Entry Type ID Date Applicable Rating System Primary Credit Inquiry (LIs) Ruling (LIs) Related Addenda/LIs Related Resources Campus Applicable Internationally Applicable Country Applicability Reference Guide (Addenda) Page (Addenda) Location (Addenda) Description of Change (Addenda) "LEED Interpretation" "1640" "2006-12-06" "New Construction" "The ASHRAE 62.1-2004 User\'s Guide includes an Excel calculation tool (ASHRAE Tool) which calculates system ventilation efficiency (Ev) and zone ventilation efficiency (Evz). Please advise whether use of the ASHRAE 62.1 User Manual Calculation Tool can be used to document compliance with this LEED credit. The ASHRAE Tool includes inputs for zone air distribution effectiveness (Ez) which is considered equivalent to air change effectiveness (ACE) as noted in EQc2 CIR ruling dated 07/20/2004. The ASHRAE Tool also includes inputs for Space Type, Floor Area of Zone, Design Population of Zone, and Design Discharge Airflow to Zone. The ASHRAE Tool seems to be an alternative method which can be used to determine compliance with this LEED credit. The ASHRAE Tool calculations also seems to be more current and accurate than the allowed LEED option as described in EQc2 CIR ruling dated 07/19/2004 which determines ADPI using an ASHRAE Handbook, and selects Ez from a table in Standard 62.1-2001, Addendum N. We propose the following calculation alternative which is based on the CIR ruling dated 07/19/2004 but has been adjusted if the ASHRAE Tool is used to document compliance with this LEED credit. LEED-NC v2.2 basis credit compliance on system ventilation efficiency (Ev). This method is similar but it identifies Evz values for each zone in both heating and cooling modes which are both required by the CIR ruling dated 07/19/2004. Zone__ADPI__Ez Heat__Ez Cool__Evz Heat__Evz Cool__Evz Min 1 2 n TABLE NOTES: (a) ADPI: Not required if using the ASHRAE 62.1-2004 User\'s Guide Excel Calculation Tool. (b) Ez Heat / Ez Cool: Based on ASHRAE 62-2004, Table 6.2, Zone Air Distribution Effectiveness. Ez Heat equals Ez in Heating Mode. Ez Cool equals Ez in Cooling Mode. (c) Evz Heat / Evz Cool: Based on results calculated by the ASHRAE 62.1-2004 User\'s Guide Excel Calculation Tool using Ez values. Evz Heat equals Evz in Heating Mode. Evz Cool equals Evz in Cooling Mode. (d) Evz Min: Minimum Evz value for heating and cooling modes. Must be greater than 0.90 to meet the requirements of this credit for each zone. We realize that the LEED-NC v2.2 rules can be used document this credit, but the restrictions imposed by the USGBC in using v2.2 rules to document this credit force it to also comply with v2.2 requirements for EQ Credit 1. The v2.2 rules are also based on increasing the minimum amount of fresh air by 30%, and not on achieving a minimum Evz 0.90." "CIR ruling dated 6/8/05 allows for the use of ASHRAE 62-2004 in lieu of ASHRAE 62-1999. If ASHRAE 62-2004 is applied, it must be applied consistently throughout a project in all associated prerequisites and credits referencing ASHRAE 62. Note that ADPI calculations are still required regardless of which version of ASHRAE Standard 62 is used, so Note (a) in the table above is incorrect. Applicable Internationally." "None" "None" "X" "LEED Interpretation" "502" "2003-03-11" "New Construction" "Our project is an Environmental Studies Building on a community college campus in California. The building is two stories and roughly 22,000 square feet. It is divided into two wings - one of which is mechanically ventilated with an underfloor system and one of which is naturally ventilated. The naturally ventilated wing is roughly 9,000 square feet and includes some classroom space, tech support areas for the classrooms, and open study and lounge space. We do not have any questions about how this credit applies to the ""mechanically ventilated"" wing. For the Naturally Ventilated spaces, we would like to know what methods we can use to show compliance with the requirements for this credit. We have heard some reference that a simulation run is not the only acceptable path to validation/documentation, one alternative being a detailed airflow diagram and accompanying narrative and related cutsheets based on established principals of natural ventilation. However all of the official language in LEED Version 2.0 and 2.1 appears to point to a ""simulation"" requirement. We believe that the credit\'\'s intent to ""provide for the effective delivery and mixing of fresh air to support the health, safety, and comfort of building occupants"" can be met without a ""simulation"" run being undertaken but would like confirmation as to whether or not this is the case. If a simulation is required, it will add significant cost to the project. The question is: What of the following (alone or in combination) will the USGBC accept as validation that the project meets the credit intent (the following has been listed in increasing order of effort/cost). 