Does ASHRAE’s Residential Ventilation Standard 62.2 make sense in a cold climate in a pretty good house?
I’m designing a pretty good home (R33 walls, R60 ceiling, R7 windows and less than 0.6 air changes per hour at 50 Pascals pressure) in Zone 6 and I’m trying to configure a balanced ventilation system. I read several Green Building Advisor articles on mechanical ventilation, including “How Much Fresh Air Does Your Home Need?” which pointed out the potential for moisture issues in warmer climates when designing to ASHRAE’s Residential Ventilation Standard (Standard 62.2), which sets the minimum ventilation rate at 7.5 cfm per occupant plus 3 cfm for every 100 square feet of occupied floor area. So, I’m wondering what ventilation rate should I be designing for a pretty good home in Zone 6?
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Replies
Brad,
You should design your ventilation system to comply with ASHRAE 62.2.
Note that the standard governs the (potential) airflow rate of the installed equipment. It doesn't require you to operate it at any particular rate (and, frankly, if any code or regulation tried to dictate how residential ventilation equipment is operated, the law would be unenforceable).
Once you move into the house, you can experiment. You may be quite happy with ventilation at a low rate -- especially if you don't smoke indoors, you don't cook greasy food, and you have few noxious hobbies. On the other hand, you may prefer to ventilate at a high rate.
Almost all ventilation systems can be controlled by a 24-hour timer. Many have variable-speed fans. So choose the right equipment, and don't worry (yet) about how the equipment will be operated.