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LEED v2009
Commercial Interiors
Energy and Atmosphere
Optimize Energy Performance—HVAC

LEED CREDIT

CI-2009 EAc1.3: Optimize energy performance - HVAC 5-10 points

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Marcus Sheffer

7group / Energy Opportunities
LEED Fellow

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Credit language

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

Intent

To achieve increasing levels of energy conservation beyond the prerequisite standard to reduce environmental and economic impacts associated with excessive energy use.

Requirements

MANDATORY POINT MINIMUM: Project registered on or after April 8, 2016 must earn four points in this credit, but can come from any of the four sub-sections.
Option 1
Implement 1 or both of the following strategies:
  • Equipment Efficiency—(5 points) Install heating, ventilation and air conditioning (HVAC) systems that comply with the efficiency requirements outlined in the New Building Institute’s Advanced Buildings™ Core Performance™ Guide Sections 1.4: Mechanical System Design, 2.9: Mechanical Equipment Efficiency and 3.10: Variable Speed Control.
  • Appropriate Zoning and Controls: (5 points) Zone tenant fit out of spaces to meet the following requirements:
    • Every solar exposure must have a separate control zone.
    • Interior spaces must be separately zoned.
    • Private offices and special occupancies (conference rooms, kitchens, etc.) must have active controls capable of sensing space use and modulating the HVAC system in response to space demand.

OR

Option 2
Reduce design energy cost compared with the energy cost budget for regulated energy components described in the requirements of ANSI/ASHRAE/IESNA Standard 90.1-2007 (with errata but without addenda1). Projects outside the U.S. may use a USGBC approved equivalent standard2.

AND

Path 1 (5 points)
Demonstrate that HVAC system component performance criteria used for tenant space are 15% better than a system in minimum compliance with ANSI/ASHRAE/IESNA Standard 90.1–2007 (with errata but without addenda1) or USGBC approved equivalent.

OR

Path 2 (10 points)
Demonstrate that HVAC system component performance criteria used for tenant space are 30% better than a system that is in minimum compliance with ANSI/ASHRAE/IESNA Standard 90.1-2007 (with errata but without addenda1) or USGBC approved equivalent. See all forum discussions about this credit »

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.

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Frequently asked questions

If pursuing Option 2, what is the scope of the energy model if the space shares a central plant, and what type of software should be used?

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For Option 1, Zoning and Controls, is a thermostat considered an “active control capable of sensing space demand"?

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Addenda

10/1/2012Updated: 2/14/2015
Global ACP
Description of change:
Add "or USGBC approved equivalent" to the end of the sentence.
Campus Applicable
No
Internationally Applicable:
Yes
4/1/2012Updated: 2/14/2015
Reference Guide Correction
Description of change:
Under "STEP 7", in the first sentence, changes the first "2" to "multiple" and the second "2" to "3". Replace the period with a comma at the end of last sentence in the first paragraph, and add "but should only be used if the central plants in the baseline and the design cases are modeled identically."
Campus Applicable
No
Internationally Applicable:
No
11/3/2010Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the second sentence in the first paragraph with the following text: Section 1.4 covers mechanical system design intended to closely match actual building loads and to meet ASHRAE 55; Section 2.9 covers Mechanical Equipment Efficiency Requirements; Section 3.10 covers Variable Frequency Drives.
Campus Applicable
No
Internationally Applicable:
No
10/1/2013Updated: 2/14/2015
Reference Guide Correction
Description of change:
In the example listed in Table 3, the points earned for a 36.3% and a 15.8% reduction should be 10 and 5, respectively.
Campus Applicable
No
Internationally Applicable:
Yes
10/1/2012Updated: 2/14/2015
Global ACP
Description of change:
Add "or USGBC approved equivalent" to the end of the sentence.
Campus Applicable
No
Internationally Applicable:
Yes
10/1/2012Updated: 2/14/2015
Global ACP
Description of change:
Add "Projects outside the U.S. may use a USGBC approved equivalent standard ." to the end of the option.
Campus Applicable
No
Internationally Applicable:
Yes
1/8/2010Updated: 2/14/2015
Reference Guide Correction
Description of change:
Insert the term "Tenant space" in alphabetical order with the accompanying text "Tenant space is the area within the LEED project boundary. For more information on what can and must be in the LEED project boundary see the Minimum Program Requirements (MPRs) and LEED 2009 MPR Supplemental Guidance. Note: tenant space is the same as project space."
Campus Applicable
No
Internationally Applicable:
No
4/1/2012Updated: 2/14/2015
Reference Guide Correction
Description of change:
Above "7. Documentation Guidance", add the following:Equation 3. Percent Annual HVAC Energy Cost Reduction For use when Central Plant improvements are included in the project scope.(See supplement document for equation)
Campus Applicable
No
Internationally Applicable:
No
10/1/2012Updated: 2/14/2015
Global ACP
Description of change:
Add the following footnote to the bottom of the page: "Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1-2007 if it is approved by USGBC as an equivalent standard using the process located at www.usgbc.org/leedisglobal"
Campus Applicable
No
Internationally Applicable:
Yes
6/30/2009
LEED Interpretation
Inquiry:

Our project consists of multifamily rental units. We are performing the energy model using TRACE 700, a program that meets ASHRAE Standard 140-2004: Building Thermal Envelope and Fabric Load Tests. TRACE 700 does not have the capability of modeling domestic hot water energy usage. In order to account for domestic hot water energy usage we are proposing to use the Department of Energy sponsored Lawrence Berkeley National Laboratory calculation methodology. The spreadsheet can be found at www.doa.state.wi.us/docs_view2.asp?docid=2249. This spreadsheet estimates the energy consumption of water heaters based on power source, energy factor, and recovery efficiency. In addition, the spreadsheet estimates the energy reductions associated with hot water consumption of Energy Star clothes washers and dishwashers. According to the CIR ruling dated 4/25/2007, credit cannot be taken for low flow fixtures accounted for in WE credit 3. However, clothes washers and dishwashers are not accounted for in LEED NC v2.2 WE credit 3. An exceptional calculation in accordance with Appendix G will be provided to demonstrate energy savings for the Energy Star appliance itself. In addition, we believe the reduction in the amount of hot water required by Energy Star clothes washers and dishwashers should be accounted for in the water heating calculation. The basis for these calculations found at http://hes.lbl.gov/hes/aboutwhm.html will be uploaded as supporting documentation. 1. Can we use the Lawrence Berkeley National Laboratory spreadsheet since TRACE 700 does not model energy consumption for domestic water heaters? 2. Can the energy savings for the reduced hot water consumption for Energy Star clothes washers and dishwashers be accounted for in the domestic hot water energy consumption calculation?

Ruling:

The applicant is asking for confirmation that LBNL spreadsheet calculations can be used to document domestic hot water use and asking if hot water savings resulting from Energy Star clothes washers and dishwashers can be accounted for in the exceptional calculation. 1. It seems that the LBNL spreadsheet calculations are an appropriate method for calculating domestic hot water use and for documenting the energy savings associated with Energy Star equipment. However in order to be accepted as an exceptional calculation, be sure to include a detailed narrative with all assumptions and supporting calculations with the submittal. 2. Yes, energy savings for reduced hot water consumption can be counted in DHW energy calculation. ***Please note, this CIR was updated on 7/10/2009.***

Campus Applicable
No
Internationally Applicable:
No
4/25/2008
LEED Interpretation
Inquiry:

Recently, USGBC approved a CIR regarding savings from key cards in hotel rooms (5/14/07 - see attached). We are requesting that under LEED-NC savings from submetering of multi-family buildings be accepted as an exceptional calculation method. There are no code requirements for submetering of apartment or condominiums in multi-family buildings. Submetering of utilities for individual tenants or owners in multi-family buildings is an added construction cost, but significant energy savings result. Studies have shown that a minimum of 10% energy savings are achieved once individual metering is implemented. Research done by the New York State Energy Research and Development Authority (NYSERDA: http://www.nyserda.org/publications/SubmeterManual.pdf) estimates that installing sub-meters in a master-metered building can reduce building-wide electricity consumption by 10-26%. In Ontario, Canada, non-electrically heated submetered apartments have shown a 16-22% reduction in electricity consumption while electrically heated apartments with submetering showed a reduction in consumption of 30% (http://www.frpo.org/Document/Topics&Issues/UtilitiesEnergy/Options%20to%...). Based on these studies and the fact that submetering is not required by the energy codes, we request that USGBC allow an exceptional calculation method to account for the savings from submetering. We are proposing that 10% cost savings of all submetered end uses be allowed by the calculation method. So, if a living unit is submetered for electricity and gas, the project can assume 10% cost savings for each of these fuel sources based on the energy use within the unit. Energy use in common areas of the building would be excluded from the calculation. Is this acceptable? Related CIR\'s 4/12/2007 - Credit Interpretation Request Per ASHRAE 90.1-1999 and 2004 mandatory requirements, hotel guestrooms must include a master control device at the main room entry that controls all permanently installed luminaires and switched receptacles. We are considering automating this lighting control with the use of a key card-activated master switch. The control would turn off all permanently installed and switched receptacle lighting after the guestroom is unoccupied for more than 30 minutes. The controls may also be configured to allow the interior window shades to be closed automatically when the guestroom is unoccupied. Monitored data for hotel lighting usage patterns is provided in a 1999 Research study by Erik Page and Michael Siminovitch entitled "Lighting Energy Savings in Hotel Guestrooms." This study indicates an average daily usage of nearly 8 hours for the bathroom light, 2 hours for the desk table lamp, 5 hours for the bedside lamp, and 3 hours for a floor lamp. The study also showed that the high use fixtures (the bathroom fixture and bed lamp) did not experience a significant drop during typically unoccupied periods. Instead, these lights were 20% - 25% on during these periods; and the lighting energy consumed during these periods accounted for about 60% of the total guestroom lighting energy consumption. Another study for ACEEE entitled the "Emerging Energy-Savings Technologies and Practices for the Building Sector as of 2004" projects an energy savings for key card lighting controls of 30%. Based on the information provided in these two studies, it seems reasonable to credit hotel guestroom lighting fixtures with a 30% energy savings for automated control based on room occupancy. We propose to model the energy savings achieved through automated control of lighting and interior window shades as an exceptional calculation measure. The lighting savings would be calculated by adjusting the proposed case lighting schedules for all permanently installed and switched receptacle fixtures to 50% lower than the budget case for the percentage of guestrooms modeled as unoccupied. Lighting during all occupied periods will be modeled identically to the budget case. The guestroom lighting energy savings achieved through this measure for the affected lighting fixtures would be 30%. Automated control of the blinds is intended to limit solar heat gains, since the building is in a hot dry climate. The blinds will be modeled identically during the occupied periods as 50% open during daylit hours, and 25% open during evening hours. During unoccupied periods, the shades will be modeled as 25% open. As with all exceptional calculation measures, the savings for this automated control measure will include a narrative documenting the lighting and interior shading schedules and assumptions, and the calculation methodology, and will include a separate line item on the ECB report documenting the savings achieved from this measure. We would like confirmation whether the proposed modeling methodology is acceptable, or direction regarding any modifications that would need to be made to the proposed modeling methodology in order to comply with LEED ECB modeling requirements. 5/14/2007 - Ruling The applicant is requesting confirmation on the proposed strategy for two exceptional calculations. Based on the description of the lighting assumptions, the proposed approach is acceptable. In the LEED submittal please include a narrative documenting the lighting schedules and assumptions and the calculation methodology. Also include a separate line item on the ECB report documenting the savings achieved from this measure. Please provide enough detail in the documentation to allow the review team to ascertain the amount of credit claimed. Based on the description of the automated blinds, the assumptions concerning blind control are insufficient to model the proposed building.

Ruling:

The project team is inquiring as to whether or not sub-metering of multi-family residential buildings would be acceptable as an exceptional calculation method. The energy savings associated with sub-metering are due to a change in occupant behavior and not due to building efficiency. As a result, the schedules in the baseline case must be modeled identically to those in the design case. Therefore project teams may not claim credit for sub-metering of a multi-family residential building through the exceptional calculation method.

Campus Applicable
No
Internationally Applicable:
No
2/20/2009
LEED Interpretation
Inquiry:

We are pursuing LEED NC for a high end high rise residence in Tokyo, Japan. We are showing compliance for EA-P2 and energy cost reduction for EA-C1 using the Performance Rating Method (Appendix G - PRM). ASHRAE 90.1 requires that the ratings for fenestration U-values, SHGC, and VLT are determined in accordance with NFRC 100 and 200. We will be using double paned and double paned Low E flat glass produced by AGC (Asahi Glass Co) here in Japan. AGC is one of the largest flat glass manufacturers and the parent company of AGC Flat Glass North America (formerly AFG - American Flat Glass). As this is a very high end residential project, with large glazed surfaces, a great deal of attention was paid to specifying glass in the design. Our issue is that AGC Japan products are rated using the Japanese Industrial Standards (JIS) and not NFRC as required. Although not explicitly stated in Appendix G - PRM, it is our understanding that if products are not NFRC rated, the poor default values provided in Normative Appendix A (Tables A8.1 and A8.2) of ASHRAE 90.1 are required to be used in place of manufacturer provided data for modeling purposes. NFRC rated products are not available in the in Japanese market. We have contacted AGC Japan to inquire if they have knowledge of NFRC rating procedures. Their response was that they do not, and only rate to JIS standards as required in Japan. The Japanese Industrial Standards (JIS) used for determining the solar optical and thermal properties of windows are JIS R 3106 and JIS R 3107. These two standards are stated by the Japanese Standards Association as being equivalent to ISO 9050 (Glass in building - Determination of light transmittance, solar direct transmittance, total solar energy transmittance, ultraviolet transmittance and related glazing factors) and ISO 10292 (Glass in building - Calculation of steady-state U values of multiple glazing). We understand that ISO 9050 and ISO 10292 form the referenced technical basis for ISO 15099 (Thermal performance of windows, doors and shading devices - Detailed calculations) which is the technical standard for determining optical and thermal properties of fenestration assemblies. ISO 15099 in turn defines the technical basis of NFRC 100 and NFRC 200. Other than the requirement for fenestration products being tested in a NFRC approved laboratory, which do not exist in Japan, we believe the JIS rated properties provided by AGC are in compliance with the technical requirements of NFRC standards and thus ASHRAE 90.1. Given this we have the following questions: 1) Can we use optical and thermal properties provided by AGC for Japanese domestically produced flat glass to model performance compliance in eQuest/DOE-2 using the performance rating method? 2) If 1) above is unacceptable, can we substitute optical and thermal properties of similar AGC NA (AFG) glass products for the eQuest/DOE-2 simulations? If the above is unacceptable, we have not identified any other way around this issue other than to import glass or have glass tested in the U.S. Both of these options are costly and not practical, and would deter this and any future LEED NC projects from being undertaken in Japan. In addition, we believe importing from abroad is not environmentally preferable in terms of CO2 impacts associated with transport.

Ruling:

The applicant is requesting the use of optical and thermal properties for fenestration determined by standards other than NFRC 100 and NFRC 200. The Japanese Industrial Standards (JIS) appear to be technically equivalent to the NFRC standards referenced in ASRHAE 90.1-2004. The use of optical and thermal properties determined by JIS 3106 and 3107 represent the actual thermal performance of fenestration products and may be used to determine fenestration parameters for use in the energy simulation. Please note that the NFRC ratings refer to the optical and thermal properties of the whole assembly. When preparing the EAc1 submission, the applicant should confirm that the optical and thermal properties determined by the applicable JIS standards and used in the energy simulation represent the properties of the whole fenestration assembly. Applicable Internationally; Japan.

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

Can we take credit for a demand ventilation system for an automotive service area?Essentially we propose to model the service area in the Baseline Cases at 100% outside air at 1.5 CFM/sq.ft. during occupied periods to meet ASHRAE 62.1. We plan to model the service area in the Proposed Case with typical storage ventilation rate. See rationale below to validate our assumptions.We further propose to model this energy efficiency measure in the standard credit energy models (not as an exceptional calculation) as part of the Baseline and Proposed Cases in order to accurately account for the differences in ventilation load. The differences are based on outside air conditions which change throughout the year and they also impact the supply air unit and fan sizes. The simulation program must size the equipment for the Baseline Case at the peak load and model it use 8760 hours in the year. ASHRAE 62.1 lists a specific minimum ventilation rate for automotive service areas at 1.5 CFM/sq. ft. Ventilation reduction controls are not stated in Ashrae 62.1, nor are they mandated in ASHRAE 90.1-2007. The governing Mechanical Code (International Mechanical Code) optionally permits the use of approved automatic detection devices to control the required ventilation fans and/or make-up air systems. Large make-up air systems providing 100% outside air are still readily available and utilized in order to meet the mandated code. We have utilized the following assumptions for modeling energy usage:Baseline Case - The exhaust ventilation system is modeled to operate at 1.5 CFM/sq.ft. during occupied hours per occupancy schedule. The modeling software automatically sizes the air conditioning system to operate as a 100% outside air system as the total CFM requirement exceeds the design load amount. The unoccupied fan cycle does not include the ventilation and only operates to maintain unoccupied thermostat set point.Proposed Case - The exhaust ventilation system is modeled to be non-operational at any time. We make this assumption based on calculation and witnessed operation at like facilities with the identical control system in place. We have calculated carbon monoxide production based upon maximum estimated daily vehicle round trips through the service area. Eighteen service stalls with an average of 3 vehicles per day and 1 minute round trip drive time yields an estimated total vehicle drive time in the service area to be 54 minutes. The average modern vehicle with catalytic converter produces approximately 150 CFM of exhaust airflow at idle to slow speed containing approximately 1,000 PPM of carbon monoxide. 150 CFM X (0.1%) = 0.15 CFM of carbon monoxide production. The requirement to engage the exhaust ventilation system is 50 PPM of carbon monoxide. The volume of the space is 236,900 cu.ft. and would require 11.845 cu.ft. of carbon monoxide to engage the system. This would require 78.97 minutes of continuous operation without any dilution in a facility this size which exceeds the estimated maximum vehicle operation time of 54 minutes by 30%. The air conditioning equipment serving the area provides 800 CFM outside air and is equivalent to a complete air change twice a day and therefore doubling the daily total required operation time to 157.94 minutes. Operation of vehicles for diagnostic testing is excluded as there is a separate tailpipe extraction system in place to remove all exhaust during testing. Calculations are no substitute for actual conditions. We have interviewed service managers as to the operations of the emergency exhaust system controlled with a CO monitor system. The feed back is overwhelming that the emergency system is never engaged during normal operation. The technicians in these facilities have been trained in the control systems operations and do not desire to have their "conditioned" air purged from the building due to excessive operation of the vehicles within the space.

Ruling:

A project team cannot be awarded credit for demand controlled ventilation in an automotive service area, due to concerns over contaminants, and possible effects on indoor evironmental quality. As there is no current accepted methodology, the potential human health risks outweigh the energy savings.

Campus Applicable
No
Internationally Applicable:
No
10/3/2008
LEED Interpretation
Inquiry:

Conventional vented domestic clothes dryers require approximately 200 cfm of exhaust when operating. In large multi-story residential buildings, the dryer exhaust is typically provided by dryer exhaust risers that vertically link multiple units with a constant or variable speed exhaust fan. Several exhaust risers may be used to meet the needs of all apartments in a building. Variable speed fans typically modulate based on static pressure in the exhaust riser and are limited no less than 25 percent of design flow. Constant speed fans assume some diversity and do not modulate. Either fan operates 24 hours per day. The dryer exhaust requires continuous makeup air that must be conditioned either at an outside air handling unit or as in additional infiltration load in individual residences. An alternative to conventional vented dryers are ventless condenser dryers. Condenser dryers still use heated air to evaporate water from the clothes, but use an air-to-air heat exchanger to condense water from the humid air rather than exhausting the air and replacing it with fresh air from the room. Heat from the dryer remains in the room and no external venting or makeup air is required. Vented dryers are the "standard practice" in large residential buildings. This is probably due to the fact that (1) vented dryers are the more familiar technology, (2) drying times are shorter with conventional dryers than with condenser dryers, and also because (3) vented dryers are less expensive than condenser dryers. Based on a 1998 study by James Kao of the National Institute of Standards and Technology (NIST) titled "Energy Test Results of a Conventional Clothes Dryer and a Condenser Clothes Dryer," condenser clothes dryers use between 5 and 30 percent more energy per pound of laundry than a conventional vented dryer (depending on the size of each load). The NIST study only accounts for the energy to operate the dryer. The study does not account for the additional effects on the HVAC system due to the outside air requirements. The net effect of using condenser dryers in lieu of conventional dryers is a reduction in overall energy use in the climate zone for the building we are studying (New York City climate). We propose the following as an exceptional calculation methodology to simulate the performance of condenser dryers over standard vented dryers: Baseline Building: 1. Model typical dryer energy patterns based on standard washing machine use patterns from EnergyStar. 2. Model the dryer such that none of the dryer energy results in heat gain in the space. 3. Model the Baseline Building with 50 cfm of air exhausted from each residential unit with a dryer. To do this, include dryer exhaust fan energy assuming that the fan runs at an average of 50 cfm, 24 hours per day, at the same static pressure as the other rooftop exhaust fans. Include 50 cfm of additional infiltration 24 hours per day for every residence with a dryer. Proposed Building: 1. Increase the dryer energy use by 20 percent based on a conservative rounding of the average results from Kao\'s study of dryer energy use. 2. Model the dryer such that all of the dryer energy results in heat gain in the space. 3. Model the proposed building without the dryer exhaust fans and without the additional 50 cfm of infiltration. Is this exceptional calculation method acceptable for LEED EAc1 credit?

