coils if purchased heating is present.
    • Option 1, Path 2: Do not apply ASHRAE 90.1-2010 requirements for baseline systems. Model baseline systems in accordance with NECB requirements for onsite generated equipment (i.e. assume building is not connected to a DES and the proposed building is modeled with a virtual plant according to LEED v4 Reference Guide requirements).
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    What does it cost?

    Cost estimates for this credit

    On each BD+C v4 credit, LEEDuser offers the wisdom of a team of architects, engineers, cost estimators, and LEED experts with hundreds of LEED projects between then. They analyzed the sustainable design strategies associated with each LEED credit, but also to assign actual costs to those strategies.

    Our tab contains overall cost guidance, notes on what “soft costs” to expect, and a strategy-by-strategy breakdown of what to consider and what it might cost, in percentage premiums, actual costs, or both.

    This information is also available in a full PDF download in The Cost of LEED v4 report.

    Learn more about The Cost of LEED v4 »

    Frequently asked questions

    Do the required savings for this prerequisite (and credit) need to come only from building energy, or also process loads?

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    Our project doesn't have enough energy savings to earn the prerequisite. Can we get there by incorporating onsite renewables?

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    Our proposed design has insulation R-values that are below those prescribed by ASHRAE 90.1-2010. Can we still meet the prerequisite?

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    See all forum discussions about this credit »

    Addenda

    11/9/2020Updated: 12/7/2020
    Regional ACP
    Description of change:
    See the Resource Library for full ACP requirements and documentation.
    Campus Applicable
    No
    Internationally Applicable:
    No
    4/6/2018Updated: 11/6/2020
    Reference Guide Correction
    Description of change:
    Add the following to the bottom of the International Tips section:

    "Developed by members of the European Roundtable, this table provides further guidance for project teams in Europe wishing to use European standards in lieu of certain ASHRAE 90.1-2010 mandatory provisions in LEED v4. The guidance covers ASHRAE 90.1-2010 Mandatory Provision Sections 5.4, 6.4, 7.4, 8.4, 9.4 and 10. Column 1 of the table references the specific subsection used in ASHRAE 90.1-2010. Column 2 displays the requirement as written in ASHRAE 90.1-2010. Column 3 outlines the compliance pathway available for European projects. Column 4 includes, in some cases, further information about the proposal, differences between the proposal and the ASHRAE requirement, or a reference to further documentation.

    Please refer back to the LEED v4 web-based reference guide (Further Explanation > International Tips > Europe) for further information on the regional alternative compliance path.

    Additionally, for projects using the Performance Option for compliance with EAp2: Minimum Energy Performance and EAc1: Optimize Energy Performance, the documentation must also use the calculated U-factor for fenestration products including windows and skylights based on either the LBNL Windows 6 program, or a simulation software program that approximates the NFRC rating methodologies. Alternatively, a narrative shall be provided supporting the claim that the fenestration U-factor used in the model is similar to the values that would be achieved using the NFRC rating. The CE-marked fenestration does not account for thermal bridging and seasonal performance in the same way as the NFRC rating, and when accounted for in the energy model, has been observed to lead to savings that exceed those claimed for the same fenestration rated under the NFRC ratings."
    Campus Applicable
    No
    Internationally Applicable:
    No
    4/6/2018Updated: 11/6/2020
    Regional ACP
    Description of change:
    Add the following to the bottom of the International Tips section:

    "Developed by members of the European Roundtable, this table provides further guidance for project teams in Europe wishing to use European standards in lieu of certain ASHRAE 90.1-2010 mandatory provisions in LEED v4. The guidance covers ASHRAE 90.1-2010 Mandatory Provision Sections 5.4, 6.4, 7.4, 8.4, 9.4 and 10. Column 1 of the table references the specific subsection used in ASHRAE 90.1-2010. Column 2 displays the requirement as written in ASHRAE 90.1-2010. Column 3 outlines the compliance pathway available for European projects. Column 4 includes, in some cases, further information about the proposal, differences between the proposal and the ASHRAE requirement, or a reference to further documentation.

    Please refer back to the LEED v4 web-based reference guide (Further Explanation > International Tips > Europe) for further information on the regional alternative compliance path.

    Additionally, for projects using the Performance Option for compliance with EAp2: Minimum Energy Performance and EAc1: Optimize Energy Performance, the documentation must also use the calculated U-factor for fenestration products including windows and skylights based on either the LBNL Windows 6 program, or a simulation software program that approximates the NFRC rating methodologies. Alternatively, a narrative shall be provided supporting the claim that the fenestration U-factor used in the model is similar to the values that would be achieved using the NFRC rating. The CE-marked fenestration does not account for thermal bridging and seasonal performance in the same way as the NFRC rating, and when accounted for in the energy model, has been observed to lead to savings that exceed those claimed for the same fenestration rated under the NFRC ratings."
    Campus Applicable
    No
    Internationally Applicable:
    No
    7/10/2020Updated: 7/10/2020
    Form Update
    Description of change:
    add "Dining Area" space type to the dropdown list under "Table 9.6.1 Space Type" in the lighting tab.
    Campus Applicable
    No
    Internationally Applicable:
    No
    7/1/2014Updated: 3/29/2018
    Regional ACP
    Description of change:
    Add the following as a USGBC-approved equivalent standard for projects outside the U.S.

    "Projects in Canada may instead demonstrate a percentage improvement in the proposed building performance rating compared with the baseline according to the National Energy Code for Buildings (NECB) 2011. The same percentage improvement in energy performance is required to meet the Prerequisite, and the same points for percentage improvement in energy performance are applicable for the Credit.

    The following conditions (where applicable) must be met. Note that unless otherwise noted, CanQUEST (the Canadian energy modelling software based on eQUEST that performs NECB 2011 compliance runs) does not implement these conditions correctly and would require corresponding modifications to the Reference case.

    1. Comply with mandatory requirements of ASHRAE 90.1-2010
    ASHRAE 90.1-2010 mandatory requirements must be met, in addition to the performance path limitations referenced in the NECB 2011 Sections 3.4.1.2, 5.4.1.2 and 6.4.1.2. In cases where ASHRAE and the NECBC reference requirements concerning the same item, the more stringent requirement shall be adhered to.

    2. Apply fenestration area convention similar to ASHRAE 90.1-2010
    Maintain the same FWR (as defined by NECB, including doors) for the Reference as exists in the Proposed Design, up to the prescribed maximum. If the Proposed Design’s FWR exceeds the prescribed FWR, scale down the fenestrations in the Reference case accordingly.

