When is it more efficient to open your house's windows than to use the A/C?
July 6, 2010 6:50 AM Subscribe
What is the summertime temp/humidity differential that makes it more efficient to open the windows and turn off the A/C in one's house than it is to keep the house closed up?
posted by fishpatrol to home & garden (13 answers total) 4 users marked this as a favorite
When we bought our first house, we got quite a lot of advice from inspectors and contractors, including guidelines on using the central air-conditioning system efficiently during the Summer. Our contractor said that you should keep the windows closed at night, even when it's cooler outside, because the A/C works to reduce the indoor humidity as well as the temp. Letting in all that humid air overnight means the compressor will have to work even harder the next day.
While this makes sense, there must also be some tipping point at which it's more efficient to open up every window and flush out the house with cooler outside air. What is that tipping point? What factors need to be measured, and what math needs to be done? I'd like to keep our cooling costs down and also be more comfortable in our house.