Ruling:

The applicant is inquiring about the acceptability of a proposed exceptional calculation method that takes credit for using domestic condensing dryers instead of standard vented dryers in a multi-family high rise residential project. Using an exceptional calculation method to determine energy savings is a generally acceptable pathway. However, the information presented is not sufficient to determine if this exact calculation is adequate enough to determine the correct amount of savings (if there is a savings). The design team must provide justification for their specific assumptions in both the baseline case and the proposed case. Baseline Building: 1. Model typical dryer energy patterns based on standard washing machine use patterns from EnergyStar. This is acceptable. 2. Model the dryer such that none of the dryer energy results in heat gain in the space. Assuming no heat gain to the space is not self evident. Documentation in the form of industry accepted studies indicating as such would be required to ensure that this is an acceptable assumption. 3. Model the Baseline Building with 50 cfm of air exhausted from each residential unit with a dryer. To do this, include dryer exhaust fan energy assuming that the fan runs at an average of 50 cfm, 24 hours per day, at the same static pressure as the other rooftop exhaust fans. Include 50 cfm of additional infiltration 24 hours per day for every residence with a dryer. Assuming 50 cfm of continuous ventilation per dwelling may be excessive. A study of use patterns combine with cfm values for expected dryer type applied to this particular building would be required. Calculations on static pressure that include data on the height of the building, the max. static pressure per dryer and the expected duct size would also assist the reviewer in determining appropriate energy savings. Proposed Building: 1. Increase the dryer energy use by 20 percent based on a conservative rounding of the average results from Kao\'s study of dryer energy use. 20 percent is not necessarily a conservative figure. Further justification needs to be provided. Provide manufacturers data on the units and their proposed energy use. 2. Model the dryer such that all of the dryer energy results in heat gain in the space. Again, assuming that all of the energy used in the drying cycle results in heat gain to the space is not self evident. Industry accepted studies would be required to ensure that this is an acceptable assumption. 3. Model the proposed building without the dryer exhaust fans and without the additional 50 cfm of infiltration. This is acceptable as long as the figures determine from # 3 in the baseline case are used. Also, since the design team is proposing energy savings for the entire building based on the use of condensing dryers, some assurances must be given that all units will use condensing dryers.

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

This project is located on a multi-building medical campus in Illinois. Typical of a campus, it is composed of numerous existing buildings, parking structures, surface lots and circulation streets. The campus is proposing to build, as separately bid projects, a new inpatient building, some additions to existing buildings, and a new parking structure. Our intent is to pursue LEED Certification for the new inpatient building, a new multi-level parking structure and new portions of site work on the campus, but not the additions to existing buildings. One of the buildings included in the project boundary is an open parking structure. The parking structure includes an enclosed combination stair/elevator lobby. We intend to heat this stair/elevator lobby as well as ventilate the space. A telecommunication closet along with an electrical room will be heated and conditioned as well. The parking garage is not required to be ventilated since it is classified as an open parking structure. The parking garage and stair/elevator lobby will have lighting as required. LEED for Multiple Buildings allows a weighted aggregate for the group of buildings based on their conditioned square footage or aggregate PRM calculation. We would like to confirm only the areas being heated and conditioned are required to be included in the square footage calculation for this particular structure when being considered into the overall aggregate or overall PRM. The lighting square footage will take into account the overall square footage being covered by lighting. Please confirm that we are using the correct calculation methodology for this point.

Ruling:

The applicant has requested confirmation that the weighted average building method from the Multiple Buildings Application Guide is based only on the conditioned area of each building. This is a correct assumption. The language from the EA Credit 1 Multiple language guide states that the "weighted average for the group of buildings (should) be based on their conditioned square footage." The definitions of space types from ASHRAE 90.1-2004, page 13, should be used to identify whether spaces are defined as "conditioned", "semi-heated", or "unconditioned". The ASHRAE 90.1 Performance Rating Method (Appendix G) should be used to model each building in the project boundary, including the parking structure. Therefore, all interior and exterior parking garage lighting, elevator energy, etc. should be included into the energy model for the parking structure, regardless of whether the spaces are conditioned or unconditioned. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
5/26/2009
LEED Interpretation
Inquiry:

Background: Our project consists of a 4-story office building approximately 105,800 square feet in area. The building will be conditioned by a variable air volume system which includes a single, custom penthouse air handling unit on the roof. The project has been designed to meet ASHRAE Standards 62.1-2004 and 90.1-2004 including the application of demand controlled ventilation strategies. Each temperature control zone will include a series fan-powered terminal unit with electric reheat and each is equipped with an ECM motor. While the basic benefits of ECM motors include motor efficiencies nearly twice that of a traditional PSC motor, negligible heat gain from the motor to the airstream, and the ability to perpetually maintain a given supply airflow, the ability to modulate the terminal fan via the building automation system (BAS) is now feasible allowing control strategies never before possible. Series fan-powered terminal units have traditionally operated at a constant airflow during occupied periods. The proposed terminal unit control strategy for this project includes multiple, unique operating airflow levels: 1. During cooling demand, the fan will operate at the maximum cooling airflow condition (while the primary air damper modulates). 2. Under no call for heating or cooling, the fan will slow to the "deadband" airflow of approximately 50% of the peak cooling airflow. 3. At initial heating demand, the first stage of reheat will be energized and the terminal fan will increase to the first heating airflow setpoint. 4. On a call for additional heat, the second stage of reheat will be energized and the terminal fan will increase to the second heating airflow setpoint, and likewise with the third and final stage of reheat. Note that the heating airflow setpoints are specifically calculated to result in a consistent discharge temperature of 83F for optimum diffuser performance and blending in the space. Intent: Develop a strategy that accounts for the energy savings provided by series fan-powered terminal units with ECM motors. Proposed Strategy: A Whole Building Simulation and energy analysis has been performed towards LEED certification via the Building Performance Rating Method and in accordance with Appendix G of Standard 90.1-2004 utilizing the Trane Trace 700 analysis software (v6.1.3). In detailed review of the program input tables and output reports, we determined that the software was unable to model the control strategy proposed above. This was confirmed via direct communication with the software engineers. Through additional research, we further understand that Carrier HAP, EQuest, nor any other DOE-2 based energy simulation program has the algorithms or capability required. We are requesting confirmation that the following strategy conforms to the modeling requirements of Appendix G. 1. Utilize the Trace 700 energy program to perform a complete building analysis determining all energy consumption for both the proposed building and baseline comparison building in accordance with Appendix G. 2. Apply the Exceptional Calculation Method specifically and only to the terminal fan energy consumption as allowed by Paragraph G2.5 of Appendix G. The Exceptional Calculation Methodology will be as follows: a. Energy savings will be calculated for each individual terminal fan size and at each reduced operating speed based upon the manufacturers fan power data. b. Operating run time at each fan speed within the proposed control strategy will be determined using the heating and cooling load profiles from the Trace 700 output reports. c. Fan terminal energy savings will be calculated by multiplying the run time of the fan by the reduction in KW of fan energy at each specific operating condition. d. The terminal energy savings will be subtracted from the Trace 700 simulation output summary. Is the proposed strategy acceptable?

Ruling:

The project has requested clarification regarding the use of a specific method of computing the additional savings of using Fan-Powered Boxes with a 3-Stage Heating Coil and Electronically Commutated Motors (ECM motors) over traditional PSC motors. This approach is valid and acceptable, but more detailed information must be provided on how fan run time is determined at each of the three heating stages. The motor efficiency should be verified for each airflow condition chosen in the post-processing. Hourly simulation tools such as Trace 700 use complex computation routines and these should be accounted for in any hand calculations that are used to substitute for a Trace 700 energy simulation. Specifically, simply assigning the fans to run at full load (where they are far more efficient than their traditional PSC counterpart) continuously for a large portion of a season (i.e. peak heating months) would not be accurate. To calculate savings for ECM motors the following analysis should be done in the energy model to show compliance with ASHRAE Standard 90.1:

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

Many space types will not function as regularly-occupied private/individual or multi-occupant spaces, nor will those spaces be utilized for extended periods of time (such as kitchen/break room, meeting room, or conference room). Some unique and smaller (less than 200 SF) programmed space types are infrequently occupied (less than 1 hour) and by only one or a few people at a time. One exception to the credit requirement that "private offices" must have active controls is granted in LEED Interpretation #1645 and clarified in the IDC Reference Guide 2009 Edition, which states that "small private spaces intended for single, temporary occupancy (e.g. for making confidential telephone calls) may be included as part of a larger thermal zone, since changes in occupancy will not cause large swings in the heating and cooling loads." Given the credit intent to reduce energy in occupied spaces and the ruling of LEED Interpretation #1645, we propose to expand the definition for small, temporarily-occupied spaces in two ways: 1. For laboratory buildings/spaces, where loads are typically based on equipment loads, we propose a more specific addition to the definition of Special Occupancy to include spaces that are less than or equal to 200 SF and occupied by two or fewer people for short periods of time. 2. For all project types, we propose an expanded definition of Special Occupancy to include spaces with equal or less than 300 cfm, per ASHRAE 90.1-2007 definition of small zones. ASHRAE 90.1-2007 defines small zones as those with less than 300 cfm, as referenced in Sections 6.3.2.n Criteria, 6.4.3.4.3 Shutoff Damper Controls, and 6.5.2.1.a.4 Simultaneous Heating and Cooling Limitation - Zone Controls. In both of these cases, we propose the space types described above be considered Special Occupancy spaces that may be included as part of a larger thermal zone. Are these definitions acceptable?

Ruling:

No, these spaces cannot be considered Special Occupancy. The credit requirements state that private offices and specialty use spaces must have their own active controls capable of sensing space use and modulating the HVAC system in response to changes in space demand.Specialty use spaces are considered to be conference rooms, break rooms, classrooms, gymnasiums with variable use patterns, cafeterias, hotel guest rooms, residential dwelling units, and other occupied spaces where energy savings can be achieved by adjusting the temperature setpoints and/or air volume supplied to the space when the space is unoccupied, or densely occupied space where energy savings can be achieved by adjusting the ventilation air supplied to the space when the space is partially occupied. Laboratory spaces would be considered to be specialty use spaces, since these spaces generally have 100% outside air, where setting back the temperatures and/or the fume hood ventilation when the space is unoccupied or the fume hood(s) are not actively in use would lead to significant energy savings. Laboratory prep and laboratory support spaces, and resource rooms would also be expected to achieve energy savings by adjusting the temperature setpoints and/or air volume supplied to the space when the space is unoccupied, since these spaces are frequently unoccupied throughout each day; therefore, these rooms would be considered to be specialty use spaces. Exception: Spaces that would otherwise be considered specialty use spaces but are smaller than 75 square feet, such as the phone rooms referenced in LEED Interpretation #1645, or a lactation room smaller than 75 square feet are not required to have individual active controls capable of sensing space use and modulating in response to changes in space demand.Spaces not considered to be specialty use spaces: Open offices, reception areas, warehouse or storage spaces, merchandising spaces, lobbies, nursing stations, manufacturing spaces, auto service bays, library stacks, library multi-occupant reading areas, bank teller areas, hallways, and similar spaces are not considered to be specialty use spaces since these spaces would be expected to be at least partially occupied for the majority of the time the HVAC system is operational, and would not be expected to achieve energy savings by adjusting the temperature setpoints and/or air volume supplied to the space when the space is unoccupied. Controls capable of sensing space use and modulating the HVAC system in response to changes in space demand include the following:Interior private offices or interior non-densely occupied specialty use spaces - a separate thermal control for each space. This would be considered sufficient because the space demand is related to internal loads (lighting, occupants, and plug loads). When the occupant leaves the space, particularly if the space has lighting occupant sensors and Energy Star computing equipment, the thermostat will be able to sense a change in space demand, and modulate the HVAC system in response to the change in space demand.Perimeter offices or perimeter non-densely occupied specialty use spaces - a separate thermal control for each space paired with an occupant-sensing or CO2 sensing device, which is used to set back the temperature setpoint and airflow to the space when the space is unoccupied. In many cases, the occupant sensors used for lighting can be integrated with the HVAC controls. This is necessary in perimeter spaces because the space has both envelope loads and internal loads, and the HVAC system would respond minimally to changes in space occupancy if additional occupant-based setback controls were not in place. For a VRF system, fan coils, or packaged single-zone system, the fan coil serving the room must have the fans set to cycle on and off with loads or to operate on the lowest multi-speed setting for multi-speed fans when the space is detected as unoccupied. VAV systems with supply air diffusers and room thermostats: Per LEED Interpretation #5273, VAV systems having supply air diffusers equipped with room thermostats for each private office or non-densely occupied specialty use space may be used in lieu of a separate thermal zone per private office or non-densely occupied specialty use space. If this compliance path is followed, the following additional requirements apply:1. The system must be capable of modulating AHU and zone minimum supply volume down below 0.30 cfm/sf of supply volume for standard VAV terminals, or below 22.5% of the peak design flow rate for fan-powered VAV boxes. For spaces where the minimum outdoor air exceeds the minimum supply volumes specified here, some form of occupant sensing or demand controlled ventilation must be employed to allow these minimum supply volumes to be met. 2. The building control system must include controls for fan static pressure reset. 3. The mandatory requirements of ASHRAE Standards 90.1-2007 and 62.1-2007 must be met. Densely Occupied specialty use spaces (such as a conference room) - a separate thermal control for each space paired with a CO2 or occupant sensing device, which is used for demand control ventilation and to set back the temperature setpoint to the space when the space is unoccupied. Applicable Internationally.

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
10/3/2008
LEED Interpretation
Inquiry:

The purpose of this CIR is to obtain written confirmation and clarification that the use of TAS 9.0.7 software (by EDSL) can be approved as a energy modeling tool for pursuing EA Credit 1 and EA Pre-requisite 2 After reviewing ASHRAE 90.1-2004 Appendix G section G2, where all requirements are specified, we would confirm that the TAS 9.0.7 computer simulation software tool has the following capabilities: a. 8760 hours per year: TAS is able to simulate on an hourly basis over a total of 8760 year. b. Hourly variations in occupancy, lighting power, miscellaneous equipment power, thermostat set points, and HVAC system operation, deigned separately for each day of the week and holidays: TAS has the capability of adding schedules for all of the above. Different load profile can be created for different times of the day and for different days in the week. The possibility of creating out of hours conditions, nigh time setback temperature, etc. is also available. c. Thermal mass effect: TAS accounts for thermal inertia in the space. d. Ten or more thermal zones: TAS can handle more than ten different thermal zones e. Part-load performance curves for mechanical equipment: TAS is able to simulate part load performance for fans and pumps. TAS can model both constant and variable speed pump systems for primary and secondary. In the air side, different systems can be simulated (i.e. VAV, fancoils, etc) with variation in fan consumption as the load varies. f. Capacity and efficiency correction curves for mechanical heating and cooling equipment: TAS has the capability to incorporate correction curves, even combination of numbers of different types of boilers and chillers within the same project. g. Air-side economizers with integrated control: TAS can incorporate free cooling chillers. It has also the capability to model heat recovery air handling units with by-pass control with an air temperature set point. h. Baseline building design characteristics specified in ASHRAE 90.1-2004 Appendix G section G3: TAS allows the user to build a model for the baseline building using the characteristics specified in G3 and also those in G2.1 (same weather data and same energy rates), although the program does not generate it automatically and it is the user that has to carry out the modeling. 2.0 CIR - Design Energy Builder Energy Plus Modeling Tool Approval Please could you confirm whether the USGBC have approved the use of Design Energy Builder latest Version 2.2 of Energy Plus Software modeling Tool and if this is not the case is the software tool currently accepted by the USGBC.

Ruling:

The applicant is requesting approval to use EDSL TAS 9.0.7 software to document compliance with the energy simulation requirements in EAp2 and EAc1. USGBC does not maintain a list of approved energy modeling software. Instead, the project team must ensure that the simulation tool satisfies the requirements of ASHRAE 90.1-2004 Appendix G Section G2. The Design Builder energy simulation and visualization tool incorporates the EnergyPlus simulation engine. EnergyPlus should meet the ASHRAE 90.1 Appendix G Section G.2.2 requirements. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
6/4/2009
LEED Interpretation
Inquiry:

The question is based on ASHRAE 90.1 requirements for Performance Rating Method for building modeling. This building has very high internal loads with the baseline process load at 49% of the total building energy based on actual equipment. The internal load is primarily computer desktops and monitors. Both baseline and proposed building energy usage numbers are based on a calculation worksheet as published by the US dept of Energy for computer desktops and monitors. The Energy Star usage value increases the proposed energy building performance reduction by 10-15%. This lower value for the process load is still above the 25% requirement for the total building energy amount as outlined in the LEED requirements of this point. The equipment in the new building that the owner will provide will consist of Energy Star computer desktops and monitors. We request clarification that we can run the baseline with standard energy load based on LBNL 2007 standards and proposed building with Energy Star energy loads.

Ruling:

The applicant is requesting clarification on how to account for energy savings due to Energy Star rated equipment. Plug in equipment falls under the Process Loads category and any savings claimed under process loads have to be taken as an Exceptional Calculation. Please model the same process loads in both the baseline and proposed building. Then run a separate run of the proposed building with the Energy Star rated equipment. Report savings from this run Exceptional Calculation table in the LEED Submittal Template. Be sure to include a detailed narrative with all assumptions and supporting calculations with the submittal. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
12/14/2006
LEED Interpretation
Inquiry:

The purpose of this project is to allow Bank of America employees an opportunity to work closer to home and reduce their commute to the office. One of the features for the plan on this project is the "Focus" Rooms. These rooms allow the people throughout the floor to conduct phone/conference calls confidentially. These spaces are approximately 35 square feet in area. Based on the point for Appropriate Zoning and Controls, it requires private offices, conference rooms and kitchens to have their own controls. Currently, there are 4 of these spaces zoned together on one side of the floor plan. On the other side of the plan, 2 focus rooms are zoned with a wellness room (approx. 62 sf). I am requesting that these focus rooms be excluded from this requirement due to their low airflow requirements and intermittent use. Please clarify if these rooms will be accepted as they are currently zoned.

Ruling:

The project team is requesting clarification regarding the occupancy-type classification of small spaces used exclusively for making confidential phone calls. These rooms are not intended for use as regularly occupied private office spaces. Also, since these rooms are intended for single occupancy, changes in occupancy will not result in large swings in the heating and cooling loads, as would be true for a break room or conference room. Accordingly, these spaces may be included as part of a larger thermal zone. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
10/24/2008
LEED Interpretation
Inquiry:

Our project is a 65,000 SF injection molding manufacturing facility and office near Detroit, MI. The project consists of 10,000 SF of air-conditioned office space, and 55,000 SF of air-conditioned manufacturing space, which includes injection molding equipment, as well as occupied assembly areas. The energy required for the manufacturing process exceeds 85% of the facility\'s total energy load. To achieve the 14% minimum energy savings, process load energy savings must be taken into account. As a result of the high energy loads associated with the manufacturing process, as well as the energy not falling under ASHRAE 90.1-2004, an exceptional calculation method must be established for the manufacturing area. Both the office area and the manufacturing area are conditioned. Space cooling in these areas will be achieved through constant volume rooftop units, and will be modeled through a standard energy modeling software like Trane Trace 700. The manufacturing process includes injection molding machinery which is cooled through a chiller & cooling tower assembly. The load on the chiller and cooling tower will not fluctuate (except for operational and non-operational hours, which will be achieved through a schedule). The chiller and cooling tower performance will be run in a separate energy model using this constant load to determine the overall energy used based on the outdoor air conditions throughout the year. The Chiller and cooling tower energy used will then be input into the original model as annual process energy. The Chiller and Cooling Tower efficiencies for the baseline will be based off ASHRAE 90.1-2004 minimum standards. The injection molding equipment proposed is state-of-the-art and very energy efficient compared to the standard injection molding machinery that is the industry standard. Using the client-provided operational times for the equipment we will be able to estimate the total energy used by this injection molding equipment, as well as the total energy that would be used by industry standard equipment. This will be used to determine the annual energy for both the baseline and the proposed design. We will then input these amounts into the original energy model as annual process energy. For comparison purposes, we also have a similar plant by the same client that uses the industry standard machines. By comparing the amount of equipment and square footage of this plant, we can achieve a very accurate idea of how much energy the new plant is saving. All calculations showing how the machinery energy was determined, and results of planned field monitoring, will be explained in an excel spreadsheet. Equipment descriptions and energy loads will be shown for all machines that will be used, as well as for comparable industry standard machines. Once the process equipment, both baseline and proposed, have been input into the overall energy model as process loads, the standard reports issued from the model will be used for the LEED Reports. In addition, we will provide the sub-energy models of the process equipment that is weather-based. Please confirm that our assumptions and method of calculating the process energy load for both the base and proposed design cases are acceptable for EAc1.

Ruling:

The applicant is requesting acceptance of the proposed energy modeling methodology for a process dominated project. While the overall process for exceptional calculations seems reasonable, the applicant must make the following changes to the calculation methodology: 1. Include all loads in the same model and not in two separate models. This will allow the models to accurately reflect any interactions between the process loads and the space conditioning loads. 2. Provide a side-by-side comparison of the industry standard equipment, its age with the new proposed equipment and define an energy efficiency metric for each piece of equipment (e.g. kWh/ pound of material processed). Also provide list of modifications that make the new equipment more efficient. 3. Provide detailed utility bills from the comparison facility for reference. 4. Provide the operation schedules for the facility and the equipment. Please note that while this Credit Interpretation Ruling provides guidance on the exceptional calculation methodology, the actual savings and credit available for the strategies will be determined only during the review of the actual documentation. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
10/24/2008
LEED Interpretation
Inquiry:

This project is a major renovation to the existing building envelope (new skin added, new windows) and to the common area part of a tenant occupied office building. We have received approval from the USGBC to use LEED for New Construction. The core space lighting (elevator areas, lobby, restrooms, conference rooms), ductwork and finishes will be modified but the central air handling system and air cooled chiller and the tenant spaces will be only minimally altered. The question has been posed by the building manager regarding if they need to replace the tenant lighting in the space as the tenant space is not in the scope of work for the project. According to the ASHRAE 90.1-2004 users guide, if you were to replace more than 50% of the lighting fixtures in the building, you would have to meet ASHRAE 90.1-2004 lighting requirements, which, based on our analysis of what the base case and current design is in terms of lighting power density for this office building, means the building managers would have to replace all the tenant lighting with T8, 25 Watt lamps. However, if we replace less than 50% of the lighting in the building, we are not dictated by ASHRAE 90.1-2004, unless the renovation increases installed lighting power. However, according to the LEED Reference Guide for the prerequisite EAp2, lighting applies to all lighting installed on the building site including interior and exterior lighting. If the total installed interior lighting power is lower than the interior lighting power allowance calculated using ASHRAE 90.1-2004, the project complies. These two statements contradict each other if there is less than 50% of the lighting replaced, but the LEED Reference Guide does refer to the ASHRAE 90.1 users manual as a reference. Please advise on what to assume for the tenant space lighting power density in both the base case ASHRAE 90.1-2004 compliant building and the design case if less than 50% of the lighting is replaced.