    3. Apply skylight area convention similar to ASHRAE 90.1-2010
    Maintain the same SRR for the Reference as exists in the Proposed Design, up to the prescribed 5% maximum. If the Proposed Design’s SRR exceeds 5%, scale down the skylights in the Reference case accordingly.

    4. Model proposed and reference outside air similar to ASHRAE 90.1-2010
    Proposed and reference (baseline) outside air rates shall be modelled as per ASHRAE 90.1 – 2010 (G3.1.2.6).

    5. Apply ASHRAE kitchen exhaust demand ventilation requirements
    Provide for the same demand ventilation requirements as described in ASHRAE Appendix G3.1.1.d.

    6. Apply ASHRAE’s chiller heat recovery requirements
    Provide for the same chiller heat recovery requirements as applies to ASHRAE.

    7. Apply supply air temperature reset controlled based on warmest zone
    Reset the minimum supply air temperature to satisfy the cooling requirements of the warmest zone, as stipulated in NECB Section 5.2.8.8. Note that this control setting is already corrected in CanQUEST for the Reference case.

    8. Account for uninsulated structural penetrations if they exceed 2% of net wall area
    The 2% allowance may be applied, but based on the net opaque wall area, not the entire building envelope area.

    9. Follow ASHRAE/LEED rules for renovations to existing buildings
    Model existing components consistent with ASHRAE and LEED provisions.

    10. Account for all anticipated energy use in building
    Fully account for all energy end-uses in the energy performance modeling."
    Campus Applicable
    No
    Internationally Applicable:
    Yes
    7/25/2017Updated: 8/1/2017
    Form Update
    Description of change:
    v2009/v4 Minimum Energy Performance Calculator:
    • Fixed formatting issues in the Performance Outputs tab
    • Corrected calculation within the Service Water Heating tab.
    Campus Applicable
    Yes
    Internationally Applicable:
    Yes
    4/14/2017Updated: 4/24/2017
    Reference Guide Correction
    Description of change:
    In the Project Type Variations section, under Path 1. ASHRAE 90.1-2010, Appendix G, at the bottom of the section with the title "Energy Rates" in italics, insert the following guidance for projects where no tariffs or rates are available from the district energy system servicing the project:

    "Energy Rates for Path 1:
    • If tariffs or rates are not available from the district plant servicing the project (e.g. for campus or military plants), calculate the rates based on the virtual electric and fossil fuel rates from the model:
    o If a flat rate structure is being used for all energy sources (meaning the cost per unit energy is the same throughout the year, and there are no demand charges), then these flat rates simply become the virtual energy rates for the project.
    o Otherwise, if all energy rate structures are not flat, then a preliminary run of the Option 1 Baseline Case energy model must first be completed to identify the virtual electric and fossil fuel rates for the project. For this preliminary run only, the rate for the DES-supplied energy may be left blank, or may be entered as any value.
    o Once all the virtual energy rates are known for electricity and fossil fuel, the virtual DES rates for both the Baseline and Proposed Case are then derived as follows:
    District Chilled Water Rate:
    Units of $/(Btu x 106) = Virtual Electric Rate (in $/kWh) x 71
    Units of $/ton-hour = Virtual Electric Rate (in $/kWh) x 0.85
    Units of $/kWh = Virtual Electric Rate (in $/kWh) x 0.24
    District Hot Water Rate:
    Units of $/(Btu x 106) = Virtual Fuel Rate (in $/(Btu x 106)) x 1.59 + Virtual Electric Rate (in $/kWh) x 3
    Units of $/kWh = Virtual Fuel Rate (in $/kWh) x 1.59 + Virtual Electric Rate (in $/kWh) x 0.01
    Units of $/therm = Virtual Fuel Rate (in $/therm) x 1.59 + Virtual Electric Rate (in $/kWh x 0.3)

    District Steam Rate:
    Units of $/ (Btu x 106) = Virtual Fuel Rate (in $/(Btu x 106)) x 1.81 + Virtual Electric Rate (in $/kWh) x 3
    Units of $/kWh = Virtual Fuel Rate (in $/kWh) x 1.81 + Virtual Electric Rate (in $/kWh) x 0.01
    Units of $/therm = Virtual Fuel Rate (in $/therm) x 1.81 + Virtual Electric Rate (in $/kWh x 0.3)

    o Exception: to obtain the virtual fuel rate when the connected building does not use fossil fuel but the DES central plant does, use a flat rate consistent with the central plant rates or the historic average local market rates (no preliminary model run is needed). The virtual fuel rates must match in the Baseline and Proposed Case.
    o The virtual DES rates are then input into the modeling software for each DES source and used for the remainder of the process. Alternatively, the virtual DES rates may be used to calculate the DES energy costs directly by multiplying the DES energy consumption for each DES source by its virtual DES rate. All virtual DES energy rates must be identical in the Baseline and Proposed Case."

    Campus Applicable
    No
    Internationally Applicable:
    Yes
    4/14/2017Updated: 4/19/2017
    Form Update
    Description of change:
    • Functionality has been added to allow for eQUEST and TRACE files to be automatically imported into the calculator.
    • Bug fixes for the Opaque Assemblies, Shading and Fenestration, and Schedules tabs.
    • Bug fixes for the Service Hot Water Flow calculations.
    • Bug Fixes for Schedules tab
    • v2009 Only – Bug fix to allow macros to make automatic changes for LEED v3 BD+C: Multifamily Midrise
    • v2009 Only – ASHRAE 90.1-2010 requirement has been removed from the General HVAC tab confirmation boxes.
    Campus Applicable
    Yes
    Internationally Applicable:
    Yes
    9/13/2016Updated: 11/15/2016
    Form Update
    Description of change:
    (calculator dated 8/23/2016, published 9/13/2016)
    • Baseline System Helpful Notes Section has been updated in the Water-Side HVAC tab
    • District energy system (DES) Path 3 calculations have been revised
    • Optional notes column has been added to each tab for project teams to provide further clarification
    • Exceptional calculation formulas have been revised
    • Performance upgrade to the General Information tab has been implemented
    • Baseline case fan power formulas have been updated
    • Lighting table language has been updated (v2009)
    • Exterior lighting quality assurance (QA) checks have been updated
    • Further guidance has been provided for determining unitary cooling efficiency in the Helpful Notes section of the Air-Side HVAC tab
    • Performance Outputs tab formulas have been revised to be more robust for multiple building projects
    • Summary tab formulas have been revised to reference total cost savings with and without renewable energy contribution
    • Receptacle Equipment Modeling Method tables have been revised to be more robust for multiple building projects
    Campus Applicable
    No
    Internationally Applicable:
    No
    1/15/2016Updated: 4/7/2016
    Form Update
    Description of change:
    Campus Applicable
    No
    Internationally Applicable:
    No
    7/1/2015Updated: 10/2/2015
    Reference Guide Correction
    Description of change:
    After the first paragraph, add the following:

    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
    10/1/2014Updated: 2/14/2015
    Reference Guide Correction
    Description of change:
    Revise footnote #1 to:

    ANSI/ASHRAE/IES 90.1–2010 Final Determination Quantitative Analysis, p. 29, https://www.energycodes.gov/sites/default/files/documents/BECP_FinalQuan... (accessed July 11, 2014).
    Campus Applicable
    No
    Internationally Applicable:
    Yes
    7/1/2015
    LEED Interpretation
    Inquiry:

    For projects located in Seattle, can the 2012 Seattle Energy Code be used to demonstrate compliance in lieu of ASHRAE 90.1-2010?

