Exhaust-only ventilation assumptions
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Is it the assumption of exhaust-only ventilation that between meterological factors and normal use of bathroom fans, dryers, and range hoods, you will have sufficient air changes in a day to have good indoor air? Since getting a few IAQ monitors recently, I have noted I am not happy with normal, undirected use with my family of 7 (6 homeschooling most of most days) in 2000~ ft2, but am generally happy with the numbers from my dad’s 3800 ft2 home with 7 people in it (5 homeschooling most of most days). I am extrapolating from that that our typical customer with between 600-1500 ft2 per person is probably doing ok, albeit dealing unconsciously with whatever comes into the house with infiltration.
P.S. Until I get my ERV, I have hit upon the practice of continuously running my master shower fan on low (80cfm), and that is more than sufficient to maintain and improve our CO2 levels.
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Replies
Tupchurch,
Q. "Is it the assumption of exhaust-only ventilation that between meterological factors and normal use of bathroom fans, dryers, and range hoods, you will have sufficient air changes in a day to have good indoor air?"
A. No. If you are commissioning an exhaust-only ventilation system, you must set the fan's control (controls can vary, but the control often consists of a timer that allows for intermittent ventilation settings) to ventilate the house at the rate set by ASHRAE 62.2. For more information, see "Revisiting Ventilation."
That makes sense. I am not aware of this ever happening on any of our jobs, probably because this market and code enforcement don't require it. To put this in context, we are still submitting 2009 energy code certificates in Memphis. Trying to figure out the difference between what's right and what's done...