Ruling:

According to the requirements of the ASHRAE 90.1-2004, Appendix G Table G3.1 section 6, for the proposed case, if a complete lighting system exists, the actual lighting power needs to be modeled. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
8/7/2007
LEED Interpretation
Inquiry:

Background: Our project is the 25,000 sf expansion of a school campus including three new buildings - two 1-story structures and one 2-story structure. Our goal is to lower energy use as much as possible, including the selection of process load appliances with low energy use. All of the new spaces in the three new buildings are complete build outs, except four classrooms in the 2-story structure that are being built out as core and shell spaces only. These classrooms will be a low-scale lab environment, metal shop, wood shop or some very light work shop component as yet not defined and will be finished as a future tenant improvement. The scope of our current project does not include the installation of any plug or process load equipment for the core and shell space, only HVAC (heating and basic ventilation only, none for process equipment) and lighting shall be installed. The overall core and shell area of this project is relatively small (3000sf) compared to the overall project area. Proposed Modeling Strategy: For the purposes of documenting the baseline and proposed energy use of this combined full build out and core and shell project, we propose the following methodology. For all completely built out spaces, create a model with baseline energy use including process loads at 25% of total baseline building energy use. The proposed case for the fully built out spaces would have the envelope, systems, lighting and process loads modeled as designed, with documentation available for the new process loads. For the core and shell spaces, since these do not have any associated plug or process loads to be installed at this time, we propose to create a separate model for these spaces that only addresses envelope, lighting, domestic hot water and HVAC systems. This model would provide baseline and proposed case annual energy use for these non-process load related components. Once the annual energy use figures are available for both the full build out and core and shell spaces, it is proposed that the baseline energy use figures be added together for both cases to achieve an overall baseline energy use for the project. Similarly, the proposed case annual energy use would be the combined proposed energy use of the fully built out and core and shell spaces. In this way, an accurate representation of the scope of the project can be modeled for both baseline and proposed cases. Request: Please confirm that the following approaches are acceptable to accurately demonstrate the condition of the proposed building. 1. Is it acceptable to keep the baseline process load energy cost at 25% of the baseline total energy cost, while modeling and inputting the actual installed process loads for the proposed case? This would allow the building to achieve some credit for specifying lower energy use plug and process load equipment than a baseline case. Note that the proposed process energy costs may or may not be 25% of the total energy cost, and may or may not be equal to the process energy load for the baseline case. 2. Is it acceptable for the core and shell spaces to not include process loads in the total energy cost for either the baseline or proposed cases? This would most accurately reflect the project condition. Process loads would be included in the model simulation for the purpose of demonstrating heating and cooling load compliance only, but would be separated out when determining total energy cost for the core and shell spaces. 3. Is it acceptable to create two separate building models for the project, one for the full build out portion of the project and a separate model for the core and shell portion? The core and shell model would exclude process energy cost from its total energy cost. Is it acceptable to sum the total energy costs of the full build out and core and shell spaces to achieve the total project energy cost?

Ruling:

The questions will be addressed in the order that they were presented: [1] It is acceptable to vary the design case process load to reflect energy efficiency measures (ie Energy Start Appliances) that affect the process energy load. This is considered an Exception Calculation Method (ECM) and thus full documentation should be provided justifying the differences and highlighting the assumptions and inputs that were used to create both the baseline and design case process energy loads. It is not allowable to use the default 25% process load value for the baseline case if the proposed case process energy has been inputted piece-by-piece (for example, by inputting the energy usage for each computer, copier, etc.). Instead the baseline model must also have piece-by-piece inputs using identical input power and energy rating as the proposed case unless the applicant can demonstrate that the proposed equipment represents a significant verifiable departure from documented conventional practice. In that case, the values for conventional practice may be used for the baseline equipment with the same use schedule as the proposed case. [2] It is NOT acceptable to ignore process energy usage in future build-out spaces. The LEED Core & Shell Reference Guide provides some guidance in how to address future build-out spaces, though it is more geared to address tenant-leased spaces. Key concepts to follow for future build out spaces include, but are not limited to: [A] Model receptacle and other loads (process) based on estimates for the building type. Table G-B of the ASHRAE 90.1-2004 User\'s Manual (note, this is not the same document as the ASHRAE 90.1-2004 Standard) provides acceptable receptacle power densities, occupancy densities, and hot water usage for varying occupancy types. [B] Use the same values for receptacle and process loads in both the baseline and design cases for the future build-out spaces. [C] If default values cannot be found for certain occupancy types, make reasonable estimates based on modeling and design experience. Please note where these values were used and what estimates are based on. [3] Separate building models for the full build-out and core and shell portions of the project are not recommended. Energy usage calculations are compromised when the model is broken apart because, among other issues, the model is no longer able to apply diversity factors across all project spaces or properly size systems based on peak demand. It may be permissible to separate portions of the model for an ECM, but this is only in the case that limitations in the modeling software prevent adequate representation of the design. If this is the case, full ECM documentation will need to be provided, as described in ASHRAE 90.1-2004 G2.5. Applicable Internationally.

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

Our project is a newly constructed, 825,751 square foot automotive manufacturing facility in the midwest. The ventilation requirements for our facility, as set forth by ASHRAE 62.1, Section 2.2 states: "Additional requirements for laboratory, industrial, and other spaces may be dictated by workplace and other standards,.". Industrial facilities in this location fall under the requirements of the Michigan Occupational Safety and Health Administration (MIOSHA). Per MIOSHA\'s, health standards ("Part 520. Ventilation Control"), R325.52007 Exhaust ventilation systems, Rule 7 states : "The minimum rate of exhaust ventilation for places of manufacturing, processing, assembling, maintenance and repair, or storage of material shall be 1 cubic foot of air per minute per square foot of floor area. This amount of exhaust ventilation may be provided by local exhaust, general exhaust, or both. The director may permit a variance if contaminant control is accomplished at a lesser rate of ventilation." MIOSHA has stated that an allowable level of contaminant control for dust/mist particulate would be 5 mg/cubic meter. In an attempt to save ongoing heating, cooling and ventilation expenses, the Owner chose to design the new facility in an innovative manner that could attain contaminant control at a much lesser ventilation rate than the default 1 CFM/SF that is set forth by MIOSHA and used by other automotive manufacturing facilities. The manufacturing facility has set a target of 0.5 mg/cubic meter, significantly lower than the MIOSHA required level of contaminant control. In order to reach this high level of contaminant control, they implemented the following innovative approaches: 1 - For the machining and grinding processes, enclosures were constructed and oil mist/dust collection systems were implemented with HEPA filtration. 2 - For the parts washers, enclosures were constructed and local exhaust ventilation systems were designed to capture contaminants at the source. 3 - For processes using hazardous materials, local exhaust ventilation systems were designed to capture contaminants at the source. 4 - "Dry floor guarding" systems have been implemented in the machine tool enclosures in order to minimize any escaping mist from the process. 5 - Micro-bacteria resistant coolants are used in the plant and biocides and utilized and monitored in order to control the bacterial counts in such systems. These control measures are over and above what is done in a typical, newly constructed manufacturing plant. With these control measures being utilized, extensive testing was done through the manufacturing facility to ensure that MIOSHA (and the much more stringent company requirements) exposure limits were being met. During the testing, the facility was ventilated at a rate of 0.21 CFM per square foot. At this ventilation rate, the facility was far below the company\'s target exposure limits, never measuring higher than a 0.13 mg/cubic meter exposure level. The Owner operates their facility at a ventilation rate of 0.5 CFM per square foot. This adds another level of safety factor to the building design. We are proposing that we run the energy model, in both the baseline and proposed case, with a ventilation rate of 1.0 CFM per square foot. We then intend to use the Exceptional Calculation Methodology of ASHRAE 90.1 to quantify our energy cost savings by lowering the ventilation rate. We intend to re-run our "proposed" model with 0.5 CFM per square foot to determine the cost savings for this exceptional calculation.

Ruling:

The applicant is proposing that energy savings due to ventilation load reduction resulting from several pollutant source control measures be approved as an Exceptional Calculation Methodology (ECM). The use of baseline and proposed case exhaust rates above those required by ASHRAE 62.1-2004 Section 6.2.8 are acceptable per ASHRAE 62.1-2004 Section 2.2 and the requirements specified by Michigan Occupational Health and Safety Administration (MIOSHA). Since it is a non-regulated process load, the project team must establish reasonable assumptions under full operational conditions for the baseline and proposed case. It appears that the project team has put a substantial effort into identifying and controlling sources of indoor pollutants and in an effort to reduce ventilation loads. Additionally, testing has been conducted to verify that the particulate concentrations are well below MIOSHA requirements even at reduced ventilation rates. The proposed documentation of energy savings from ventilation load reductions in the proposed case may be documented as an ECM. Please note that the favorable ruling of this CIR does not guarantee credit acceptance during a review. The project team should provide sufficient documentation to support the proposed ECM. Also note that the ruling is specifically applicable to the project in question due to the substantial efforts made to control sources of indoor air contamination at the source and testing for compliance; the ruling is not necessarily applicable to projects with different circumstances.

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

How much HVAC equipment must be installed within a LEED for Commercial Interiors or LEED for Retail: Commercial Interiors project scope of work in order to meet the intent of EA credit 1.3, Option 1, Equipment Efficiency?

Ruling:

The project is eligible to earn the credit if the project scope of work includes one of the following:1. Air handlers with Variable Speed Controls complying with the requirements of the Core Performance Guide Section 3.10 that supply at least 60% of the total supply air volume used within the project scope OR2. Mechanical equipment that complies with the prescriptive efficiency requirements of the Core Performance Guide Section 2.9, and provides at least 60% of the cooling or heating capacity for the project scopeNote that requiring 60% correlates to the LEED CI MPR #2 requirement that there must be tenant improvements made for 60% of the project scope in order to pursue a LEED for Commercial Interiors or LEED for Retail: CI rating.OR3. The project can comply with the requirements of the credit if the project team can show that the relevant criteria have been met for all HVAC systems serving the area within the project scope, whether or not the HVAC systems are installed as part of the tenant scope of work.

Campus Applicable
No
Internationally Applicable:
No
9/24/2007
LEED Interpretation
Inquiry:

The project wishes to use Therma-Fusers in private offices to satisfy the intent of LEED CI Eac1.3. Therma-Fusers are supply air diffusers, which are each equipped with an individual thermostat, meaning they have "active controls capable of sensing space demand." However, although the Therma-Fusers do not specifically "modulate the HVAC system in response to space demand," they do satisfy the intent of the credit which is to "achieve increasing levels of energy conservation beyond the prerequisite standard to reduce environmental impacts associated with excessive energy use." Therma-Fusers function at low pressure, which can reduce the horsepower (and therefore reduce the energy demand) necessary to run the fan motor. This fan energy is further reduced because the VAV system serving this particular space incorporates variable speed drives, which allow the system to turn down even further to save more energy. Also, because a typical pressure independent VAV terminal unit can only turn down to 30%, Therma-Fusers save even more fan energy because they can turn down to less than 10% and maintain individual temperature control. Also, because each Therma-Fuser is a zone of control providing individual room control, heating and cooling energy are reduced because no portion of the building is ever over-cooled or over-heated. An independent study has shown 40% energy savings for interior zones and 29% energy savings for perimeter zones when individual room control was compared to multi-room control. Although Therma-Fusers may not save HVAC energy precisely in the manner specified by the credit, we believe, given the energy saving capabilities of incorporating Therma-Fusers within the space mentioned above, their use satisfies the intent of LEED CI EA credit 1.3.

Ruling:

The applicant has requested confirmation that supply air diffusers equipped with room thermostats" meet the requirements of EAc1.3 Option A: Appropriate Zoning and Controls to provide "active controls capable of sensing space use and modulating HVAC system in response to space demand." The supply air diffusers with room thermostats do not meet this requirement alone. In order to meet this requirements, the following criteria need to be met: 1. The system must be capable of modulating AHU and zone minimum supply volume down below 0.30 cfm/sf of supply volume for standard VAV terminals, or below 22.5% of the peak design flow rate for fan-powered VAV boxes. For spaces where the minimum outdoor air exceeds the minimum supply volumes specified here, some form of occupant sensing or demand controlled ventilation must be employed to allow these minimum supply volumes to be met. 2. The building control system must include controls for fan static pressure reset. 3. The mandatory requirements of ASHRAE Standards 90.1-2004 and 62.1-2004 must be met. These criteria apply only when there is not a separate method employed for modulating the HVAC system in response to space demand such as Demand Controlled Ventilation, or modulation of the HVAC system tied to occupant sensor controls. Applicable Internationally.

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

This Project involves the construction of a Testing Facility for High Volume Low Velocity circulation fans. The building consists of a 1940 S.F. General Office Area, a 1940 S.F. Shop Area, and a 40550 S.F. Testing Area with a 50\' joist height. The Testing Area will have in it at most (4) four High Volume Low Velocity circulation fans operating at the same time. The building will have no transient occupants, and a maximum of (6) six employees that will occupy the entire building during normal business hours. This CIR is in reference to the Testing Area. 1. Testing Area: As part of the USGBC New Construction & Major Renovation Version 2.2, the building is required to meet ASHRAE 90.1 2004 (Energy Standard for Buildings Except Low-Rise Residential Buildings), and ASHRAE 62.1 2004 (Ventilation for Acceptable Indoor Air Quality). In accordance with ASHRAE 90.1 2004 the Testing Area is given a baseline LPD (Lighting Power Density) of 1.4 W/SF as is standard for a Laboratory. The only reference in ASHRAE 62.1 2004 (Ventilation for Acceptable Indoor Air Quality) with regard to a Laboratory is listed in Table 6-1 under "Educational Facilities" - "Science Laboratories". The classification that most closely matches the actual use of the space in the Testing Area for ventilation purposes is a Warehouse, since the population density is low (6760 SF/Person), and the area will never contain "Laboratory" chemicals, "Laboratory" exhaust hoods, Make-Up air or a population density on par with an Educational Facility Science Laboratory. The Ventilation and Exhaust requirements for a Science Lab are (3) three times that of a Warehouse, and subsequently (3) three times the energy cost. Since the "actual" usage of the Testing Area fits the lighting energy requirements of a Laboratory (ASHRAE 90.1 2004) and the ventilation requirements of a Warehouse (ASHRAE 62.1 2004), can the design team consider this space as such for calculations, or does the requirement to stay consistent with room classifications supersede actual building function?

Ruling:

The applicant is requesting to use the lighting power calculations for one space type and ventilation calculations for a different space type. The ventilation quantities for the Testing facility appear to be associated with process issues associated only with the tests being run, not ventilation requirements associated with Standard 62.1-2004 requirements for indoor air quality. The project team should model the ventilation the same in the Baseline and Proposed Case, and should model the lighting power density requirements based on the closest space type from the ASHRAE Space-by-Space method.

Campus Applicable
No
Internationally Applicable:
No
4/14/2009
LEED Interpretation
Inquiry:

Background: Our project is a 3 story, 16,500-sq.ft. addition to an existing 3 story, 84,000 sq.ft. building. The existing building is predominately laboratory space with some office space. The addition will be of similar use. The heating and cooling of the existing building is served by a central utility plant which provides chilled water and hot water via a steam boiler and heat exchanger. It is proposed that the addition also be served by the central plant. The central plant serves several other buildings on the site as well. In order to make a decision on whether we would like to obtain LEED registration on just the new addition or on the entire building with the new addition, a preliminary building simulation is being modeled. For the ASHRAE baseline, the system is modeled as a "System 3 - PSZ-AC" (packaged rooftop, constant volume, direct expansion, and fossil fuel furnace) per table G3.1.1A of ASHRAE 90.1-2004. Though the combined building size would categorize building with addition as a "System 5 - Packaged VAV w/ Reheat.", section G3.1.1(c) mandates conforming to the requirements of System 3 as an exception due to the special pressurization relationship/ cross-contamination requirement of the laboratory. Interpretation Request: Little is stated in ASHRAE 90.1 2004 on the most appropriate way to model a system that has chilled water and hot water heat supplied from a central plant. However, there are a few CIRs concerning similar circumstance that allude to it such as the 1/27/2004-2/24/2004 EA1.1 CIR. In it, it is stated that "While the situation described is not using purchased chilled water or steam, this HVAC description for the budget building is the closest to the proposed design and should be used for the energy modeling purposes." This approach for the budget building model is quite workable since the building owner has costs available for both chilled water and heating hot water. However, the baseline is modeled as a DX cooling and gas fired furnace. Is it appropriate to model the budget building with chilled water and heating hot water, when the baseline model is using neither of these? If not, how should the baseline and budget building be modeled?

Ruling:

The applicant is requesting clarification regarding modeling methodologies for projects which include a central utility plant. Note that the USGBC published a document titled "Required Treatment of District Thermal Energy in LEED-NC version 2.2 and LEED for Schools" in May of 2008 located at the following website: http://www.usgbc.org/ShowFile.aspx?DocumentID=4176 Please refer to this guidance document, which is also referenced in a CIR dated 5/28/2008. Also note that the exception in ASHRAE 90.1-2004 Section G3.1.1 Exception (c) is only applicable for zones that have special pressurization requirements. All zones of the building or addition that do not meet the exception requirements must be modeled using System 5 - Packaged VAV w/ Reheat in the baseline. Applicable Internationally.

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

We are seeking clarification on the definition of active controls for non-VAV systems. The response from USGBC to CIR 5273 states that thermal control is not sufficient alone if it does not include for variable central plant such as VAV AHU. In some versions of VAV, thermal control can be achieved without modulating the central plant and this delivers no energy savings. These systems deal with low flow situations by allowing the excess air to discharge back to the ceiling void or similar whilst keeping the AHU at a constant speed, which does not result in any energy savings. Thus for the case proposed by the design team on CIR 5273, it is possible to achieve an equipment configuration which does not realize any energy savings from thermal controls.This inquiry refers to a Variable Refrigerant Flow (VRF) system. The VRF system operates by delivering refrigerant to the room device/terminal to deliver heating or cooling to the space. Each space has thermal control. The thermal control operates by varying the amount of refrigerant delivered to the room device/terminal and as such varying or modulating the central plant. This ability to vary the heating or cooling delivered to the space allows the central plant to modulate and match the instantaneous load in the space at any given time. This delivers energy savings in the central plant. Furthermore the VRF system also has heat recovery, which allows for heat taken from a space which is in cooling mode to be used in a space in heating mode and vice versa.Note that because of the closed-loop nature of the VRF system, it is not possible to operate the system in a mode, which does not save energy, as it is not possible to "vent" any excess refrigerant in low load situations. The variability of the system comes not from changing the amount of air into the space, but by varying the amount of refrigerant from the central system to the project space. The requirement by the reviewers to provide demand controlled ventilation as part of the response to CIR 5273 is inappropriate for a VRF system, which - by definition - ramps up and down based on temperature readings, not air flow measurements. Since the trigger for a VRF system to ramp up and down is related to temperature, we believe that the thermal controls in each room are sufficient active controls for a VRF system, as they provide both individual control in the meeting rooms and private offices and realise energy savings resulting from individual controls.With this system, we are still able to meet the requirements of ASHRAE 62.1 for the highest design occupancy and provide adequate ventilation to the project space.We do not believe that the argument that the thermostat will not pick up on when a person leaves the room, as this may not be the major load in the space, is relevant. While this is correct, with a thermostat, the system will modulate to control the space regardless of what is generating the load, e.g. solar, people, equipment. The fact that the people load is not the significant load means that the control of the other loads is the more important element, therefore the system will respond to whatever changes the load, whether it is people, equipment, lighting or something else. It was suggested that the proposed design also does not meet the intent of the credit, because of the lack of ability to vary the amount of fresh air into the space. However, feedback seems to suggest that occupancy and CO2 sensors would help achieve this credit, although it is unclear whether installing these in the system would achieve the credit or if this is only in the context of VAV systems.

