Ultimate Guide To Garage AC: Cool & Improve Your Garage’s Ventilation
A cool garage can help make life easier, making garage AC something many think about. However, there are so many types of garage AC out there, and the price range can be wide.
In this post, we prepared an ultimate guide to help you understand more about garage AC.
Learn why a garage AC is different from home ones, its features, and how to choose one that suits your garaging needs. Let’s go.
Why Install Garage Air Conditioners?
Many people may think installing air conditioners for their garage is a silly idea.
But before you also join the bandwagon and dismiss the idea, there are many reasons having a garage AC to cool down your garage makes sense.
Your Garage Isn’t Just for Cars Anymore
Garages aren’t just parking spots. These days, they also double as:
- home gyms,
- workshops, and even
- game rooms.
But try to do all that in your garage, without air conditioning? Brutal.
A garage AC keeps your space cool and comfortable, turning it into a functional extension of your home.
Heat Ruins Everything Inside
Your tools, paint cans, etc. All suffer in extreme temperatures.
Heat causes wood to warp, metal to rust, and electronics to die an early death. Not to mention turning it into a warm space for bugs, snakes, roaches and unwanted guests.
Installing the right air conditioning unit protects your stuff and keeps garage air at a safe temperature.
It Makes Working in the Garage Bearable
Ever tried fixing a car or building something while sweating like you’re in a boxing match? Miserable.
A ductless mini-split system or a portable AC unit transforms your garage into a workspace where you won’t overheat.
The right AC options can keep your garage cool and comfortable, even when it’s scorching outside.
Extreme Heat Can Damage Your Car
Think your car is safe just because it’s parked inside? Think again.
A closed garage without proper ventilation can turn into a heat trap, causing battery damage and premature tire wear.
A garage air conditioner helps regulate the garage temperature, preventing unnecessary wear and tear on your vehicle.
It Stops Heat from Spreading into Your Home
A sweltering garage can significantly impact the rest of your house. If your garage shares a wall with your living space, that hot air seeps in, making your HVAC system work harder.
Installing a mini-split system or a through-the-wall air conditioning unit helps keep the garage temperature in check and prevents heat from sneaking inside.
Types of Garage AC Units
There are many types of garage AC types in the market, each with their own strengths and weaknesses.
Here’s a breakdown of them, their features, and what they’ll cost you.
Ductless Mini-Split System
A ductless mini-split is one of the best ways to keep your garage cool. It has an indoor unit mounted on the wall and an outdoor condenser that disperses hot air.
This type of AC provides powerful cooling and heating, making it usable all year round. It is highly energy-efficient with precise temperature control.
Unlike traditional AC units, it runs quietly without a noisy compressor inside the garage.
Having a ductless mini-split AC may set you back by roughly $800 to $3,500, including installation.
This air conditioning unit is perfect for garages without existing ductwork. If you want a long-term cooling system, this is your best bet.
Window Air Conditioner
A window AC unit is a simple and effective way to cool your garage. Just pop it into a suitable window, and you’re good to go.
This unit is budget-friendly and easy to install. It works best for smaller garages, providing quick cooling. Some models also offer heating options, making it a versatile choice.
One of the more cost effective options, window air conditioners costs around $200 to $800.
If your garage door stays closed most of the time, a window air conditioner keeps garage air at a comfortable level without breaking the bank.
Portable Air Conditioner
A portable unit is a quick, flexible cooling option. It doesn’t require a window mount—you just need a ventilation hose to push hot air outside.
It is easy to move around, requires no permanent installation, and works well for garage environments with no windows.
Price range for getting a portable AC can be wide, with lower end models starting from as low as $250. Better ones may cost up to $700.
A portable air conditioner is perfect for short-term cooling. Just be aware that it can take up valuable garage space.
Through-the-Wall Air Conditioner
If your garage doesn’t have a suitable window, a through-the-wall air conditioner is a great alternative. It functions like a window AC but is installed permanently into the garage wall.
