ASHRAE 62.2 Residential Ventilation Standard
All areas of a home, even those that are not regularly occupied, require some measure of air circulation. ASHRAE 62.2 provides residential guidelines for air changes per hour (ACH) for every area of a home under various conditions.
Air changes per hour is the measure of how many times the air within a space is replaced. It is calculated by the air volume added to or removed from a space, divided by the volume of the space. The number of occupants should also be taken into account. As a rule of thumb, residential living spaces such as kitchens family rooms, home offices, bathrooms, hallways, bedrooms, etc., require between five and seven air changes per hour, sometimes more. ASHRAE 62.2 will help steer a contractor or designer to the minimum air changes needed to properly size an HVAC system.
To calculate air changes, multiply the CFM (cubic feet per minute) times 60 minutes per hour, then divide by the volume of the room in cubic feet. For example, a room that is 10’ x 10’ x 10’ = 1,000 cubic feet. If you have 100 CFM provided to the space, 100 CFM x 60 = 6,000 / 1,000 cubic feet = 6 air changes per hour for that particular space.
Keep in mind that unoccupied areas such as basements, crawlspaces, closets, attics, and other stagnant air zones may require ventilation in the form of exhaust systems to allow heat and moisture to escape and prevent odors, rot, mold and dust. These systems should not be included in the HVAC design calculation. Customers may complain of stagnant areas that smell musty and explaining guidelines may help you make a sale and a satisfied customer.
About E.P. Homiek
E.P. Homiek Sheet Metal Fabrication & HVAC Supply, with two convenient locations in Lakewood, NJ and Union, NJ, provides one- to two-day turnaround on all residential and light commercial ductwork, as well as one- to two-hour emergency fabrication service, rapid delivery, and competitive prices. HVAC parts, supplies, and equipment lines include Goodman, Honeywell, Bryant, Bradford White, Crown Boiler, Daikin, Weil-McLain, Sea Breeze, Generac, Fantech, ZM, A.O. Smith, Hart & Cooley, Malco, Mueller, and many more.
