Just like water heaters, air conditioners and washers and dryers, hot tubs use electricity to function.
To calculate the amount of electricity your hot tub uses, you’ll have to take a few factors into account, such as:
- The amount of money you pay per kilowatt-hour (kWh).
- The temperature of the air around your hot tub.
- The temperature you want your hot tub water to be.
- The size of your hot tub.
There are also a handful of things you can do to reduce your hot tub’s energy consumption, such as:
- Improving your hot tub’s insulation.
- Leaving your hot tub on continuously if you use it multiple times per week.
- Turning your hot tub off between uses if you use it one time per week or less.
Let’s take a closer look at how much energy a hot tub uses and how you can make yours more energy efficient.
How to Calculate Your Hot Tub’s Electricity Usage
As we mentioned above, to calculate the amount of electricity your hot tub uses, you’ll need to know:
- The temperature of the air around your hot tub.
- The temperature you want your hot tub water to be.
- The size of your hot tub.
Let’s go over some basic thermodynamics to get you started.
It takes 8.33 British thermal units (BTUs) to heat one gallon of water by 1℉. To find out how many BTUs it will take to heat your hot tub, simple multiply 8.33 by the number of degrees Fahrenheit the water will be heated, and then multiply that number by the gallons of water in your hot tub.
For example, if you have a 400-gallon hot tub and need to heat its water from 65℉ to 100℉ (a difference of 35 degrees), it will take 116,620 BTUs to do so.
Since 116,620 BTUs is equivalent to 34.18 kWh, that means it will take 34.18 kWh to heat your 400-gallon hot tub from 65℉ to 100℉.
You can use that number of kWh to quickly find out how much that electricity usage will cost you, too.
If you pay 12.95 cents per kWh (the national average cost per kWh, according to the U.S. Energy Administration), that means it will cost you $4.43 to heat your 400-gallon hot tub from 65℉ to 100℉.
How to Make Your Hot Tub More Energy Efficient
To make your hot tub more energy efficient (and reduce your electric bill as a result), one of the best things you can do is improve your hot tub’s insulation.
There are a number of tools you can use to do so, including:
- A hot tub cover: A thick, high-quality hot tub cover can go a long way toward preventing heat from escaping. Plus, keeping the cover on while your hot tub heats up will cut down on the amount of time it takes for the water to reach your desired temperature.
- Full insulation: When shopping for a hot tub, be sure to keep each hot tub’s insulation in mind. All hot tubs have either full or partial insulation, and full insulation will help your hot tub use less electricity, especially if you live in a cold climate.
- Thermal blankets: By floating on the surface of your hot tub’s water, thermal blankets keep heat from being released from the water’s surface, even if you’re using the hot tub.
In addition to improving your hot tub’s insulation, you can also save energy by purchasing an energy efficient pump and blowers or using solar power.
Finally, remember to run your hot tub based on your own personal usage.
If you use your hot tub multiple times per week, it will likely be less expensive for you to keep it on all the time. On the other hand, if you use your hot tub one time per week or less, you’ll probably be better off shutting the hot tub off between uses.
It’s unavoidable that hot tubs will consume a certain level of energy, just like every other type of appliance.
However, with the right knowledge, you can not only calculate exactly how much electricity your hot tub uses but also make it more energy efficient in the long-run.
