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How Much Energy Does A Fan Use?
Fans are a great way to save energy since they allow you to set your thermostat higher in the summer and still feel comfortable. How much energy fans use depends on the size of the motor, pitch of the blades and what speed is selected. Savegreenly recently tested the power use of fans, air purifiers and humidifiers and found a big difference in how many watts they each drew.
Testing A Box Fan's Energy Use
The first fan we tested, shown above, was a common box fan which sells at discount stores for around $30. This model is made by Galaxy. We hooked the Kill a Watt power meter up to the fan and measured 103 watts of energy use on the high setting. On the medium setting the fan used 77 watts and on low power use of the fan was 56 watts. Overall that's not unreasonable, considering how much air the fan moved. If the fan was used in a living room and it allowed a family to turn up the AC thermostat a few degrees, or even turn off the air conditioning system entirely, it would be a worthwhile use of energy. It should be noted that fans do not cool the room, they only cool people. They work by evaporating perspiration from our skin and only if we are in the room are they worth running. You should always turn a fan off when leaving a room for more than a few minutes. It is a fallacy that things like fans and lights use more energy to start up than could be saved by turning them off.
Galaxy Box Fan Energy Consumption Test Results: 105 watts on high, 77 watts on medium, 56 watts on low.
Testing A Compact Table Top Fan's Energy Consumption
Small fans may be used on a bedside table to keep you comfortable at night, again allowing you to raise the thermostat in summer a few degrees. Small fan energy consumption is not nearly as much as larger box fans, although they don't move as much air and aren't practical for large rooms.
We tested a smaller countertop fan made by Massey, shown above.
Results: This small fan drew 28 watts of power on high, 25 watts on medium and 20 watts on low.
Power Use Of Window Fans
I use several window fans to draw in outside air during the springtime. They are a great way to delay when you have to start using your air conditioner in hot climates. Some window fans are reversible, allowing you to draw hot air out of upstairs windows and some, such as the model shown above, made by Holmes, feature a thermostat which turns the fan on when temperatures reach a certain level. We tested the amount of energy used by this window fan in the off, high, medium and low settings.
Results: This window fan drew 61 watts on high, 52 watts on medium and 48 watts on low. In the off position it drew two watts for the thermostat circuit.
These fans offer a good amount of air flow for the wattage used.
What Does It Cost To Run A Fan?
The cost to run a small box fan depends on how many watts it uses and how often it is used. As an example let's use the Galaxy fan seen above, running on the medium setting for ten hours a day. If we figure that our energy costs are ten cents per kilowatt (your cost may be different), and that the fan uses 77 watts of energy on medium, we can do the calculation as follows. 10 hours x 77 watts = 770 watt hours or .77 Kwh. At a cost of ten cents per Kwh your daily cost to run a fan would be 7.7 cents a day. That's a pretty good value as energy use goes.
How Much Energy Do Ceiling Fans Use?
Ceiling fan energy is is a bit harder to test since you can't plug them into a power use meter. Going by manufacturer labeling and information posted on the websites of ceiling fan manufacturers such as Hunter, you'll find that ceiling fan energy use in watts ranges from around sixty watts (high) to over two hundred watts for some models. Before buying any ceiling fan make sure it bears the Energy Star label. You want a ceiling fan to move enough air to be practical, so try to balance power consumption and cubic feet of air moved per minute.