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In 2003, the ventilation market saw the birth of a new standard for exhaust fans of the future: ASHRAE 62.2-2003. Created by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), Standard 62.2 defines certain parameters of quality bathroom exhaust fans and other like products. This was made in response to homes getting “tighter” with insulation and the like. Although ASHRAE already had a ventilation standard as early as 1989 (Standard 62), it wasn't specific for residential use. Standard 62.2 specifies indoor air quality in a typical home by defining the requirements and limitations such as ventilation rate and design standards. Popular brands of exhaust fans such as Broan have already adopted Standard 62.2 in their designs to help consumers make the most out of their exhaust fans. Here are some of the details Standard 62.2 defines: Ventilation Rate Any standard for exhaust fans wouldn't leave out details on the proper ventilation rate. Before 62.2, the defined ventilation rate was set at 0.35 air changes per hour (ach), with every person in the home getting at least 15 cubic feet of air per minute (cfm). However, ASHRAE changed the rates in response to the varying occupancy of homes. ASHRAE took into consideration the size of the home to be ventilated in Standard 62.2. Today, any ventilation system must be able to provide 7.5 cfm per person but with an extra 3 cfm per 100 square feet. In this case, a 64-square-foot bedroom for two requires a ventilation system that can deliver at least 17 cfm (15 cfm for two plus 1.92 cfm for the bedroom). Natural Ventilation Even with quality roof exhaust fans installed, ASHRAE still requires homes to have operable openings for natural ventilation, namely windows. If the home is close to a source of pollution or noise such as an airport or factory, an expert assessment will be necessary to evaluate the feasibility. In this case, a mechanical ventilation system may be a prudent option to maintain air quality and reduce pollution or noise. Otherwise, at least four percent of the floor area must have operable openings. ASHRAE made a lot of changes in Standard 62 to specify a standard for residential use. If you want to look more into the details, you can check out the whitepaper at this link: web.ornl.gov/sci/buildings/2012/2004%20B9%20papers/012_Password_Removed.pdf.
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bathroom exhaust fans, roof exhaust fans,
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