    Ruling:

    Instead of ASHRAE 90.1-2010 Appendix G, projects in Seattle may demonstrate compliance with with all mandatory provisions of the 2012 Seattle Energy Code AND demonstrate a percentage improvement in the proposed building performance rating compared with the baseline according to the 2012 Seattle Energy Code Total Building Performance (Section C407). The same percentage improvement in energy performance is required to meet the Prerequisite, and the same points for percentage improvement in energy performance are applicable for the Credit.
    The following conditions (where applicable) must be met:
    • Energy Cost shall be used as the performance metric rather than site energy (versus Section C407.3 which indicates that site energy shall be used). Exception: A Pilot ACP allowing alternate metrics may be applied as applicable.
    • Model proposed and reference outside air similar to ASHRAE 90.1-2010.
    o Proposed and reference (baseline) outside air rates shall be modeled as per ASHRAE 90.1 – 2010 (G3.1.2.6).
    • In addition to the documentation requirements established by the Seattle Energy Code, all required LEED documentation must be provided (and must include the same information as is required for ASHRAE 90.1-2010, with all baseline and proposed inputs shown) including:
    o The LEED EAp2: Minimum Energy Performance form
    o The LEED EAc1: Optimize Energy Performance form
    o The LEED v4 Minimum Energy Performance Calculator (http://www.usgbc.org/resources/minimum-energy-performance-calculator) (or a document with equivalent information) with Baseline inputs updated to refer to Seattle Energy Code.
    • Multifamily high-rise and dormitory projects are not eligible for this alternative compliance path.
    • BD+C: The equivalence applies for new construction only and does not apply to major renovations.
    • ID+C: The energy model must be modeled using the Title-24 new construction requirements for HVAC, DHW, lighting and envelope.

    Campus Applicable
    Yes
    Internationally Applicable:
    No
    1/10/2020
    LEED Interpretation
    Inquiry:

    Our project is located in California and subject to compliance with Title 24 2019. Title 24 2019 has requirements for lighting power density more stringent than those requirements in ASHRAE 90.1-2010, and unfinished spaces in our project will be subject to the Title 24 2019 requirements.

    For LEED credit compliance, our team plans to follow ASHRAE 90.1-2010 modeling. How can we document credit for Title 24 2019 compliant lighting in unfinished spaces?

    Ruling:

    Building Type*
    Unfinished Space Lighting Power Density

    Automotive Facility
    0.70

    Convention Center
    0.80

    Courthouse
    0.80

    Dining: Bar Lounge/Leisure
    0.75

    Dining: Cafeteria/Fast Food
    0.70

    Dining: Family
    0.70

    Dormitory
    0.61

    Exercise Center
    0.70

    Fire Station
    0.71

    Gymnasium
    0.80

    Healthcare Clinic
    0.87

    Hospital
    1.05

    Hotel
    1.00

    Library
    0.95

    Manufacturing Facility
    0.90

    Motel
    0.88

    Motion Picture Theater
    0.75

    Multifamily
    0.60

    Museum
    1.06

    Office
    0.72

    Parking Garage
    0.17

    Penitentiary
    0.97

    Performing Arts Theater
    1.10

    Police Station
    0.96

    Post Office
    0.8

    Religious Building
    0.85

    Retail: Grocery
    1.05

    Retail
    1.00

    School/University
    0.72

    Sports Arena
    0.78

    Town Hall
    0.85

    Transportation
    0.60

    Warehouse
    0.55

    Workshop
    1.10

    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
    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
    10/2/2017
    LEED Interpretation
    Inquiry:

    Our project is in the process of determining the exterior lighting power allowance for an ASHRAE 90.1-2010 Appendix G energy model. What qualifies within LEED as a surface that is “designed to be illuminated” per ASHRAE 90.1-2010 Section 9.4.3?

    Ruling:

    ASHRAE 90.1-2010 Interpretation 33 states: “It was the intent of the Standard that spaces, areas, or applications that claim Lighting Power Density for compliance or performance rating have been designed to some reasonable lighting design criteria that meets industry standards, good design practice, and client desires.” Aligning with this intent, the average illumination of a surface “designed to be illuminated” must meet or exceed published minimum recommended illumination levels for the surface type (such as the IESNA Handbook, Zumtobel – the Lighting Handbook, EN1264-2, local code regulations, etc.).

    Campus Applicable
    No
    Internationally Applicable:
    Yes
    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
    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
    7/1/2015
    LEED Interpretation
    Inquiry:

    For projects located in California, can the 2013 Title 24 Part 6 California Energy Code be used to demonstrate compliance in lieu of ASHRAE 90.1-2010?

    Ruling:

    Instead of ASHRAE 90.1-2010 Appendix G, projects in California may demonstrate compliance with the 2013 Title 24 Part 6 California Energy Code using the Performance method. The same percentage improvement in energy performance is required to meet the Prerequisite, and the same points for percentage improvement in energy performance are applicable for the Credit.
    The following conditions (where applicable) must be met:
    • Energy Cost shall be used as the performance metric rather than TDV energy. Exception: A Pilot ACP allowing alternate metrics may be applied as applicable.
    • Model all process energy consumption within and associated with the building as designed. Model all enclosed building spaces within and associated with the building even if the space types are not regulated by Title-24.
    • BD+C: Major renovations must be modeled using the Title-24 new construction modeling requirements for HVAC, DHW, and lighting (as opposed to existing conditions). However, for LEED-BD&C, the baseline envelope conditions may be modeled using existing conditions prior to renovation.
    • ID+C: The energy model must be modeled using the Title-24 new construction requirements for HVAC, DHW, lighting and envelope.