This type of AC is more powerful than window AC units and saves window space for garage ventilation. It is also more energy-efficient than portable units.
Setting these AC up will take a bit of work, making the price range higher, around $500 to $1,500.
A through-the-wall air conditioner is an excellent investment if you need long-term cooling without taking up floor space.
Ceiling-Mounted Air Conditioners
A ceiling-mounted AC unit is a sleek and space-saving cooling system that keeps garage air comfortable. It works well for larger garages or workspaces.
This system doesn’t take up wall or floor space, distributes cool air evenly throughout the garage, and is ideal for garage use with limited room.
Setting a ceiling-mounted garage AC will cost a bit, since there will be serious installation work required. Expect to shell out around $1,000 – $4,000 to have one installed at your garage.
If your garage doubles as a workspace, this is a high-end solution that delivers proper air circulation without clutter.
Heavy-Duty Fan Air Conditioners
A heavy-duty fan air conditioner combines powerful fans with cooling elements to handle extreme garage temperatures.
This system is ideal for garages where traditional AC units might struggle due to excessive heat buildup.
These units provide high airflow, pushing out hot air while introducing cooler air. They work well in garages without insulation or where ventilation is an issue.
Heavy duty garage AC costs between $300 – $1,200.
This is a great option for those who need garage air conditioning without committing to a ducted system.
Exhaust Fan Air Conditioners
An exhaust fan air conditioner works by pulling warm air out of the garage while drawing in fresh, cool air from outside.
It improves air quality and reduces humidity, making the garage more comfortable.
This type of AC is low-cost and energy-efficient, helping to ventilate a garage while maintaining airflow. It works well for garages without existing ductwork that suffer from stagnant air.
One of the most affordable garage AC options, exhaust fan air conditioners costs between $100 – $500.
This option is best for garages where air circulation is a problem, especially in larger garages with limited ventilation.
Evaporative Air Conditioners (Swamp Coolers)
An evaporative air conditioner, also called a swamp cooler, uses water evaporation to cool the air. It is an excellent alternative to traditional AC units in dry climates.
It consumes far less electricity than standard air conditioning units, making it an eco-friendly option. It also adds moisture to garage air, preventing dryness that can affect tools and equipment.
This type of AC works best in garages without high humidity. If you live in a humid area, it may not be as effective as a mini-split system or window AC unit.
This is a great solution for those in hot, dry climates who need an affordable way to cool a garage. It is also a more affordable option here, costing between $100 to $600.
What Features To Look Into When Shopping For Garage AC?
Getting a garage AC is not as simple as going into a store and picking up one. Some thoughts need to be put in, specifically to look into the features, and decide if they are suitable for your garage.
Here are seven key features you need to consider when choosing the right air conditioning system for your garage.
Cooling Capacity (BTU Rating)
Size matters when it comes to cooling. If the garage air conditioner is too weak, it won’t cool a garage effectively. If it’s too powerful, it wastes energy.
The British Thermal Unit (BTU) rating tells you how much cooling power an AC unit has.
A small garage (150–250 sq. ft.) needs around 6,000–8,000 BTUs. A larger garage (400–600 sq. ft.) requires 12,000–18,000 BTUs.
If your garage doubles as a workshop or gym, you’ll need even more power.
A ductless mini-split system offers high BTU output with excellent efficiency. A portable air conditioner is great for smaller spaces but may struggle with extreme heat.
Ventilation and Airflow
Garages trap hot air, especially with a closed garage door. A good air conditioning unit needs proper ventilation to push warm air out and bring in cooler air.
A window air conditioner or through-the-wall air conditioner needs a suitable window or wall cutout. A portable AC unit requires a hose to vent outside.
If you have garages without existing ductwork, a ductless mini-split is a great option because it requires only a small hole for refrigerant lines.
Poor air circulation leads to hot spots, making one corner of the garage freezing and the other an oven.