Ruling:

The definition of active controls that meet the requirements in LEED-CI 2009 EA credit 1.3, and clarifications on what non-VAV systems are eligible for active controls are listed below. Active control is the control capable of sensing space occupancy and adjusting the HVAC system demand based on the changes in space occupancy, which does not equal a thermostat or a separate thermal zone for each space. For VAV systems and non-VAV systems, active controls typically regulate the required outdoor air flow for ventilation, such as using demand controlled ventilation with CO2 sensors in each private office and specialty occupancy space, or regulate temperature set point based on occupancy by adjusting the HVAC system to operate under the unoccupied set back when occupant sensors indicate that the space is unoccupied.Alternatively, VAV systems meeting all the requirements in LEED Interpretation 5273 are also eligible. However, those systems which do not modulate the system level supply air flow but only redirect the excess air back to the ceiling void or return air duct under low demand conditions are not eligible for this alternative compliance path. For a VRF system or another constant volume system with separate thermal zones for each specialty occupancy or private office, the following active controls would be considered sufficient to meet the credit criteria:PRIVATE OFFICES: Occupant sensor controls or CO2 sensors in each private office sense space occupancy, and modulate the HVAC temperature set points when the space is detected as unoccupied. Additionally, the fan coil serving the room has the fans set to cycle on and off with loads or to operate on the lowest multi-speed setting for multi-speed fans when the space is detected as unoccupied.SPECIALTY USE SPACES: Conference rooms and other specialty use spaces have CO2 sensors or occupant sensor controls, which modulate the HVAC temperature set points when the space is detected as unoccupied. Additionally, demand control ventilation is used to limit the outdoor air supplied to the space based on CO2 levels or space occupancy. Please note, although the VRF system as described can vary the amount of refrigerant supply to the project spaces and save energy, the thermostat controls described are not considered active controls due to the following two reasons: 1. The system is controlled based only on thermostats. For private offices and specialty occupancies where the occupancy varies during the occupied period, thermostat control is not sensitive to the change of occupancy and therefore is not capable adjusting the VRF system to respond to the change, because occupant load is not a major load of the perimeter zones, and is also likely not very significant compared to the cooling load from lighting and equipment in the internal zones. When the occupants are absent or reduced, the HVAC system cannot effectively respond to the change and reduce heating and cooling supply, and/or the ventilation rate. 2. The VRF system is a constant volume system. It cannot reduce airflow to respond to the load change. Please note that the alternative compliance path in LEED Interpretation 5273 requires the system achieve significant supply flow reduction at both the system and zone levels. To achieve this, the system must have fan static pressure reset, and especially, for the spaces where the minimum outdoor air exceeds the required minimum supply volumes, some form of occupant sensing or demand controlled ventilation must be employed to allow the minimum supply volumes to be met. This requires projects to use either CO2 sensors or occupancy sensors in conference rooms or other specialty occupancies, because the room airflow in these spaces cannot typically be reduced to the required percentage of the peak supply volumes while still maintaining the ASHRAE 62.1 ventilation requirements associated with peak occupancy. With variable refrigerant flow and heat recovery which essentially allows for heat exchange between spaces under cooling mode and spaces under heating mode, the VRF system has high cooling and heating efficiency and can achieve high part-load energy performance. This may qualify the project for Option 1 - Equipment Efficiency. Please consider attempting this option in lieu of the option for active zoning and controls, if active controls will not be used with the VRF system.

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

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

Ruling:

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

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

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

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

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

We have multiple new projects on the University of Colorado at Boulder\'s campus all seeking LEED certification which will be serviced by a new heating and cooling plant, also seeking LEED certification. The schedule of the projects is such that the earliest building complete will be complete and occupied approximately one year prior to the completion and start up of the new heating and cooling plant. Although this project is completely designed to be serviced by the new plant (and the drawings will reflect this), the project schedules will create a lapse where the building will have to be serviced by a temporary means until the new heating and cooling plant is operational. The current plan is to utilize temporary chillers and boilers. We believe it is appropriate for our energy model and all other LEED submittals to reflect the final connection to the CUP and not the temporary equipment. Please confirm this approach is acceptable. In addition, please clarify whether the temporary equipment must be commissioned to satisfy EAp1. The new CUP will be commissioned as well as all "downstream" equipment at each building in accordance with the May 28, 2008 CUP memo.

Ruling:

The project team is requesting permission to use the designed central plant specifications for EAc1 Option 1 and all LEED submittals versus the temporary plant that will be connected to the newest building on campus seeking LEED certification. The project team has also requested exception from the EAp1 requirement for commissioning the temporary equipment. The permanent equipment intended for the campus central plant may be used in submitting for EAc1 if the project team provides a letter on owner letterhead stating that the permanent central plant is fully funded. Please also include in the letter a comparison of the schedule of completion for the building in question to a schedule of completion for the central plant. Additionally, if the intent is to use this for other prerequisites and/or credits, this letter should address adequately how the requirements for all credits and prerequisites are being met effectively. However, the temporary equipment shall not be exempt from meeting the requirements of EAp2 - Minimum Energy Performance or EAp1 - Fundamental Commissioning, as this temporary equipment will be in operation for at least one year, if not more. It is necessary that the project team meet those requirements, i.e., a basic minimum level of energy performance and fundamental building systems commissioning for even the temporary equipment.

Campus Applicable
No
Internationally Applicable:
No
4/14/2009
LEED Interpretation
Inquiry:

This project is to renovate 300,000 square feet of an old factory and convert to a distribution center. The owner strongly desires to be sustainable and will use many sustainable features whether or not LEED certification is sought. We will use high efficiency lighting and high efficiency infrared heaters, but no cooling. If we use the ASHRAE appendix G, we have to model the baseline cooling system for the baseline and the proposed. Since the cooling energy will be much larger than the heating energy the 14% reduction from ASHRAE will not be possible. This force the project to be penalized for energy never actually used. In this case we feel that the ASHRAE standard does not rationally apply. This project will reuse a large facility and incorporate significant sustainability features and we would not like to be excluded because the ASHRAE standard does not apply logically to this facility. Is there any alternative method for compliance in this situation?

Ruling:

The project has requested clarification regarding the use of the ASHRAE Baseline requirements in Appendix G. Although a cooling system must be modeled in both the Baseline and Design case, there are no requirements for Temperature Setpoint. Therefore, both cases may have the Cooling Temperature Setpoint elevated such that both systems do not ever run and thus does not consume any energy. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
9/19/2006
LEED Interpretation
Inquiry:

The project consists of a single story 6,300 sf office building attached to a 160,000 sf manufacturing facility. The issue is how to model the heated only manufacturing area. The requirements from ASHRAE 90.1-2004, Appendix G state, "all conditioned spaces in the proposed design shall be simulated as being both heated and cooled even if no heating or cooling system is to be installed." Furthermore, "where no cooling system exists or no cooling system has been specified, the cooling system shall be identical to the system modeled in the baseline building design." These ASHRAE 90.1 requirements indicate that the proposed Constant Volume, 100% Outdoor Air, Gas-Fired, Make-Up Air Unit would need to include the baseline Variable Volume, 100% Outdoor Air, Chilled Water, Packaged Rooftop Unit for cooling. Current industry energy modeling software, approved by ASHRAE 90.1, cannot model this system for a single space. It also is unrealistic to compare the proposed Make-Up Air Units to a VAV w/Reheat System in a manufacturing facility. Our design team suggests that any heated only space should be modeled as heated only (no cooling) for the proposed and baseline model. This is mainly because if it were possible to model the "imaginary" cooling system for heated only spaces it would provide the project with unwarranted energy credit or debit. Specifically, if the loads were reduced between each simulation, for reasons such as improved insulation, the project could use less electricity and therefore gain energy credit from a cooling system that does not exist. Please advise if our recommended procedure to model "heated only" spaces is acceptable, and if not, what is the USGBC\'s recommended method to comply with ASHRAE 90.1-2004 requirements in this instance?

Ruling:

The proposed modeling procedure does not comply with the requirements of ASHRAE 90.1-2004, Appendix G, which is the referenced standard for the purpose of the credit. Table G3.1, #10(d) states clearly: "(d) Where no cooling system exists or no cooling system has been specified, the cooling system shall be identical to the system modeled in the baseline building design." There isn\'t sufficient information about the design HVAC system provided in the request, to identify the correct baseline system configuration. If indeed there is no simulation tool that is capable of modeling the systems, the Exceptional Calculation Method (Section G2.5, Appendix G) should be employed. Table G3.1, # 13. Modeling Limitations to the Simulation Program states clearly "If the simulation program cannot model a component or system included in the proposed design explicitly, substitute a thermodynamically similar component model that can approximate the expected performance of the component that cannot be modeled explicitly." Applicable Internationally.

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

The design of an 11,000 square foot library and offices in a new LEED NC building targeted low energy use and superior indoor air quality as two of its most important green building goals. From the beginning of design, our mechanical engineering team has prioritized efficient equipment to meet the E-Benchmark prescriptive criteria for efficiency requirements (EQc1.3 Option A point 1) and EQ credit 5 for high filtration media. We are limited by those requirements to a single proprietary mechanical system of water source heat pumps. As-built conditions in the space revealed that in order to fit our heat pump units in the available head heights, two units serving the Entry Lobby/Children\'s Room and Auditorium needed to be changed to split units. This split effectively reduces the EER and COP standards to slightly lower than the E-Benchmark standards. The total average of system efficiency by capacity remains well above the EER and COP E-Benchmark threshold requirements. These HP-2 split units are sized for a maximum occupancy load that will only occur several times a year in the Lobby and occasionally in the Children\'s Room and Auditorium. As it is not required for LEED-CI, we do not have an energy model to show annual expected use. However, since these split units are sized for a maximum capacity that does not occur regularly, we conclude that the actual average of system efficiency by usage will be much higher than the average by capacity which already meets the threshold. Unit AC-1/ Quantity 1 / Capacity 3 tons / EER=14.0/COP=5.0 Unit AC-2/ Quantity 1 / Capacity 2 tons / EER=18.1/COP=5.7 Unit HP-1/ Quantity 4 / Capacity 10 tons/ EER=16.0/COP=5.0 Unit HP-2/ Quantity 2 / Capacity 8 tons / EER=13.1/COP=4.5 Unit HP-3/ Quantity 1 / Capacity 2 tons / EER=16.5/COP=5.6 Average by capacity: EER=15.25/COP=4.91 E-Benchmark Standard: EER=14.00/COP=4.60 * * 2005 New Building Institute E-Benchmark Standard, Table 2.5.2 Unitary & Applied Heat Pumps, Electrically Operated, p. 69 We propose that we meet the intent of the credit to provide highly efficient HVAC units which meet a high standard, increase our level of energy conservation, and associated environmental impacts.

Ruling:

The project team is inquiring as to whether or not they can deviate from one of the prescriptive requirements of the Advanced Buildings Energy Benchmark Standard. Per LEED NC EAc1 CIR ruling dated 4/23/2008; prescriptive compliance paths and the standards they reference must be met exactly as specified in order to ensure credit compliance. Option 1 - Whole Building Simulation, offers the flexibility that the project team requires. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
9/19/2006
LEED Interpretation
Inquiry:

Our project consists of a two story retail building. The building is open seven days a week from 9:00 am to 9:00 pm for business. We are requesting clarification regarding the modeling of lighting power density for the Proposed Design Case. In an effort to limit lighting energy usage, the project has developed two completely separate ambient lighting systems, which will NEVER operate simultaneously. A Building Automation System will be used to control the lighting systems, and to ensure that these systems do NOT ever operate in combination with one another. - System 1 consists of the general illumination (ambient lighting) having an overall LPD of 0.53 watts/sf, operational during business hours. - System 2 consists of the emergency/cleaning lighting system having an overall LPD of 0.9 watts/sf (using the ASHRAE 90.1-2004 Building Area Method). This system is a completely separate bank of lighting fixtures, which will only operate during the night for a few hours for housekeeping and maintenance, and during emergencies to provide code required egress lighting. Since the dual lighting systems have been designed for the purpose of limiting energy usage, and since these systems will never operate at the same time, we believe it would be unfair to require the project to model the cumulative lighting power density for the two systems for the "Proposed Lighting Power Density". Instead, we propose to model the lighting power density for the proposed case as two independent interior lighting systems for the building. The lighting power density for each system will then be compared to the base case ASHRAE 90.1-2004 building having a LPD of 1.5 watts/sf, based on the Building Area Method. For example, during store hours, the regulated lighting power would be modeled as 0.53 W/sf versus 1.5 W/sf allowed, and during cleaning hours the regulated lighting power would be modeled as 0.90 W/sf versus 1.5 W/sf allowed. We believe this modeling strategy meets the intent of the LEED v2.1 EAc1 credit by encouraging energy efficient design and controls, and by limiting total building energy consumption and costs.

Ruling:

The proposed modeling strategy does not comply with ASHRAE 90.1-2004. Per ASHRAE 90.1-2004, Section 9; "Exception to 9.1.3: If two or more independently operating lighting systems in a space are capable of being controlled to prevent simultaneous user operation, the installed interior lighting power shall be based solely on the lighting system with the highest wattage." Therefore, the proposed design must be modeled using 0.9 W/sf, for the purpose of the Energy Cost Budget calculation.

Campus Applicable
No
Internationally Applicable:
No
3/22/2007
LEED Interpretation
Inquiry:

Our project consists of two small buildings close to the ocean that will achieve substantial energy savings by incorporating a natural ventilation strategy. No mechanical heating or cooling is intended for either building, with the exception of a small electrical/server room. The building is designed with a very narrow and long floor plate situated perpendicular to prevailing winds in the area. Ventilation openings are consistent with the requirements of ASHRAE 62.1-2004 Section 6.8. The project also meets the requirements outlined in the CIBSE Applications Manual 10: 2005 as referenced in EQc2 for Natural ventilation in non-domestic buildings. Per Title-24 2005 requirements for natural ventilation, the sum of operable windows will be greater than 5% of the floor area of each space that is naturally ventilated. The openings will also be readily accessible to the occupants of each space at all times. Outdoor airflow through the openings in regularly occupied spaces will come directly from the outdoors, not through intermediate spaces such as other occupied spaces or corridors. Openings include operable windows, through-the roof ventilators, and vents between interior spaces. Control mechanisms for the natural ventilation openings are manual. A long, tall hallway situated perpendicular to the prevailing winds will collect heated air and exhaust it the outside. The roof over much of the space is sloped allowing air to enter on the low side and exit on the high side. In all cases, the building is designed to facilitate cross-ventilation with windows low on the walls for drawing the air in, and windows and vents high in opposite walls or on the roof to draw air out. Under ASHRAE 55 definitions, the building spaces are defined as "naturally conditioned spaces, occupant controlled" where the thermal conditions of the spaces are regulated primarily by the opening and closing of windows or vents by the occupants. Since the building will have a limited number of occupants most of the time, manual control of the windows and vents has been determined the most appropriate strategy for the building to allow control over individual thermal comfort. As indicated by ASHRAE 55-2004, section 5.3, the occupants of the space will be engaged in near sedentary activities with metabolic rates ranging from 1.0 met to 1.3 met. The mean monthly outdoor temperature for the project is greater than 50 deg. F, and less than 92.3 deg. F all months of the year, as required under ASHRAE 55-2004, section 5.3 for naturally ventilated buildings. The User\'s Manual for ASHRAE 90.1-2004 Appendix G states on page G-21: The proposed building default cooling system does not exclude natural ventilation from consideration. It just means that the proposed building is modeled as a hybrid system where cooling is provided by natural ventilation when conditions are acceptable and by the default mechanical cooling system when natural ventilation is inadequate to provide thermal comfort. We are requesting confirmation that the following modeling strategy conforms to the requirements of ASHRAE 90.1-2004 Appendix G modeling protocol: 1. EnergyPlus will be used to model the building since the EnergyPlus software has the capability to evaluate energy and comfort parameters tied to natural ventilation. 2. The Exceptional Calculation Methodology will be applied to calculate the natural ventilation savings. 3. The Proposed Design model will be developed to reflect the design parameters for the envelope and lighting. Operable windows will be modeled as fixed, and vents will not be included in the model. Mechanical systems will be modeled identically to the default heating, cooling and fan systems in the Baseline case, except that fans in the proposed case will be modeled as cycling on and off to meet heating and cooling loads during all hours in the proposed case, and will operate continuously during occupied hours in the Baseline Case (per the exception shown in Table G3.1.4). 4. Using the Exceptional Calculation Methodology, The Proposed Design case will be modified to include natural ventilation for all hours when the cooling and heating loads can be met. Operable windows and vents will be modeled as designed. Cooling and heating setpoint temperatures will be identical to those in the Baseline Case. Schedules will be adjusted to switch on mechanical cooling during hours when natural ventilation alone cannot meet the space temperature setpoints. The final model will meet the ASHRAE G3.1.2.2 requirements stipulating that the Proposed Design cannot exceed the Baseline Design unmet load hours by more than 50, and that unmet load hours for the Proposed Design and Baseline Design cannot exceed 300. 5. (Plan B) If the hybrid system cannot be manipulated to meet the unmet load hour requirements within the energy model, hourly output data from a natural ventilation model (having no mechanical cooling) and the Proposed Design model will be combined in a spreadsheet. Each hour where cooling and heating setpoints are met in the natural ventilation model, the hourly results for that model will be used. For all other hours, the hourly results from the Proposed Design Model will be used. 6. An Exceptional Calculation Methodology narrative provided with the EAc1 submittal will document any schedule adjustments and assumptions that were made to develop the hybrid system. The savings will also be included as a separate line item on the EAc1 submittal. Is our proposed energy modeling strategy for natural ventilation acceptable?

Ruling:

The project is requesting approval for the method of modeling natural ventilation as an energy efficiency measure and for taking credit under EA credit 1. Submittals for natural ventilation savings will be evaluated on a case by case basis. The tools and analysis protocol proposed is acceptable for modeling ventilation savings in this instance. Other analysis tools may also be appropriate. To be able to adequately document the process and the results, please be sure to provide in the LEED submittal the following:

  • A detailed project description
  • Clear identification of the areas that are taking credit for natural ventilation
  • A detailed description or references that document the modeling algorithms and/or methodology for the natural ventilation portion of the energy model
  • All thermostat, fan, infiltration and other appropriate schedules for naturally ventilated areas

Also, the submitted evaluation must demonstrate that the range of unmet load hours is similar for both the proposed and baseline building, to ensure that savings are not claimed for hours outside of the control parameters. In this case, the project has proposed to meet these peak loads with a hypothetical cooling system in the proposed building.

The project will also need to clearly demonstrate that the operational schedule for the natural ventilation system as modeled aligns with anticipated occupant behavior in terms of scheduled occupancy vs. modeled operation. For example, the model cannot assume that natural ventilation will occur when no one is in the building to operate the system. Because manual control is not addressed by the Appendix G modeling methodology, the manual control features of this project must be submitted under the exceptional calculation methodology for case by case review. The project must be prepared to demonstrate convincingly that a manual control strategy is appropriate and workable for this project. Please also be sure to take credit for this measure as a separate item on the LEED-NC v2.2 Submittal Template. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
10/24/2008
LEED Interpretation
Inquiry:

Our project includes a 120,000SF addition/renovation to a 140,000SF office building. Lighting control systems were installed to provide increasing levels of energy performance savings by adjusting the initial foot-candle levels down to IESNA acceptable maintained foot-candle levels. The project includes expansion of the existing Eaton\'s POW-R-Command lighting control system. Our approach is not proprietary to the Eaton system and could be applied to any automatic lighting control system. Use of our lighting control approach results in energy savings beyond the default 10% energy savings limit identified in Table G2.3 within ASHRAE 90.1-2004, Appendix G. We are requesting the USGBC allow us to use the alternative method to modify the lighting schedules beyond the 10% limit in accordance with the standard as outlined below. Standard lighting foot-candle design is based on maintained foot-candle levels understanding that initial levels will be higher and will degrade over time. For this project, the light loss factor is 85% of initial fixture performance. This standard design approach typically results in initial lighting designs that are over-lit and a higher w/sf value. For this project, the lighting foot-candle design and layout provides roughly 20%+ more initial illuminance than IESNA Recommended Guidelines, however upon installation, the lighting levels are dimmed through the lighting control system to those foot-candle levels which meet the IESNA Guidelines for maintained lighting illuminance. Over time, as lamp depreciation occurs, the illumination performance is automatically increased to consistently maintain the IESNA Guidelines level. This control approach has been in use within the existing facility for the past ten years. Dimming control of the system is programmed and performed by facilities staff only and the individual occupants do not have control capabilities. This feature can not be overridden by the occupants. Controlling and operating the lamps in this manner in the existing building have resulted in a 33% reduction in electrical energy use plus additional cooling capacity savings when compared to an un-controlled lighting approach and have resulted in approximately 40% lighting energy savings within the new addition. ASHRAE 90.1 - 2004 Appendix G, Paragraph G.25 - Exceptional Calculation Methods, states "When no simulation program is available that adequately models a design, material, or device, the rating authority may approve an exceptional calculation method to demonstrate above-standard performance using this method". However, in Table G3.1, paragraph 6(g), the standards states "For automatic lighting controls in addition to those required for minimum code compliance under 9.2, credit may be taken for automatically controlled systems by reducing the connected lighting by the applicable percentages listed in Table G2.3. Alternatively, credit may be taken for these devices by modifying the lighting schedules used for the proposed design, provided that credible technical documentation for the modifications are provided to the rating authority. We believe our project approach meets the intent of the alternative modified schedule approach. The system, as installed: Exceeds the energy savings allowed using standard building modeling protocol Meets the intent of the credit Provides a creative method to produce additional measurable energy performance savings Reduces environmental impact

Ruling:

The project team is requesting an allowance to account for energy savings from lighting control above the 10% as defined in ASHRAE 90.1-2004. As stated in ASHRAE 90.1-2004 Table G3.1, No. 4 Baseline Building Performance, non-standard efficiency measures such as lighting controls can be modeled by modifying schedules. The schedule change and energy savings should be modeled and submitted as an exceptional calculation method (Section G2.5 of ASHRAE 90.1-2004, Appendix G), with documentation that supports the proposed lighting schedule. Applicable Internationally.

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

In the LEED for Commercial Interiors and LEED for Retail: Commercial Interiors rating systems, EA credit 1.3, Option A (for 2.0) or Option 1 (for 2009), Appropriate Zoning and Controls, the credit language states, "Zone tenant fit-out of space to meet the following requirements ... Private offices and specialty occupancies (conference rooms, kitchens, etc.) must have active controls capable of sensing space use and modulating HVAC system in response to space demand". The Interior Design and Construction Reference Guide states that, "requirements need only apply to the extent of the project scope". Does "project scope" refer to all spaces that are within the LEED project boundary, regardless of whether they are included in the scope of work for the project? Must each private office have its own controls, or can private offices be grouped together?

