If you’re searching for a new AC unit to install in your home, you may notice the BTU acronym on the packaging. It represents a basic unit of measurement that indicates how much energy the air conditioner uses when removing heat from a home. While air conditioners with higher BTU measurements often have better performance than the alternatives, buying an air conditioner with a high BTU isn’t always the right move. Before purchasing your next AC system, you might want to learn about BTUs and what they stand for.

What Are BTUs?

BTU is an acronym for British thermal unit. It’s a unit that measures an air conditioner’s thermal energy. A single BTU is the total energy required to increase a pound of water by one degrees Fahrenheit at sea level. When BTU is used with air conditioners, it describes the number of BTUs per hour that the unit can remove or add to the air.

Importance of BTUs

It’s easier to know how BTUs work by first learning about air conditioners and how they work. An air conditioner removes heat from indoor air before moving it outside. These systems are comprised of a series of fans and coils that can replace a home’s hot air with much cooler air that enters the home through ductwork.

When an air conditioner removes heat from the home, it means that the system is moving energy. The BTU measurement indicates the amount of energy that your air conditioner uses up when moving heat. If an air conditioner comes with 10,000 BTUs, this reading means that the unit absorbs 10,000 BTUs of heat every hour when it’s on.

Converting BTU to Kilowatts

If you want to determine how much electricity the AC unit will use to cool your home’s indoor air, it’s best to convert the BTU measurement into kilowatts. The kilowatt reading identifies the amount of energy that an appliance requires to operate. BTUs must be multiplied by the number of kilowatt hours in one BTU. A single kilowatt hour tells you the amount of energy that your appliance will use up in one hour. One BTU is equal to 0.000293 kilowatts.

When taking a 10,000 BTU AC unit into account, the kilowatt reading will be calculated as 0.000293 x 10,000 BTU = 2.93 kW. One kilowatt is the same as 1,000 watts, which means that 10,000 BTUs are equal to 2,930 watts.

To find out how much you’ll pay in energy costs while your air conditioner is running, let’s say that the unit is turned on for five hours per day. You will calculate this as five hours x 2.93 kW = 14.65 kilowatt hours every day. If this is the average daily reading, the unit will use 439.5 kilowatt hours of energy every month.

You then can multiply the kilowatt hours by your local electricity rate. If this rate is $0.13, you will multiply 0.13 x 439.5 kilowatt hours, which equals $57.14 in energy costs per month. By making these calculations, you can figure out how much the air conditioner will cost to run monthly.

Considering Higher BTUs

The number of BTUs that are ideal for your home depends on the size of your indoor space. Air conditioners typically require 20 BTUs for every square foot of space. Even if you’re just purchasing a smaller unit that’s meant to cool a single room, the 20 BTU figure still applies. Multiply the square footage in your home or room by 20 to determine the number of BTUs your air conditioner should accommodate.

If you purchase an AC unit that has BTU readings that are much higher than your home requires, your energy costs might increase. If the unit comes with more power than your space needs, it could be inefficient, which would waste energy.

When an air conditioner doesn’t have enough BTUs, it’s likely that the unit will be unable to keep your space cool. In this scenario, the air conditioner would need to run constantly to reach your preferred indoor temperature. Over time, your energy bills will likely increase.

Number of BTUs You Need

When using the 20 BTU reading mentioned previously, a 2,000 square foot home would require a 40,000 BTU air conditioner. However, a 30,000 BTU unit might provide sufficient cooling for the same area. With these guidelines in mind, you can figure out the BTU range that your next air conditioner must have to do its job effectively while saving you money on energy costs. Keep in mind that 5,000-7,000 BTUs are the lowest that you can find with a stationary AC unit. The ideal BTU per square footage is:

  • 5,000 BTU: 100-150 square feet
  • 8,000 BTU: 300-350 square feet
  • 10,000 BTU: 400-450 square feet
  • 23,000 BTU: 1,200-1,400 square feet
  • 30,000 BTU: 1,500-2,000 square feet

Additional Factors to Consider

Even though the square footage in your home should be enough to figure out what your AC unit’s BTU should be, there are several more variables that play a role in BTUs.

Availability of Shade

If you want to install an air conditioner on the second story of your home because it’s warmer than the first floor, you may need to add around 10% to the total BTUs. The same is true if your home receives an ample amount of direct sunlight during the day. When ambient heat gets into the environment in your home, more cooling power is necessary.

If your home receives a lot of shade and not much sunlight, you could lower the recommended BTU by around 10%. However, not having enough BTUs is worse than having too many.

Add BTUs

If three or more people will be in the home at a given time, around 600 additional BTUs are required per person. When the air conditioner is being used to cool your kitchen, around 3,000-4,000 BTUs should be added to the ideal cooling power because of the amount of heat that’s generated by numerous appliances in a small space.

Closed or Open Space

You should also consider if your space is closed or open. Square footage recommendations are often based on relatively confined spaces. If the room you want to cool opens to another room without a door between the two areas, combine these spaces when making your calculations.

Are you thinking of upgrading your air conditioner? If so, our team at Apollo Plumbing, Heating & Air Conditioning can help. Before work starts, we’ll look at the installation site to determine what needs to be done. We’ll also remove your old AC unit to make way for the new one.

Our team has the skills necessary to install central air conditioners, ductless mini-splits, and all other types of AC units. We can repair air conditioners as well. Some of the other services you can obtain for your Troutdale, OR home include leak detection, drain cleaning, heating repair and installation, and indoor air quality services. Contact us today if you have any questions or would like to request service.

Meet the Author
Brandon Bird
Brandon Bird

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