Window fan

Window fans have been used for many decades to maintain comfortable temperatures and ventilation within one's home, and operate at a tiny fraction of the cost of central air conditioning.

[1] Most window fans have two or three speeds, and some are electrically reversible so that the user can switch between intake and exhaust modes.

Manufacturers have added features to their models over the years.

Some fans contain thermostats which will turn the fan off if the temperature drops to a certain point, or adjustable grilles to direct the flow of air in a particular direction.

Other fans offer sophisticated electronic features such as a remote control, automatic shut-off timers, and dimmer-like variable-speed motor controls.