    Campus Applicable
    Yes
    Internationally Applicable:
    No
    7/8/2017
    LEED Interpretation
    Inquiry:

    ASHRAE 90.1-2010 mandatory requirement 8.4.2 Automatic Receptacle Control applies to 125 Volt receptacles in private offices, open offices, and computer classrooms. Are there any cases where exceptions to these mandatory requirements will be allowed?

    Ruling:

    The project team is requesting clarification regarding how to model spaces where mandatory ASHRAE 90.1 receptacle controls are not implemented. Projects using one of the following two compliance paths are exempt from the receptacle control requirements:

    1. Path 1: Projects Using Option 1. Whole Building Energy Simulation may model a penalty in the Proposed model for the spaces where mandatory ASHRAE 90.1 receptacle controls are not implemented. The following modeling requirements apply:
    • The receptacle power density modeled for these spaces shall be the greater of 0.75 Watts per square foot (8.1 Watts per square meter) or the design coincident peak receptacle power density (if known).
    • The receptacle schedule modeled in the Baseline for these spaces shall have a minimum Equivalent Full Load Hours of operation no less than:
    o The ASHRAE 90.1-2010 User’s Manual default schedule for office occupancy (2,920 Equivalent Full Load Hours per year)
    OR
    o 120% of the occupied hours of operation for the facility
    OR
    o Detailed justification shall be provided supporting an alternate schedule.

    • The Proposed model shall include either a 20% increase in the receptacle power density for these spaces OR a 20% increase in the scheduled receptacle Equivalent Full Load Hours of Operation versus the Baseline model.

    2. Path 2: Projects must demonstrate that the project has implemented efficiency measures that will achieve an equal or greater reduction in receptacle energy consumption, and will persist for a similar timeframe to those achieved by ASHRAE 90.1-2010 Section 8.4.2. It is recommended that a Credit Interpretation Request be submitted when pursuing this approach. The project must provide documentation regarding the receptacle equipment controls that will be implemented for the project; and must provide justification supporting the claim that the savings over the life of the efficiency measure will be similar to those anticipated for a project compliant with Section 90.1-2010 Section 8.4.2. Note: The baseline and proposed receptacle energy consumption for these spaces must be modeled identically if using this approach; the project is not eligible for any further receptacle savings in these spaces using the Exceptional Calculation Method.

    Update 11/9/20:
    Where ASHRAE 90.1 receptacle controls are not implemented in accordance with Section 8.4.2 mandatory requirements, LEED v4.1 projects may apply either Path 1 or Path 2, subject to the following requirements for Path 1:
    • Path 1: LEED v4.1 projects Using the Appendix G Performance Rating Method may model a penalty in the energy model. The following modeling requirements apply:
    o The Proposed receptacle power density modeled for these spaces shall be the greater of 0.75 Watts per square foot (8.1 Watts per square meter) or the design coincident peak receptacle power density (if known)
    o The receptacle schedule modeled in the Proposed design for these spaces shall have a minimum Equivalent Full Load Hours of operation no less than: the ASHRAE 90.1-2016 User’s Manual default schedule for office occupancy (2,920 Equivalent Full Load Hours per year); or 120% of the occupied hours of operation for the facility; or detailed justification shall be provided supporting an alternate schedule.
    o The Baseline model shall include either a 20% decrease in the receptacle power density for these spaces OR a 20% decrease in the scheduled receptacle Equivalent Full Load Hours of Operation versus the Proposed model.

    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
    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
    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
    See all forum discussions about this credit »

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    Intent

    To reduce the environmental and economic harms of excessive energy use by achieving a minimum level of energy efficiency for the building and its systems.

    Requirements

    Option 1. Whole-building energy simulation

    Demonstrate an improvement of 5% for new construction, 3% for major renovations, or 2% for core and shell projects in the proposed building performance rating compared with the baseline building performance rating. Calculate the baseline building performance according to ANSI/ASHRAE/IESNA Standard 90.1–2010, Appendix G, with errata (or a USGBC-approved equivalent standard for projects outside the U.S.), using a simulation model.

    Projects must meet the minimum percentage savings before taking credit for renewable energy systems.

    The proposed design must meet the following criteria:

    Document the energy modeling input assumptions for unregulated loads. Unregulated loads should be modeled accurately to reflect the actual expected energy consumption of the building.

    If unregulated loads are not identical for both the baseline and the proposed building performance rating, and the simulation program cannot accurately model the savings, follow the exceptional calculation method (ANSI/ASHRAE/IESNA Standard 90.1–2010, G2.5). Alternatively, use the COMNET Modeling Guidelines and Procedures to document measures that reduce unregulated loads.

    OR

    Option 2. Prescriptive compliance: ASHRAE 50% Advanced Energy Design Guide

    Comply with the mandatory and prescriptive provisions of ANSI/ASHRAE/IESNA Standard 90.1–2010, with errata (or a USGBC-approved equivalent standard for projects outside the U.S.).

    Comply with the HVAC and service water heating requirements, including equipment efficiency, economizers, ventilation, and ducts and dampers, in Chapter 4, Design Strategies and Recommendations by Climate Zone, for the appropriate ASHRAE 50% Advanced Energy Design Guide and climate zone:

    • ASHRAE 50% Advanced Energy Design Guide for Small to Medium Office Buildings, for office buildings smaller than 100,000 square feet (9 290 square meters);
    • ASHRAE 50% Advanced Energy Design Guide for Medium to Large Box Retail Buildings, for retail buildings with 20,000 to 100,000 square feet (1 860 to 9 290 square meters);
    • ASHRAE 50% Advanced Energy Design Guide for K–12 School Buildings; or
    • ASHRAE 50% Advanced Energy Design Guide for Large Hospitals. Over 100,000 square feet (9 290 square meters)

    For projects outside the U.S., consult ASHRAE/ASHRAE/IESNA Standard 90.1–2010, Appendixes B and D, to determine the appropriate climate zone.

    OR

    Option 3. Prescriptive compliance: Advanced BuildingsTM Core PerformanceTM Guide

    Comply with the mandatory and prescriptive provisions of ANSI/ASHRAE/IESNA Standard 90.1-2010, with errata (or USGBC approved equivalent standard for projects outside the U.S.).

    Comply with Section 1: Design Process Strategies, Section 2: Core Performance Requirements, and the following three strategies from Section 3: Enhanced Performance Strategies, as applicable. Where standards conflict, follow the more stringent of the two. For projects outside the U.S., consult ANSI/ASHRAE/IESNA Standard 90.1-2010, Appendixes B and D, to determine the appropriate climate zone.

