How to Keep a Garage Cool in the Summer (2024 Guide)

When you open your garage door on a hot summer day, you know the rush of heat and humidity that greets you. Garages without air conditioning can be 10-15 degrees warmer than the air outside because they trap heat due to poor ventilation and insulation.

This can be a real problem if you use your garage as a living space, workshop, or home gym. Ready to reclaim your space? From installing a portable air conditioner to adding insulation, HVAC.com offers tips on keeping your garage cool and comfy this summer.

Why Do Garages Get So Hot in the Summer?

First, garages usually lack proper ventilation, so heat gets trapped inside which makes the space hot and stuffy. Second, most garages are poorly insulated, causing them to absorb a lot of heat from the sun. These factors create a heat trap, making garages noticeably warmer than the outside air.

Tips for Cooling Down Your Garage

If you’re ready to turn your garage into a livable space this summer, consider the following tips:

1. Install Air Conditioning

Although probably the most expensive option, if you’re serious about keeping your garage cool in the summer, installing an air conditioning system is the way to go. Common AC options for garages include:

• Ductless Mini-Splits. Ductless mini-splits are commonly used in rooms that are difficult to keep cool such as bonus rooms above garages and sunrooms. They are also found in areas of homes that are not connected to the central HVAC system including attics, basements, and garages. A mini-split consists of an outdoor condenser unit and an indoor air handling unit. The indoor and outdoor units are connected through a 3-inch hole, which houses the conduit for refrigerant tubing, power cables, and a condensate drain. Although the most expensive option, mini-splits are energy efficient and provide consistent, powerful cooling to keep an average-sized garage cool throughout the summer. A mini-split is the ideal choice if you plan to spend a lot of time in your garage this summer.
• Portable Air Conditioners. Installing a portable air conditioner is a more affordable option and is recommended if you only use your garage occasionally. While not as powerful as a mini-split, portable ACs are easier to install and can effectively cool smaller garages. Most portable garage air conditioners come with wheels so you can move them around. Keep in mind that these units have an exhaust hose that needs to be vented outside, either through a window or by drilling a hole.
• Window Air Conditioners. Window air conditioners are easy to install and can help maintain a comfortable temperature in smaller garages during hot weather. They cost about $150 to $800, making them an affordable option.

2. Add Insulation

Adding insulation can help slow heat transfer and keep the cool air from your air conditioner inside. Sealing gaps around windows and doors also prevents heat from entering. Together, these steps can create a more stable indoor temperature and improve overall energy efficiency.

3. Park Hot Cars Outside

Driving a car, especially on a hot day, causes the engine, tires, and other components to heat up quickly. Parking a hot car in a garage only intensifies this heat, raising temperatures inside. If you plan to use your garage for work or relaxation, parking your car in the driveway will help keep the garage cooler later on.

4. Open the Garage Door

Even on 90+-degree days, the outside temperature can often fall into the 60s or 70s overnight depending on where you live. Consider opening the garage door – and windows, if applicable – for an hour or so in the morning to let the hot air escape and cool air enter. This is a smart idea whether you have a garage AC or not. Naturally cooling the space will ease the workload on your AC, reducing strain and lowering your energy bills.

5. Improve Ventilation

You can enhance ventilation in your garage by strategically placing box fans to improve airflow. Installing a ceiling fan or exhaust fan can also help circulate air and remove hot air from the garage.

6. Declutter Your Garage

Is your garage full of junk? While garages are often ideal spaces to store belongings, all of that clutter can absorb heat and restrict airflow. Clearing out unnecessary items can create a cooler, more comfortable environment.

7. Install Reflective Window Films or Shades

Adding window films or shades can reduce heat gain through windows. These can be an effective, low-cost solution for garages with windows.