How to Keep Your Garage Cool in Summer? 15 Helpful Tips For Keeping Your Garage Cool

Updated January 10th, 2024

You would like to use your garage for a home gym or workshop but it’s too hot in the summer. You need to cool down your hot garage a bit so it becomes a comfortable place to spend time. There are several things you can do to your existing garage to cool it down a bit. Let us take a look at how to keep your garage cool in summer.

How to keep your garage cool in summer

There are several things you can do to help keep your garage from getting hot to begin with. Lets look at some of the things you can do to help keep the heat out of your garage.

1 – Use powertools outside of your garage

Powertools generate heat when they are being used. The more you use them, the more they will heat up the air inside of your garage. Open up the garage door and take your work outside if it’s not too hot out there. Let your tools cool off before bringing them back into the garage for storage. Battery chargers and most electronic devices generate heat when they are running.

2 – Let your car cool off before pulling it into the garage

Your car has a lot of built up heat after it’s been driving around for awhile. The engine block and other metal parts can store and radiate a lot of heat energy. They will radiate heat off for an hour or so after the engine stops. If you want your garage to stay cool inside, let your car sit outside and cool off when you get home.

3 – Open the garage door and use a garage fan

If you want to exercise or work on a project inside your garage, opening the garage door can help. If it’s bright and hot outside and you want to take advantage of the shade in your garage, open the door. Use some fans to blow the hot air out.

4 – Use your garage in the morning and evening

It is less hot out in the morning and evening when the sun isn’t at it’s highest. Your garage will be less hot in the morning and evening. If can help to do your garage workout or project during these times there is cooler air temperatures. This will help you avoid overheating in your garage.

5 – Reduce clutter in your garage

Filling your garage space with clutter and junk will block the airflow. This reduction in air circulation will help heat build up inside of your garage. Your fans or air conditioning will not work as well. Keep your garage as open as you can to make it easy to cool.

6 – Replace incandescent bulbs with LEDs

LED lightbulbs generage much less heat than Incandescent bulbs. They use much less electricity as well. Replace all the lights in your garage with LEDs. LED bulbs can interfere with garage door openers. If you have incandescent bulbs in your garage door light and you would like to use LEDs you still can. There are special LED bulbs that do not interfere with your garage door opener.

7 – Insulate your garage walls and garage door

Before you consider installing a garage air conditioner you should install insulation. Insulating the walls and garage door will help keep your cold air inside the garage. Use fiberglass batt insulation and use some kind of finishing such as drywall on the inside. This makes a much better looking finished garage look then exposed fiberglass insulation in between studs.

After insulating the walls, you need an insulated garage door. You can install a garage door insulation kit. These use reflective radiant barrier which is installed on each door panel. Use reflective film on the windows. You can easily make an insulated door in a few hours that will go a long ways towards making your garage more comfortable.

Don’t forget attic insulation when you are insulating your garage. See our article on garage ceiling insulation to learn more.

Check all the windows and doors for air leaks and use caulking to seal them. Remember to check your garage door gasket for air sealing. Does it seal against the garage floor or have large gaps you can see daylight through?

8 – Improve your garage ventilation

Your garage will be cooler if you keep the air circulating so you don’t trap heat inside. Ventilation fans are needed to move hot air and humidity out of your garage. A ceiling fan can help move the air around inside your garage. An exhaust fan can help move the warm air generated in your garage out.

Make sure the attic above your garage has proper vents. You don’t want to trap the heated air in the garage ceiling. If you don’t have a few attic vents you should install them. An attic fan can help hot air circulate out of your garage too.

9 – Use lighter colors for garage doors and roofing

Using a lighter shade of color for your garage will help keep it from building up heat inside. It is easy to repaint the garage door lighter colors. If you are replacing your roof and siding, consider using lighter colors if your garage is too hot now.

10 – Plant trees to shade your garage

Planting a large tree that will shade your garage will help keep the sun from heating it up. If you have space, plant some trees on the south facing side of your garage to shade it from the sun. For more information on what kind of trees to grow for shade see this article on the fastest growing shade trees.

11 – Use a dehumidifier in your garage

If you are in a very humid area a dehumidifier can help keep your garage cooler. Hooking up a dehumidifier will take the moisture out of the air and make your garage feel less humid and swampy. You will need either a drain for the accumulated water or remember to drain the collection bucket.

12 – DIY Swamp cooler with a fan and bucket of ice

On the opposite end of the spectrum, if you are in a very dry hot area, you can make a swamp cooler to help cool your garage. A swamp cooler involves taking a bucket of cold water (the colder the better) and blowing a fan across the top of it to function as an evaporative cooler. This will cool and add humidity to the air as it passes over the bucket. Using ice in the water will make it more effective. Don’t use a freezer in your garage to make the ice. The heat given off by your freezer while it’s running will be more than you will cool with your DIY swamp cooler.

The video below shows how to make your own swamp cooler for your garage.

13 – Install air conditioning

If you want your garage to be temperature controlled all the time then you need air conditioning. Air conditioning won’t do much good without proper insulation. All the cool air you are making will pass right through your uninsulated walls. Address garage insulation and ventilation first.

If you have an attached garage you may be able to tap into your home AC unit if there is ducting nearby a garage wall. For most houses, this is not the case. If you have a detached garage you won’t be able to use your home heating and coolinng either.

Even if you can tap into your home heating and cooling system, it may not be the best idea. Most AC systems have return ducting to take air back to the air conditioner/furnace. The air in your garage may have car exhaust and other fumes which you don’t want to circulate around your home.

If you have windows you can install a window air conditioning unit or a portable air conditioner that can vent out the garage window. I personally have never had any luck with a window air conditioner. They have all died or lost their refrigerant after 1 or 2 summers.

The best solution to air conditioning your garage is a ductless air conditioner. You don’t need ducting in your home or windows to use this. They make use of a condenser that gets mounted outside with air handler inside. You can install more than one air handler inside if you have a large garage or certain areas you want more cooling. It can also heat your garage in the winter. See our article on how to keep your garage warmer to learn more.

Zero Breeze makes an excellent small air conditioner that can run off AC or battery power. It is perfect for cooling small spaces. It is very easy to install compared to a Split Unit or even a window unit.

ZERO BREEZE Mark 2 A/C

View at ZERO BREEZE

14 – How much cooling power do I need to keep my garage cool?

To determine the size air conditioner you need for your garage you can use the 30 BTU per square foot rule. For every square foot of garage space you have, you need 30 BTUs. If you have a 400 square foot garage (typical 2 car garage) you need 12000 BTU’s to cool it on a 100 degree day. Look here for a nice calculator for sizing the air conditioner in your home or garage.

15 – What temperature should I keep my garage at?

You want to keep the garage temperature above the dew point but low enough to be comfortable. The dew point is the temperature where the air has 100% humidity and condensation will form if you go any lower. The dew point is about 40F for inland areas and 65F for humid coastal areas. You should not cool your garage below those temperatures. For storing a car, the ideal temperature is 70F with humidity between 40% to 50%. To learn more about the ideal conditions for car storage go here.

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