1) Conformance with Title-24 requirements for a naturally ventilated space - Section 121(b)1 The code reads: ""Natural outdoor ventilation may be provided for spaces where all areas of the space are within 20 feet of an operable wall or roof opening through which outdoor air can flow. The sum of the areas of the openings must total at least 5 percent of the floor area of each space that is naturally ventilated. The openings must also be readily accessible to the occupants of the space at all times. Air flow through the openings must come directly from the outdoors; air may not flow through any intermediate spaces such as other occupied spaces, unconditioned spaces, corridors, or atriums. High windows or operable skylights should be accessible from the floor."" 2) Airflow diagram(s) based on established principals of natural ventilation 3) Narrative based on established principals of natural ventilation 4) A single-node based simulation using our own internal software that would then provide air change rates for the space (but not air diffusion effectiveness). 5) A multi-nodal cfd based simulation 6) Some other method not listed above We appreciate your clarification on this topic." "The California Title 24 requirements for naturally ventilated spaces (very similar to ASHRAE 62 requirements for naturally ventilated spaces) are appropriate for documenting compliance of a naturally ventilated building with EQ prerequisite 1, but not for documenting achievement of EQ credit 2. The best way to demonstrate ventilation effectiveness in a naturally ventilated building is to develop a multinodal model of airflow. However, a convincing narrative using demonstrated natural ventilation principles, and including diagrams accurately representing the spaces in question, and supporting calculations based on space characteristics could be used to demonstrate achievement of this credit. Such a narrative would need to be well crafted, clear, and convincing. A single node model could be used to support this evaluation, but by itself would not be adequate to demonstrate achievement. Applicable Internationally." "None" "None" "X" "LEED Interpretation" "5605" "2002-01-18" "New Construction" "In most residential buildings outside air is supplied through operable windows, and indirectly, through infiltration. Mechanical ventilation for outside air is typically not required by code (and is specifically not required in New York City). The ventilation effectiveness criteria cited in this credit are meant for more sophisticated commercial facilities, where mechanical ventilation is mandatory. The developer is implementing the following measures for this project, and proposes that these be considered adequate to meet the intent of this credit: 1) All apartments are provided a positive mechanical supply of outside air. The supply ventilation will meet, or surpass, the criteria of ASHRAE 62-1999. While this method does not ensure an air change effectiveness of 0.9, it does mandate mechanical ventilation where none would otherwise be provided. IAQ is improved through dilution. 2) Operable windows are provided in all living rooms and bedrooms. 3) 100% outside air is provided for all public corridors. With these criteria, we feel that the intent of this credit is met for the high-rise residential building context." "The LEED Steering Committee provided an interpretation of this Inquiry. The Committee determined that the proposed approach to EQ Credit 2 does not meet the intent of the credit. The Committee had the following comments: EQ Credit 2 requires that the project demonstrate an air change effectiveness of 0.9 using ASHRAE Standard 129-1997. In order to meet the EQ Prerequisite 2, the project is already proposing to conduct ASHRAE 129 testing, so the opportunity exists to modify the test to gather data on air change effectiveness as specifically described in the requirements of this credit. EQ Prerequisite 1 requires that the project comply with requirements of ASHRAE 62-1999 to meet minimum ventilation effectiveness. Standard 62 includes language addressing residential-type occupancies, and the Committee therefore feels that meeting this standard does not demonstrate an