Ventilation cost guide
How much does a window fan cost to run all night?
Fans usually draw far less power than compressor-based cooling. Enter the wattage printed on the fan and the number of hours you expect to use it.
Appliance energy cost
Use the power label on your appliance and the electricity rate shown on your bill.
Formula: watts ÷ 1,000 × hours per day × days × electricity rate. Cycling appliances and variable-speed equipment can use less than their full rated power.
What changes the answer?
Fan speed changes power draw
The nameplate may show maximum watts. Low and medium settings can use less, so measure the speed you actually use when you need a closer estimate.
A fan cools people and exchanges air
It does not remove heat the way an air conditioner does. The best savings occur when outdoor air is cooler and drier than indoor air.
Pair nighttime ventilation with daytime shade
Exhausting warm air after sunset and limiting solar gain during the day can reduce the hours when compressor cooling is needed.
Use this result as a planning range
Do not use a window fan where rain, poor outdoor air quality or an unsecured opening creates a safety problem.
Review the formulas and public sources in our methodology.