Ruling:

Yes, "project scope" refers to all spaces within the LEED project boundary, regardless of whether or not they are included in the project\'s scope of work. The project can comply with the requirements of the credit as long as all spaces within the "project scope" satisfy the requirements.Each private office must have its own active controls. Grouping of offices using a single control does not meet the intent of the requirements.

Campus Applicable
No
Internationally Applicable:
No
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Intent

To achieve increasing levels of energy conservation beyond the prerequisite standard to reduce environmental and economic impacts associated with excessive energy use.

Requirements

MANDATORY POINT MINIMUM: Project registered on or after April 8, 2016 must earn four points in this credit, but can come from any of the four sub-sections.
Option 1
Implement 1 or both of the following strategies:
  • Equipment Efficiency—(5 points) Install heating, ventilation and air conditioning (HVAC) systems that comply with the efficiency requirements outlined in the New Building Institute’s Advanced Buildings™ Core Performance™ Guide Sections 1.4: Mechanical System Design, 2.9: Mechanical Equipment Efficiency and 3.10: Variable Speed Control.
  • Appropriate Zoning and Controls: (5 points) Zone tenant fit out of spaces to meet the following requirements:
    • Every solar exposure must have a separate control zone.
    • Interior spaces must be separately zoned.
    • Private offices and special occupancies (conference rooms, kitchens, etc.) must have active controls capable of sensing space use and modulating the HVAC system in response to space demand.

OR

Option 2
Reduce design energy cost compared with the energy cost budget for regulated energy components described in the requirements of ANSI/ASHRAE/IESNA Standard 90.1-2007 (with errata but without addenda1). Projects outside the U.S. may use a USGBC approved equivalent standard2.

AND

Path 1 (5 points)
Demonstrate that HVAC system component performance criteria used for tenant space are 15% better than a system in minimum compliance with ANSI/ASHRAE/IESNA Standard 90.1–2007 (with errata but without addenda1) or USGBC approved equivalent.

OR

Path 2 (10 points)
Demonstrate that HVAC system component performance criteria used for tenant space are 30% better than a system that is in minimum compliance with ANSI/ASHRAE/IESNA Standard 90.1-2007 (with errata but without addenda1) or USGBC approved equivalent.

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10/1/2012Updated: 2/14/2015
Global ACP
Description of change:
Add "or USGBC approved equivalent" to the end of the sentence.
Campus Applicable
No
Internationally Applicable:
Yes
4/1/2012Updated: 2/14/2015
Reference Guide Correction
Description of change:
Under "STEP 7", in the first sentence, changes the first "2" to "multiple" and the second "2" to "3". Replace the period with a comma at the end of last sentence in the first paragraph, and add "but should only be used if the central plants in the baseline and the design cases are modeled identically."
Campus Applicable
No
Internationally Applicable:
No
11/3/2010Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the second sentence in the first paragraph with the following text: Section 1.4 covers mechanical system design intended to closely match actual building loads and to meet ASHRAE 55; Section 2.9 covers Mechanical Equipment Efficiency Requirements; Section 3.10 covers Variable Frequency Drives.
Campus Applicable
No
Internationally Applicable:
No
10/1/2013Updated: 2/14/2015
Reference Guide Correction
Description of change:
In the example listed in Table 3, the points earned for a 36.3% and a 15.8% reduction should be 10 and 5, respectively.
Campus Applicable
No
Internationally Applicable:
Yes
10/1/2012Updated: 2/14/2015
Global ACP
Description of change:
Add "or USGBC approved equivalent" to the end of the sentence.
Campus Applicable
No
Internationally Applicable:
Yes
10/1/2012Updated: 2/14/2015
Global ACP
Description of change:
Add "Projects outside the U.S. may use a USGBC approved equivalent standard ." to the end of the option.
Campus Applicable
No
Internationally Applicable:
Yes
1/8/2010Updated: 2/14/2015
Reference Guide Correction
Description of change:
Insert the term "Tenant space" in alphabetical order with the accompanying text "Tenant space is the area within the LEED project boundary. For more information on what can and must be in the LEED project boundary see the Minimum Program Requirements (MPRs) and LEED 2009 MPR Supplemental Guidance. Note: tenant space is the same as project space."
Campus Applicable
No
Internationally Applicable:
No
4/1/2012Updated: 2/14/2015
Reference Guide Correction
Description of change:
Above "7. Documentation Guidance", add the following:Equation 3. Percent Annual HVAC Energy Cost Reduction For use when Central Plant improvements are included in the project scope.(See supplement document for equation)
Campus Applicable
No
Internationally Applicable:
No
10/1/2012Updated: 2/14/2015
Global ACP
Description of change:
Add the following footnote to the bottom of the page: "Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1-2007 if it is approved by USGBC as an equivalent standard using the process located at www.usgbc.org/leedisglobal"
Campus Applicable
No
Internationally Applicable:
Yes
6/30/2009
LEED Interpretation
Inquiry:

Our project consists of multifamily rental units. We are performing the energy model using TRACE 700, a program that meets ASHRAE Standard 140-2004: Building Thermal Envelope and Fabric Load Tests. TRACE 700 does not have the capability of modeling domestic hot water energy usage. In order to account for domestic hot water energy usage we are proposing to use the Department of Energy sponsored Lawrence Berkeley National Laboratory calculation methodology. The spreadsheet can be found at www.doa.state.wi.us/docs_view2.asp?docid=2249. This spreadsheet estimates the energy consumption of water heaters based on power source, energy factor, and recovery efficiency. In addition, the spreadsheet estimates the energy reductions associated with hot water consumption of Energy Star clothes washers and dishwashers. According to the CIR ruling dated 4/25/2007, credit cannot be taken for low flow fixtures accounted for in WE credit 3. However, clothes washers and dishwashers are not accounted for in LEED NC v2.2 WE credit 3. An exceptional calculation in accordance with Appendix G will be provided to demonstrate energy savings for the Energy Star appliance itself. In addition, we believe the reduction in the amount of hot water required by Energy Star clothes washers and dishwashers should be accounted for in the water heating calculation. The basis for these calculations found at http://hes.lbl.gov/hes/aboutwhm.html will be uploaded as supporting documentation. 1. Can we use the Lawrence Berkeley National Laboratory spreadsheet since TRACE 700 does not model energy consumption for domestic water heaters? 2. Can the energy savings for the reduced hot water consumption for Energy Star clothes washers and dishwashers be accounted for in the domestic hot water energy consumption calculation?

Ruling:

The applicant is asking for confirmation that LBNL spreadsheet calculations can be used to document domestic hot water use and asking if hot water savings resulting from Energy Star clothes washers and dishwashers can be accounted for in the exceptional calculation. 1. It seems that the LBNL spreadsheet calculations are an appropriate method for calculating domestic hot water use and for documenting the energy savings associated with Energy Star equipment. However in order to be accepted as an exceptional calculation, be sure to include a detailed narrative with all assumptions and supporting calculations with the submittal. 2. Yes, energy savings for reduced hot water consumption can be counted in DHW energy calculation. ***Please note, this CIR was updated on 7/10/2009.***

Campus Applicable
No
Internationally Applicable:
No
4/25/2008
LEED Interpretation
Inquiry:

Recently, USGBC approved a CIR regarding savings from key cards in hotel rooms (5/14/07 - see attached). We are requesting that under LEED-NC savings from submetering of multi-family buildings be accepted as an exceptional calculation method. There are no code requirements for submetering of apartment or condominiums in multi-family buildings. Submetering of utilities for individual tenants or owners in multi-family buildings is an added construction cost, but significant energy savings result. Studies have shown that a minimum of 10% energy savings are achieved once individual metering is implemented. Research done by the New York State Energy Research and Development Authority (NYSERDA: http://www.nyserda.org/publications/SubmeterManual.pdf) estimates that installing sub-meters in a master-metered building can reduce building-wide electricity consumption by 10-26%. In Ontario, Canada, non-electrically heated submetered apartments have shown a 16-22% reduction in electricity consumption while electrically heated apartments with submetering showed a reduction in consumption of 30% (http://www.frpo.org/Document/Topics&Issues/UtilitiesEnergy/Options%20to%...). Based on these studies and the fact that submetering is not required by the energy codes, we request that USGBC allow an exceptional calculation method to account for the savings from submetering. We are proposing that 10% cost savings of all submetered end uses be allowed by the calculation method. So, if a living unit is submetered for electricity and gas, the project can assume 10% cost savings for each of these fuel sources based on the energy use within the unit. Energy use in common areas of the building would be excluded from the calculation. Is this acceptable? Related CIR\'s 4/12/2007 - Credit Interpretation Request Per ASHRAE 90.1-1999 and 2004 mandatory requirements, hotel guestrooms must include a master control device at the main room entry that controls all permanently installed luminaires and switched receptacles. We are considering automating this lighting control with the use of a key card-activated master switch. The control would turn off all permanently installed and switched receptacle lighting after the guestroom is unoccupied for more than 30 minutes. The controls may also be configured to allow the interior window shades to be closed automatically when the guestroom is unoccupied. Monitored data for hotel lighting usage patterns is provided in a 1999 Research study by Erik Page and Michael Siminovitch entitled "Lighting Energy Savings in Hotel Guestrooms." This study indicates an average daily usage of nearly 8 hours for the bathroom light, 2 hours for the desk table lamp, 5 hours for the bedside lamp, and 3 hours for a floor lamp. The study also showed that the high use fixtures (the bathroom fixture and bed lamp) did not experience a significant drop during typically unoccupied periods. Instead, these lights were 20% - 25% on during these periods; and the lighting energy consumed during these periods accounted for about 60% of the total guestroom lighting energy consumption. Another study for ACEEE entitled the "Emerging Energy-Savings Technologies and Practices for the Building Sector as of 2004" projects an energy savings for key card lighting controls of 30%. Based on the information provided in these two studies, it seems reasonable to credit hotel guestroom lighting fixtures with a 30% energy savings for automated control based on room occupancy. We propose to model the energy savings achieved through automated control of lighting and interior window shades as an exceptional calculation measure. The lighting savings would be calculated by adjusting the proposed case lighting schedules for all permanently installed and switched receptacle fixtures to 50% lower than the budget case for the percentage of guestrooms modeled as unoccupied. Lighting during all occupied periods will be modeled identically to the budget case. The guestroom lighting energy savings achieved through this measure for the affected lighting fixtures would be 30%. Automated control of the blinds is intended to limit solar heat gains, since the building is in a hot dry climate. The blinds will be modeled identically during the occupied periods as 50% open during daylit hours, and 25% open during evening hours. During unoccupied periods, the shades will be modeled as 25% open. As with all exceptional calculation measures, the savings for this automated control measure will include a narrative documenting the lighting and interior shading schedules and assumptions, and the calculation methodology, and will include a separate line item on the ECB report documenting the savings achieved from this measure. We would like confirmation whether the proposed modeling methodology is acceptable, or direction regarding any modifications that would need to be made to the proposed modeling methodology in order to comply with LEED ECB modeling requirements. 5/14/2007 - Ruling The applicant is requesting confirmation on the proposed strategy for two exceptional calculations. Based on the description of the lighting assumptions, the proposed approach is acceptable. In the LEED submittal please include a narrative documenting the lighting schedules and assumptions and the calculation methodology. Also include a separate line item on the ECB report documenting the savings achieved from this measure. Please provide enough detail in the documentation to allow the review team to ascertain the amount of credit claimed. Based on the description of the automated blinds, the assumptions concerning blind control are insufficient to model the proposed building.

Ruling:

The project team is inquiring as to whether or not sub-metering of multi-family residential buildings would be acceptable as an exceptional calculation method. The energy savings associated with sub-metering are due to a change in occupant behavior and not due to building efficiency. As a result, the schedules in the baseline case must be modeled identically to those in the design case. Therefore project teams may not claim credit for sub-metering of a multi-family residential building through the exceptional calculation method.

Campus Applicable
No
Internationally Applicable:
No
2/20/2009
LEED Interpretation
Inquiry:

We are pursuing LEED NC for a high end high rise residence in Tokyo, Japan. We are showing compliance for EA-P2 and energy cost reduction for EA-C1 using the Performance Rating Method (Appendix G - PRM). ASHRAE 90.1 requires that the ratings for fenestration U-values, SHGC, and VLT are determined in accordance with NFRC 100 and 200. We will be using double paned and double paned Low E flat glass produced by AGC (Asahi Glass Co) here in Japan. AGC is one of the largest flat glass manufacturers and the parent company of AGC Flat Glass North America (formerly AFG - American Flat Glass). As this is a very high end residential project, with large glazed surfaces, a great deal of attention was paid to specifying glass in the design. Our issue is that AGC Japan products are rated using the Japanese Industrial Standards (JIS) and not NFRC as required. Although not explicitly stated in Appendix G - PRM, it is our understanding that if products are not NFRC rated, the poor default values provided in Normative Appendix A (Tables A8.1 and A8.2) of ASHRAE 90.1 are required to be used in place of manufacturer provided data for modeling purposes. NFRC rated products are not available in the in Japanese market. We have contacted AGC Japan to inquire if they have knowledge of NFRC rating procedures. Their response was that they do not, and only rate to JIS standards as required in Japan. The Japanese Industrial Standards (JIS) used for determining the solar optical and thermal properties of windows are JIS R 3106 and JIS R 3107. These two standards are stated by the Japanese Standards Association as being equivalent to ISO 9050 (Glass in building - Determination of light transmittance, solar direct transmittance, total solar energy transmittance, ultraviolet transmittance and related glazing factors) and ISO 10292 (Glass in building - Calculation of steady-state U values of multiple glazing). We understand that ISO 9050 and ISO 10292 form the referenced technical basis for ISO 15099 (Thermal performance of windows, doors and shading devices - Detailed calculations) which is the technical standard for determining optical and thermal properties of fenestration assemblies. ISO 15099 in turn defines the technical basis of NFRC 100 and NFRC 200. Other than the requirement for fenestration products being tested in a NFRC approved laboratory, which do not exist in Japan, we believe the JIS rated properties provided by AGC are in compliance with the technical requirements of NFRC standards and thus ASHRAE 90.1. Given this we have the following questions: 1) Can we use optical and thermal properties provided by AGC for Japanese domestically produced flat glass to model performance compliance in eQuest/DOE-2 using the performance rating method? 2) If 1) above is unacceptable, can we substitute optical and thermal properties of similar AGC NA (AFG) glass products for the eQuest/DOE-2 simulations? If the above is unacceptable, we have not identified any other way around this issue other than to import glass or have glass tested in the U.S. Both of these options are costly and not practical, and would deter this and any future LEED NC projects from being undertaken in Japan. In addition, we believe importing from abroad is not environmentally preferable in terms of CO2 impacts associated with transport.

Ruling:

The applicant is requesting the use of optical and thermal properties for fenestration determined by standards other than NFRC 100 and NFRC 200. The Japanese Industrial Standards (JIS) appear to be technically equivalent to the NFRC standards referenced in ASRHAE 90.1-2004. The use of optical and thermal properties determined by JIS 3106 and 3107 represent the actual thermal performance of fenestration products and may be used to determine fenestration parameters for use in the energy simulation. Please note that the NFRC ratings refer to the optical and thermal properties of the whole assembly. When preparing the EAc1 submission, the applicant should confirm that the optical and thermal properties determined by the applicable JIS standards and used in the energy simulation represent the properties of the whole fenestration assembly. Applicable Internationally; Japan.

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

Can we take credit for a demand ventilation system for an automotive service area?Essentially we propose to model the service area in the Baseline Cases at 100% outside air at 1.5 CFM/sq.ft. during occupied periods to meet ASHRAE 62.1. We plan to model the service area in the Proposed Case with typical storage ventilation rate. See rationale below to validate our assumptions.We further propose to model this energy efficiency measure in the standard credit energy models (not as an exceptional calculation) as part of the Baseline and Proposed Cases in order to accurately account for the differences in ventilation load. The differences are based on outside air conditions which change throughout the year and they also impact the supply air unit and fan sizes. The simulation program must size the equipment for the Baseline Case at the peak load and model it use 8760 hours in the year. ASHRAE 62.1 lists a specific minimum ventilation rate for automotive service areas at 1.5 CFM/sq. ft. Ventilation reduction controls are not stated in Ashrae 62.1, nor are they mandated in ASHRAE 90.1-2007. The governing Mechanical Code (International Mechanical Code) optionally permits the use of approved automatic detection devices to control the required ventilation fans and/or make-up air systems. Large make-up air systems providing 100% outside air are still readily available and utilized in order to meet the mandated code. We have utilized the following assumptions for modeling energy usage:Baseline Case - The exhaust ventilation system is modeled to operate at 1.5 CFM/sq.ft. during occupied hours per occupancy schedule. The modeling software automatically sizes the air conditioning system to operate as a 100% outside air system as the total CFM requirement exceeds the design load amount. The unoccupied fan cycle does not include the ventilation and only operates to maintain unoccupied thermostat set point.Proposed Case - The exhaust ventilation system is modeled to be non-operational at any time. We make this assumption based on calculation and witnessed operation at like facilities with the identical control system in place. We have calculated carbon monoxide production based upon maximum estimated daily vehicle round trips through the service area. Eighteen service stalls with an average of 3 vehicles per day and 1 minute round trip drive time yields an estimated total vehicle drive time in the service area to be 54 minutes. The average modern vehicle with catalytic converter produces approximately 150 CFM of exhaust airflow at idle to slow speed containing approximately 1,000 PPM of carbon monoxide. 150 CFM X (0.1%) = 0.15 CFM of carbon monoxide production. The requirement to engage the exhaust ventilation system is 50 PPM of carbon monoxide. The volume of the space is 236,900 cu.ft. and would require 11.845 cu.ft. of carbon monoxide to engage the system. This would require 78.97 minutes of continuous operation without any dilution in a facility this size which exceeds the estimated maximum vehicle operation time of 54 minutes by 30%. The air conditioning equipment serving the area provides 800 CFM outside air and is equivalent to a complete air change twice a day and therefore doubling the daily total required operation time to 157.94 minutes. Operation of vehicles for diagnostic testing is excluded as there is a separate tailpipe extraction system in place to remove all exhaust during testing. Calculations are no substitute for actual conditions. We have interviewed service managers as to the operations of the emergency exhaust system controlled with a CO monitor system. The feed back is overwhelming that the emergency system is never engaged during normal operation. The technicians in these facilities have been trained in the control systems operations and do not desire to have their "conditioned" air purged from the building due to excessive operation of the vehicles within the space.

Ruling:

A project team cannot be awarded credit for demand controlled ventilation in an automotive service area, due to concerns over contaminants, and possible effects on indoor evironmental quality. As there is no current accepted methodology, the potential human health risks outweigh the energy savings.

Campus Applicable
No
Internationally Applicable:
No
10/3/2008
LEED Interpretation
Inquiry:

Conventional vented domestic clothes dryers require approximately 200 cfm of exhaust when operating. In large multi-story residential buildings, the dryer exhaust is typically provided by dryer exhaust risers that vertically link multiple units with a constant or variable speed exhaust fan. Several exhaust risers may be used to meet the needs of all apartments in a building. Variable speed fans typically modulate based on static pressure in the exhaust riser and are limited no less than 25 percent of design flow. Constant speed fans assume some diversity and do not modulate. Either fan operates 24 hours per day. The dryer exhaust requires continuous makeup air that must be conditioned either at an outside air handling unit or as in additional infiltration load in individual residences. An alternative to conventional vented dryers are ventless condenser dryers. Condenser dryers still use heated air to evaporate water from the clothes, but use an air-to-air heat exchanger to condense water from the humid air rather than exhausting the air and replacing it with fresh air from the room. Heat from the dryer remains in the room and no external venting or makeup air is required. Vented dryers are the "standard practice" in large residential buildings. This is probably due to the fact that (1) vented dryers are the more familiar technology, (2) drying times are shorter with conventional dryers than with condenser dryers, and also because (3) vented dryers are less expensive than condenser dryers. Based on a 1998 study by James Kao of the National Institute of Standards and Technology (NIST) titled "Energy Test Results of a Conventional Clothes Dryer and a Condenser Clothes Dryer," condenser clothes dryers use between 5 and 30 percent more energy per pound of laundry than a conventional vented dryer (depending on the size of each load). The NIST study only accounts for the energy to operate the dryer. The study does not account for the additional effects on the HVAC system due to the outside air requirements. The net effect of using condenser dryers in lieu of conventional dryers is a reduction in overall energy use in the climate zone for the building we are studying (New York City climate). We propose the following as an exceptional calculation methodology to simulate the performance of condenser dryers over standard vented dryers: Baseline Building: 1. Model typical dryer energy patterns based on standard washing machine use patterns from EnergyStar. 2. Model the dryer such that none of the dryer energy results in heat gain in the space. 3. Model the Baseline Building with 50 cfm of air exhausted from each residential unit with a dryer. To do this, include dryer exhaust fan energy assuming that the fan runs at an average of 50 cfm, 24 hours per day, at the same static pressure as the other rooftop exhaust fans. Include 50 cfm of additional infiltration 24 hours per day for every residence with a dryer. Proposed Building: 1. Increase the dryer energy use by 20 percent based on a conservative rounding of the average results from Kao\'s study of dryer energy use. 2. Model the dryer such that all of the dryer energy results in heat gain in the space. 3. Model the proposed building without the dryer exhaust fans and without the additional 50 cfm of infiltration. Is this exceptional calculation method acceptable for LEED EAc1 credit?

