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. Fortunately, there are several ways to cool a garage with no windows, from DIY evaporative coolers to a full air conditioner installation. No matter what your budget, you can keep that garage cool, whether you’re dealing with dry heat in Arizona or the humid climate of Florida or East Texas.
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
For an inexpensive cooling option, you can combine one or more of these ideas to get cool air into your garage whenever you need it. This might be all you need during the shoulder seasons, and many are quite eco-friendly choices.
1. 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.
2. Add Powerful Portable Fans
Improving garage ventilation will help draw cooler air in and push the hot air out. A stiff breeze also makes your skin feel cooler, so consider adding an industrial-strength floor fan to your cooling arsenal. This will work best if you set it up near the open door and point it into your garage to draw cooler air from the outside. If you have a smaller side door, try pointing the fan to blow out of this door to draw cool air in from the garage door. Depending on the size of your garage, you may want more than one floor fan.
3. 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.
4. Build a Low-Tech Swamp Cooler
Harness the power of evaporation to cool your garage by bringing in some ice. The simplest “swamp cooler” is just a bucket of ice with a fan blowing across it to give a boost to the cool air your circulate around the room. If you’re handy, you can also build your own cooling system by cutting a small hole or two into the sides of a 5-gallon bucket, then cutting a larger hole in the lid to insert a fan. Fill the bottom of the bucket with ice and turn on the fan to force cold air out the holes for an inexpensive garage air conditioner to take the edge off of the hottest days.
5. Buy a Portable Air Conditioner
A portable A/C unit is a great solution for a room with no windows, since it stands on its own and can cool a medium to large space with ease. You will have to vent your portable unit, though, and this can be a challenge without a window. Most portable air conditioning systems come with a hose and adaptor to vent to the outdoors — this looks like a dryer vent hose. You can vent the system through either the door or the wall, which will require cutting a small hole and fitting the parts into place.
Cooling a Garage With No Windows: Permanent Solutions
If you plan to spend a lot of time in your garage — and want to actually enjoy yourself while you’re out there — you may need to make more permanent changes to your garage and its infrastructure.
6. Install a Garage Ceiling Fan
A high-powered fan that you mount to the garage ceiling will allow you to add a breeze every time you enter your garage. Choose an industrial-strength fan instead of a residential version to get the most power and to make sure the blades stand up to sawdust and other debris you may create in your workspace.
7. Adapt a Window AC Unit for the Wall
In a windowless garage, you can still use a traditional window unit — but you’ll have to cut a hole in the wall so you can install it. This job requires that you know your way around a reciprocating saw and that you can frame the opening to install an air conditioning unit with a slide-out chassis for stability and proper exhaust ventilation. If you can handle the work, it’s an inexpensive way to cool a smaller garage.
8. Install a Mini Split Air Conditioner
Mini split units are designed to be installed in the wall, and they require no ductwork since the ventilation system goes right through the wall to the outside. They function like a central air unit with an outdoor compressor but don’t take up any room in your yard, since the whole unit is contained in the wall apparatus. These units can be pricey and are best installed by a pro, but they’re one of the most convenient garage air conditioning solutions around if you can afford it.
9. 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.
10. Add Insulation
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.
11. 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.