additional level of ventilation effectiveness, but rather is part of the prerequisite. There is an apparent contradiction between the narrative describing how additional ventilation effectiveness (EQc2) is achieved by providing positive supply to the residential units, and the previous discussion for EQ Prerequisite 2 where the residential units are described as having negative pressure. There may be other strategies to meet the intent this credit, but the strategy proposed does not meet the intent of the credit." "None" "None" "LEED Interpretation" "5688" "2004-07-19" "New Construction" "Our design project consists of Classrooms, offices, conference rooms, dining rooms, library, atrium, and support spaces. The supply air system is a mixing system with supply air (Group A outlets) and return air devices at the ceiling level in all regularly occupied areas of the building. In order to obtain this credit, we have chosen to follow the second path of compliance, through design verification, as described on page 234 of the LEED reference guide by following guidelines mentioned in Chapter 31 of ASHRAE Fundamentals Handbook. However, we have the following questions: 1. ASHRAE Handbook of Fundamentals, Chapter 31, recommends a minimum ADPI of 80. Can we assume that an ADPI of 80 or more in each of the major spaces would satisfy the intent of the credit? If not, what value of ADPI will be acceptable? 2. In addition to submitting narratives, plans, sections, air velocities, location of supply and return air devices, we propose to submit outputs of a commercially available program that calculates Room ADPI based upon an actual design layout. This would be submitted for each of the typical spaces such as Classrooms, offices, conference rooms, dining rooms, library, and atrium. Would these be sufficient to comply with the requirements of the credit? A sample output sheet for a conference room is listed below for your review. Titus GRD Selection Room Air Device Calculations Large conference room ADPI: 82.0 Room Data Length x Width: 39.0 x 19.0 Ft. Maximum Room NC Level: 35 Ceiling Height: 9.0 Ft. Sensible Room Load: 26 BTUh/sf dT: 20 Area: 741.0 Sq. Ft. Air Changes: 8.0 ACPH Perimeter: 0 Ft. Mounting Type: Lay-in Supply Diffuser Data CD-2 Room Design Supply: 880 CFM: Room Comfort Model No.: PCS CFM: 110 Actual Max. Min Neck: 8 RND Throw: 6.0 Border Style: 1 - Surface Mount Pd: 0.03 ADPI 82 91.9 0.0 Throw Pattern: 4-way NC Level: 30 Description: Perforated Ceiling Diffuser Vt: 50.00 Heating TR: 0.4 Supply Drafting Data Tag: CD-2 No. of Diffusers: 8 CFM: (each):110Module Size: 24x24 Neck Size: 8 Throw: 4-way Layout: 2x 4 Return Device Data Room Design Return: 440 CFM: Model No.: : 0 Neck: 22x22 Pd: Module: 24x24 NC Level: 35 Border Style: Return Drafting Data Tag: No. of Returns: 2 Neck Size: CFM: (each):0 Module Size: " "The submittal requirements and v2.1 Letter Template are in need of clarification. A table intended for the EQc2 Letter Template was in fact erroneously omitted, thus causing this confusion. Note that the credit requirements specify ""ventilation systems that result in an air change effectiveness greater than or equal to 0.9"" The first compliance path for this credit is a performance path. The system is designed and then tested using ASHRAE Standard 129-1997 to demonstrate that the air change effectiveness (ACE) is greater than or equal to 0.9. The test may be a field test of the actual diffuser installation or may utilize laboratory tests of diffusers tested under similar operating conditions. The second compliance path for this credit, and the subject of this CIR, is a design solution. ASHRAE Handbook of Fundamentals Chapter 32 may be used to document proper positioning and design of diffusers as described in the LEED v2.0 and v2.1 Reference Guides to achieve good air distribution. Diffusers must be located and selected to achieve an estimated Air Diffusion Performance Index (ADPI) of 80% or greater as described in Chapter 32, Table 4, ADPI Selection Guide, under all expected occupied operating conditions. The v2.1 submittal requirements and Letter Template are, as you point out, in need of clarification. A table intended for the EQc2 Letter Template was in fact erroneously omitted, thus causing this confusion. The estimated ADPI from Chapter 32, or ADPI measured according to ASHRAE Standard 113, can not be used in lieu of Air Change Effectiveness (ACE) for determining compliance with this credit. However, provided the HVAC design has been developed according to Chapter 32, Table 4, ADPI Selection Guide, for an