Ruling:

The applicant is inquiring about the acceptability of a proposed exceptional calculation method that takes credit for using domestic condensing dryers instead of standard vented dryers in a multi-family high rise residential project. Using an exceptional calculation method to determine energy savings is a generally acceptable pathway. However, the information presented is not sufficient to determine if this exact calculation is adequate enough to determine the correct amount of savings (if there is a savings). The design team must provide justification for their specific assumptions in both the baseline case and the proposed case. Baseline Building: 1. Model typical dryer energy patterns based on standard washing machine use patterns from EnergyStar. This is acceptable. 2. Model the dryer such that none of the dryer energy results in heat gain in the space. Assuming no heat gain to the space is not self evident. Documentation in the form of industry accepted studies indicating as such would be required to ensure that this is an acceptable assumption. 3. Model the Baseline Building with 50 cfm of air exhausted from each residential unit with a dryer. To do this, include dryer exhaust fan energy assuming that the fan runs at an average of 50 cfm, 24 hours per day, at the same static pressure as the other rooftop exhaust fans. Include 50 cfm of additional infiltration 24 hours per day for every residence with a dryer. Assuming 50 cfm of continuous ventilation per dwelling may be excessive. A study of use patterns combine with cfm values for expected dryer type applied to this particular building would be required. Calculations on static pressure that include data on the height of the building, the max. static pressure per dryer and the expected duct size would also assist the reviewer in determining appropriate energy savings. Proposed Building: 1. Increase the dryer energy use by 20 percent based on a conservative rounding of the average results from Kao\'s study of dryer energy use. 20 percent is not necessarily a conservative figure. Further justification needs to be provided. Provide manufacturers data on the units and their proposed energy use. 2. Model the dryer such that all of the dryer energy results in heat gain in the space. Again, assuming that all of the energy used in the drying cycle results in heat gain to the space is not self evident. Industry accepted studies would be required to ensure that this is an acceptable assumption. 3. Model the proposed building without the dryer exhaust fans and without the additional 50 cfm of infiltration. This is acceptable as long as the figures determine from # 3 in the baseline case are used. Also, since the design team is proposing energy savings for the entire building based on the use of condensing dryers, some assurances must be given that all units will use condensing dryers.

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

This project is located on a multi-building medical campus in Illinois. Typical of a campus, it is composed of numerous existing buildings, parking structures, surface lots and circulation streets. The campus is proposing to build, as separately bid projects, a new inpatient building, some additions to existing buildings, and a new parking structure. Our intent is to pursue LEED Certification for the new inpatient building, a new multi-level parking structure and new portions of site work on the campus, but not the additions to existing buildings. One of the buildings included in the project boundary is an open parking structure. The parking structure includes an enclosed combination stair/elevator lobby. We intend to heat this stair/elevator lobby as well as ventilate the space. A telecommunication closet along with an electrical room will be heated and conditioned as well. The parking garage is not required to be ventilated since it is classified as an open parking structure. The parking garage and stair/elevator lobby will have lighting as required. LEED for Multiple Buildings allows a weighted aggregate for the group of buildings based on their conditioned square footage or aggregate PRM calculation. We would like to confirm only the areas being heated and conditioned are required to be included in the square footage calculation for this particular structure when being considered into the overall aggregate or overall PRM. The lighting square footage will take into account the overall square footage being covered by lighting. Please confirm that we are using the correct calculation methodology for this point.

Ruling:

The applicant has requested confirmation that the weighted average building method from the Multiple Buildings Application Guide is based only on the conditioned area of each building. This is a correct assumption. The language from the EA Credit 1 Multiple language guide states that the "weighted average for the group of buildings (should) be based on their conditioned square footage." The definitions of space types from ASHRAE 90.1-2004, page 13, should be used to identify whether spaces are defined as "conditioned", "semi-heated", or "unconditioned". The ASHRAE 90.1 Performance Rating Method (Appendix G) should be used to model each building in the project boundary, including the parking structure. Therefore, all interior and exterior parking garage lighting, elevator energy, etc. should be included into the energy model for the parking structure, regardless of whether the spaces are conditioned or unconditioned. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
5/26/2009
LEED Interpretation
Inquiry:

Background: Our project consists of a 4-story office building approximately 105,800 square feet in area. The building will be conditioned by a variable air volume system which includes a single, custom penthouse air handling unit on the roof. The project has been designed to meet ASHRAE Standards 62.1-2004 and 90.1-2004 including the application of demand controlled ventilation strategies. Each temperature control zone will include a series fan-powered terminal unit with electric reheat and each is equipped with an ECM motor. While the basic benefits of ECM motors include motor efficiencies nearly twice that of a traditional PSC motor, negligible heat gain from the motor to the airstream, and the ability to perpetually maintain a given supply airflow, the ability to modulate the terminal fan via the building automation system (BAS) is now feasible allowing control strategies never before possible. Series fan-powered terminal units have traditionally operated at a constant airflow during occupied periods. The proposed terminal unit control strategy for this project includes multiple, unique operating airflow levels: 1. During cooling demand, the fan will operate at the maximum cooling airflow condition (while the primary air damper modulates). 2. Under no call for heating or cooling, the fan will slow to the "deadband" airflow of approximately 50% of the peak cooling airflow. 3. At initial heating demand, the first stage of reheat will be energized and the terminal fan will increase to the first heating airflow setpoint. 4. On a call for additional heat, the second stage of reheat will be energized and the terminal fan will increase to the second heating airflow setpoint, and likewise with the third and final stage of reheat. Note that the heating airflow setpoints are specifically calculated to result in a consistent discharge temperature of 83F for optimum diffuser performance and blending in the space. Intent: Develop a strategy that accounts for the energy savings provided by series fan-powered terminal units with ECM motors. Proposed Strategy: A Whole Building Simulation and energy analysis has been performed towards LEED certification via the Building Performance Rating Method and in accordance with Appendix G of Standard 90.1-2004 utilizing the Trane Trace 700 analysis software (v6.1.3). In detailed review of the program input tables and output reports, we determined that the software was unable to model the control strategy proposed above. This was confirmed via direct communication with the software engineers. Through additional research, we further understand that Carrier HAP, EQuest, nor any other DOE-2 based energy simulation program has the algorithms or capability required. We are requesting confirmation that the following strategy conforms to the modeling requirements of Appendix G. 1. Utilize the Trace 700 energy program to perform a complete building analysis determining all energy consumption for both the proposed building and baseline comparison building in accordance with Appendix G. 2. Apply the Exceptional Calculation Method specifically and only to the terminal fan energy consumption as allowed by Paragraph G2.5 of Appendix G. The Exceptional Calculation Methodology will be as follows: a. Energy savings will be calculated for each individual terminal fan size and at each reduced operating speed based upon the manufacturers fan power data. b. Operating run time at each fan speed within the proposed control strategy will be determined using the heating and cooling load profiles from the Trace 700 output reports. c. Fan terminal energy savings will be calculated by multiplying the run time of the fan by the reduction in KW of fan energy at each specific operating condition. d. The terminal energy savings will be subtracted from the Trace 700 simulation output summary. Is the proposed strategy acceptable?

Ruling:

The project has requested clarification regarding the use of a specific method of computing the additional savings of using Fan-Powered Boxes with a 3-Stage Heating Coil and Electronically Commutated Motors (ECM motors) over traditional PSC motors. This approach is valid and acceptable, but more detailed information must be provided on how fan run time is determined at each of the three heating stages. The motor efficiency should be verified for each airflow condition chosen in the post-processing. Hourly simulation tools such as Trace 700 use complex computation routines and these should be accounted for in any hand calculations that are used to substitute for a Trace 700 energy simulation. Specifically, simply assigning the fans to run at full load (where they are far more efficient than their traditional PSC counterpart) continuously for a large portion of a season (i.e. peak heating months) would not be accurate. To calculate savings for ECM motors the following analysis should be done in the energy model to show compliance with ASHRAE Standard 90.1:

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

Many space types will not function as regularly-occupied private/individual or multi-occupant spaces, nor will those spaces be utilized for extended periods of time (such as kitchen/break room, meeting room, or conference room). Some unique and smaller (less than 200 SF) programmed space types are infrequently occupied (less than 1 hour) and by only one or a few people at a time. One exception to the credit requirement that "private offices" must have active controls is granted in LEED Interpretation #1645 and clarified in the IDC Reference Guide 2009 Edition, which states that "small private spaces intended for single, temporary occupancy (e.g. for making confidential telephone calls) may be included as part of a larger thermal zone, since changes in occupancy will not cause large swings in the heating and cooling loads." Given the credit intent to reduce energy in occupied spaces and the ruling of LEED Interpretation #1645, we propose to expand the definition for small, temporarily-occupied spaces in two ways: 1. For laboratory buildings/spaces, where loads are typically based on equipment loads, we propose a more specific addition to the definition of Special Occupancy to include spaces that are less than or equal to 200 SF and occupied by two or fewer people for short periods of time. 2. For all project types, we propose an expanded definition of Special Occupancy to include spaces with equal or less than 300 cfm, per ASHRAE 90.1-2007 definition of small zones. ASHRAE 90.1-2007 defines small zones as those with less than 300 cfm, as referenced in Sections 6.3.2.n Criteria, 6.4.3.4.3 Shutoff Damper Controls, and 6.5.2.1.a.4 Simultaneous Heating and Cooling Limitation - Zone Controls. In both of these cases, we propose the space types described above be considered Special Occupancy spaces that may be included as part of a larger thermal zone. Are these definitions acceptable?

Ruling:

No, these spaces cannot be considered Special Occupancy. The credit requirements state that private offices and specialty use spaces must have their own active controls capable of sensing space use and modulating the HVAC system in response to changes in space demand.Specialty use spaces are considered to be conference rooms, break rooms, classrooms, gymnasiums with variable use patterns, cafeterias, hotel guest rooms, residential dwelling units, and other occupied spaces where energy savings can be achieved by adjusting the temperature setpoints and/or air volume supplied to the space when the space is unoccupied, or densely occupied space where energy savings can be achieved by adjusting the ventilation air supplied to the space when the space is partially occupied. Laboratory spaces would be considered to be specialty use spaces, since these spaces generally have 100% outside air, where setting back the temperatures and/or the fume hood ventilation when the space is unoccupied or the fume hood(s) are not actively in use would lead to significant energy savings. Laboratory prep and laboratory support spaces, and resource rooms would also be expected to achieve energy savings by adjusting the temperature setpoints and/or air volume supplied to the space when the space is unoccupied, since these spaces are frequently unoccupied throughout each day; therefore, these rooms would be considered to be specialty use spaces. Exception: Spaces that would otherwise be considered specialty use spaces but are smaller than 75 square feet, such as the phone rooms referenced in LEED Interpretation #1645, or a lactation room smaller than 75 square feet are not required to have individual active controls capable of sensing space use and modulating in response to changes in space demand.Spaces not considered to be specialty use spaces: Open offices, reception areas, warehouse or storage spaces, merchandising spaces, lobbies, nursing stations, manufacturing spaces, auto service bays, library stacks, library multi-occupant reading areas, bank teller areas, hallways, and similar spaces are not considered to be specialty use spaces since these spaces would be expected to be at least partially occupied for the majority of the time the HVAC system is operational, and would not be expected to achieve energy savings by adjusting the temperature setpoints and/or air volume supplied to the space when the space is unoccupied. Controls capable of sensing space use and modulating the HVAC system in response to changes in space demand include the following:Interior private offices or interior non-densely occupied specialty use spaces - a separate thermal control for each space. This would be considered sufficient because the space demand is related to internal loads (lighting, occupants, and plug loads). When the occupant leaves the space, particularly if the space has lighting occupant sensors and Energy Star computing equipment, the thermostat will be able to sense a change in space demand, and modulate the HVAC system in response to the change in space demand.Perimeter offices or perimeter non-densely occupied specialty use spaces - a separate thermal control for each space paired with an occupant-sensing or CO2 sensing device, which is used to set back the temperature setpoint and airflow to the space when the space is unoccupied. In many cases, the occupant sensors used for lighting can be integrated with the HVAC controls. This is necessary in perimeter spaces because the space has both envelope loads and internal loads, and the HVAC system would respond minimally to changes in space occupancy if additional occupant-based setback controls were not in place. For a VRF system, fan coils, or packaged single-zone system, the fan coil serving the room must have the fans set to cycle on and off with loads or to operate on the lowest multi-speed setting for multi-speed fans when the space is detected as unoccupied. VAV systems with supply air diffusers and room thermostats: Per LEED Interpretation #5273, VAV systems having supply air diffusers equipped with room thermostats for each private office or non-densely occupied specialty use space may be used in lieu of a separate thermal zone per private office or non-densely occupied specialty use space. If this compliance path is followed, the following additional requirements apply:1. The system must be capable of modulating AHU and zone minimum supply volume down below 0.30 cfm/sf of supply volume for standard VAV terminals, or below 22.5% of the peak design flow rate for fan-powered VAV boxes. For spaces where the minimum outdoor air exceeds the minimum supply volumes specified here, some form of occupant sensing or demand controlled ventilation must be employed to allow these minimum supply volumes to be met. 2. The building control system must include controls for fan static pressure reset. 3. The mandatory requirements of ASHRAE Standards 90.1-2007 and 62.1-2007 must be met. Densely Occupied specialty use spaces (such as a conference room) - a separate thermal control for each space paired with a CO2 or occupant sensing device, which is used for demand control ventilation and to set back the temperature setpoint to the space when the space is unoccupied. Applicable Internationally.

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
10/3/2008
LEED Interpretation
Inquiry:

The purpose of this CIR is to obtain written confirmation and clarification that the use of TAS 9.0.7 software (by EDSL) can be approved as a energy modeling tool for pursuing EA Credit 1 and EA Pre-requisite 2 After reviewing ASHRAE 90.1-2004 Appendix G section G2, where all requirements are specified, we would confirm that the TAS 9.0.7 computer simulation software tool has the following capabilities: a. 8760 hours per year: TAS is able to simulate on an hourly basis over a total of 8760 year. b. Hourly variations in occupancy, lighting power, miscellaneous equipment power, thermostat set points, and HVAC system operation, deigned separately for each day of the week and holidays: TAS has the capability of adding schedules for all of the above. Different load profile can be created for different times of the day and for different days in the week. The possibility of creating out of hours conditions, nigh time setback temperature, etc. is also available. c. Thermal mass effect: TAS accounts for thermal inertia in the space. d. Ten or more thermal zones: TAS can handle more than ten different thermal zones e. Part-load performance curves for mechanical equipment: TAS is able to simulate part load performance for fans and pumps. TAS can model both constant and variable speed pump systems for primary and secondary. In the air side, different systems can be simulated (i.e. VAV, fancoils, etc) with variation in fan consumption as the load varies. f. Capacity and efficiency correction curves for mechanical heating and cooling equipment: TAS has the capability to incorporate correction curves, even combination of numbers of different types of boilers and chillers within the same project. g. Air-side economizers with integrated control: TAS can incorporate free cooling chillers. It has also the capability to model heat recovery air handling units with by-pass control with an air temperature set point. h. Baseline building design characteristics specified in ASHRAE 90.1-2004 Appendix G section G3: TAS allows the user to build a model for the baseline building using the characteristics specified in G3 and also those in G2.1 (same weather data and same energy rates), although the program does not generate it automatically and it is the user that has to carry out the modeling. 2.0 CIR - Design Energy Builder Energy Plus Modeling Tool Approval Please could you confirm whether the USGBC have approved the use of Design Energy Builder latest Version 2.2 of Energy Plus Software modeling Tool and if this is not the case is the software tool currently accepted by the USGBC.

Ruling:

The applicant is requesting approval to use EDSL TAS 9.0.7 software to document compliance with the energy simulation requirements in EAp2 and EAc1. USGBC does not maintain a list of approved energy modeling software. Instead, the project team must ensure that the simulation tool satisfies the requirements of ASHRAE 90.1-2004 Appendix G Section G2. The Design Builder energy simulation and visualization tool incorporates the EnergyPlus simulation engine. EnergyPlus should meet the ASHRAE 90.1 Appendix G Section G.2.2 requirements. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
6/4/2009
LEED Interpretation
Inquiry:

The question is based on ASHRAE 90.1 requirements for Performance Rating Method for building modeling. This building has very high internal loads with the baseline process load at 49% of the total building energy based on actual equipment. The internal load is primarily computer desktops and monitors. Both baseline and proposed building energy usage numbers are based on a calculation worksheet as published by the US dept of Energy for computer desktops and monitors. The Energy Star usage value increases the proposed energy building performance reduction by 10-15%. This lower value for the process load is still above the 25% requirement for the total building energy amount as outlined in the LEED requirements of this point. The equipment in the new building that the owner will provide will consist of Energy Star computer desktops and monitors. We request clarification that we can run the baseline with standard energy load based on LBNL 2007 standards and proposed building with Energy Star energy loads.

Ruling:

The applicant is requesting clarification on how to account for energy savings due to Energy Star rated equipment. Plug in equipment falls under the Process Loads category and any savings claimed under process loads have to be taken as an Exceptional Calculation. Please model the same process loads in both the baseline and proposed building. Then run a separate run of the proposed building with the Energy Star rated equipment. Report savings from this run Exceptional Calculation table in the LEED Submittal Template. Be sure to include a detailed narrative with all assumptions and supporting calculations with the submittal. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
12/14/2006
LEED Interpretation
Inquiry:

The purpose of this project is to allow Bank of America employees an opportunity to work closer to home and reduce their commute to the office. One of the features for the plan on this project is the "Focus" Rooms. These rooms allow the people throughout the floor to conduct phone/conference calls confidentially. These spaces are approximately 35 square feet in area. Based on the point for Appropriate Zoning and Controls, it requires private offices, conference rooms and kitchens to have their own controls. Currently, there are 4 of these spaces zoned together on one side of the floor plan. On the other side of the plan, 2 focus rooms are zoned with a wellness room (approx. 62 sf). I am requesting that these focus rooms be excluded from this requirement due to their low airflow requirements and intermittent use. Please clarify if these rooms will be accepted as they are currently zoned.

Ruling:

The project team is requesting clarification regarding the occupancy-type classification of small spaces used exclusively for making confidential phone calls. These rooms are not intended for use as regularly occupied private office spaces. Also, since these rooms are intended for single occupancy, changes in occupancy will not result in large swings in the heating and cooling loads, as would be true for a break room or conference room. Accordingly, these spaces may be included as part of a larger thermal zone. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
10/24/2008
LEED Interpretation
Inquiry:

Our project is a 65,000 SF injection molding manufacturing facility and office near Detroit, MI. The project consists of 10,000 SF of air-conditioned office space, and 55,000 SF of air-conditioned manufacturing space, which includes injection molding equipment, as well as occupied assembly areas. The energy required for the manufacturing process exceeds 85% of the facility\'s total energy load. To achieve the 14% minimum energy savings, process load energy savings must be taken into account. As a result of the high energy loads associated with the manufacturing process, as well as the energy not falling under ASHRAE 90.1-2004, an exceptional calculation method must be established for the manufacturing area. Both the office area and the manufacturing area are conditioned. Space cooling in these areas will be achieved through constant volume rooftop units, and will be modeled through a standard energy modeling software like Trane Trace 700. The manufacturing process includes injection molding machinery which is cooled through a chiller & cooling tower assembly. The load on the chiller and cooling tower will not fluctuate (except for operational and non-operational hours, which will be achieved through a schedule). The chiller and cooling tower performance will be run in a separate energy model using this constant load to determine the overall energy used based on the outdoor air conditions throughout the year. The Chiller and cooling tower energy used will then be input into the original model as annual process energy. The Chiller and Cooling Tower efficiencies for the baseline will be based off ASHRAE 90.1-2004 minimum standards. The injection molding equipment proposed is state-of-the-art and very energy efficient compared to the standard injection molding machinery that is the industry standard. Using the client-provided operational times for the equipment we will be able to estimate the total energy used by this injection molding equipment, as well as the total energy that would be used by industry standard equipment. This will be used to determine the annual energy for both the baseline and the proposed design. We will then input these amounts into the original energy model as annual process energy. For comparison purposes, we also have a similar plant by the same client that uses the industry standard machines. By comparing the amount of equipment and square footage of this plant, we can achieve a very accurate idea of how much energy the new plant is saving. All calculations showing how the machinery energy was determined, and results of planned field monitoring, will be explained in an excel spreadsheet. Equipment descriptions and energy loads will be shown for all machines that will be used, as well as for comparable industry standard machines. Once the process equipment, both baseline and proposed, have been input into the overall energy model as process loads, the standard reports issued from the model will be used for the LEED Reports. In addition, we will provide the sub-energy models of the process equipment that is weather-based. Please confirm that our assumptions and method of calculating the process energy load for both the base and proposed design cases are acceptable for EAc1.

Ruling:

The applicant is requesting acceptance of the proposed energy modeling methodology for a process dominated project. While the overall process for exceptional calculations seems reasonable, the applicant must make the following changes to the calculation methodology: 1. Include all loads in the same model and not in two separate models. This will allow the models to accurately reflect any interactions between the process loads and the space conditioning loads. 2. Provide a side-by-side comparison of the industry standard equipment, its age with the new proposed equipment and define an energy efficiency metric for each piece of equipment (e.g. kWh/ pound of material processed). Also provide list of modifications that make the new equipment more efficient. 3. Provide detailed utility bills from the comparison facility for reference. 4. Provide the operation schedules for the facility and the equipment. Please note that while this Credit Interpretation Ruling provides guidance on the exceptional calculation methodology, the actual savings and credit available for the strategies will be determined only during the review of the actual documentation. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
10/24/2008
LEED Interpretation
Inquiry:

This project is a major renovation to the existing building envelope (new skin added, new windows) and to the common area part of a tenant occupied office building. We have received approval from the USGBC to use LEED for New Construction. The core space lighting (elevator areas, lobby, restrooms, conference rooms), ductwork and finishes will be modified but the central air handling system and air cooled chiller and the tenant spaces will be only minimally altered. The question has been posed by the building manager regarding if they need to replace the tenant lighting in the space as the tenant space is not in the scope of work for the project. According to the ASHRAE 90.1-2004 users guide, if you were to replace more than 50% of the lighting fixtures in the building, you would have to meet ASHRAE 90.1-2004 lighting requirements, which, based on our analysis of what the base case and current design is in terms of lighting power density for this office building, means the building managers would have to replace all the tenant lighting with T8, 25 Watt lamps. However, if we replace less than 50% of the lighting in the building, we are not dictated by ASHRAE 90.1-2004, unless the renovation increases installed lighting power. However, according to the LEED Reference Guide for the prerequisite EAp2, lighting applies to all lighting installed on the building site including interior and exterior lighting. If the total installed interior lighting power is lower than the interior lighting power allowance calculated using ASHRAE 90.1-2004, the project complies. These two statements contradict each other if there is less than 50% of the lighting replaced, but the LEED Reference Guide does refer to the ASHRAE 90.1 users manual as a reference. Please advise on what to assume for the tenant space lighting power density in both the base case ASHRAE 90.1-2004 compliant building and the design case if less than 50% of the lighting is replaced.

