I do not have central air. My apartment has two window AC units — one in the living room, one in the bedroom — and they cost me about $80 extra in electricity every summer month. A window fan costs maybe $2 a month to run. For those mild summer days when it is 78°F outside and you just need air moving, a good window fan is the move.

What to Look For

• Reversible airflow: You want a fan that can pull cool air in at night and push hot air out during the day. Models with two independent fans (one in, one out) are ideal because they create a cross-breeze without opening a second window.
• Thermostat: Sets the fan to turn on and off automatically at certain temperatures. This is the feature that makes it worth spending $50 instead of $20.
• Expandable side panels: Most windows are wider than the fan. Side panels seal the gap so hot air does not leak in around the edges.

The Best Options by Budget

• Best overall ($60-80): Bionaire Twin Reversible Airflow Window Fan. Two independently controlled fans, remote, thermostat. Quiet on low.
• Best budget ($25-35): Holmes Dual Blade Twin Window Fan. Manual controls, no thermostat, but it moves a ton of air and has lasted me three summers.
• Best for quiet operation ($70-90): Vornado Transom Window Fan. Not reversible, but nearly silent and throws air across the room better than any other window fan. Use it to pull cool night air in; take it out during the day.