Common Questions about Window Air Conditioners

by Paul Sanders
Published May 27, 2010 | Updated August 5, 2015

A great way to beat the heat is by installing a window air conditioner in your home or office. Using individual air conditioners and heaters in your home can take the load off of your central heating and air conditioning system, providing you with significant energy savings over the course of a year. Here are some frequently asked questions about window air conditioners and how you can use them in your home.

Window Air Conditioners:

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• Will window air conditioners work in any window?

  Window air conditioners are built to fit multiple window types, including those that open vertically or horizontally. Many window air conditioners include adjustable panels, which help them expand to fit and seal most window openings. Be sure to measure your window and compare it to the air conditioner dimensions.

• What is a "SEER" rating?

  The SEER rating is a rating of window air conditioner efficiency. The higher the SEER rating, the more BTUs of cooling power your window air conditioner creates for every watt of power. SEER ratings are calculated by dividing the number of BTUs by the watts used per hour.

• How much energy does a window air conditioner use?

  To calculate your window air conditioner's energy use, divide the BTUs by the SEER rating. This gives you the watts per hour. Divide that by 1,000 to get kilowatt hours (kWh), which is probably how your electric company calculates your energy bill. You can then multiply the kWh by your power company rate to learn your costs per hour. For example, a 12,000 BTU air conditioner with a SEER rating of 10 and a cost of 25 cents per kWh would calculate as follows:

  12,000 BTUs / SEER 10 = 1,200 W = 1.2 kWh

  1.2 kWh x $0.25 = $0.30 per hour to run your window air conditioner.

  At 8 hours a day for 125 days of summer, your window air conditioner will have an annual running cost of $300 a year.

• How often should I clean the air filter?

  Usually, window air conditioners need new filters every three months. If you live in an area with a lot of dust or pollen, you may want to replace it more frequently. Clogged air filters can impair the performance of your window air conditioner and increase your energy costs.