If you have a garage with no windows, you already know it can be uniquely challenging to keep it cool during the hot months of the year. Windows provide valuable natural light and opportunities for cross-ventilation, but not every garage is blessed with one. This is especially true in condominiums and row homes, where your garage might be wedged in between other buildings. This setup in a hot climate can cause temperatures to skyrocket on a sunny day as hot air gets trapped with no place to escape.
How Much Cool Air Do You Need?
Before you run out to buy an air conditioning system for your garage, consider just how much time you spend in the space and how cold you need it to get. If you only use your garage for deep storage and rarely venture out there — or if it really is a home for your garage that you merely pass through for a minute or two each day — you might only need a temporary or portable system to make it bearable once in a while.
On the other hand, if your two- or three-car garage also hosts your hobby station, workshop, potting bench or other work space where you spend a lot of time, you’ll want to look into a more permanent way to keep hot air at bay. If you use your garage to store valuables that are sensitive to temperature and/or humidity, you’ll also want to invest in a more comprehensive garage air conditioning system.
Cooling a Garage With No Ventilation: Portable Options
Open the Garage Door
Depending on the angle of the sun and how well-insulated your garage is, opening the door will provide a big breath of fresh air. If your garage door is on the north side of the building, you’ll be letting in air that’s been shaded all day, so it’s likely to be cooler than the stuffy air in the garage, especially if your garage isn’t insulated and acts like a hot box. If you have a standard entry door for humans instead of vehicles, be sure to open that up too to encourage cross-ventilation.
Add Powerful Portable Fans
Try a Dehumidifier
Lowering the humidity in your garage will help make it more comfortable, as high humidity traps heat and makes it feel hotter than it actually is. It’s also a crucial component of climate control if you want to store sensitive items without worrying about mildew, rust and other moisture-related issues. A dehumidifier will remove moisture and make your garage more comfortable, but it won’t blow out cold air like an AC unit. For this reason, it’s a good idea to combine a dehumidifier with fans or other cooling options outlined below for best results.
Build a Low-Tech Swamp Cooler
Buy a Portable Air Conditioner
Cooling a Garage With No Windows: Permanent Solutions
Install a Garage Ceiling Fan
Adapt a Window AC Unit for the Wall
Install a Mini Split Air Conditioner
Install Attic Vents
Heat rises, but you can help the worst of it escape through your garage attic by installing vents on the gable ends of the house. This is likely the highest point, and you’ll help heat escape as it rises. The airflow your create will help ventilate the space and cool your garage with passive convection as cool air moves from the floor upward and forces the hot air out.
One of the most likely causes of an overheated garage is a lack of insulation. Insulation isn’t just for keeping heat in over the winter — it also keeps heat from the sun out in the summer. If your garage is uninsulated, consider retrofitting the walls with blown-in cellulose insulation if your walls are finished on the inside, or with batt insulation if the studs are visible. Adding attic insulation and garage door insulation will also work wonders to keep your garage cool. This energy-saving job will make any cooling solution more efficient and effective.
Consider the Color
If you’re up for a new look, the color of your garage can make a difference when it comes to how much heat your garage absorbs during the day. A light or white roof will reflect the sun’s rays and keep your garage cooler than black or charcoal gray shingles, so it’s worth switching the color if you need to replace the roof anytime soon. Likewise, a light garage door and exterior siding will also help cool things down.
The perfect garage cooling solution for your home will depend on your budget and the ways you use your garage. If you choose to use an air conditioning unit to cool your windowless garages, be sure to measure your total area in square feet to correctly size your permanent or portable air conditioning units. No matter what methods you choose, a cool, comfortable garage is within reach.