Can you satisfy ASHRAE 62.2 with a recirculating kitchen range fan?
As a Green Rater for the LEED Homes program, I am involved in a fair number of new construction projects that are attempting Passivhaus level building tightness (< 0.6 ACH50). Of course, ventilation systems are a critical piece of all of these homes. All are using HRV/ERV systems to meet the Whole Building Ventilation requirements in 62.2 – Section 4. All are meeting bathroom exhaust requirements of Section 5, with either continuous or intermittent ventilation. However, we have several projects that want to avoid exhausting the kitchen to the exterior – primarily in an effort to meet the Passivhaus tightness standard. My question is about the “Note” in Table 5.1. “Vented range hood required if exhaust fan flow rate is less than 5 ACH” Does this note imply that a recirculating range hood that moves 5 ACH (kitchen) s acceptable? My interpretation of the Note in Table 5.1 is that you need a Vented Range Hood if the exhaust airflow rate is less than 5 ACH. I think this is addressing non-hood style exhaust, such as downdraft. I interpret exhaust as airflow to the exterior of the building, and “Ventilation” is defined in the standard as “the process of supplying outdoor air to or removing indoor air from a dwelling…” My interpretation of the standard is that recirculating kitchen exhaust does not meet the requirements of Local Exhaust, 5.2. However, it could be used in conjunction with adequate continuous ventilation (balanced or exhaust) as part of a strategy to meet 5.3. Can anyone help me clarify the intent of the Note in Table 5.1 – thanks!
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