    3.5 Supply Air Temperature Reset (VAV)
    3.9 Premium Economizer Performance
    3.10 Variable Speed Control

    To be eligible for Option 3, the project must be less than 100,000 square feet (9 290 square meters).

    Note: Healthcare, Warehouse or Laboratory projects are ineligible for Option 3.

    Alternative Compliance Paths (ACPs)

    Canada ACP - NECB

    Projects in Canada may instead demonstrate a percentage improvement in the proposed building performance rating compared with the baseline according to the National Energy Code for Buildings (NECB) 2011. The same percentage cost improvement in energy performance is required to meet the Prerequisite, and the same points for cost percentage improvement in energy performance are applicable for the Credit.

    The following conditions (where applicable) must be met. Note that unless otherwise noted, CanQUEST (the Canadian energy modelling software based on eQUEST that performs NECB 2011 compliance runs) does not implement many of these conditions correctly and would require corresponding modifications to the Reference case.

    1. Comply with mandatory requirements of ASHRAE 90.1-2010
    2. ASHRAE 90.1-2010 mandatory requirements must be met, in addition to the performance path limitations referenced in the NECB 2011 Sections 3.4.1.2, 5.4.1.2 and 6.4.1.2. In cases where ASHRAE and the NECBC reference requirements concerning the same item, the more stringent requirement shall be adhered to.

      The following exceptions apply:

    • ASHRAE 90.1-2010 mandatory items 6.4.3.9, 9.4.1.2b, 9.4.1.4, 9.4.1.5, 9.4.3
  • Apply fenestration area convention similar to ASHRAE 90.1-2010
  • Maintain the same FWR (as defined by NECB, including doors) for the Reference as exists in the Proposed Design, up to the prescribed maximum. If the Proposed Design’s FWR exceeds the prescribed FWR, scale down the fenestrations in the Reference case accordingly.

  • Apply skylight area convention similar to ASHRAE 90.1-2010
  • Maintain the same SRR for the Reference as exists in the Proposed Design, up to the prescribed 5% maximum. If the Proposed Design’s SRR exceeds 5%, scale down the skylights in the Reference case accordingly.

  • Model proposed and reference outside air similar to ASHRAE 90.1-2010
  • Proposed and reference (baseline) outside air rates shall be modeled as per ASHRAE 90.1 – 2010 (G3.1.2.6).

  • Apply ASHRAE kitchen exhaust demand ventilation requirements
  • Provide for the same demand ventilation requirements as described in ASHRAE Appendix G3.1.1.d.

  • Apply ASHRAE’s chiller heat recovery requirements
  • Provide for the same chiller heat recovery requirements as applies to ASHRAE.

  • Apply supply air temperature reset controlled based on warmest zone
  • Reset the minimum supply air temperature to satisfy the cooling requirements of the warmest zone, as stipulated in NECB Section 5.2.8.8. Note that this control setting is already corrected in CanQUEST for the Reference case.

  • Account for uninsulated structural penetrations if they exceed 2% of net wall area
  • The 2% allowance may be applied, but based on the net opaque wall area, not the entire building envelope area.

  • Follow ASHRAE/LEED rules for renovations to existing buildings
  • Model existing components consistent with ASHRAE and LEED provisions.

  • Account for all anticipated energy use in building
  • Fully account for all energy end-uses in the energy performance modelling.

  • DES Systems are to be modeled according to Option 1, Path 1 or Option 1, Path 2 as indicated in the LEED v4 Reference Guide
  • The following exceptions apply:

    • Option 1, Path 1 - Do not apply ASHRAE 90.1-2010 requirements for purchased heating and cooling. Under this ACP, purchased heating and cooling (as applicable) are modeled as cost-neutral in the baseline and proposed case. Local rates for purchased heating (fossil fuel based) and cooling are used to establish the purchased heating and cooling costs. The energy model's scope accounts for only downstream equipment, plus purchased heating and cooling. NECB clause 8.4.3.6 does not apply for LEED projects.
    • Model baseline systems in accordance with NECB requirements, with DX coils replaced with chilled water coils if purchased cooling is present and fossil-fired furnaces replaced with hot water coils if purchased heating is present.
    • Option 1, Path 2: Do not apply ASHRAE 90.1-2010 requirements for baseline systems. Model baseline systems in accordance with NECB requirements for onsite generated equipment (i.e. assume building is not connected to a DES and the proposed building is modeled with a virtual plant according to LEED v4 Reference Guide requirements).

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    Do the required savings for this prerequisite (and credit) need to come only from building energy, or also process loads?

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    11/9/2020Updated: 12/7/2020
    Regional ACP
    Description of change:
    See the Resource Library for full ACP requirements and documentation.
    Campus Applicable
    No
    Internationally Applicable:
    No
    4/6/2018Updated: 11/6/2020
    Reference Guide Correction
    Description of change:
    Add the following to the bottom of the International Tips section:

    "Developed by members of the European Roundtable, this table provides further guidance for project teams in Europe wishing to use European standards in lieu of certain ASHRAE 90.1-2010 mandatory provisions in LEED v4. The guidance covers ASHRAE 90.1-2010 Mandatory Provision Sections 5.4, 6.4, 7.4, 8.4, 9.4 and 10. Column 1 of the table references the specific subsection used in ASHRAE 90.1-2010. Column 2 displays the requirement as written in ASHRAE 90.1-2010. Column 3 outlines the compliance pathway available for European projects. Column 4 includes, in some cases, further information about the proposal, differences between the proposal and the ASHRAE requirement, or a reference to further documentation.

    Please refer back to the LEED v4 web-based reference guide (Further Explanation > International Tips > Europe) for further information on the regional alternative compliance path.

    Additionally, for projects using the Performance Option for compliance with EAp2: Minimum Energy Performance and EAc1: Optimize Energy Performance, the documentation must also use the calculated U-factor for fenestration products including windows and skylights based on either the LBNL Windows 6 program, or a simulation software program that approximates the NFRC rating methodologies. Alternatively, a narrative shall be provided supporting the claim that the fenestration U-factor used in the model is similar to the values that would be achieved using the NFRC rating. The CE-marked fenestration does not account for thermal bridging and seasonal performance in the same way as the NFRC rating, and when accounted for in the energy model, has been observed to lead to savings that exceed those claimed for the same fenestration rated under the NFRC ratings."
    Campus Applicable
    No
    Internationally Applicable:
    No
    4/6/2018Updated: 11/6/2020
    Regional ACP
    Description of change:
    Add the following to the bottom of the International Tips section:

    "Developed by members of the European Roundtable, this table provides further guidance for project teams in Europe wishing to use European standards in lieu of certain ASHRAE 90.1-2010 mandatory provisions in LEED v4. The guidance covers ASHRAE 90.1-2010 Mandatory Provision Sections 5.4, 6.4, 7.4, 8.4, 9.4 and 10. Column 1 of the table references the specific subsection used in ASHRAE 90.1-2010. Column 2 displays the requirement as written in ASHRAE 90.1-2010. Column 3 outlines the compliance pathway available for European projects. Column 4 includes, in some cases, further information about the proposal, differences between the proposal and the ASHRAE requirement, or a reference to further documentation.