A ceiling-mounted air conditioner distributes cool air evenly, preventing this problem.
Dual Heating and Cooling
A freezing garage in the winter is just as bad as a scorching one in the summer. If you spend a lot of time in the garage, consider a unit that can cool and heat.
A ductless mini-split system or through-the-wall air conditioner with heat functionality keeps the garage temperature comfortable year-round.
A portable unit with a heat pump is another option but isn’t as effective in extreme cold.
If your garage is used as a workshop, gym, or home office, heating and air conditioning in one unit is a game-changer.
Air Quality and Humidity Control
Garages are dust magnets. They trap warm air, fumes from chemicals, and sometimes moisture.
A good garage air conditioning system should improve air quality and control humidity.
A portable air conditioner with a built-in dehumidifier helps keep the garage comfortable in humid climates.
A ductless indoor unit with an air filtration system removes dust and allergens.
If your garage has poor ventilation, pairing your AC system with an exhaust fan air conditioner can prevent air from becoming stale.
Noise Level
Nobody wants an air conditioner that sounds like a jet engine taking off. Noise levels are measured in decibels (dB). Anything over 60 dB can be disruptive.
A ductless mini-split AC runs as quietly as 25–40 dB, making it the quietest option. A window AC unit or portable AC unit is noisier, especially at full blast.
If you need a comfortable garage for long hours of work, choose an air conditioning unit with low noise levels.
Installation and Maintenance
Some AC units need professional installation, while others are plug-and-play. A window AC unit is easy to install but requires a suitable window.
A portable unit only needs an exhaust hose but takes up garage space.
A ductless mini-split system requires professional installation but is low maintenance. A through-the-wall air conditioner is more permanent but offers powerful cooling.
Consider how much work you’re willing to do before deciding on an AC system for your garage.
How Big Air Conditioner and BTUs Do I Need for a Garage?
All ductless air condition units are capable of cooling only a certain amount of space depending on the design and capacity of the device. Also, the unit lasts longer when it does not have to work at full power all the time. Sizing the air conditioner right is essential to have enough cooling capacity.
Air conditioners and heaters are rated by BTUs (British Thermal Unit) that describe how much heat can be removed from or added into a closed space.
When determining the needed cooling capacity for the garage, you first need to know the size of the garage. Let’s say you have a typical two-car garage around 20 x 20 feet. Calculating the area comes to a total of 400 square feet. Then we multiply the 400 sq. ft by 25 BTUs which provides adequate cooling for most climates, whether it is hot, sunny, humid, or moist, rainy day. So the total comes 400 x 25 = 10,000 BTU cooling capacity needed. Or 400 x 30 = 12,000 BTU cooling capacity needed.
EPA recommends an energy-saving factor of 20 BTUs per sq. ft for living spaces. Other sources say the factor should be 30 BTUs per sq. ft, especially in scorching areas. So 25 BTU is a good compromise. Consider your region and garage insulation level and if the garage is in the shade or sun all day. Often garages don’t have very much insulation, and you need to oversize the air conditioner somewhat. So a factor of 30 can also be used. It’s usually enough when you are in the “ballpark” for the size of the unit.
Calculation Variables
- If the garage is mainly shaded all day, reduce capacity by 10%
- If the garage is in direct sun most of the day, increase capacity by 10%
- Add 2,000 – 4,000 BTUs if the garage is uninsulated
When deciding between larger or smaller capacity units, go with a slightly bigger capacity unit. This is because smaller capacity BTU units will run continuously without cooling the area effectively trying to keep up. Increasing the electric costs and shortening the unit’s lifetime.
Also, don’t choose something that is overkill. Air conditioning units remove moisture/humidity from the air. If the unit does not run long enough (too big unit cycling on and off), the moisture will be left in the air, making you feel like being outside camping on a damp, misty and cool night.
So getting the optimal size air conditioning unit is important. Calculate the BTUs needed and get a proper size unit. This article has the best units available for different-sized spaces for your convenience.