estimated ADPI of at least 80%, one may use the Zone Air Distribution Effectiveness, Ez, in ASHRAE Standard 62-2001, Addendum n, Table 6.2, to identify the ACE for each zone. This table prescribes the Zone Air Distribution Effectiveness values for various HVAC air distribution designs. To apply the values in the table correctly, requires consideration of both heating and cooling occupied modes for each zone. Separately analyze each unique space design. Projects must document designed performance in a table showing, for each zone, estimated ADPI of 80% or greater as well as an average ACE of 0.9 or greater for the occupied hours under worst case ACE conditions (e.g. the design day where the greatest number of occupied hours are projected for the ventilation mode with the lowest ACE, e.g. typically the design day with the greatest number of occupied hours with heating). For example, the documentation table will show: Zone___ADPI*___ACE, Heating**___ACE, Cooling**___ACE, Average *** 1 2 n * Based on ASHRAE Handbook of Fundamentals Chapter 32, Table 4, ôADPI Selection Guideö ** Based on ASHRAE 62-2001, Addendum n, Table 6.2. ôZone Air Distribution Effectivenessö. *** Time averaged ACE based on above ACE heating and cooling values, and ASHRAE 62-2001, Addendum n, Equation 6-9, for calculating the average ACE during the occupied hours. Calculation to be made using the worst case conditions representing the design day where the greatest number of occupied hours are projected for the ventilation mode with the lowest ACE. Software created by diffuser manufacturers or other credible sources may be used to calculate estimated ADPI as long as the LEED application narrative for this credit identifies the program by name and company. Any space with heating capability, such as a heating coil, serving a space with exterior walls or roof will typically operate in a heating mode at some point when the space is occupied. These spaces must document ACE under heating mode. Spaces without this type of heating condition can document ACE under cooling mode only. For designs with heating capability, where heating is designed to only occur during unoccupied hours (e.g. morning warm up), ACE may be documented under cooling mode only, provided submittal documentation demonstrates that heating does not occur during occupied hours,. For designs with heating capability, where both heating and cooling are expected to occur during occupied hours, one may use ASHRAE 62-2001, Appendix n Section 6.2.5.2, Short Term Conditions, Equation 6-9, to determine the average conditions over a defined time period, T, where T equals 3 times the room volume (ft3) divided by the breathing zone outdoor air flowrate (cfm) calculated in Equation 6-1. FOR EXAMPLE: In a 1000 ft2 office space with 5 occupants and 13 ft ceilings, including return air space above the suspended ceiling, Equation 6-1 requires 85 cfm per 1000 ft2. From Equation 6-9, T equals 3 times 13,000 ft3 divided by 85 cfm, or 459 minutes or 7.64 hours. This is the maximum time allowed for averaging. If the morning warm up continues for the first two hours of a 10 hour occupied period (e.g. 8AM to 6PM), followed by 8 hours of cooling, then the average ACE is calculated as follows for ceiling diffusers with a Zone Air Distribution Effectiveness of 1.0 in cooling mode and 0.8 in heating mode (i.e. supply air greater than 15 oF warmer than space and ceiling return air temperature) : For the first 7.64 hours (i.e. the maximum averaging period, T, as determined by Equation 6-9 above) the average ACE is calculated as (2 hours times 0.8 + 5.64 hours times 1.0) divided by 7.64 hours, for an average ACE of 0.95. This average is then averaged with the remaining 2.36 hours of cooling only, which has an ACE of 1.0 as follows: (7.64 hours times 0.95 + 2.36 hours times 1.0) divide by 10 hours, for an average ACE for the 10 hour occupied period of 0.96. The submitted table would provide this information, for example: Zone: 1 ADPI: 0.80 ACE, Heating: 0.80 ** ACE, Cooling: 1.0 ** ACE, Average: 0.96 *** Regarding how to proceed with a design using perforated and louvered ceiling diffusers in a laboratory with room loads in excess of 50 BTU/hr-ft2, we acknowledge that there are no data for these higher room loads in Chapter 32 Table 4, or to our knowledge in any diffuser manufacturer calculation programs. There are other diffuser types that provide estimated ADPI values for room loads as high as 80 BTU/hr-ft2. Also, since as room cooling loads increase, the mixing of the indoor air increases (e.g. results in ACE values