    Please refer back to the LEED v4 web-based reference guide (Further Explanation > International Tips > Europe) for further information on the regional alternative compliance path.

    Additionally, for projects using the Performance Option for compliance with EAp2: Minimum Energy Performance and EAc1: Optimize Energy Performance, the documentation must also use the calculated U-factor for fenestration products including windows and skylights based on either the LBNL Windows 6 program, or a simulation software program that approximates the NFRC rating methodologies. Alternatively, a narrative shall be provided supporting the claim that the fenestration U-factor used in the model is similar to the values that would be achieved using the NFRC rating. The CE-marked fenestration does not account for thermal bridging and seasonal performance in the same way as the NFRC rating, and when accounted for in the energy model, has been observed to lead to savings that exceed those claimed for the same fenestration rated under the NFRC ratings."
    Campus Applicable
    No
    Internationally Applicable:
    No
    7/10/2020Updated: 7/10/2020
    Form Update
    Description of change:
    add "Dining Area" space type to the dropdown list under "Table 9.6.1 Space Type" in the lighting tab.
    Campus Applicable
    No
    Internationally Applicable:
    No
    7/1/2014Updated: 3/29/2018
    Regional ACP
    Description of change:
    Add the following as a USGBC-approved equivalent standard for projects outside the U.S.

    "Projects in Canada may instead demonstrate a percentage improvement in the proposed building performance rating compared with the baseline according to the National Energy Code for Buildings (NECB) 2011. The same percentage improvement in energy performance is required to meet the Prerequisite, and the same points for percentage improvement in energy performance are applicable for the Credit.

    The following conditions (where applicable) must be met. Note that unless otherwise noted, CanQUEST (the Canadian energy modelling software based on eQUEST that performs NECB 2011 compliance runs) does not implement these conditions correctly and would require corresponding modifications to the Reference case.

    1. Comply with mandatory requirements of ASHRAE 90.1-2010
    ASHRAE 90.1-2010 mandatory requirements must be met, in addition to the performance path limitations referenced in the NECB 2011 Sections 3.4.1.2, 5.4.1.2 and 6.4.1.2. In cases where ASHRAE and the NECBC reference requirements concerning the same item, the more stringent requirement shall be adhered to.

    2. Apply fenestration area convention similar to ASHRAE 90.1-2010
    Maintain the same FWR (as defined by NECB, including doors) for the Reference as exists in the Proposed Design, up to the prescribed maximum. If the Proposed Design’s FWR exceeds the prescribed FWR, scale down the fenestrations in the Reference case accordingly.

    3. Apply skylight area convention similar to ASHRAE 90.1-2010
    Maintain the same SRR for the Reference as exists in the Proposed Design, up to the prescribed 5% maximum. If the Proposed Design’s SRR exceeds 5%, scale down the skylights in the Reference case accordingly.

    4. Model proposed and reference outside air similar to ASHRAE 90.1-2010
    Proposed and reference (baseline) outside air rates shall be modelled as per ASHRAE 90.1 – 2010 (G3.1.2.6).

    5. Apply ASHRAE kitchen exhaust demand ventilation requirements
    Provide for the same demand ventilation requirements as described in ASHRAE Appendix G3.1.1.d.

    6. Apply ASHRAE’s chiller heat recovery requirements
    Provide for the same chiller heat recovery requirements as applies to ASHRAE.

    7. Apply supply air temperature reset controlled based on warmest zone
    Reset the minimum supply air temperature to satisfy the cooling requirements of the warmest zone, as stipulated in NECB Section 5.2.8.8. Note that this control setting is already corrected in CanQUEST for the Reference case.

    8. Account for uninsulated structural penetrations if they exceed 2% of net wall area
    The 2% allowance may be applied, but based on the net opaque wall area, not the entire building envelope area.

    9. Follow ASHRAE/LEED rules for renovations to existing buildings
    Model existing components consistent with ASHRAE and LEED provisions.

    10. Account for all anticipated energy use in building
    Fully account for all energy end-uses in the energy performance modeling."
    Campus Applicable
    No
    Internationally Applicable:
    Yes
    7/25/2017Updated: 8/1/2017
    Form Update
    Description of change:
    v2009/v4 Minimum Energy Performance Calculator:
    • Fixed formatting issues in the Performance Outputs tab
    • Corrected calculation within the Service Water Heating tab.
    Campus Applicable
    Yes
    Internationally Applicable:
    Yes
    4/14/2017Updated: 4/24/2017
    Reference Guide Correction
    Description of change:
    In the Project Type Variations section, under Path 1. ASHRAE 90.1-2010, Appendix G, at the bottom of the section with the title "Energy Rates" in italics, insert the following guidance for projects where no tariffs or rates are available from the district energy system servicing the project:

    "Energy Rates for Path 1:
    • If tariffs or rates are not available from the district plant servicing the project (e.g. for campus or military plants), calculate the rates based on the virtual electric and fossil fuel rates from the model:
    o If a flat rate structure is being used for all energy sources (meaning the cost per unit energy is the same throughout the year, and there are no demand charges), then these flat rates simply become the virtual energy rates for the project.
    o Otherwise, if all energy rate structures are not flat, then a preliminary run of the Option 1 Baseline Case energy model must first be completed to identify the virtual electric and fossil fuel rates for the project. For this preliminary run only, the rate for the DES-supplied energy may be left blank, or may be entered as any value.
    o Once all the virtual energy rates are known for electricity and fossil fuel, the virtual DES rates for both the Baseline and Proposed Case are then derived as follows:
    District Chilled Water Rate:
    Units of $/(Btu x 106) = Virtual Electric Rate (in $/kWh) x 71
    Units of $/ton-hour = Virtual Electric Rate (in $/kWh) x 0.85
    Units of $/kWh = Virtual Electric Rate (in $/kWh) x 0.24
    District Hot Water Rate:
    Units of $/(Btu x 106) = Virtual Fuel Rate (in $/(Btu x 106)) x 1.59 + Virtual Electric Rate (in $/kWh) x 3
    Units of $/kWh = Virtual Fuel Rate (in $/kWh) x 1.59 + Virtual Electric Rate (in $/kWh) x 0.01
    Units of $/therm = Virtual Fuel Rate (in $/therm) x 1.59 + Virtual Electric Rate (in $/kWh x 0.3)