Here is a convenient chart for you. Remember this is not exact science and “ballpark” figure is usually enough.
| Square Feet | BTUs (x25) | BTUs (x30) |
|---|---|---|
| 200 | 5000 | 6000 |
| 250 | 6250 | 7500 |
| 300 | 7500 | 9000 |
| 350 | 8750 | 10500 |
| 400 | 10000 | 12000 |
| 450 | 11250 | 13500 |
| 500 | 12500 | 15000 |
| 550 | 12500 | 16500 |
| 600 | 15000 | 18000 |
| 650 | 16250 | 19500 |
| 700 | 17500 | 21000 |
| 750 | 18750 | 22500 |
| 800 | 20000 | 24000 |
| 850 | 21250 | 25500 |
| 900 | 22500 | 27000 |
| 950 | 23750 | 28500 |
| 1000 | 25000 | 30000 |
| 1100 | 27500 | 33000 |
| 1200 | 30000 | 36000 |
| 1300 | 32500 | 39000 |
| 1400 | 35000 | 42000 |
| 1500 | 37500 | 45000 |
You can also use calculators online. Such as:
Energy Efficiency (EER and SEER Ratings)
An inefficient air conditioning unit will drain your wallet faster than the summer heat drains your energy.
Look for high Energy Efficiency Ratio (EER) and Seasonal Energy Efficiency Ratio (SEER) ratings.
A ductless mini-split AC typically has a SEER rating above 20, making it highly efficient. A window AC unit has a lower rating but is still a good choice for smaller garages.
If your garage space sees a lot of use, invest in an energy-efficient system to keep the electric bill manageable.
EER – Is the Energy Efficiency Ratio of an air conditioner or heat pump. It measures how efficiently the unit uses electricity to remove heat from the space. EER rating is used for all types of air conditioners. The rating should be listed on the energy label in the unit or the owner’s guide. A higher rating means a more efficient unit that uses less electricity.
SEER – Is the Seasonal Energy Efficiency Ratio. SEER measures how efficiently the unit performs over an entire cooling season. It’s not as precise as EER and can be inaccurate or misleading depending on the climate.
https://en.wikipedia.org/wiki/Seasonal_energy_efficiency_ratio
CEER – Is the Combined Energy Efficiency Rating. This tells how much energy the unit uses when idle and when operating.
Higher the number, the more efficient the unit is. The number does not tell how much it will cost to operate the system. A system with a SEER of 25 is more efficient than a system with a SEER of 15. Generally, SEER-25 units cost less to operate than SEER-15 devices in the same climate conditions.
When comparing different products, keep in mind that the EER, SEER, and CEER measure different things. Only compare EER to EER, SEER to SEER or CEER to CEER.
Energy Guide – To help you figure out whether an appliance is energy efficient, the federal government requires most appliances to display the bright yellow and black EnergyGuide label. Although these labels will not show you which appliance is the most efficient on the market, they will show you the annual energy consumption and operating cost for each appliance so you can compare them yourself. (source https://www.energy.gov/energysaver/shopping-appliances )
Energy Star Label – The ENERGY STAR logo is on all qualified products that meet specific standards for energy efficiency. ENERGY STAR-qualified products exceed the federal minimum standards for efficiency and quality — sometimes significantly. Look for the label on appliances, electronics, water heaters, windows, and other products that consume energy in your home. (source https://www.energy.gov/energysaver/shopping-appliances )
How to Read the EnergyGuide Label
The EnergyGuide label is required to be placed on all appliances by the manufacturers. The label provides information about energy consumption and shows you how much energy an appliance uses compared with similar models. Remember that the numbers are averages: actual costs will differ somewhat depending on how you use them. The label shows the following:
- Maker, model number, and size of the appliance.
- Estimated yearly operating cost (based on the national average cost of electricity) and the range of operating costs for similar models.
- The ENERGY STAR® logo indicates that this model meets strict criteria for energy efficiency.
