A Window Fan Needs A Direction

A window fan is more useful when it has one job. Mine either brings cool air in or pushes warm air out. It should not do both from the same window and hope the room figures it out.

For a Seattle summer night, I put the fan in the bedroom window facing out for 20–30 minutes before bed. A second window on the other side of the room stays open. That pulls the warm air across the room instead of just making a loud breeze near the fan.

During smoke season, I reverse the plan. The fan comes out of the window, the window closes, and the air purifier does the work. I learned this after treating a smoky August evening like an ordinary warm one. The room got cooler and smelled worse.

The useful checklist is small:

• fan facing out when exhausting warm indoor air
• another window cracked open on the opposite side
• fan off and window closed when outdoor air is bad
• filter or grille cleaned before the first hot week

The fan is not an air-quality device. It is a hole in the wall with a motor attached. Direction matters more than speed.