    District Steam Rate:
    Units of $/ (Btu x 106) = Virtual Fuel Rate (in $/(Btu x 106)) x 1.81 + Virtual Electric Rate (in $/kWh) x 3
    Units of $/kWh = Virtual Fuel Rate (in $/kWh) x 1.81 + Virtual Electric Rate (in $/kWh) x 0.01
    Units of $/therm = Virtual Fuel Rate (in $/therm) x 1.81 + Virtual Electric Rate (in $/kWh x 0.3)

    o Exception: to obtain the virtual fuel rate when the connected building does not use fossil fuel but the DES central plant does, use a flat rate consistent with the central plant rates or the historic average local market rates (no preliminary model run is needed). The virtual fuel rates must match in the Baseline and Proposed Case.
    o The virtual DES rates are then input into the modeling software for each DES source and used for the remainder of the process. Alternatively, the virtual DES rates may be used to calculate the DES energy costs directly by multiplying the DES energy consumption for each DES source by its virtual DES rate. All virtual DES energy rates must be identical in the Baseline and Proposed Case."

    Campus Applicable
    No
    Internationally Applicable:
    Yes
    4/14/2017Updated: 4/19/2017
    Form Update
    Description of change:
    • Functionality has been added to allow for eQUEST and TRACE files to be automatically imported into the calculator.
    • Bug fixes for the Opaque Assemblies, Shading and Fenestration, and Schedules tabs.
    • Bug fixes for the Service Hot Water Flow calculations.
    • Bug Fixes for Schedules tab
    • v2009 Only – Bug fix to allow macros to make automatic changes for LEED v3 BD+C: Multifamily Midrise
    • v2009 Only – ASHRAE 90.1-2010 requirement has been removed from the General HVAC tab confirmation boxes.
    Campus Applicable
    Yes
    Internationally Applicable:
    Yes
    9/13/2016Updated: 11/15/2016
    Form Update
    Description of change:
    (calculator dated 8/23/2016, published 9/13/2016)
    • Baseline System Helpful Notes Section has been updated in the Water-Side HVAC tab
    • District energy system (DES) Path 3 calculations have been revised
    • Optional notes column has been added to each tab for project teams to provide further clarification
    • Exceptional calculation formulas have been revised
    • Performance upgrade to the General Information tab has been implemented
    • Baseline case fan power formulas have been updated
    • Lighting table language has been updated (v2009)
    • Exterior lighting quality assurance (QA) checks have been updated
    • Further guidance has been provided for determining unitary cooling efficiency in the Helpful Notes section of the Air-Side HVAC tab
    • Performance Outputs tab formulas have been revised to be more robust for multiple building projects
    • Summary tab formulas have been revised to reference total cost savings with and without renewable energy contribution
    • Receptacle Equipment Modeling Method tables have been revised to be more robust for multiple building projects
    Campus Applicable
    No
    Internationally Applicable:
    No
    1/15/2016Updated: 4/7/2016
    Form Update
    Description of change:
    Campus Applicable
    No
    Internationally Applicable:
    No
    7/1/2015Updated: 10/2/2015
    Reference Guide Correction
    Description of change:
    After the first paragraph, add the following:

    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
    10/1/2014Updated: 2/14/2015
    Reference Guide Correction
    Description of change:
    Revise footnote #1 to:

    ANSI/ASHRAE/IES 90.1–2010 Final Determination Quantitative Analysis, p. 29, https://www.energycodes.gov/sites/default/files/documents/BECP_FinalQuan... (accessed July 11, 2014).
    Campus Applicable
    No
    Internationally Applicable:
    Yes
    7/1/2015
    LEED Interpretation
    Inquiry:

    For projects located in Seattle, can the 2012 Seattle Energy Code be used to demonstrate compliance in lieu of ASHRAE 90.1-2010?

    Ruling:

    Instead of ASHRAE 90.1-2010 Appendix G, projects in Seattle may demonstrate compliance with with all mandatory provisions of the 2012 Seattle Energy Code AND demonstrate a percentage improvement in the proposed building performance rating compared with the baseline according to the 2012 Seattle Energy Code Total Building Performance (Section C407). The same percentage improvement in energy performance is required to meet the Prerequisite, and the same points for percentage improvement in energy performance are applicable for the Credit.
    The following conditions (where applicable) must be met:
    • Energy Cost shall be used as the performance metric rather than site energy (versus Section C407.3 which indicates that site energy shall be used). Exception: A Pilot ACP allowing alternate metrics may be applied as applicable.
    • Model proposed and reference outside air similar to ASHRAE 90.1-2010.
    o Proposed and reference (baseline) outside air rates shall be modeled as per ASHRAE 90.1 – 2010 (G3.1.2.6).
    • In addition to the documentation requirements established by the Seattle Energy Code, all required LEED documentation must be provided (and must include the same information as is required for ASHRAE 90.1-2010, with all baseline and proposed inputs shown) including:
    o The LEED EAp2: Minimum Energy Performance form
    o The LEED EAc1: Optimize Energy Performance form
    o The LEED v4 Minimum Energy Performance Calculator (http://www.usgbc.org/resources/minimum-energy-performance-calculator) (or a document with equivalent information) with Baseline inputs updated to refer to Seattle Energy Code.
    • Multifamily high-rise and dormitory projects are not eligible for this alternative compliance path.
    • BD+C: The equivalence applies for new construction only and does not apply to major renovations.
    • ID+C: The energy model must be modeled using the Title-24 new construction requirements for HVAC, DHW, lighting and envelope.

    Campus Applicable
    Yes
    Internationally Applicable:
    No
    1/10/2020
    LEED Interpretation
    Inquiry:

    Our project is located in California and subject to compliance with Title 24 2019. Title 24 2019 has requirements for lighting power density more stringent than those requirements in ASHRAE 90.1-2010, and unfinished spaces in our project will be subject to the Title 24 2019 requirements.

    For LEED credit compliance, our team plans to follow ASHRAE 90.1-2010 modeling. How can we document credit for Title 24 2019 compliant lighting in unfinished spaces?

