Garage Air Conditioners: How To Cool Garage In Summer

Garages can be:

  • Icy cold in the winter.
  • Hot as hell in the summer.

Most garages are an appendix to our home, as well as to our heating/air conditioning system. They have, on average, poorly insulated which causes higher temperature spikes.

How to cool a garage?

If you spend a lot of your time in the garage and don’t like sweating all the time, you could use a garage air conditioner.

Garage air conditioners have several functions, apart from cooling yourself:

  • Stuff we usually keep in the garage – paint, mechanic tools, glues – don’t handle heat all that well. The recommended maximum temperature for garage items might be lower than the current temperature of your garage. Keeping a cool garage will help prolong the lifespan of garage items.
  • Paint and gas are volatile, and even more so in high garage temperatures. Volatile organic compounds (VOCs) can evaporate a lot easier (and create an awful smell, be a detriment to your health) at higher temperatures. The best garage air conditioners can drive the temperature down and keep the VOCs in check.
  • Keep your car safe. It doesn’t matter if you have a 1-car, 2-car, 3-car, or 4-car garage. Keeping your car at extremely high temperatures for longer periods of time can speed up the rusting and can slowly damage the paint, and other essential car elements.
Your garage tools withstand the long-term high temperatures much better than paint or cars. Or your sweating body, of course.

Pretty much every garage in the US gets super hot in the summer.

Does that mean that all 2-car, 3-car, 4-car garages need an AC unit for the garage?

Not necessarily. There are millions of people who don’t have a garage air conditioner. That doesn’t mean having a cool garage is not a good idea; it just means that people have not upgraded their garages or just don’t use the garage all that much to justify the investment.

Before you go ahead and buy the first air conditioner for the garage you see (further on you’ll find recommendations for the best garage air conditioners), let’s look if you even need a garage air conditioner. Maybe you don’t even need one.

We will also establish what you have to check in your garage before buying a garage air conditioner.

Do You Even Need An Air Conditioner In Your Garage?

Just because you have a garage, it doesn’t necessarily mean you need an air conditioner. Whether or not you should buy a garage air conditioner depends on some obvious factors:

  1. How hot does your garage get? Garages in Houston are, on average, hotter than those in Chicago. Some air conditioning systems can include the garage already, others do not. Is your garage exposed to the direct sun? If you constantly have 100°F in your garage every summer day, you absolutely need a garage AC unit.
  2. How much time do you spend in the garage? If the garage is ‘just a place where I park my car’, you probably don’t need an AC in there. If you use the garage as your day-to-day workspace, DIY project headquarters, or just a place where you can get some beers with the guys, an air conditioner wouldn’t be a bad idea.
  3. How long do high summer temperatures persist? If you live in Chicago and have short summers, a garage AC unit might be useful but not essential. If you live in Texas with a 3-5 month long summer, you better get an AC before your sweat your brains out.
  4. BONUS: AC for garage gym. Some people might use the garage as the perfect workout space. But it can get scorching hot in there. Buying an air conditioner for the garage gym is always a good idea.

You really have to ask these questions in order not to buy a garage air conditioner unnecessarily. That would be a waste of time and money.

If you decided that it might be useful to cool your garage in the summer, we have prepared a shortlist of air conditioner types that are best for garage cooling.

Before we look at those, however, let’s make sure that our garage is actually prepared for an air conditioner. We’ll look at how to prevent cool air from leaving the garage, how to properly vent a garage air conditioner, and how many BTUs you need for 2-car, 3-car, 4-car garages:

Checking For Holes And Insulating Your Garage Before Installing An AC Unit

Even installing the best garage air conditioner will be of no use, if the garage is “leaking” air. We don’t have that problem with standard room air conditioners. Garages, however, tend to have quite a lot of holes.

The air leakage can happen via the garage door, uninsulated walls, and even a hole in the window.

Before you buy and turn on an AC unit, make sure that your garage is airtight. Any bigger hole will render the air conditioner useless because the cold conditioned air will leak through that hole, and will be readily replaced by hot 100°F air.

Preparing a seal for a hole in the garage’s wall.

If you find a hole, use a simple garage insulation kit to block the potential cold air leakage.

Obviously, you will require at least one hole, however:

Properly Venting Hot Air Out Of The Garage

Every AC unit, including the one in your garage, has to be properly vented. Venting is just letting the hot air out, and there is no way around that.

For proper venting, you need an opening in your garage. Window venting is most commonly used but for that, you do need a garage window. The exhaust hose is simply installed through the window with a specialized window seal kit that envelops the exhaust hose and covers the window, preventing cool air leakage.

Garage windows are the most convenient places (apart from a hole in the wall) to vent a garage air conditioner.

Of course, everybody who doesn’t have a garage window immediately asks this question:

“How do I use an air conditioner for a garage with no windows?”

