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Window AC units use a fair amount of electricity, but significantly less than central AC systems. Because they are more energy-efficient for cooling individual rooms or small spaces, their usage is comparatively low. On average, a window AC unit consumes between 500 and 1,400 watts, while a central AC system uses over 3,500 watts—meaning a window unit uses about one-third of the energy. This typically translates to a monthly running cost of $15 to $40, although this can vary depending on external factors.

If you have central air conditioning, it’s fine to run your AC all day if that’s what you want—as long as the AC unit is in good condition. But if your AC runs constantly when you don’t want it to, there may be a problem with your system (like the ones we’ve mentioned above). Window AC units and wall air conditioners aren’t as powerful as central AC, so you should only run those kinds of air conditioners for eight to 12 hours at a time.

A blower door test shouldn’t take more than an hour, and most can be completed in less than 30 minutes. Expect the test to take longer once you start searching for leaks with thermal imaging or want to include sealing such leaks in the time estimate. The test doesn’t take much time and can’t be rushed, but it will take longer in large homes or those with many air leaks.