A fresh breeze is one of the best things about summer, but sometimes you don’t want to have to go outside to get it. Capture it instead with a fan that sits in your window and sucks air into the house rather than just circulating what’s already in there. A window fan should have one airflow setting to pull in outside air and another that spins the blades in reverse, to blow the room air out. For optimum circulation, look for a twin-fan unit (with two small fans instead of just one) that offers an “exchange” setting, which lets one fan blow out while the other blows in.

Best For: Rooms that get hot quickly (such as those with large windows that receive direct sunlight) or where floor or counter space is tight. They’re also great for use in the morning and the evening, when the air outside is cooler than the air inside. At night, window fans can clear out the stale air that makes you toss and turn.

Placement: Usually they’re held in place by the lowered sash of your window (no screws or drilling); they should come with extension panels so they’ll fit into most openings. They can be mounted horizontally or vertically, depending on the direction in which your window opens.

Features to Look For: Twin fans with three airflow settings (air intake, exhaust, and exchange), extension panels, horizontal- and vertical-mount capability, remote control.

RS Pick: Holmes Twin Window Fan, $55, www.sears.com.