Change to ASHRAE Standard for Multi-family Projects

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Safety

February 1, 2020

ASHRAE recently approved “Addendum Y” to Standard 62.2, “Standard for Ventilation and Acceptable Indoor Air Quality in Residential Buildings” that will impact ventilation in multifamily projects with closed corridors.

For apartment and condo buildings with fully enclosed corridors, some designs satisfy ASHRAE 62.2 requirements for whole dwelling ventilation with “exhaust only” systems, such as operating a bath fan continuously to induce the infiltration of outdoor ventilation. With Addendum Y, this approach will no longer be allowed.

“Addendum ‘Y’ addresses concerns regarding dwelling unit ventilation of new multifamily dwellings that are accessed by an enclosed common corridor where the operation of exhaust systems for dwelling unit may draw air from the corridor,” the Home Ventilating Institute reported. “For such dwelling units, operation of exhaust systems for dwelling unit ventilation is no longer permitted in the standard’s prescriptive path based on concerns that corridor air may be contaminated and not suitable for use as make-up air for dwelling unit exhaust systems. Supply and balanced systems are allowed in the prescriptive path because they introduce ventilation air directly from the outdoors.”

With exhaust-only designs no longer applicable to meet ASHRAE 62.2, engineers will need to focus on one of two options: supply (i.e., with an inline fan) or balanced (i.e., with a fresh air appliance) ventilation.

Multi-family dwelling units still need “local” exhaust systems for bathrooms and kitchens, but the “dwelling unit” ventilation component (sometimes referred to as “continuous ventilation”) cannot be satisfied by such exhaust systems.