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.