Here’s what you can do: Use an opening in the garage door to vent the air conditioner. You’ll have to insulate all the openings that are created when the garage doors are opened. The best choice is to create a hole in the wall yourself – especially useful for garage mini-split AC units – and vent the air conditioner directly through the wall.

Here’s what you can’t do: Use an evaporative cooler for the garage. It’s the that these units don’t need to be vented, and there is a good explanation for that. Evaporative coolers or ‘swamp coolers’ are not air conditioners at all; they do not decrease the garage temperature, they have 0 BTU of cooling effect, and if put in an insulated space like a garage, they will rather increase the temperature instead of lowering it.

In short, a window, garage door opening, or drilling hole in the wall are the only 3 options.

How Many BTUs To Cool A Garage?

The No. 1 thing you need to know when buying a new unit is how many BTUs should a garage air conditioner have. If you buy one that’s too big, you’ll unnecessarily waste energy and money. On the other hand, if you’ll put 8,000 BTU unit in a 4-car garage, it won’t cool the garage adequately.

Big garage, big BTUs. Small garage, small BTUs. This is simple enough.

However, you need to at least have a rough estimate for what capacity AC would be best for your garage. EPA usually recommends an energy-saving 20 BTUs per sq ft of living space; a good rule of thumb for sizing air conditioners.

For picking garage air conditioner capacity, it’s better to use the ’30 BTUs per sq ft’ rule. This is due to insulation differences, sun exposure, and higher garage ceilings. To help you out, we have calculated some BTUs for the most common garage sizes:

Size of Garage AC Size (in BTUs)
200 sq ft garage 6,000 BTU
1-car garage (12×20) 7,200 BTU
300 sq ft garage 9,000 BTU
2-car garage (22×20) 13,200 BTU
500 sq ft garage 15,000 BTU
3-car garage (31×20) 18,600 BTU
700 sq ft garage 21,000 BTU
4-car garage (40×20) 24,000 BTU
1,000 sq ft garage 30,000 BTU

The type of air conditioner is highly correlated with how many BTUs you need for your garage. Let’s have a look at the most popular garage air conditioners:

Best Types Of Air Conditioners For Garage

The central air conditioning system usually doesn’t cover the garage; we need an additional unit. When picking which type of AC is best for your garage, keep in mind these few rules:

  1. How will you vent it? If you don’t have a window, thru the wall garage mini split is the best choice.
  2. How many BTUs will you need? Big garages need high BTUs – garage mini-splits, small garages need low BTUs – portable air conditioners.
  3. Important: Energy-efficiency. If you will use the AC quite a lot, an energy-efficient unit will save you $100/year on electricity costs. Mini-splits for the garage are by far the most energy-efficient (highest EER and SEER rating).
  4. Window AC unit is only an option if you have a wide enough window and a smaller garage.

With all that in mind, let’s look at different types of air conditioners you can use to cool down a garage. With each type, we also recommend a specific unit that works best for garages:

1. Garage Ductless Mini Split Air Conditioner (Best Choice, Especially For Bigger Garages)

Mini-split AC units are the best type of air conditioner for the garage. Unlike central AC, they are ductless and can deliver up to 30,000 BTUs of cooling effect. This makes them appropriate even for the biggest 4-car garages.

Here are the specific advantages ductless AC units for the garage have:

  1. Above all, extremely energy efficient. The SEER rating is through the roof; 20 or even more. They are the most cost-saving AC for the garage.
  2. Can be vented via a designated hole in the wall. Mini-splits consist of 1-5 inside units and 1 outside unit, connected via AC cables. You can easily drill a hole in the wall and have a dedicated AC for the garage.
  3. They can provide heating in the winter. Most mini-splits for the garage are heat pumps; they can deliver let’s say 15,000 BTU of cooling effect in the summer and 12,000 BTU of heating effect in the winter. It’s a 2-in-1 all season device, and you won’t have to buy a garage heater for the winter.
Mini-splits: Indoor unit is fixed on the wall inside the garage, the outdoor unit is installed next to the garage.

They are usually the only viable option for bigger 3-car and 4-garages. What is more, most 2-car garages can also be cooled with 12,000 BTU mini-splits.

The only initial drawback is the higher price of the unit. In short term, that might be a problem, but in long term, mini-splits are the most cost-efficient ACs for garages because they have superb energy-efficiency and a long lifespan (up to 20 years).

Which mini splits are the best for garages? Here are the two best options:

MrCool DIY series is perfect for garages. They offer 12,000 BTU unit for 2-car garages, 18,000 BTU unit for 3-car garages, and even the powerful 36,000 BTU unit for 4- and 5-car garages. All units are extremely energy efficient (SEER rating = 20) and, get this, they are designed for DIY installation. You can install them yourself quite easily and save $1000s on an HVAC professional installer:

MrCool DIY ductless ac for garage
MrCool is by far the best mini split AC for garages. 20 SEER rating and DIY installation (you have everything you need included, as seen from the photo) provide for major long-term savings. You can check and buy 12k, 18k, and 36k BTU here.