closer to unity). For applications with room cooling loads greater than those listed in ASHRAE Chapter 32, Table 4, we recommend use of the estimated ADPI and the T50/L range for the highest room load listed for that diffuser type. For designs utilizing different types of diffusers, air distribution configurations, or T50/LÆs not described in ASHRAE Chapter 32 or Standard 62 tables, the only options for this credit are to conduct measurements of ACE (ASHRAE 129) or ADPI (ASHRAE Standard 113) either in the field or in a laboratory simulation. Also, for application of ASHRAE 129 in the field for this credit, we note that the requirements in Section 4, ""Criteria for Acceptable Test Space"", are not required, provided the space is operated under normal design conditions. " "None" "None" "LEED Interpretation" "6038" "2002-01-02" "New Construction" "We believe that following portion of the proposed LEED 2.1 revision from the IEQ TAG is applicable to multi-family residential and should be used for projects seeking certification under LEED 2.0: . . provide operable windows within 20 feet and effective air distribution [this needs to be defined by the IEQ TAG] for 90% of all occupied spaces . . . OR We propose that effective ventilation can be induced by a timed cycle, low sone, ducted, ventilation fan in the bathroom and/or kitchen, or the furthest room from the perimeter of the building where the windows are located. Window crackage and/or slot ventilation openings in the window frames or wall can be used as the fresh air source with an acknowledgment in the design of how the moisture issues from differential pressurization will be addressed. OR Provide fan assisted ventilation in conjunction with operable window area exceeding 5% of the floor area. [BOCA requires the following: 1208.2 Ventilation area required: The minimum openable area to the outdoors shall be 4 percent of the floor area being ventilated]. OR Provide ducted, filtered, outside, ventilated air for all dwelling units." "LEED v2.0 is intended for commercial, institutional and hi-rise residential buildings but not all credits will apply to all possible occupancies. Equivalent methods of achieving a credit intent may be proposed, but only within the requirements of the existing credit. If you are suggesting a prescriptive method of calculating compliance, you must demonstrate through a calculation that an equivalent level of performance is achieved. The LEED v2.0 Reference Guide June 2001 provides some guidance on page 232, staing ""that operable windows combined with fan-powered mixing boxes do not qualify under this credit without a demonstrable architectural strategy for natural ventilation"". This statement also applies to residential occupancies. Therefore the LEED v2.0 requirement for natural ventilation under this credit applies: ""demonstrate a distribution and laminar flow pattern that involves not less than 90% of the room or zone area in the direction of air flow for at least 95% of hours of occupancy."" Modifications to performance criteria in order to accommodate vertical market differences, or occupancy variations within a vertical market, are handled outside the Credit Inquiry Request process. This process is under development by the LEED Steering Committee. The LEED Steering Committee advises that: ""Technical Advisory Group discussions are preliminary and ongoing. This CIR will be reviewed by the Indoor Environmental Quality TAG for their review and ruling.""" "None" "None" "LEED Interpretation" "948" "2005-02-07" "New Construction" "The credit intent is to, Provide for the effective delivery and mixing of fresh air to support the safety, comfort and well-being of the occupants. We will demonstrate our compliance through the second compliance by submitting a detailed narrative illustrating the design approaches that were used per the ASHRAE Fundamentals Handbook 2001, Chapter 32: Space Air Diffusion, as described in the edition of the Reference Guide (May 2003 edition). We understand from the Reference Guide that in the case of an audit we must provide scale airflow pattern diagrams, among other data, on all major room types. We would like verification of our interpretation of the major room types of our project and our approach to meeting the credit intent. Our major room types are defined on the basis of room size, shape, extent of mechanical recirculation, the location of heat generating objects, and air motion. We have determined that 5 room types can represent the majority of the regularly occupied rooms at the health center. 