Ruling:

According to the requirements of the ASHRAE 90.1-2004, Appendix G Table G3.1 section 6, for the proposed case, if a complete lighting system exists, the actual lighting power needs to be modeled. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
8/7/2007
LEED Interpretation
Inquiry:

Background: Our project is the 25,000 sf expansion of a school campus including three new buildings - two 1-story structures and one 2-story structure. Our goal is to lower energy use as much as possible, including the selection of process load appliances with low energy use. All of the new spaces in the three new buildings are complete build outs, except four classrooms in the 2-story structure that are being built out as core and shell spaces only. These classrooms will be a low-scale lab environment, metal shop, wood shop or some very light work shop component as yet not defined and will be finished as a future tenant improvement. The scope of our current project does not include the installation of any plug or process load equipment for the core and shell space, only HVAC (heating and basic ventilation only, none for process equipment) and lighting shall be installed. The overall core and shell area of this project is relatively small (3000sf) compared to the overall project area. Proposed Modeling Strategy: For the purposes of documenting the baseline and proposed energy use of this combined full build out and core and shell project, we propose the following methodology. For all completely built out spaces, create a model with baseline energy use including process loads at 25% of total baseline building energy use. The proposed case for the fully built out spaces would have the envelope, systems, lighting and process loads modeled as designed, with documentation available for the new process loads. For the core and shell spaces, since these do not have any associated plug or process loads to be installed at this time, we propose to create a separate model for these spaces that only addresses envelope, lighting, domestic hot water and HVAC systems. This model would provide baseline and proposed case annual energy use for these non-process load related components. Once the annual energy use figures are available for both the full build out and core and shell spaces, it is proposed that the baseline energy use figures be added together for both cases to achieve an overall baseline energy use for the project. Similarly, the proposed case annual energy use would be the combined proposed energy use of the fully built out and core and shell spaces. In this way, an accurate representation of the scope of the project can be modeled for both baseline and proposed cases. Request: Please confirm that the following approaches are acceptable to accurately demonstrate the condition of the proposed building. 1. Is it acceptable to keep the baseline process load energy cost at 25% of the baseline total energy cost, while modeling and inputting the actual installed process loads for the proposed case? This would allow the building to achieve some credit for specifying lower energy use plug and process load equipment than a baseline case. Note that the proposed process energy costs may or may not be 25% of the total energy cost, and may or may not be equal to the process energy load for the baseline case. 2. Is it acceptable for the core and shell spaces to not include process loads in the total energy cost for either the baseline or proposed cases? This would most accurately reflect the project condition. Process loads would be included in the model simulation for the purpose of demonstrating heating and cooling load compliance only, but would be separated out when determining total energy cost for the core and shell spaces. 3. Is it acceptable to create two separate building models for the project, one for the full build out portion of the project and a separate model for the core and shell portion? The core and shell model would exclude process energy cost from its total energy cost. Is it acceptable to sum the total energy costs of the full build out and core and shell spaces to achieve the total project energy cost?

Ruling:

The questions will be addressed in the order that they were presented: [1] It is acceptable to vary the design case process load to reflect energy efficiency measures (ie Energy Start Appliances) that affect the process energy load. This is considered an Exception Calculation Method (ECM) and thus full documentation should be provided justifying the differences and highlighting the assumptions and inputs that were used to create both the baseline and design case process energy loads. It is not allowable to use the default 25% process load value for the baseline case if the proposed case process energy has been inputted piece-by-piece (for example, by inputting the energy usage for each computer, copier, etc.). Instead the baseline model must also have piece-by-piece inputs using identical input power and energy rating as the proposed case unless the applicant can demonstrate that the proposed equipment represents a significant verifiable departure from documented conventional practice. In that case, the values for conventional practice may be used for the baseline equipment with the same use schedule as the proposed case. [2] It is NOT acceptable to ignore process energy usage in future build-out spaces. The LEED Core & Shell Reference Guide provides some guidance in how to address future build-out spaces, though it is more geared to address tenant-leased spaces. Key concepts to follow for future build out spaces include, but are not limited to: [A] Model receptacle and other loads (process) based on estimates for the building type. Table G-B of the ASHRAE 90.1-2004 User\'s Manual (note, this is not the same document as the ASHRAE 90.1-2004 Standard) provides acceptable receptacle power densities, occupancy densities, and hot water usage for varying occupancy types. [B] Use the same values for receptacle and process loads in both the baseline and design cases for the future build-out spaces. [C] If default values cannot be found for certain occupancy types, make reasonable estimates based on modeling and design experience. Please note where these values were used and what estimates are based on. [3] Separate building models for the full build-out and core and shell portions of the project are not recommended. Energy usage calculations are compromised when the model is broken apart because, among other issues, the model is no longer able to apply diversity factors across all project spaces or properly size systems based on peak demand. It may be permissible to separate portions of the model for an ECM, but this is only in the case that limitations in the modeling software prevent adequate representation of the design. If this is the case, full ECM documentation will need to be provided, as described in ASHRAE 90.1-2004 G2.5. Applicable Internationally.

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

Our project is a newly constructed, 825,751 square foot automotive manufacturing facility in the midwest. The ventilation requirements for our facility, as set forth by ASHRAE 62.1, Section 2.2 states: "Additional requirements for laboratory, industrial, and other spaces may be dictated by workplace and other standards,.". Industrial facilities in this location fall under the requirements of the Michigan Occupational Safety and Health Administration (MIOSHA). Per MIOSHA\'s, health standards ("Part 520. Ventilation Control"), R325.52007 Exhaust ventilation systems, Rule 7 states : "The minimum rate of exhaust ventilation for places of manufacturing, processing, assembling, maintenance and repair, or storage of material shall be 1 cubic foot of air per minute per square foot of floor area. This amount of exhaust ventilation may be provided by local exhaust, general exhaust, or both. The director may permit a variance if contaminant control is accomplished at a lesser rate of ventilation." MIOSHA has stated that an allowable level of contaminant control for dust/mist particulate would be 5 mg/cubic meter. In an attempt to save ongoing heating, cooling and ventilation expenses, the Owner chose to design the new facility in an innovative manner that could attain contaminant control at a much lesser ventilation rate than the default 1 CFM/SF that is set forth by MIOSHA and used by other automotive manufacturing facilities. The manufacturing facility has set a target of 0.5 mg/cubic meter, significantly lower than the MIOSHA required level of contaminant control. In order to reach this high level of contaminant control, they implemented the following innovative approaches: 1 - For the machining and grinding processes, enclosures were constructed and oil mist/dust collection systems were implemented with HEPA filtration. 2 - For the parts washers, enclosures were constructed and local exhaust ventilation systems were designed to capture contaminants at the source. 3 - For processes using hazardous materials, local exhaust ventilation systems were designed to capture contaminants at the source. 4 - "Dry floor guarding" systems have been implemented in the machine tool enclosures in order to minimize any escaping mist from the process. 5 - Micro-bacteria resistant coolants are used in the plant and biocides and utilized and monitored in order to control the bacterial counts in such systems. These control measures are over and above what is done in a typical, newly constructed manufacturing plant. With these control measures being utilized, extensive testing was done through the manufacturing facility to ensure that MIOSHA (and the much more stringent company requirements) exposure limits were being met. During the testing, the facility was ventilated at a rate of 0.21 CFM per square foot. At this ventilation rate, the facility was far below the company\'s target exposure limits, never measuring higher than a 0.13 mg/cubic meter exposure level. The Owner operates their facility at a ventilation rate of 0.5 CFM per square foot. This adds another level of safety factor to the building design. We are proposing that we run the energy model, in both the baseline and proposed case, with a ventilation rate of 1.0 CFM per square foot. We then intend to use the Exceptional Calculation Methodology of ASHRAE 90.1 to quantify our energy cost savings by lowering the ventilation rate. We intend to re-run our "proposed" model with 0.5 CFM per square foot to determine the cost savings for this exceptional calculation.

Ruling:

The applicant is proposing that energy savings due to ventilation load reduction resulting from several pollutant source control measures be approved as an Exceptional Calculation Methodology (ECM). The use of baseline and proposed case exhaust rates above those required by ASHRAE 62.1-2004 Section 6.2.8 are acceptable per ASHRAE 62.1-2004 Section 2.2 and the requirements specified by Michigan Occupational Health and Safety Administration (MIOSHA). Since it is a non-regulated process load, the project team must establish reasonable assumptions under full operational conditions for the baseline and proposed case. It appears that the project team has put a substantial effort into identifying and controlling sources of indoor pollutants and in an effort to reduce ventilation loads. Additionally, testing has been conducted to verify that the particulate concentrations are well below MIOSHA requirements even at reduced ventilation rates. The proposed documentation of energy savings from ventilation load reductions in the proposed case may be documented as an ECM. Please note that the favorable ruling of this CIR does not guarantee credit acceptance during a review. The project team should provide sufficient documentation to support the proposed ECM. Also note that the ruling is specifically applicable to the project in question due to the substantial efforts made to control sources of indoor air contamination at the source and testing for compliance; the ruling is not necessarily applicable to projects with different circumstances.

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

How much HVAC equipment must be installed within a LEED for Commercial Interiors or LEED for Retail: Commercial Interiors project scope of work in order to meet the intent of EA credit 1.3, Option 1, Equipment Efficiency?

Ruling:

The project is eligible to earn the credit if the project scope of work includes one of the following:1. Air handlers with Variable Speed Controls complying with the requirements of the Core Performance Guide Section 3.10 that supply at least 60% of the total supply air volume used within the project scope OR2. Mechanical equipment that complies with the prescriptive efficiency requirements of the Core Performance Guide Section 2.9, and provides at least 60% of the cooling or heating capacity for the project scopeNote that requiring 60% correlates to the LEED CI MPR #2 requirement that there must be tenant improvements made for 60% of the project scope in order to pursue a LEED for Commercial Interiors or LEED for Retail: CI rating.OR3. The project can comply with the requirements of the credit if the project team can show that the relevant criteria have been met for all HVAC systems serving the area within the project scope, whether or not the HVAC systems are installed as part of the tenant scope of work.

Campus Applicable
No
Internationally Applicable:
No
9/24/2007
LEED Interpretation
Inquiry:

The project wishes to use Therma-Fusers in private offices to satisfy the intent of LEED CI Eac1.3. Therma-Fusers are supply air diffusers, which are each equipped with an individual thermostat, meaning they have "active controls capable of sensing space demand." However, although the Therma-Fusers do not specifically "modulate the HVAC system in response to space demand," they do satisfy the intent of the credit which is to "achieve increasing levels of energy conservation beyond the prerequisite standard to reduce environmental impacts associated with excessive energy use." Therma-Fusers function at low pressure, which can reduce the horsepower (and therefore reduce the energy demand) necessary to run the fan motor. This fan energy is further reduced because the VAV system serving this particular space incorporates variable speed drives, which allow the system to turn down even further to save more energy. Also, because a typical pressure independent VAV terminal unit can only turn down to 30%, Therma-Fusers save even more fan energy because they can turn down to less than 10% and maintain individual temperature control. Also, because each Therma-Fuser is a zone of control providing individual room control, heating and cooling energy are reduced because no portion of the building is ever over-cooled or over-heated. An independent study has shown 40% energy savings for interior zones and 29% energy savings for perimeter zones when individual room control was compared to multi-room control. Although Therma-Fusers may not save HVAC energy precisely in the manner specified by the credit, we believe, given the energy saving capabilities of incorporating Therma-Fusers within the space mentioned above, their use satisfies the intent of LEED CI EA credit 1.3.

Ruling:

The applicant has requested confirmation that supply air diffusers equipped with room thermostats" meet the requirements of EAc1.3 Option A: Appropriate Zoning and Controls to provide "active controls capable of sensing space use and modulating HVAC system in response to space demand." The supply air diffusers with room thermostats do not meet this requirement alone. In order to meet this requirements, the following criteria need to be met: 1. The system must be capable of modulating AHU and zone minimum supply volume down below 0.30 cfm/sf of supply volume for standard VAV terminals, or below 22.5% of the peak design flow rate for fan-powered VAV boxes. For spaces where the minimum outdoor air exceeds the minimum supply volumes specified here, some form of occupant sensing or demand controlled ventilation must be employed to allow these minimum supply volumes to be met. 2. The building control system must include controls for fan static pressure reset. 3. The mandatory requirements of ASHRAE Standards 90.1-2004 and 62.1-2004 must be met. These criteria apply only when there is not a separate method employed for modulating the HVAC system in response to space demand such as Demand Controlled Ventilation, or modulation of the HVAC system tied to occupant sensor controls. Applicable Internationally.

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

This Project involves the construction of a Testing Facility for High Volume Low Velocity circulation fans. The building consists of a 1940 S.F. General Office Area, a 1940 S.F. Shop Area, and a 40550 S.F. Testing Area with a 50\' joist height. The Testing Area will have in it at most (4) four High Volume Low Velocity circulation fans operating at the same time. The building will have no transient occupants, and a maximum of (6) six employees that will occupy the entire building during normal business hours. This CIR is in reference to the Testing Area. 1. Testing Area: As part of the USGBC New Construction & Major Renovation Version 2.2, the building is required to meet ASHRAE 90.1 2004 (Energy Standard for Buildings Except Low-Rise Residential Buildings), and ASHRAE 62.1 2004 (Ventilation for Acceptable Indoor Air Quality). In accordance with ASHRAE 90.1 2004 the Testing Area is given a baseline LPD (Lighting Power Density) of 1.4 W/SF as is standard for a Laboratory. The only reference in ASHRAE 62.1 2004 (Ventilation for Acceptable Indoor Air Quality) with regard to a Laboratory is listed in Table 6-1 under "Educational Facilities" - "Science Laboratories". The classification that most closely matches the actual use of the space in the Testing Area for ventilation purposes is a Warehouse, since the population density is low (6760 SF/Person), and the area will never contain "Laboratory" chemicals, "Laboratory" exhaust hoods, Make-Up air or a population density on par with an Educational Facility Science Laboratory. The Ventilation and Exhaust requirements for a Science Lab are (3) three times that of a Warehouse, and subsequently (3) three times the energy cost. Since the "actual" usage of the Testing Area fits the lighting energy requirements of a Laboratory (ASHRAE 90.1 2004) and the ventilation requirements of a Warehouse (ASHRAE 62.1 2004), can the design team consider this space as such for calculations, or does the requirement to stay consistent with room classifications supersede actual building function?

Ruling:

The applicant is requesting to use the lighting power calculations for one space type and ventilation calculations for a different space type. The ventilation quantities for the Testing facility appear to be associated with process issues associated only with the tests being run, not ventilation requirements associated with Standard 62.1-2004 requirements for indoor air quality. The project team should model the ventilation the same in the Baseline and Proposed Case, and should model the lighting power density requirements based on the closest space type from the ASHRAE Space-by-Space method.

Campus Applicable
No
Internationally Applicable:
No
4/14/2009
LEED Interpretation
Inquiry:

Background: Our project is a 3 story, 16,500-sq.ft. addition to an existing 3 story, 84,000 sq.ft. building. The existing building is predominately laboratory space with some office space. The addition will be of similar use. The heating and cooling of the existing building is served by a central utility plant which provides chilled water and hot water via a steam boiler and heat exchanger. It is proposed that the addition also be served by the central plant. The central plant serves several other buildings on the site as well. In order to make a decision on whether we would like to obtain LEED registration on just the new addition or on the entire building with the new addition, a preliminary building simulation is being modeled. For the ASHRAE baseline, the system is modeled as a "System 3 - PSZ-AC" (packaged rooftop, constant volume, direct expansion, and fossil fuel furnace) per table G3.1.1A of ASHRAE 90.1-2004. Though the combined building size would categorize building with addition as a "System 5 - Packaged VAV w/ Reheat.", section G3.1.1(c) mandates conforming to the requirements of System 3 as an exception due to the special pressurization relationship/ cross-contamination requirement of the laboratory. Interpretation Request: Little is stated in ASHRAE 90.1 2004 on the most appropriate way to model a system that has chilled water and hot water heat supplied from a central plant. However, there are a few CIRs concerning similar circumstance that allude to it such as the 1/27/2004-2/24/2004 EA1.1 CIR. In it, it is stated that "While the situation described is not using purchased chilled water or steam, this HVAC description for the budget building is the closest to the proposed design and should be used for the energy modeling purposes." This approach for the budget building model is quite workable since the building owner has costs available for both chilled water and heating hot water. However, the baseline is modeled as a DX cooling and gas fired furnace. Is it appropriate to model the budget building with chilled water and heating hot water, when the baseline model is using neither of these? If not, how should the baseline and budget building be modeled?

Ruling:

The applicant is requesting clarification regarding modeling methodologies for projects which include a central utility plant. Note that the USGBC published a document titled "Required Treatment of District Thermal Energy in LEED-NC version 2.2 and LEED for Schools" in May of 2008 located at the following website: http://www.usgbc.org/ShowFile.aspx?DocumentID=4176 Please refer to this guidance document, which is also referenced in a CIR dated 5/28/2008. Also note that the exception in ASHRAE 90.1-2004 Section G3.1.1 Exception (c) is only applicable for zones that have special pressurization requirements. All zones of the building or addition that do not meet the exception requirements must be modeled using System 5 - Packaged VAV w/ Reheat in the baseline. Applicable Internationally.

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

We are seeking clarification on the definition of active controls for non-VAV systems. The response from USGBC to CIR 5273 states that thermal control is not sufficient alone if it does not include for variable central plant such as VAV AHU. In some versions of VAV, thermal control can be achieved without modulating the central plant and this delivers no energy savings. These systems deal with low flow situations by allowing the excess air to discharge back to the ceiling void or similar whilst keeping the AHU at a constant speed, which does not result in any energy savings. Thus for the case proposed by the design team on CIR 5273, it is possible to achieve an equipment configuration which does not realize any energy savings from thermal controls.This inquiry refers to a Variable Refrigerant Flow (VRF) system. The VRF system operates by delivering refrigerant to the room device/terminal to deliver heating or cooling to the space. Each space has thermal control. The thermal control operates by varying the amount of refrigerant delivered to the room device/terminal and as such varying or modulating the central plant. This ability to vary the heating or cooling delivered to the space allows the central plant to modulate and match the instantaneous load in the space at any given time. This delivers energy savings in the central plant. Furthermore the VRF system also has heat recovery, which allows for heat taken from a space which is in cooling mode to be used in a space in heating mode and vice versa.Note that because of the closed-loop nature of the VRF system, it is not possible to operate the system in a mode, which does not save energy, as it is not possible to "vent" any excess refrigerant in low load situations. The variability of the system comes not from changing the amount of air into the space, but by varying the amount of refrigerant from the central system to the project space. The requirement by the reviewers to provide demand controlled ventilation as part of the response to CIR 5273 is inappropriate for a VRF system, which - by definition - ramps up and down based on temperature readings, not air flow measurements. Since the trigger for a VRF system to ramp up and down is related to temperature, we believe that the thermal controls in each room are sufficient active controls for a VRF system, as they provide both individual control in the meeting rooms and private offices and realise energy savings resulting from individual controls.With this system, we are still able to meet the requirements of ASHRAE 62.1 for the highest design occupancy and provide adequate ventilation to the project space.We do not believe that the argument that the thermostat will not pick up on when a person leaves the room, as this may not be the major load in the space, is relevant. While this is correct, with a thermostat, the system will modulate to control the space regardless of what is generating the load, e.g. solar, people, equipment. The fact that the people load is not the significant load means that the control of the other loads is the more important element, therefore the system will respond to whatever changes the load, whether it is people, equipment, lighting or something else. It was suggested that the proposed design also does not meet the intent of the credit, because of the lack of ability to vary the amount of fresh air into the space. However, feedback seems to suggest that occupancy and CO2 sensors would help achieve this credit, although it is unclear whether installing these in the system would achieve the credit or if this is only in the context of VAV systems.

