BTU Ratings for Air Conditioners

What Is a BTU?

• A BTU is a unit of measure for cooling equipment. It is based on a scientific measurement of heating and cooling. One BTU is the total amount of energy required to create a one-degree-Fahrenheit increase in the temperature of a single pound of water. Since the amount of energy needed to boil water changes with elevation, this measurement refers to water at sea level. This is just a unit of measurement for temperature; it is not an electrical unit of measure. However, BTUs can be transferred into joules and kilowatt hours using a mathematical equation: one BTU equals 1,055.05 joules.

How Does it Affect Your Air Conditioner?

• A BTU rating gives you a starting point for comparing different air conditioner units. If one unit has a BTU rating of 1000 and another has a BTU rating of 2000, it is safe to assume the second unit produces more cooling power. This unit has double the cooling capacity of the first unit. This is not to say that only the unit with the higher BTU rating is the right one for your home.

How Many BTUs Do I Need?

• Even though one unit has double the BTUs of another, it may not be right for your home. BTU units are meant to guide installers and consumers toward the right machine for the job. The right way to approach BTU units is to select a machine rated for the size of the area you want to cool. This applies both to room air conditioners and central air conditioners that cool an entire house. Buying an air conditioner with more BTUs than necessary may cost more down the road.

Room Size and BTU Selection

• There are charts that show how many BTU units an air conditioner needs in order to cool a certain area. In other words, how many BTUs are needed to cool so many square feet. For instance, a chart may begin with 100 to 150 square feet, which requires an air conditioner with 5,000 BTU. This is a common rating among many single-room air conditioners. Additionally, a chart may indicate that 24,000 BTUs are necessary to cool a home with 1,000 to 1,400 square feet. To accurately select the right air conditioner, you should measure the size of the area and select a unit with enough BTU power to cool the area.