1) 100 ft2, 4 ACH 2) 100 ft2, 12 ACH 3) 170 ft2, 4 ACH 4) 170 ft2, 9 ACH 5) 400 ft2, 4 ACH All room types above have 1 diffuser in the center of the room, except for room type 5, which has 2 diffusers Assumptions: - tests will be completed in cooling mode because we do not have air-based in-room heating - radiant panels located at the perimeter walls and will negate exterior wall effects - furnishings are neglected because they are minimal in offices and patient rooms and based on literature, will not contribute significantly to our ADPI calculations Hospital rooms, such as operating rooms, requiring specialized ventilation systems are excluded from our testing. These systems are characterized by high air change rates and laminar flow outlets. We feel that the high air change rate is sufficient to achieve the required ventilation effectiveness. Further, this system type cannot be evaluated using ASHRAE\'s Standard 113. We have also excluded non-regularly-occupied spaces such as corridors, storage rooms etc. as defined in credits EQc8 We have also excluded non-typical rooms from the testing process because they are not major spaces. However, ADPI calculations will still be performed on these rooms as per ASHRAE Fundamentals Handbook 2001, Chapter 32: Space Air Diffusion. For each of the 5 major room types, we will provide the following, as per the May 2003 version of the Reference Guide and the : 1. the predicted ADPI as determined by mock ups in accordance with ASHRAE Standard 113; 2. scale diagrams graphically illustrating the air throw patterns and air directions in the test planes. 3. ACE _cooling calculations per the USGBC ruling dated July 19, 2004 Because of the large variety of rooms we are representing, we cannot provide section and plan drawings showing inlets, outlets, furniture and occupants, as requested. Based on preliminary tests we expect that the test results will support our predicted ADPI. We feel that we will sufficiently demonstrate that the intent of this credit has been met by: 1) following the design recommendations in ASHRAE Fundamentals, Chapter 32; 2) evaluating the ADPI and ACE for all regularly occupied spaces as per the calculation guidelines provided in that document and ASHRAE 62 2001; and, 3) supporting the ADPI calculations with measured ADPI values and scale graphic airflow illustrations at two sections each for the 5 major room types described, We propose to base the design on test results acquired during the design phase. The test results will be submitted, as described above, to demonstrate that the design meets the credit intent to provide for the effective delivery and mixing of fresh air to support the safety, comfort and well-being of building occupants. Please advise us whether this approach is acceptable." "The course of action proposed by the applicant is above and beyond what is required. Per the EQc2 ruling dated 7/19/2004, provided the HVAC design has been developed according to Chapter 32, Table 4, ADPI Selection Guide, for an estimated ADPI of at least 80%, one may use the Zone Air Distribution Effectiveness, Ez, , in ASHRAE Standard 62-2001, Addendum n, Table 6.2, to identify the ACE for each zone."" This does not require testing to establish the estimated ADPI. Measured values and graphic airflow illustrations are not needed. Since the heating is not air-based, the heating mode need not be considered if heating occurs in the zone during occupied hours. The EQc2 ruling dated 7/19/2004 provides guidance and useful examples of how to use the ACE calculation procedure once the minimum ADPI of 80% has been established; it also illustrates how to average the ACE for heating and cooling. The establishment of major room types is a reasonable way to approach the calculations. In addition to the major room types given, other regularly occupied rooms such as waiting rooms and operating rooms should be addressed. Contrary to your statement, ASHRAE Standard 113 may be used to measure ADPI of operating rooms as the scope of this test method says that the method is applicable to all types of supply outlets. Furthermore as stated in the EQc2 ruling dated 7/19/2004, the ADPI need not be measured but may be estimated from Table 4 in Chapter 32 of the ASHRAE Handbook of Fundamentals. Please note that higher ventilation rates do not correlate with better mixing of the ventilation air. Higher ventilation rates (ach) will reduce the air change effectiveness, because at these higher ventilation rates the residence time (age) of the air is lower, so there is less time to mix the air. " "None" "None"