Ruling:

The definition of active controls that meet the requirements in LEED-CI 2009 EA credit 1.3, and clarifications on what non-VAV systems are eligible for active controls are listed below. Active control is the control capable of sensing space occupancy and adjusting the HVAC system demand based on the changes in space occupancy, which does not equal a thermostat or a separate thermal zone for each space. For VAV systems and non-VAV systems, active controls typically regulate the required outdoor air flow for ventilation, such as using demand controlled ventilation with CO2 sensors in each private office and specialty occupancy space, or regulate temperature set point based on occupancy by adjusting the HVAC system to operate under the unoccupied set back when occupant sensors indicate that the space is unoccupied.Alternatively, VAV systems meeting all the requirements in LEED Interpretation 5273 are also eligible. However, those systems which do not modulate the system level supply air flow but only redirect the excess air back to the ceiling void or return air duct under low demand conditions are not eligible for this alternative compliance path. For a VRF system or another constant volume system with separate thermal zones for each specialty occupancy or private office, the following active controls would be considered sufficient to meet the credit criteria:PRIVATE OFFICES: Occupant sensor controls or CO2 sensors in each private office sense space occupancy, and modulate the HVAC temperature set points when the space is detected as unoccupied. Additionally, the fan coil serving the room has the fans set to cycle on and off with loads or to operate on the lowest multi-speed setting for multi-speed fans when the space is detected as unoccupied.SPECIALTY USE SPACES: Conference rooms and other specialty use spaces have CO2 sensors or occupant sensor controls, which modulate the HVAC temperature set points when the space is detected as unoccupied. Additionally, demand control ventilation is used to limit the outdoor air supplied to the space based on CO2 levels or space occupancy. Please note, although the VRF system as described can vary the amount of refrigerant supply to the project spaces and save energy, the thermostat controls described are not considered active controls due to the following two reasons: 1. The system is controlled based only on thermostats. For private offices and specialty occupancies where the occupancy varies during the occupied period, thermostat control is not sensitive to the change of occupancy and therefore is not capable adjusting the VRF system to respond to the change, because occupant load is not a major load of the perimeter zones, and is also likely not very significant compared to the cooling load from lighting and equipment in the internal zones. When the occupants are absent or reduced, the HVAC system cannot effectively respond to the change and reduce heating and cooling supply, and/or the ventilation rate. 2. The VRF system is a constant volume system. It cannot reduce airflow to respond to the load change. Please note that the alternative compliance path in LEED Interpretation 5273 requires the system achieve significant supply flow reduction at both the system and zone levels. To achieve this, the system must have fan static pressure reset, and especially, for the spaces where the minimum outdoor air exceeds the required minimum supply volumes, some form of occupant sensing or demand controlled ventilation must be employed to allow the minimum supply volumes to be met. This requires projects to use either CO2 sensors or occupancy sensors in conference rooms or other specialty occupancies, because the room airflow in these spaces cannot typically be reduced to the required percentage of the peak supply volumes while still maintaining the ASHRAE 62.1 ventilation requirements associated with peak occupancy. With variable refrigerant flow and heat recovery which essentially allows for heat exchange between spaces under cooling mode and spaces under heating mode, the VRF system has high cooling and heating efficiency and can achieve high part-load energy performance. This may qualify the project for Option 1 - Equipment Efficiency. Please consider attempting this option in lieu of the option for active zoning and controls, if active controls will not be used with the VRF system.

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

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

Ruling:

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

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

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

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

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

We have multiple new projects on the University of Colorado at Boulder\'s campus all seeking LEED certification which will be serviced by a new heating and cooling plant, also seeking LEED certification. The schedule of the projects is such that the earliest building complete will be complete and occupied approximately one year prior to the completion and start up of the new heating and cooling plant. Although this project is completely designed to be serviced by the new plant (and the drawings will reflect this), the project schedules will create a lapse where the building will have to be serviced by a temporary means until the new heating and cooling plant is operational. The current plan is to utilize temporary chillers and boilers. We believe it is appropriate for our energy model and all other LEED submittals to reflect the final connection to the CUP and not the temporary equipment. Please confirm this approach is acceptable. In addition, please clarify whether the temporary equipment must be commissioned to satisfy EAp1. The new CUP will be commissioned as well as all "downstream" equipment at each building in accordance with the May 28, 2008 CUP memo.

Ruling:

The project team is requesting permission to use the designed central plant specifications for EAc1 Option 1 and all LEED submittals versus the temporary plant that will be connected to the newest building on campus seeking LEED certification. The project team has also requested exception from the EAp1 requirement for commissioning the temporary equipment. The permanent equipment intended for the campus central plant may be used in submitting for EAc1 if the project team provides a letter on owner letterhead stating that the permanent central plant is fully funded. Please also include in the letter a comparison of the schedule of completion for the building in question to a schedule of completion for the central plant. Additionally, if the intent is to use this for other prerequisites and/or credits, this letter should address adequately how the requirements for all credits and prerequisites are being met effectively. However, the temporary equipment shall not be exempt from meeting the requirements of EAp2 - Minimum Energy Performance or EAp1 - Fundamental Commissioning, as this temporary equipment will be in operation for at least one year, if not more. It is necessary that the project team meet those requirements, i.e., a basic minimum level of energy performance and fundamental building systems commissioning for even the temporary equipment.

Campus Applicable
No
Internationally Applicable:
No
4/14/2009
LEED Interpretation
Inquiry:

This project is to renovate 300,000 square feet of an old factory and convert to a distribution center. The owner strongly desires to be sustainable and will use many sustainable features whether or not LEED certification is sought. We will use high efficiency lighting and high efficiency infrared heaters, but no cooling. If we use the ASHRAE appendix G, we have to model the baseline cooling system for the baseline and the proposed. Since the cooling energy will be much larger than the heating energy the 14% reduction from ASHRAE will not be possible. This force the project to be penalized for energy never actually used. In this case we feel that the ASHRAE standard does not rationally apply. This project will reuse a large facility and incorporate significant sustainability features and we would not like to be excluded because the ASHRAE standard does not apply logically to this facility. Is there any alternative method for compliance in this situation?

Ruling:

The project has requested clarification regarding the use of the ASHRAE Baseline requirements in Appendix G. Although a cooling system must be modeled in both the Baseline and Design case, there are no requirements for Temperature Setpoint. Therefore, both cases may have the Cooling Temperature Setpoint elevated such that both systems do not ever run and thus does not consume any energy. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
9/19/2006
LEED Interpretation
Inquiry:

The project consists of a single story 6,300 sf office building attached to a 160,000 sf manufacturing facility. The issue is how to model the heated only manufacturing area. The requirements from ASHRAE 90.1-2004, Appendix G state, "all conditioned spaces in the proposed design shall be simulated as being both heated and cooled even if no heating or cooling system is to be installed." Furthermore, "where no cooling system exists or no cooling system has been specified, the cooling system shall be identical to the system modeled in the baseline building design." These ASHRAE 90.1 requirements indicate that the proposed Constant Volume, 100% Outdoor Air, Gas-Fired, Make-Up Air Unit would need to include the baseline Variable Volume, 100% Outdoor Air, Chilled Water, Packaged Rooftop Unit for cooling. Current industry energy modeling software, approved by ASHRAE 90.1, cannot model this system for a single space. It also is unrealistic to compare the proposed Make-Up Air Units to a VAV w/Reheat System in a manufacturing facility. Our design team suggests that any heated only space should be modeled as heated only (no cooling) for the proposed and baseline model. This is mainly because if it were possible to model the "imaginary" cooling system for heated only spaces it would provide the project with unwarranted energy credit or debit. Specifically, if the loads were reduced between each simulation, for reasons such as improved insulation, the project could use less electricity and therefore gain energy credit from a cooling system that does not exist. Please advise if our recommended procedure to model "heated only" spaces is acceptable, and if not, what is the USGBC\'s recommended method to comply with ASHRAE 90.1-2004 requirements in this instance?

Ruling:

The proposed modeling procedure does not comply with the requirements of ASHRAE 90.1-2004, Appendix G, which is the referenced standard for the purpose of the credit. Table G3.1, #10(d) states clearly: "(d) Where no cooling system exists or no cooling system has been specified, the cooling system shall be identical to the system modeled in the baseline building design." There isn\'t sufficient information about the design HVAC system provided in the request, to identify the correct baseline system configuration. If indeed there is no simulation tool that is capable of modeling the systems, the Exceptional Calculation Method (Section G2.5, Appendix G) should be employed. Table G3.1, # 13. Modeling Limitations to the Simulation Program states clearly "If the simulation program cannot model a component or system included in the proposed design explicitly, substitute a thermodynamically similar component model that can approximate the expected performance of the component that cannot be modeled explicitly." Applicable Internationally.

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

The design of an 11,000 square foot library and offices in a new LEED NC building targeted low energy use and superior indoor air quality as two of its most important green building goals. From the beginning of design, our mechanical engineering team has prioritized efficient equipment to meet the E-Benchmark prescriptive criteria for efficiency requirements (EQc1.3 Option A point 1) and EQ credit 5 for high filtration media. We are limited by those requirements to a single proprietary mechanical system of water source heat pumps. As-built conditions in the space revealed that in order to fit our heat pump units in the available head heights, two units serving the Entry Lobby/Children\'s Room and Auditorium needed to be changed to split units. This split effectively reduces the EER and COP standards to slightly lower than the E-Benchmark standards. The total average of system efficiency by capacity remains well above the EER and COP E-Benchmark threshold requirements. These HP-2 split units are sized for a maximum occupancy load that will only occur several times a year in the Lobby and occasionally in the Children\'s Room and Auditorium. As it is not required for LEED-CI, we do not have an energy model to show annual expected use. However, since these split units are sized for a maximum capacity that does not occur regularly, we conclude that the actual average of system efficiency by usage will be much higher than the average by capacity which already meets the threshold. Unit AC-1/ Quantity 1 / Capacity 3 tons / EER=14.0/COP=5.0 Unit AC-2/ Quantity 1 / Capacity 2 tons / EER=18.1/COP=5.7 Unit HP-1/ Quantity 4 / Capacity 10 tons/ EER=16.0/COP=5.0 Unit HP-2/ Quantity 2 / Capacity 8 tons / EER=13.1/COP=4.5 Unit HP-3/ Quantity 1 / Capacity 2 tons / EER=16.5/COP=5.6 Average by capacity: EER=15.25/COP=4.91 E-Benchmark Standard: EER=14.00/COP=4.60 * * 2005 New Building Institute E-Benchmark Standard, Table 2.5.2 Unitary & Applied Heat Pumps, Electrically Operated, p. 69 We propose that we meet the intent of the credit to provide highly efficient HVAC units which meet a high standard, increase our level of energy conservation, and associated environmental impacts.

Ruling:

The project team is inquiring as to whether or not they can deviate from one of the prescriptive requirements of the Advanced Buildings Energy Benchmark Standard. Per LEED NC EAc1 CIR ruling dated 4/23/2008; prescriptive compliance paths and the standards they reference must be met exactly as specified in order to ensure credit compliance. Option 1 - Whole Building Simulation, offers the flexibility that the project team requires. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
9/19/2006
LEED Interpretation
Inquiry:

Our project consists of a two story retail building. The building is open seven days a week from 9:00 am to 9:00 pm for business. We are requesting clarification regarding the modeling of lighting power density for the Proposed Design Case. In an effort to limit lighting energy usage, the project has developed two completely separate ambient lighting systems, which will NEVER operate simultaneously. A Building Automation System will be used to control the lighting systems, and to ensure that these systems do NOT ever operate in combination with one another. - System 1 consists of the general illumination (ambient lighting) having an overall LPD of 0.53 watts/sf, operational during business hours. - System 2 consists of the emergency/cleaning lighting system having an overall LPD of 0.9 watts/sf (using the ASHRAE 90.1-2004 Building Area Method). This system is a completely separate bank of lighting fixtures, which will only operate during the night for a few hours for housekeeping and maintenance, and during emergencies to provide code required egress lighting. Since the dual lighting systems have been designed for the purpose of limiting energy usage, and since these systems will never operate at the same time, we believe it would be unfair to require the project to model the cumulative lighting power density for the two systems for the "Proposed Lighting Power Density". Instead, we propose to model the lighting power density for the proposed case as two independent interior lighting systems for the building. The lighting power density for each system will then be compared to the base case ASHRAE 90.1-2004 building having a LPD of 1.5 watts/sf, based on the Building Area Method. For example, during store hours, the regulated lighting power would be modeled as 0.53 W/sf versus 1.5 W/sf allowed, and during cleaning hours the regulated lighting power would be modeled as 0.90 W/sf versus 1.5 W/sf allowed. We believe this modeling strategy meets the intent of the LEED v2.1 EAc1 credit by encouraging energy efficient design and controls, and by limiting total building energy consumption and costs.

Ruling:

The proposed modeling strategy does not comply with ASHRAE 90.1-2004. Per ASHRAE 90.1-2004, Section 9; "Exception to 9.1.3: If two or more independently operating lighting systems in a space are capable of being controlled to prevent simultaneous user operation, the installed interior lighting power shall be based solely on the lighting system with the highest wattage." Therefore, the proposed design must be modeled using 0.9 W/sf, for the purpose of the Energy Cost Budget calculation.

Campus Applicable
No
Internationally Applicable:
No
3/22/2007
LEED Interpretation
Inquiry:

Our project consists of two small buildings close to the ocean that will achieve substantial energy savings by incorporating a natural ventilation strategy. No mechanical heating or cooling is intended for either building, with the exception of a small electrical/server room. The building is designed with a very narrow and long floor plate situated perpendicular to prevailing winds in the area. Ventilation openings are consistent with the requirements of ASHRAE 62.1-2004 Section 6.8. The project also meets the requirements outlined in the CIBSE Applications Manual 10: 2005 as referenced in EQc2 for Natural ventilation in non-domestic buildings. Per Title-24 2005 requirements for natural ventilation, the sum of operable windows will be greater than 5% of the floor area of each space that is naturally ventilated. The openings will also be readily accessible to the occupants of each space at all times. Outdoor airflow through the openings in regularly occupied spaces will come directly from the outdoors, not through intermediate spaces such as other occupied spaces or corridors. Openings include operable windows, through-the roof ventilators, and vents between interior spaces. Control mechanisms for the natural ventilation openings are manual. A long, tall hallway situated perpendicular to the prevailing winds will collect heated air and exhaust it the outside. The roof over much of the space is sloped allowing air to enter on the low side and exit on the high side. In all cases, the building is designed to facilitate cross-ventilation with windows low on the walls for drawing the air in, and windows and vents high in opposite walls or on the roof to draw air out. Under ASHRAE 55 definitions, the building spaces are defined as "naturally conditioned spaces, occupant controlled" where the thermal conditions of the spaces are regulated primarily by the opening and closing of windows or vents by the occupants. Since the building will have a limited number of occupants most of the time, manual control of the windows and vents has been determined the most appropriate strategy for the building to allow control over individual thermal comfort. As indicated by ASHRAE 55-2004, section 5.3, the occupants of the space will be engaged in near sedentary activities with metabolic rates ranging from 1.0 met to 1.3 met. The mean monthly outdoor temperature for the project is greater than 50 deg. F, and less than 92.3 deg. F all months of the year, as required under ASHRAE 55-2004, section 5.3 for naturally ventilated buildings. The User\'s Manual for ASHRAE 90.1-2004 Appendix G states on page G-21: The proposed building default cooling system does not exclude natural ventilation from consideration. It just means that the proposed building is modeled as a hybrid system where cooling is provided by natural ventilation when conditions are acceptable and by the default mechanical cooling system when natural ventilation is inadequate to provide thermal comfort. We are requesting confirmation that the following modeling strategy conforms to the requirements of ASHRAE 90.1-2004 Appendix G modeling protocol: 1. EnergyPlus will be used to model the building since the EnergyPlus software has the capability to evaluate energy and comfort parameters tied to natural ventilation. 2. The Exceptional Calculation Methodology will be applied to calculate the natural ventilation savings. 3. The Proposed Design model will be developed to reflect the design parameters for the envelope and lighting. Operable windows will be modeled as fixed, and vents will not be included in the model. Mechanical systems will be modeled identically to the default heating, cooling and fan systems in the Baseline case, except that fans in the proposed case will be modeled as cycling on and off to meet heating and cooling loads during all hours in the proposed case, and will operate continuously during occupied hours in the Baseline Case (per the exception shown in Table G3.1.4). 4. Using the Exceptional Calculation Methodology, The Proposed Design case will be modified to include natural ventilation for all hours when the cooling and heating loads can be met. Operable windows and vents will be modeled as designed. Cooling and heating setpoint temperatures will be identical to those in the Baseline Case. Schedules will be adjusted to switch on mechanical cooling during hours when natural ventilation alone cannot meet the space temperature setpoints. The final model will meet the ASHRAE G3.1.2.2 requirements stipulating that the Proposed Design cannot exceed the Baseline Design unmet load hours by more than 50, and that unmet load hours for the Proposed Design and Baseline Design cannot exceed 300. 5. (Plan B) If the hybrid system cannot be manipulated to meet the unmet load hour requirements within the energy model, hourly output data from a natural ventilation model (having no mechanical cooling) and the Proposed Design model will be combined in a spreadsheet. Each hour where cooling and heating setpoints are met in the natural ventilation model, the hourly results for that model will be used. For all other hours, the hourly results from the Proposed Design Model will be used. 6. An Exceptional Calculation Methodology narrative provided with the EAc1 submittal will document any schedule adjustments and assumptions that were made to develop the hybrid system. The savings will also be included as a separate line item on the EAc1 submittal. Is our proposed energy modeling strategy for natural ventilation acceptable?

Ruling:

The project is requesting approval for the method of modeling natural ventilation as an energy efficiency measure and for taking credit under EA credit 1. Submittals for natural ventilation savings will be evaluated on a case by case basis. The tools and analysis protocol proposed is acceptable for modeling ventilation savings in this instance. Other analysis tools may also be appropriate. To be able to adequately document the process and the results, please be sure to provide in the LEED submittal the following:

  • A detailed project description
  • Clear identification of the areas that are taking credit for natural ventilation
  • A detailed description or references that document the modeling algorithms and/or methodology for the natural ventilation portion of the energy model
  • All thermostat, fan, infiltration and other appropriate schedules for naturally ventilated areas

Also, the submitted evaluation must demonstrate that the range of unmet load hours is similar for both the proposed and baseline building, to ensure that savings are not claimed for hours outside of the control parameters. In this case, the project has proposed to meet these peak loads with a hypothetical cooling system in the proposed building.

The project will also need to clearly demonstrate that the operational schedule for the natural ventilation system as modeled aligns with anticipated occupant behavior in terms of scheduled occupancy vs. modeled operation. For example, the model cannot assume that natural ventilation will occur when no one is in the building to operate the system. Because manual control is not addressed by the Appendix G modeling methodology, the manual control features of this project must be submitted under the exceptional calculation methodology for case by case review. The project must be prepared to demonstrate convincingly that a manual control strategy is appropriate and workable for this project. Please also be sure to take credit for this measure as a separate item on the LEED-NC v2.2 Submittal Template. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
10/24/2008
LEED Interpretation
Inquiry:

Our project includes a 120,000SF addition/renovation to a 140,000SF office building. Lighting control systems were installed to provide increasing levels of energy performance savings by adjusting the initial foot-candle levels down to IESNA acceptable maintained foot-candle levels. The project includes expansion of the existing Eaton\'s POW-R-Command lighting control system. Our approach is not proprietary to the Eaton system and could be applied to any automatic lighting control system. Use of our lighting control approach results in energy savings beyond the default 10% energy savings limit identified in Table G2.3 within ASHRAE 90.1-2004, Appendix G. We are requesting the USGBC allow us to use the alternative method to modify the lighting schedules beyond the 10% limit in accordance with the standard as outlined below. Standard lighting foot-candle design is based on maintained foot-candle levels understanding that initial levels will be higher and will degrade over time. For this project, the light loss factor is 85% of initial fixture performance. This standard design approach typically results in initial lighting designs that are over-lit and a higher w/sf value. For this project, the lighting foot-candle design and layout provides roughly 20%+ more initial illuminance than IESNA Recommended Guidelines, however upon installation, the lighting levels are dimmed through the lighting control system to those foot-candle levels which meet the IESNA Guidelines for maintained lighting illuminance. Over time, as lamp depreciation occurs, the illumination performance is automatically increased to consistently maintain the IESNA Guidelines level. This control approach has been in use within the existing facility for the past ten years. Dimming control of the system is programmed and performed by facilities staff only and the individual occupants do not have control capabilities. This feature can not be overridden by the occupants. Controlling and operating the lamps in this manner in the existing building have resulted in a 33% reduction in electrical energy use plus additional cooling capacity savings when compared to an un-controlled lighting approach and have resulted in approximately 40% lighting energy savings within the new addition. ASHRAE 90.1 - 2004 Appendix G, Paragraph G.25 - Exceptional Calculation Methods, states "When no simulation program is available that adequately models a design, material, or device, the rating authority may approve an exceptional calculation method to demonstrate above-standard performance using this method". However, in Table G3.1, paragraph 6(g), the standards states "For automatic lighting controls in addition to those required for minimum code compliance under 9.2, credit may be taken for automatically controlled systems by reducing the connected lighting by the applicable percentages listed in Table G2.3. Alternatively, credit may be taken for these devices by modifying the lighting schedules used for the proposed design, provided that credible technical documentation for the modifications are provided to the rating authority. We believe our project approach meets the intent of the alternative modified schedule approach. The system, as installed: Exceeds the energy savings allowed using standard building modeling protocol Meets the intent of the credit Provides a creative method to produce additional measurable energy performance savings Reduces environmental impact

Ruling:

The project team is requesting an allowance to account for energy savings from lighting control above the 10% as defined in ASHRAE 90.1-2004. As stated in ASHRAE 90.1-2004 Table G3.1, No. 4 Baseline Building Performance, non-standard efficiency measures such as lighting controls can be modeled by modifying schedules. The schedule change and energy savings should be modeled and submitted as an exceptional calculation method (Section G2.5 of ASHRAE 90.1-2004, Appendix G), with documentation that supports the proposed lighting schedule. Applicable Internationally.

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

In the LEED for Commercial Interiors and LEED for Retail: Commercial Interiors rating systems, EA credit 1.3, Option A (for 2.0) or Option 1 (for 2009), Appropriate Zoning and Controls, the credit language states, "Zone tenant fit-out of space to meet the following requirements ... Private offices and specialty occupancies (conference rooms, kitchens, etc.) must have active controls capable of sensing space use and modulating HVAC system in response to space demand". The Interior Design and Construction Reference Guide states that, "requirements need only apply to the extent of the project scope". Does "project scope" refer to all spaces that are within the LEED project boundary, regardless of whether they are included in the scope of work for the project? Must each private office have its own controls, or can private offices be grouped together?

Ruling:

Yes, "project scope" refers to all spaces within the LEED project boundary, regardless of whether or not they are included in the project\'s scope of work. The project can comply with the requirements of the credit as long as all spaces within the "project scope" satisfy the requirements.Each private office must have its own active controls. Grouping of offices using a single control does not meet the intent of the requirements.

Campus Applicable
No
Internationally Applicable:
No

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Marcus Sheffer

7group / Energy Opportunities
LEED Fellow

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