Measure Air Conditioner Efficiency and Calculate HP for an Air Conditioning Unit

The efficiency of an air conditioner is a measurement of how much energy is being converted to cool air compared to how much energy is being used to run the unit. If an air conditioner takes a lot of electricity to run and is converting very little to cool air, you have a very inefficient unit. You can find out the specific efficiency of your air conditioner by performing a few calculations.

How to Measure Air Conditioner Efficiency

Find out how many British thermal units BTUs per hour your air conditioner is putting out. This information is listed in a wide variety of places, including in the original documentation that came with the unit as well as on the box it came in for window or in-wall units. This information may also be accessible from your air conditioners attached thermostat, depending on the age of the unit.

Find out how many watts of electricity your air conditioner uses. This information will also likely be listed in the original documentation, and may be listed on an on-board control screen depending on the age of the unit. If you have access to a power meter one that youve purchased, borrowed or rented, you can also plug your air conditioners power cable into the power meter to find this information.

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Divide the total number of BTUs per hour that your air conditioner is outputting by the total number of watts your air conditioner is using. The number you are left with is your air conditioners energy efficiency rating. The higher the rating, the more efficient with its energy your air conditioner is.

How to Calculate HP for an Air Conditioning Unit

But though the two units generally indicate different operations, they both translate into rates of energy transfer. You can therefore specify an air conditioners output in horsepower. Multiply the air conditioners size in tons by 12,000 to convert its cooling capacity to British Thermal Units per hour.

If the air conditioner has a 1. 5 ton capacity 1. 5 x 12,000 = 18,000 BTUs per hour.

Divide this answer by 3. 412 to convert it to watts 18,000 / 3. 412 = 5,275 watts.

Divide the wattage by 745. 7 to convert it to horsepower 5,275 / 745. 7 = about 7 horsepower.

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Air conditioners and motor vehicles both transfer energy. Air conditioners move heat, and technicians describe their cooling capacities in terms of tons or BTUs. Motor vehicles perform mechanical work, and technicians describe their strength in terms of horsepower.

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