Rating System

LEED BD+C: New Construction, LEED ID+C: Commercial Interiors, LEED BD+C: Core and Shell, LEED O+M: Existing Buildings

Rating System Version

v2 - LEED 2.2, v2 - LEED 2.0, v2 - LEED 2.0, v3 - LEED 2008

Inquiry

Introduction and Request Summary: Our project is a 68 story hotel and residential condominium project in New York City, New York, applying for certification under the LEED NC 2.2 rating system. We are requesting an interpretation with regard to LEED EQ Prerequisite 1: Minimum IAQ Performance. The hotel rooms, common areas, event rooms, pre-function areas, restaurants and lounges all meet the mechanical ventilation requirements of ASHRAE 62.1-2004. However, the residential condominium units, which are naturally ventilated spaces, include some small portions of the units that are not completely within 25 feet of operable openings to the outdoors. Design Background: In our current design, the residential living units are conditioned by recirculating four-pipe fan coil units and ventilation is provided naturally via operable windows and doors to the outdoors. The corridors are mechanically ventilated by means of a 100% outside air handling unit at a rate of 0.8 cfm/sf, providing positive pressure with respect to the living units. All toilet rooms are mechanically exhausted at a rate of between 50-100 cfm continuously. All kitchens are mechanically exhausted at a rate of 150 cfm continuously. Several kitchens require an additional exhaust hood and make-up air that operate intermittently. In accordance with ASHRAE 62.1-2004, paragraph 5.1.1 for naturally ventilated spaces, the openable wall area to net occupiable floor area ratio for each living unit is 4% or greater. However, small areas within the residential units exceed 25 feet from the operable windows or doors. When the areas beyond the 25 feet are toilets or kitchens, the air is transferred by means of mechanical exhaust. However, some areas beyond the 25 feet are foyers or hallways. Conclusion and Interpretation Request: In order to meet the intent of the code, we are proposing an engineered natural ventilation system which would include a transfer air fan that would be located in the ceiling and would circulate air from the area within 25 feet from the operable windows to the area beyond the 25 feet. The fans would be sized for 0.35 ac/h or 0.6 cfm/sf, whichever is greater, for the area beyond the 25 feet boundary. In addition, the entry foyers of the living units will be ventilated by means of air infiltrating via the unit entry doors from the pressurized, conditioned and outdoor air ventilated corridors. In addition, these foyer spaces are adjacent to toilets and kitchens, both of which are exhausted continuously. The local code authority, NYC Building Code, does not restrict naturally ventilated spaces to within 25 feet from operable openings; therefore, this approach would exceed the requirements of the local code. Please confirm whether this approach for an engineered ventilation system would meet the requirements of LEED EQp1.