How to Insulate Your Window AC Unit

How to Insulate Your Window AC Unit

When it comes to keeping cool, insulating your window AC unit is key. A well-insulated AC runs more efficiently which keeps you cooler and costs less money to operate. Despite the obvious advantages, many people choose to forgo properly insulating their unit, relying on slapdash solutions. Here at Windmill, we’ve seen examples of insulation that include folded towels, taped-up cardboard, and even a pair of rolled-up socks! While any insulation is better than none, properly insulating your unit makes a world of difference. In this blog we’ll cover how to insulate a window AC unit, how to check the seal around your window AC unit, and how to winterize your unit so it can remain installed throughout the year. Even if your unit is already installed, it’s not too late to improve its insulation. As we like to say, “Better insulate than never!”


Insulating a Window AC

So how do you insulate a window AC unit? The primary purpose of insulation is to restrict airflow such that outside air stays outside, and inside air stays inside. As a reminder, window air conditioner units don’t bring in outside air. Instead, they cool inside air and recirculate it through your home. As a result, leaking outside air allows cool air to escape and warm air to infiltrate, which is what we mean when we say a lack of insulation lowers efficiency.

Insulating your window AC starts with properly installing your unit. Make sure to follow the manufacturer’s instructions. If you are unable to follow the instructions exactly, contact the manufacturer to see if they have recommended workarounds. For example, some windows have metal frames, which can make screwing the unit to the window frame impossible without special tools. We’ve also encountered customers who, as renters, aren’t allowed by their lease to drill holes in their apartment. Address any installation issues as soon as possible, as optimally installing your AC will reduce the amount of area that requires additional insulation.

Once your AC is properly installed, it’s time to check the seal around your window AC unit. This is easy on a breezy day; work your fingers around the edge of your window and feel for air leaking in. If you can detect air leaks, mark their location with a piece of tape. If it isn’t a breezy day, you still might be able to feel air leaks with your fingers. You can also ignite a lighter and move it around the edges of your unit. If the flame flickers, it’s likely due to an air leak. The lighter method isn’t foolproof, but it will give you a good sense of where you might need insulation.

Now that you know where the air leaks are, it’s a matter of installing insulation. One of the best types of insulation is flexible foam because it’s easy to cut to the appropriate size. While most ACs include a roll of black insulation foam to seal gaps around your window, at Windmill, we’ve taken this a step further. Our units come with cosmetic side panels that are made from insulated, weather-proof foam. Other types of effective insulation include fiberglass sheets, rolled fiberglass fabrics, and rigid foam boards. For heavy-duty insulation materials, consider hiring a contractor (check out our partnership with TaskRabbit!) if you want some assistance and to guarantee a well-insulated installation.

Even after your unit is fully installed, it’s a good idea to check for air leaks regularly; once a month will suffice. As weather conditions change—usually related to humidity—your window frame can swell or shrink. So remember to check your insulation regularly to make sure your window is still fully covered. 


Winter Insulation for your Window AC

While some people prefer to uninstall their window air conditioner during the winter, a well-insulated window AC can remain installed year-round. When figuring out how to insulate your window AC unit for winter, be aware of what type of winter weather you can expect. If you live in an area with heavy snowfall or other extreme weather conditions, you might want to go ahead and uninstall your window AC unit. However, if you live somewhere with moderate winters, read on for tips on keeping your AC unit installed.

The first part of how to insulate your window AC unit for winter is to follow our advice in the first section. While air leaks don’t reduce your window unit’s efficiency in the winter, they will allow cold air in, making your heat less efficient. You can find plastic window film covers at your local hardware store. These easy-to-install sheets cover the entire window, reducing drafts and keeping you warmer. They’re not a good insulation method for when your AC is in use, but make great protection for winter.

You can also get a winter cover for your AC unit. At Windmill, we’ve partnered with a local New York artist to produce a series of stylish covers perfectly tailored to your Windmill AC unit. A winter cover insulates the vents on the back of the unit, protecting them from winter condensation and blocking out drafts from creeping into your home. Many winter covers are reusable and easy to clean, making them an eco-friendly type of winter insulation.


Wrapping Up Wrapping Up

How to insulate your window AC unit is a straightforward question with a wide variety of answers. But that doesn’t diminish how important insulation can be. Remember, a well-insulated AC unit will save you money and keep you cooler during the summer. Winter insulation is equally important for keeping your home warm, and with proper insulation, you can probably keep your window AC unit installed year-round. If you need any additional help, we’ve partnered nationally with TaskRabbit to get you in touch with installation pros. And if you have any questions about your AC or its insulation, our support staff is available to provide you with advice and answers. Just make sure to install actual insulation, and skip on the rolled-up socks!