When you need space to work on home improvement projects or exercise, there's nothing like a good, large garage space. But with garages, heat is always an issue you're going to have to be aware of, especially in warmer summer months. Garages are known to trap heat and become unusable without adequate cooling in place.
So if you can only handle a few minutes in your garage before you have to return to the comfort of your home. There are several solutions to help drop temperatures there. .
This practical guide will discuss the benefits of each cooling solution to keep your garage cool.
Why Garages Get So Hot
Garages reach uncomfortable temperatures in the summer. After a few minutes, it becomes unbearable and forces you to find a cooler place to lounge. Excess heat is caused by several factors.
What Causes Extreme Conditions in Garages
- Poor Insulation: Most garage doors are not insulated, allowing extreme heat from outside to transfer quickly inside.
- Lack of Airflow: Without vents, windows, or fans, hot air trapped near the ceiling has no way to escape.
- Heat from Concrete and Roofing: Heat is generated by solar radiation, which then gets absorbed by concrete and roofing materials and is re-radiated back into the enclosed garage space.
- Sun Exposure and Orientation: Garages facing west, or those with dark-colored doors, absorb, conduct, and trap more solar heat.
Quick Ways to Cool a Garage (Fast Improvements)
Whether you own an attached or detached garage, there are several ways to fix your cooling issues.
- Open Doors Strategically: For security purposes, leaving your doors and windows open might seem risky. If done correctly, you can crack the main garage door 3 to 4 inches to let air circulate without creating a security risk.
- Use Cross-Ventilation: Use fans to move air. Set up a box fan blowing out of a window to push hot air out, creating a vacuum that pulls cooler air in, or use a high-powered shop fan.
- Add Reflective Window Coverings: Reflective window coverings, including film, will effectively block infrared rays and significantly reduce total solar energy.
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Avoid Peak Heat Usage: Close any blinds or curtains to block the sun and reduce heat during peak hours, which is typically 10 a.m. until 4 p.m. or early evening. Or, avoid using the garage during these peak hours to reduce the risk of overheating.
Best Garage Cooling Solutions (Compared)
Cooling a garage effectively requires the right combination of airflow, insulation, and the correct cooling system. For most users, a properly sized portable AC or evaporative cooler offers the best balance of performance and cost.
Are you tired of working on your car in a hot garage with no AC? Compare these cooling solutions to help make your decision easier.
Portable Air Conditioners (Best Overall Solution)
- Most effective for enclosed garages
- Works in humid climates
- Requires venting
Evaporative Coolers (Best for Dry Climates)
- Energy efficient
- Works best in low humidity
- Requires airflow
Fans and Air Circulators
- Improves airflow but doesn’t lower the temperature significantly
- Best when paired with other solutions
Mini Splits (Permanent Solution)
- Most powerful option
- Higher upfront cost
- Ideal for finished garages
How to Choose the Best AC for Your Garage
Explore the Sylvane AC Buying Guide to help choose the right AC system for your garage. The type of garage is a major contributor to the quality of air in this space.
Factors to Consider
Garage Size and BTU Requirements: The cooling capacity your garage needs is determined by the size of the space. Here’s a BTU guide to help you choose:
BTU Estimates by Garage Size
| Garage Type |
Average Size |
Recommended BTUs |
| 1-Car Garage | 240 sq. ft. | 10,000 – 12,000 BTU |
| 2-Car Garage | 480 sq. ft. | 14,000 – 18,000 BTU |
| 3-Car Garage | 720 sq. ft. | 24,000+ BTU |
- Insulated vs Non-Insulated Garages: Insulated garages require fewer BTUs than non-insulated garages. A ductless mini-split is best for insulated garages, and high-capacity portable ACs are best for non-insulated garages.
- Ceiling Height Considerations: Garage ceiling heights exceeding 8–10 feet require a 10 to 30 percent increase in AC capacity (BTUs) to account for increased air volume and heat stratification.
- Ventilation Requirements: Installing exhaust fans or roof vents will help expel trapped air. Portable ACs require proper ventilation to the outside to avoid wall damage.
Improve Garage Insulation for Better Cooling
Stop Wasting Money on AC
- Insulating Garage Doors: Prevent the transfer of heat by installing rigid foam boards or utilizing reflective kits.
- Sealing Air Leaks: Apply a rubber gasket to the bottom of your garage door, silicone caulk around window frames, and spray foam or caulk to seal any gaps.
- Wall and Ceiling Insulation: Air sealing with spray foam is a great way to insulate garage ceilings. Fiberglass batts are ideal for walls. Insulation is a multiplier for cooling efficiency. Make the most of your space by insulating the walls, ceiling, and garage door.
Ventilation Strategies That Actually Work
Reduce the Risk of Moisture
- Exhaust Fans: Remove hot air, moisture, and hazardous fumes to improve air quality.
- Intake Vents: Provide fresh air to replace hot, polluted air.
- Cross-Breeze Setups: Create a pathway for air to enter and exit a space.
How to Keep Your Garage Cool Long-Term
Maintain Long-Term Comfort
- Combine Cooling Methods: Multiple cooling solutions can work together to actively cool your garage. Pair insulation with ventilation and a cooling solution to achieve ideal temperatures.
- Maintain Equipment: Replace and repair your system, insulation, and ventilation as suggested to ensure your comfort.
- Monitor Humidity Levels: Use a digital hygrometer to monitor garage humidity. Proper monitoring will prevent mold growth.
Common Mistakes When Cooling a Garage
Using fans alone in extreme heat isn’t an effective way to keep your garage cool. If you choose to use a fan, it’s best to combine it with another cooling solution. The wrong-size AC unit won’t be able to cool your entire garage. Ignoring ventilation will create severe health and safety risks, including dangerous mold growth. Not sealing the space will allow air to flow out and raise your bill over time.
Best Products for Cooling a Garage
- Portable Air Conditioners: A flexible, low installation cooling device.
- Evaporative Coolers: Energy-efficient cooling devices that use water evaporation to lower the temperature.
- High-Powered Fans: Heavy-duty fans have long runtimes in spaces like garages.
FAQs About Cooling a Garage
What is the best AC for a garage?
The best air conditioners for a garage are ductless mini-split systems for high-efficiency, permanent cooling, and portable units for budget-friendly, temporary cooling.
Can you use a portable AC in a garage?
Yes, portable air conditioners are ideal for garages because they provide flexible, targeted cooling right where you need it without requiring permanent installation. You just need a way to vent the exhaust hose through a window, door, or wall to send the hot air outside.
How many BTUs do I need for my garage air conditioner?
For a garage, you generally need 30 to 45 BTUs per square foot. Take a look at our BTU guide above.
Do fans actually cool a garage?
No, they do not cool garages significantly. When paired with other solutions, fans can help reduce the temperature.
Is a mini split worth it for a garage?
Whether a mini-split is "worth it" depends on your plans for the garage. If you use the space daily as a workshop, gym, or office, it is often the best long-term investment due to its efficiency and year-round climate control.
