Our project is a mixed use facility with a combination of a high-rise (21-story) and mid-rise (6-story) residential apartment building. Our project utilizes all electric cooking appliances; there is no gas within the dwelling units. Table 6-4 of ASHRAE 62.1-2007 indicates 100 CFM of intermittent exhaust should be provided for residential kitchens. However, Table 6-4 also indicates that residential kitchen exhaust is Class 2 air, and ASHRAE 62.1-2007 section 5.17.3.2 indicates that Class 2 air can be re-circulated within the space. Please confirm that re-circulating kitchen hoods meet the IEQp1 prerequisite (which requires the 100 CFM of intermittent exhaust). We would also like to know if re-circulating hoods are acceptable for both mechanically ventilated and naturally ventilated apartments, since we may have both in our project. We believe re-circulated hoods should be acceptable to meet the exhaust requirements based on ASHRAE 62.1-2007 section 5.17.3.2, but wanted to confirm since this is a prerequisite.
The applicant is requesting confirmation that recirculating kitchen hoods meet the kitchen exhaust requirements of ASHRAE 62.1-2007 for IEQp1 in both mechanically and naturally ventilated kitchens. For mechanically ventilated kitchens, the exhaust rates listed in Table 6-4 of ASHRAE 62.1-2007 are by definition required to be discharged to outside the building (per Section 3 air, exhaust: air removed from a space and discharged to outside the building). Although recirculation of Class 2/3 air is permissible per section 5.17.3.2/5.17.3.3, the Table 6-4 exhaust requirements must still be provided (to outside the building) to meet the minimum requirements of Section 6 of ASHRAE 62.1-2007. Therefore recirculating hoods alone do not meet the exhaust requirements of Table 6-4 of the standard for mechanically ventilated kitchens. Additionally, LEED Interpretation 2208 (CIR ruling dated 6/25/2008) referenced in the inquiry, is indicated within the LEED Interpretation database as NOT applicable to the LEED NCv2009 rating system.In regards to naturally ventilated kitchens, natural ventilation systems designed in accordance with Section 5.1 of the standard do not need to meet the mechanical ventilation (exhaust) requirements of Table 6-4. Note, the exhaust requirements of Table 6-4 were clarified by ASHRAE through addendum O, which states "...exhaust requirements apply to all zones and/or systems regardless of the method used to determine minimum outdoor airflow rates (Ventilation Rate Procedure, IAQ Procedure, or Natural Ventilation Procedure)." Projects have the option to follow the ASHRAE 62.1-2007 addendum but it is not required.