Window fans are great to capture outside fresh air and breezes. They are particularly useful in hot and moderate climates with cool evenings or cool night air.
Window fans, as their name suggests, are mounted in windows, and - contrary to common circulation fans, that is, ceiling fans and small fans… - they do not cool by moving inside home air; they cool by bringing in outside cool air and by exhausting inside stale air.
Window Fan Prices And Customer Reviews
Lasko, Holmes or Bionnaire have high-rated window-fan models, and their online prices are mostly in the range $40-$70. See for customer reviews and online prices at Amazon.com: Window Fans.
Windows fans and insects
Window fans are especially designed to fit into windows; they can have expandable side panels to cover the entire window opening, and most of them have either one or two small-sized fans (mounted side by side, with 2 or 3 speeds). One problem with window fans is that some models only fit in windows by removing the screen first. Make sure that you choose a fan able to effectively deal with this issue.
Ventilation Strategies With Window Fans
You can use window-fans to create cross ventilation, that is, to force cool outside air into the house through windward windows while inside air is exhausted to the outdoor at the opposite side of the house, using other fans and/or windows or openings.
The simplest strategy uses a fan on the windward side of the house, while the inside air is pushed out through windows or openings on the opposite corner of the house.
A less simple strategy involves more than one fan: a fan (or two…) blowing inward (in the coolest side of the house) and one (or more) blowing outward, in the opposite side… The capacity of the fans blowing inward should match the capacity of those blowing outward.
When operating with more than a window fan, pay attention to the prevailing breeze direction and its intensity: in some cases you may not need to use the fans...
In multi-story houses, try to increase air circulation by using fans at opposite ends of the second story, while keeping windows opened on the first story. Hot air will tend to rise toward the second storey, and will be exhausted with the help of the window-fans in that second story.
Reversible Window Fans
Strategies like the ones mentioned above make reversible window-fans a good choice. With reversible fans you can change from 1) getting fresh outside air to 2) exhaust inside air, with a flip of a switch. That is: if the wind direction changes and your strategy involves cross ventilation, you can use the window-fan to either pull air into the house or to push it out... depending on which direction the wind is blowing.
Some new window fans have two sets of blades running independently, one to pull fresh air and the other to exhaust stale air. Choose according to the patterns of the wind in your area, and your needs and cooling strategies.