- Estimated yearly electricity consumption.
- Key features of the appliance and the similar models that make up the cost comparison range.
- Source https://www.energy.gov/energysaver/shopping-appliances
Increasing the Air Conditioner Efficiency in the Garage
Insulating the garage helps keep the heat in during winters and keep the cool air inside the garage during summers. So even very basic insulation in various parts of the garage helps you considerably lower the total energy costs and add value to the property. Here are key areas to consider.
Walls – Insulating all the walls around the garage is optimal, but if you are on the budget, start with the walls that get the most sunlight during the day. The wall shared with the house is already insulated in the attached garages.
Ceiling – If your garage is hot, the attic or room above it will be sweltering. Hot air rises upward, and adding insulation to the ceiling prevents this. The air conditioning unit does not have to run at max trying to keep up with air loss, keeping your garage and above spaces cooler.
Garage Door – Garage doors are usually made from metal and absorb surprisingly much heat during the day. Adding insulation to the door or replacing the door with an insulated model will reduce the temperature considerably. Check the weather seals also around and bottom of the door. There are DIY kits available for insulating the door. With many garages, this can be enough with cooling. Lowering the total temperature.
Windows – Garages usually have one or two windows or no windows. The heat coming in from small windows is not much, but it adds to the total in other areas. So covering the windows with sun-blocking/reflecting materials like curtains, shades, or windows film will help keep the garage cooler.
Read all about garage insulation here.
Garage Air Conditioner and Cooler Running Costs
Total running costs boil down to the price of electricity in your area. Also, how many hours per day do you use the AC. Reducing the total hours reduces the annual cost, and purchasing a unit with a high energy efficiency rating (EER, SEER, CEER) will save money in the long run.
The average cost of running an air conditioner is between $0.05 and $0.90 per hour.
This is only a very rough estimation, and there are some pretty good calculators available online such as:
- https://energyusecalculator.com/electricity_airconditioner.htm
- https://www.perchenergy.com/energy-calculators/cost-to-run-air-conditioner
How To Choose The Right Air Conditioning For My Garage?
Not all garages are the same. Some are small and sealed tight, while others are large, drafty, and full of tools.
Some have garage doors that stay shut all day, while others let in constant warm air from outside.
Finding the right air conditioning system depends on your space, budget, and cooling needs. Follow this step-by-step guide to select the best AC unit for your garage.
Step 1: Measure Your Garage Size
Bigger garages need more cooling power. A small portable air conditioner won’t cut it in a larger garage that’s baking in the summer sun.
Measure the garage space in square feet. Multiply the length by the width to get an accurate size. This number will help determine the British Thermal Unit (BTU) rating needed to cool your garage efficiently.
- Up to 250 sq. ft. → 6,000 – 8,000 BTUs
- 250 – 400 sq. ft. → 8,000 – 12,000 BTUs
- 400 – 600 sq. ft. → 12,000 – 18,000 BTUs
- 600+ sq. ft. → 18,000+ BTUs
If your garage is poorly insulated or has lots of hot air leaks, go for the higher BTU range.
Step 2: Identify Ventilation Options
A garage without proper ventilation turns into a heat trap. The right air conditioning system needs a way to push hot air out and bring in cooler air.
Check if your garage has:
- A window → Perfect for a window air conditioner or portable AC unit
- A wall that can be modified → Great for a through-the-wall air conditioner
- No windows but open space outside → Ideal for a ductless mini-split system
- Poor airflow? → Consider an exhaust fan air conditioner to improve air circulation
If your garage doubles as a workshop, gym, or storage space, adding garage ventilation like an exhaust system can keep your garage cool and comfortable.
Step 3: Choose Your Air Conditioner Type
Now that you know your garage size and ventilation options, pick the best air conditioning unit for your needs.
- Ductless Mini-Split AC → Best for large garages, low noise, and long-term cooling.
- Window Air Conditioner → Great for garages with a suitable window, easy to install.