    Ruling:

    Building Type*
    Unfinished Space Lighting Power Density

    Automotive Facility
    0.70

    Convention Center
    0.80

    Courthouse
    0.80

    Dining: Bar Lounge/Leisure
    0.75

    Dining: Cafeteria/Fast Food
    0.70

    Dining: Family
    0.70

    Dormitory
    0.61

    Exercise Center
    0.70

    Fire Station
    0.71

    Gymnasium
    0.80

    Healthcare Clinic
    0.87

    Hospital
    1.05

    Hotel
    1.00

    Library
    0.95

    Manufacturing Facility
    0.90

    Motel
    0.88

    Motion Picture Theater
    0.75

    Multifamily
    0.60

    Museum
    1.06

    Office
    0.72

    Parking Garage
    0.17

    Penitentiary
    0.97

    Performing Arts Theater
    1.10

    Police Station
    0.96

    Post Office
    0.8

    Religious Building
    0.85

    Retail: Grocery
    1.05

    Retail
    1.00

    School/University
    0.72

    Sports Arena
    0.78

    Town Hall
    0.85

    Transportation
    0.60

    Warehouse
    0.55

    Workshop
    1.10

    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
    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
    10/2/2017
    LEED Interpretation
    Inquiry:

    Our project is in the process of determining the exterior lighting power allowance for an ASHRAE 90.1-2010 Appendix G energy model. What qualifies within LEED as a surface that is “designed to be illuminated” per ASHRAE 90.1-2010 Section 9.4.3?

    Ruling:

    ASHRAE 90.1-2010 Interpretation 33 states: “It was the intent of the Standard that spaces, areas, or applications that claim Lighting Power Density for compliance or performance rating have been designed to some reasonable lighting design criteria that meets industry standards, good design practice, and client desires.” Aligning with this intent, the average illumination of a surface “designed to be illuminated” must meet or exceed published minimum recommended illumination levels for the surface type (such as the IESNA Handbook, Zumtobel – the Lighting Handbook, EN1264-2, local code regulations, etc.).

    Campus Applicable
    No
    Internationally Applicable:
    Yes
    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
    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
    7/1/2015
    LEED Interpretation
    Inquiry:

    For projects located in California, can the 2013 Title 24 Part 6 California Energy Code be used to demonstrate compliance in lieu of ASHRAE 90.1-2010?

    Ruling:

    Instead of ASHRAE 90.1-2010 Appendix G, projects in California may demonstrate compliance with the 2013 Title 24 Part 6 California Energy Code using the Performance method. The same percentage improvement in energy performance is required to meet the Prerequisite, and the same points for percentage improvement in energy performance are applicable for the Credit.
    The following conditions (where applicable) must be met:
    • Energy Cost shall be used as the performance metric rather than TDV energy. Exception: A Pilot ACP allowing alternate metrics may be applied as applicable.
    • Model all process energy consumption within and associated with the building as designed. Model all enclosed building spaces within and associated with the building even if the space types are not regulated by Title-24.
    • BD+C: Major renovations must be modeled using the Title-24 new construction modeling requirements for HVAC, DHW, and lighting (as opposed to existing conditions). However, for LEED-BD&C, the baseline envelope conditions may be modeled using existing conditions prior to renovation.
    • ID+C: The energy model must be modeled using the Title-24 new construction requirements for HVAC, DHW, lighting and envelope.

    Campus Applicable
    Yes
    Internationally Applicable:
    No
    7/8/2017
    LEED Interpretation
    Inquiry:

    ASHRAE 90.1-2010 mandatory requirement 8.4.2 Automatic Receptacle Control applies to 125 Volt receptacles in private offices, open offices, and computer classrooms. Are there any cases where exceptions to these mandatory requirements will be allowed?

    Ruling:

    The project team is requesting clarification regarding how to model spaces where mandatory ASHRAE 90.1 receptacle controls are not implemented. Projects using one of the following two compliance paths are exempt from the receptacle control requirements:

    1. Path 1: Projects Using Option 1. Whole Building Energy Simulation may model a penalty in the Proposed model for the spaces where mandatory ASHRAE 90.1 receptacle controls are not implemented. The following modeling requirements apply:
    • The receptacle power density modeled for these spaces shall be the greater of 0.75 Watts per square foot (8.1 Watts per square meter) or the design coincident peak receptacle power density (if known).
    • The receptacle schedule modeled in the Baseline for these spaces shall have a minimum Equivalent Full Load Hours of operation no less than:
    o The ASHRAE 90.1-2010 User’s Manual default schedule for office occupancy (2,920 Equivalent Full Load Hours per year)
    OR
    o 120% of the occupied hours of operation for the facility
    OR
    o Detailed justification shall be provided supporting an alternate schedule.

    • The Proposed model shall include either a 20% increase in the receptacle power density for these spaces OR a 20% increase in the scheduled receptacle Equivalent Full Load Hours of Operation versus the Baseline model.

    2. Path 2: Projects must demonstrate that the project has implemented efficiency measures that will achieve an equal or greater reduction in receptacle energy consumption, and will persist for a similar timeframe to those achieved by ASHRAE 90.1-2010 Section 8.4.2. It is recommended that a Credit Interpretation Request be submitted when pursuing this approach. The project must provide documentation regarding the receptacle equipment controls that will be implemented for the project; and must provide justification supporting the claim that the savings over the life of the efficiency measure will be similar to those anticipated for a project compliant with Section 90.1-2010 Section 8.4.2. Note: The baseline and proposed receptacle energy consumption for these spaces must be modeled identically if using this approach; the project is not eligible for any further receptacle savings in these spaces using the Exceptional Calculation Method.

    Update 11/9/20:
    Where ASHRAE 90.1 receptacle controls are not implemented in accordance with Section 8.4.2 mandatory requirements, LEED v4.1 projects may apply either Path 1 or Path 2, subject to the following requirements for Path 1:
    • Path 1: LEED v4.1 projects Using the Appendix G Performance Rating Method may model a penalty in the energy model. The following modeling requirements apply:
    o The Proposed receptacle power density modeled for these spaces shall be the greater of 0.75 Watts per square foot (8.1 Watts per square meter) or the design coincident peak receptacle power density (if known)
    o The receptacle schedule modeled in the Proposed design for these spaces shall have a minimum Equivalent Full Load Hours of operation no less than: the ASHRAE 90.1-2016 User’s Manual default schedule for office occupancy (2,920 Equivalent Full Load Hours per year); or 120% of the occupied hours of operation for the facility; or detailed justification shall be provided supporting an alternate schedule.
    o The Baseline model shall include either a 20% decrease in the receptacle power density for these spaces OR a 20% decrease in the scheduled receptacle Equivalent Full Load Hours of Operation versus the Proposed model.

    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
    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
    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

    LEEDuser expert

    Marcus Sheffer

    7group / Energy Opportunities
    LEED Fellow

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