Entry Type ID Date Applicable Rating System Prerequisite/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" "2045" "2008-02-12" "New Construction, Core and Shell, Schools - New Construction, Commercial Interiors, Existing Buildings" "IEQc5: Indoor Chemical and Pollutant Source Control" "Our question regards the filtration requirement for re-circulating air systems, such as VAV terminals and fan coil units, under EQc5. Per LI 5061 and LI 1795 rulings, ""Since the fan coil units re-circulate room air, they must have MERV 13 filters"", so do the VAV terminal units that re-circulate air. This conflicts with our previous understanding that the MERV13 requirement would only apply to the air handling units supplying 100% outside air - or a mix of outside and return air - to a single or several rooms. The use of MERV 13 filters is justified when HVAC systems re-circulate a part of return air - e.g. mixed return air streams from various rooms - back to different spaces. In this configuration, supply ducts of the HVAC system and return air may become contaminated by re-circulated indoor-generated pollutants. Thus, contamination generated at specific indoor locations may be spread throughout the building unless properly filtered. However, the use of MERV 13 filters cannot be justified where air is re-circulated within the room. In this configuration, there is no possibility of cross-contamination: the re-circulated air has been conditioned and returned to the same room. In general, re-circulating air units (fan coils.) are provided with MERV 6 to MERV 8 filters. Using MERV 13 would substantially increase the energy consumption to condition a space without significantly improving the indoor air quality within the space. Imposing such a requirement would also cause most commercial systems to be ineligible for achievement of this credit, and may cause the other beneficial aspects of this credit (walk-off mats and isolation of harmful contaminants) not to be incorporated. Please clarify whether MERV 13 filtration is necessary for air re-circulated within a space." "**Updated January 1, 2014\n As noted in LI 5061 and LI 1795 rulings, both outside air and re-circulated air must pass through MERV-13 filtration before being introduced into a space, even if the re-circulated air is only being returned to the space it was drawn from. If there is a source of contamination in a space, filtering the re-circulated air before re-introducing it into the space provides a more rapid method of removing the contaminants than relying on the introduction of filtered outside air alone. NOTE: UPDATED CREDIT LANGUAGE FOR 2009 STATES THAT ""PARTICLE FILTERS OF AIR CLEANING DEVICES SHALL BE PROVIDED TO CLEAN THE OUTDOOR AIR AT ANY LOCATION PRIOR TO ITS INTRODUCTION TO OCCUPIED SPACES"". REQUIREMENT FOR FILTRATION ON RETURN AIR IS NO LONGER APPLICABLE TO ANY VERSION OR ANY RATING SYSTEM. " "None" "None" "X" "LEED Interpretation" "5061" "2007-08-13" "New Construction, Core and Shell, Schools - New Construction, Commercial Interiors, Existing Buildings" "IEQc5: Indoor Chemical and Pollutant Source Control" "The project intends to meet the permanent entryway system and exhaust system requirements of the credit criteria. The project is requesting an interpretation of the acceptability of the method proposed to meet the MERV 13 filtration requirement. The project HVAC system is a dual path HVAC system: Outside air for ventilation is provided by 100% fresh air air-handlers with heat recovery from exhaust air. These air handlers will be equipped with MERV 13 filtration or better as well as other features for achieving high efficiency. Zone conditioning will be provided by fan coils receiving a mixture of return air from the space and fresh air from the air handlers described above. In this respect, the fan coils provide a similar function to that of fan powered terminal units on a conventional variable air volume system and similar to that system, MERV 13 filtration is not possible on the zone fan coil level. The design team believes that the design meets the intent of the credit for filtration since all outside air introduced into the building will be filtered to the high standard of MERV 13." "The CIR inquiry indicates that the project receives 100% of its outside air through air handling units that are equipped with MERV 13 filtration, as required by EQc5. Additional fan coil units are located within the building to provide supplemental zone conditioning. The fan coil units supply a combination of the minimum ventilation outdoor air plus air recirculated from the room. Since the fan coil units recirculate room air, they must have MERV 13 filters, which are available on the market. Therefore, the design, as described, does not appear to meet the intent of the credit. \n\n **Updated January 1, 2014\n NOTE: UPDATED CREDIT LANGUAGE FOR 2009 STATES THAT ""PARTICLE FILTERS OF AIR CLEANING DEVICES SHALL BE PROVIDED TO CLEAN THE OUTDOOR AIR AT ANY LOCATION PRIOR TO ITS INTRODUCTION TO OCCUPIED SPACES"". REQUIREMENT FOR FILTRATION ON RETURN AIR IS NO LONGER APPLICABLE TO ANY VERSION OR ANY RATING SYSTEM." "None" "None"