- Portable AC Unit → Ideal for temporary cooling, but takes up floor space.
- Through-the-Wall AC → Permanent installation, powerful cooling, but requires wall modification.
- Ceiling-Mounted Air Conditioner → Perfect for garages without space for a floor or wall unit.
- Evaporative (Swamp) Cooler → Works best in dry climates, adds humidity to garage air.
- Exhaust Fan Air Conditioner → Improves air circulation, best for hot and humid garages.
If you want an AC system that can cool and heat your garage, go for a ductless mini-split AC or a window unit with heating features.
Step 4: Consider Energy Efficiency
A powerful AC unit that drains your wallet every month is not the answer. Look for models with:
- high EER (Energy Efficiency Ratio) or
- SEER (Seasonal Energy Efficiency Ratio) ratings.
A ductless mini-split system is the most energy-efficient option, often with SEER ratings above 20.
A portable air conditioner or window unit may be cheaper upfront but cost more in electricity bills.
If you spend a lot of time in the garage, investing in an energy-efficient air conditioning unit will save money in the long run.
Step 5: Check Noise Levels
Nobody wants an air conditioning system that sounds like a jet engine. Some garage AC units are louder than others.
- Ductless Mini-Split → Quietest option (25–40 dB)
- Ceiling-Mounted AC → Low noise, ideal for workspaces
- Window Air Conditioner → Medium noise level, depends on model
- Portable AC Unit → Louder due to built-in compressors
- Heavy-Duty Fan AC → Noisy but effective for airflow improvement
If you use your garage as a workspace, gym, or recording area, choose a low-noise air conditioner.
Step 6: Factor in Installation and Maintenance
Not all garage air conditioners are easy to install. Some require professional help, while others just plug in and go.
- Easy installation → Portable AC units, window air conditioners, evaporative coolers
- Moderate installation → Through-the-wall air conditioners, ceiling-mounted AC
- Professional installation → Ductless mini-split AC, HVAC extensions
A garage air conditioning system that requires less maintenance is a smarter choice.
Ductless mini-split AC units need filter cleaning but are low-maintenance compared to portable units, which need regular drainage and venting.
Step 7: Stick to Your Budget
Buying a garage air conditioner is an investment. Some models cost more upfront but save money over time.
- Portable AC Unit → $250 – $700
- Window Air Conditioner → $200 – $800
- Through-the-Wall AC → $500 – $1,500
- Ductless Mini-Split AC → $800 – $3,500 (installation included)
- Ceiling-Mounted Air Conditioner → $1,000 – $4,000
- Exhaust Fan Air Conditioner → $100 – $500
- Evaporative (Swamp) Cooler → $100 – $600
Do understand the price range here are estimates, and may change by the time you read this.
If you plan to use your garage year-round, spend extra on a ductless mini-split AC for better cooling and heating.
If you just need occasional cooling, a window unit or portable AC unit will work.
Transform Your Garage Space With Garage Air Conditioning
Picking the right air conditioning system depends on your garage size, how often you use it, and your budget. If you want long-term cooling, go for a ductless mini-split AC.
If you need a quick fix, a window AC unit or portable air conditioner will work.
Want to keep your garage cool and comfortable? Get a garage AC that suits your needs. Your tools, car, and sanity will thank you.
Warning about Using the Home Central Air Conditioning
Never use your house’s central air conditioning system to cool the garage! Some people have attempted to add ductwork from the central AC to the garage, but this is a terrible idea and prohibited by law. Also, if something happens, the insurance won’t cover anything.
If you use the home central AC, you put enormous strain on the system, and they are not designed for such loads and will break down. Also, the garage can have dangerous fumes that can enter your home via ductwork. Carbon monoxide from the vehicle exhaust can be deadly.
- Using an entirely separate system for the garage space is the safest and most energy-efficient solution.
- LINK to building America solutions center for more info on why never use your home air conditioning.
