A natatorium space has a very high relative humidity. Innovent, a pool dehumidification unit manufacturer, does not recommend using MERV 13 filters on the return air in a pool application due to the high humidity. This unit has an outside air filter and a return air filter. There is not a supply air filter option for these units. Therefore the return air must pass through the filter prior to the dehumidification process. The humid return air in a natatorium environment will quickly saturate a standard pleated filter with moisture. The saturated filter will have a very high pressure drop and may grow mold and other organisms associated with a wet filtration media. Innovent uses an aluminum wash down filter for this application to avoid the poor air quality and reduced air flow associated with a wet filter. There is not an aluminum wash down filter currently on the market that has a MERV 13 rating. In addition the air in a natatorium space generally has a low quantity of dust and other particulate matter. We recommend that the pool dehumidification unit be exempt from the MERV 13 return air filter requirement associated with LEED v2.1 Indoor Environment Quality Credit 3.2.
The applicant is asking whether the pool dehumidification units can be exempted from the MERV 13 air filter requirement of EQc3.2. Similar to CIR ruling for EQc3.1 dated 10/24/2005, natatorium units cannot be exempted from the credit requirement for MERV 13 filtration during flush out and immediately prior to occupancy. Per CIR rulings for EQc3.1 dated 12/22/2004 and 10/24/2005, LEED-NC v2.1 addresses "MERV 13 filter installation after construction and prior to occupancy. The use of MERV 13 filters throughout the life of the building is [addressed] by LEED-EB EQc5.1." As long as MERV 13 filters are used during the flush out and are replaced following the flush out, the credit requirements can be met. The applicant may wish to conduct the flush out before the pool is filled with water in order to reduce the humidity impacts on the filters. Applicable Internationally.