EQ 4.1 allows passive ventilation as long as the system is "approved and verified by a licensed HVAC engineer as providing ventilation equivalent to that achieved by continuous ventilation" in ASHRAE Std. 62.2. What is the Green Rater responsible for verifying? Is any passive design acceptable - including just envelope leakage or operable windows? If the HVAC engineer is willing to sign-off on the design, is there any additional requirement for verification?
Green Raters should be able to verify some evidence that the design will yield air flows equivalent to those required by ASHRAE Std. 62.2. This may include model results, calculations, or on-site test results, but design features are not sufficient. Project teams should be aware of the specific air flow requirements in Std. 62.2 and informed that operable windows and natural infiltration is not sufficient because the air flows in Std. 62.2 already assume natural infiltration rates - i.e. the air flows required by the Standard are above and beyond natural infiltration. In every case that passive ventilation is used, the TASC would like the strategy to be submitted for research and information purposes.