Do you want to learn how much electricity bathroom fans use over a year?
Bathroom fan electricity use is determined by the wattage—and most fans are in the 10-50 watts range.
In this guide, I will go over...
- How to calculate the annual cost of a bathroom fan
- How Energy Star certifies highly efficient bathroom fans
Let's get started with this guide!
The energy use of bathroom exhaust fans is measured in watts. The wattage of an appliance is a measure of the total flow of electricity. A higher watt bathroom fan means that it uses more electricity and will cost more to use.
In general, bathroom exhaust fan wattage can range anywhere from a low of 10-watts and to a high of 100-watts. If the bathroom fan has a heater however, the total wattage can exceed 1400-watts.
Homeowners should keep in mind that bathroom fans aren't meant to be used continuously 24-hours a day. It is important to turn exhaust fans off when not in use, but they should be on for at least 20-minutes after a shower in order to remove all of the moisture.
Bath exhaust fans can be controlled with countdown timers, humidity sensors, and even motion sensors so that they will automatically turn on or off—saving energy.
How To Determine Bathroom Fan Electricity Cost?
If you would like to know the annual cost if your bathroom fan is run continuously for a whole year, it is a simple calculation.
The first step is to determine the wattage of your bathroom fan at its maximum speed or CFM. You can also add the max wattage if it has a heater or other extra features.
Once you have determined the maximum wattage, you will need to divide this number by 1000 in order to turn watts into kilo-watts (kW).
1. Bathroom Fan Wattage / 1000 = kilo-watts (kW)
If the bathroom fan is 50-watts, then the kWh will be 0.050-kWh.
Once you have the kilo-watts figure, you will need to multiply this number by your cost per kilo-watt-hour in your local area. The national average price of electricity per kilo-watt-hour is about ten cents or $0.10 kWh.
2. Bathroom Fan Kilo-Watts (kW) X $0.10-kWh = Bathroom Fan kWh Cost
So multiplying 0.050-kWh by $0.10-kWh will give you $0.005-kWh.
And there are 8760 hours in a whole year, so 8760-hours multiplied by $0.005-kWh gives you $43.80 annual cost.
3. Bathroom Fan kWh Cost X 8760 Hours = Annual Cost
Again, keep in mind that this is for the continuous 24/7 use of a bathroom fan, which is almost never done. For a more realistic number, you can estimate the number of hours per day the bathroom fan will run, and multiply it by 365 days.
Read Also: How To Fix A Noisy Bathroom Fan?
What Is The Electricity Use Of Popular Bathroom Fans?
Here is a table of the cost of some of the most popular bathroom exhaust fans on the market...
110-CFM & Heater
Broan Very Quiet
BV Ultra Quiet
How Bathroom Fans Get Energy Star Certified?
Energy Star is a program run by the U.S. EPA that certifies household appliances as energy efficient. For a bathroom exhaust fan to be given an Energy Star rating, it has to meet certain minimum requirements.
The main factor for Energy Star ratings is that a bathroom fan needs to have a base 'efficacy' rating which is the number of CFM per watt. The efficacy is basically a power consumption or efficiency rating. You can read my full guide on choosing the right CFM for your bath fan here.
To get this rating, you simply take the CFM of the bathroom fan and divide it by the maximum wattage. The higher the efficacy number, then the more efficient is the bathroom fan.
Minimum Efficacy For Energy Star Ratings
For bathroom fans in the 10-89 CFM range, the bathroom fan will need to have an efficacy rating of 1.4 (1.4-cfm per watt).
For bathroom fans in the 90-500 CFM range, the bathroom fan will need an efficacy of at least 2.8 (2.8-cfm per watt).
Read Also: What Are The Best Bathroom Fan Switches?
The basics of determining the electricity usage of a bathroom fan is to first determine the wattage.
If your bathroom fan has multiple CFM settings or extra features like a heater, you want to pick the maximum wattage. Once you have the max watts, you need to divide this by 1000 in order to convert it to kilo-watts. And having the kilo-watts number, you can multiply this by your local cost of kilo-watt-hours.
The national average kWh is about $0.10.
And after this multiplication, you can multiply the cost of kWh times the number of hours in a whole year which is 8760 to get your final annual cost estimate.
Read Also: How To Remove Bathroom Exhaust Fans?