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Ask the Expert: How to Buy a Room or Window Air Conditioner

Room air conditioners with the ENERGY STAR label use about 15% less energy than conventional models, which could mean a savings of about $85 over the lifetime of the unit, on average. Check out this video tutorial for instructions on choosing the right room AC and how to install the unit to maximize your savings.

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Choosing the right window or room air conditioner will help keep your home cool and save energy when the weather heats up. Room ACs that have earned EPA’s ENERGY STAR use at least 10% less energy, costing you less than $70 a year to run. You’ll save even more with improved insulation to prevent costly air leaks.

In this video, we’ll show you how to choose the right A/C unit for your room and what features to look for to save energy and money. 

First, there are a couple of things to consider when buying a room A/C unit: the size of the room that you want to cool and what is typically happening in that room.

Start by measuring your room. Here’s what you’ll need: a tape measurer; a pencil and paper; and a smartphone or computer.

Determine the square footage of the room: measure the length and the width of the room; then multiply the two numbers.

Now, look up the recommended cooling capacity for your room size at Cooling capacity is measured in BTUs per hour.

Once you have that number, you’ll want to make capacity adjustments as necessary. For example: Have a sunny room? Increase your number by 10%; More than three people in the room on a regular basis? Increase capacity by 600 BTUs for each person over three people.

Once you have a total, round down to the nearest thousand—that’s the number you should look for when choosing your unit. Selecting the right capacity is key to savings. Remember, bigger is not always better—an oversized air conditioner will have trouble removing humidity and will have your room feeling damp and clammy.

Ready to head to the store? Here are a couple of other things to think about.

Look for the ENERGY STAR when purchasing your unit. Models that have earned EPA’s ENERGY STAR are independently certified to save energy, come with clearer instructions, and better materials to improve sealing and insulation around the unit. Certified units feature tight-fitting side panels that minimize costly and uncomfortable air leaks.

Some air conditioners offer great new features. ENERGY STAR models with connected functionality give you additional convenience, comfort, and savings with the ability to turn off the unit remotely, schedule temperature changes, and even receive feedback on the energy use of your unit.

Also new this year are ENERGY STAR room air conditioners with an EPA-approved refrigerant called R-32, which has a much lower impact on the climate—two-thirds lower than the refrigerant used in other ACs.

With an ENERGY STAR certified unit, you will be helping the environment by reducing your carbon footprint, all while you stay nice and cool this summer.

Need more info at home or in the store? Find more information on ENERGY STAR certified window air conditioners at