Another good option, specifically for bigger 4- and 5-car garages is the Senville SENL-30CD 30,000 BTU mini-split. Obviously, it’s not as extremely efficient as MrCool DIY series mini-splits, but it’s a bit cheaper and robust; something you need in the garage:

Senville SENL-30CD garage ac unit
Senville SENL-30CD can produce 30,000 BTU of cooling effect at good energy-efficiency. It’s appropriate for cooling bigger garages. You can check and buy the Senville garage mini-split here.

If you have a smaller 1-car or 2-car garage, you can use the following two types of garage ACs:

2. Portable Air Conditioner For Garage (For 1-Car And 2-Car Garages)

Portable air conditioners (also referred to as ‘room air conditioners’) are a viable option to cool a garage during the summer months.

Chances are you already have a portable AC unit at home. If you do, you can just easily move it to the garage when you’re working or hanging out there. That’s the beauty of being ‘portable’.

Portable AC units for garages are most commonly vented through the window. You can use a window seal kit to cover all the window openings that are created when you pull the exhaust hose through.

Portable air conditioners have a fairly decent energy-efficient (not as high as mini-splits, of course), can achieve up to 15,000 BTU of cooling effect (enough for a bigger 2-car garage), and are quite cheap. For example, you can get a $400 12,000 BTU unit with a decent EER rating (energy-efficiency) quite easily.

The best portable air conditioner for a 2-car garage is the Whynter ARC-14S 14,000 BTU. It has a superior dual-hose design that helps it achieve one of the highest energy-efficiency ratings for a portable AC – EER rating = 12.1. It’s a robust and reliable device, perfect for workshops or garages:

Whynter ARC-14S 14,000 BTU
Whynter ARC-14S 14,000 BTU is the best 2-car garage portable AC. It has an EER rating of 12.1, a superior dual-hose design and it’s robust enough for garages. You can check and but the Whynter ARC-14S here.

Whynter is really the top-of-the-top portable AC as far as the energy-efficiency is concerned. In fact, it scores the #1 place among the most energy-efficient portable ACs

Another more classic model is the well-known BLACK+DECKER BPACT12WT. This model has a little lower BTU output – 12,000 BTU to be exact – and can be a very good choice for a 1-car garage. It has a lower energy-efficiency rating than the Whynter unit but it is also cheaper:

BLACK+DECKER BPACT12WT garage AC
BLACK+DECKER BPACT12WT is the classic portable AC unit for 1-car and smaller 2-car garages. You can check and buy BLACK+DECKER BPACT12WT here.

These units are also the most viable option as garage gym air conditioners because they are portable and easy to install.

Let’s look at the last – a bit specific – a type of air conditioner that can be used in garages:

3. Window Air Conditioner For Garages With Wide Enough Windows

Window air conditioners are as energy-efficient and can be as powerful as portable AC units. They are, comparatively, cheaper than portable AC.

In fact, window units are the cheapest garage air conditioners. Nonetheless, not many people have a window AC on their garage window sill, and here’s why:

Window ACs need good 20-inch garage windows. They also have 15+ inch height. Even if you have a garage window, installing a window AC to cool a garage might also completely steer your window. By installing the window AC unit you pretty much rob yourself of the luxury of having a garage window. 

In short, it’s difficult to find a space on the garage’s window sill to accommodate a window AC. For everybody who is looking for some suggestions for garage window air conditioners, you should look into the LG’s units. They are powerful yet compact, exactly perfect for garages. Here is an example of LG’s LW series that has models ranging from the small 5,000 BTU garage AC to the big 24,500 BTU unit:

window ac that can be installed on garage window sill
LG’s LW series window air conditioners are adequate for garage cooling. You can check and buy 5,000-24,500 BTU models here.

Those are the 3 viable options for garage cooling. Let’s finish with some of the worst garage cooling options just to dispel some myth about how to lower the temperature in the hot garage:

Absolute Worst Choices For Garage Cooling

Over the internet and visiting a neighbor’s garage, you might hear a lot of interesting ‘advice’ on how to properly cool your garage. These include the use of evaporative coolers, using dry ice, even using the new modern battery-powered air conditioners.

In short, none of them actually work well. Evaporative coolers are just elaborate fans with 0 BTU cooling effect (in fact, they increase the temperature at an insulated space), using dry ice is not a long-term solution (ice melts, obviously), and battery-powered AC units are state-of-the-art engineering but they can’t produce more than 5,000 BTU. We’ll get there, hopefully.

Basement dehumidifiers also don’t cool a garage. They do reduce the relative humidity and it might feel a bit – only a bit – cooler but the temperature of the air inside the garage will remain the same even if you use the most powerful dehumidifier units.

The standard air conditioners – mini-splits, portable, and window units – and the only 3 viable options to truly and adequately cool a garage even during the summer heatwaves.

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