woman buying an air conditioner (AC)

How to Choose the Best Garage Air Conditioner

Today more than ever, homeowners are discovering the benefits of a climate-controlled garage. They are installing air conditioners to transform their garages into home gyms, guest quarters, home offices, and other functional spaces.

When you install a cooling system in your garage, there are some important considerations to consider. Different factors, including garage size, insulation, venting, and your specific goals, will determine which systems make the most sense. 

woman buying an air conditioner (AC)

Don't Integrate Your Garage Air Conditioner into Your Central AC System

First, tying ductwork into your home’s central air conditioning system can be dangerous. Moreover, if you still park cars or other vehicles in your garage, carbon monoxide fumes can infiltrate your home’s ducts, creating a health and safety hazard.

Licensed professionals can help you install an AC in your garage and ensure proper climate control without exposing your family to harmful carbon monoxide fumes.

Best Options for Garage Air Conditioners

Air conditioners are an excellent way to cool your garage space. They work by pulling cold air from the outside and pushing it through the garage. The cold air circulates around the room, eventually cooling down the entire space.

There are a few options for either a DIY or professional installation of an air conditioner in your garage. You can purchase an air conditioner rated for use in garages, or you can buy one designed for outdoors and then install it in your garage. The first option is cheaper than the second, but it also has drawbacks such as noise and energy consumption.

Depending upon the size of your garage, your garage wall insulation, and whether or not you have an operable garage door, the type of air conditioner you choose will vary. An experienced HVAC technician can help you navigate cooling capacity requirements, energy star ratings, and your home’s unique set of circumstances.

Ductless Mini-Split Air Conditioner

Ductless systems, commonly called mini-splits, are widely popular for keeping a converted garage cool. They offer a cooling option that doesn’t require installing new ducts.

how to choose a garage air conditioner infographic

Mini-splits also have a longer lifespan than conventional air conditioners, making them an attractive option for cooling a garage. And when it comes to appearance, their streamlined aesthetic positioned high up on a wall means you don’t have to give up a window or floor space. 

Mini-splits are among the most energy-efficient AC units on the market, unlike portable or window air conditioning units, which don’t have to meet efficiency standards and can cause higher energy costs with regular use.

If you ask the Island Comfort team, we’ll tell you that a mini-split system is nearly always the best choice for cooling a garage or smaller renovated space. This is just part of the reason why Island Comfort specializes in mini-split AC installation in Hawaii. Give us a call to find out if a split system is right for your home.

Portable Air Conditioner

Portable air conditioners offer another popular alternative to traditional air conditioning systems if you’re looking to avoid putting a hole in the wall. For flexibility with installation, you might want to go with a portable AC unit so that you can move it to another location or leave it out during the winter.

These systems vent out of an existing garage window and are ideal for smaller spaces. Portable air conditioners also filter pet dander, dust, and other common particulates in garages.

An added benefit of air conditioning in your garage is that it can help dehumidify the space. Many people cool their garage after converting it into a flex space, not just a port for vehicle storage.

It’s important to know some downsides of portable air conditioners. Not only to do tend to be heavy and noisy, but they also require regular draining and take up space in an already-small area. In our opinion, portable air conditioners are a last resort when it comes deciding how to cool a garage.

Window Air Conditioner

Window units were among the most popular garage AC units before portable and mini-split systems became available. These offer an excellent solution for living spaces that don’t need long-term cooling. An added benefit of window units is that they’re low-cost and easy to install.

Keep in mind that window air conditioners can be noisier than other options and require an appropriately-sized window for installation. Access to an electrical outlet is also a requirement. Many people don’t like window units because they can be an eyesore and prevent a resident from being able to use the window.

Swamp Cooler

Evaporative coolers, or swamp coolers, might seem like the most straightforward choice for your garage. Swamp coolers use evaporation to produce cool air by running outside air from a fan through a damp pad—no venting required.

As you may already know, as a Hawaiian resident, swamp coolers don’t work well in a tropical climate that typically has high humidity. Installing an evaporative cooler in your living space will likely cause it to feel muggy, the very thing you’re trying to get away from by being indoors.

Hawaii’s persistently damp indoor environment often results in mildew, mold, and other contaminants that compromise your indoor air quality. If you want to avoid feeling like you’re living in hot air, evaporative coolers in Hawaii are probably not your best option.

How to Determine What Size AC Unit You Need

Square footage is the primary consideration for choosing what capacity air conditioner you’ll need for your garage. Because of uniquely open layouts, garages can present unique challenges for air conditioners which typically operate in balanced loops, not wide spaces.

About BTU's

BTU stands for British Thermal Unit. This is a measurement unit that measures how much energy your air conditioner consumes to remove heat from the air inside. The higher the BTU, the more power is being used by the unit.

When you buy an air conditioner, it’s essential to ensure enough BTUs. Otherwise, if your HVAC system has a weaker BTU than the needed capacity for your home, you’ll not likely be satisfied with the results.

A general rule of thumb is that a four hundred square foot garage would need an AC unit that produces 12000 BTU. A BTU represents the heat required to raise one pound of water by 1°. Also, a BTU is the universal unit of measurement for air conditioners.

A seasoned HVAC professional can help you determine the correct BTUs for the size of your garage.

picture of blue garage door and exposed garage insulation

Insulating Your Garage

When it’s hot outside, it’s even hotter inside your garage. Garages are often left uninsulated, but this is a mistake if you want to use your space as anything other than a car garage. Insulating your garage can help keep the temperature inside more stable. This will save on energy costs and make your garage more comfortable.


There are many ways to insulate your garage. The easiest way is with insulation boards or rolls. These can be installed easily and provide a good level of insulation for the cost.

There are also other more expensive options such as spray foam insulation or rigid foam panels that can provide better insulation and last longer, but these will require professional installation and may be more expensive upfront.

Attic Insulation

Some people may not realize that adding attic insulation also needs to be done in the garage. This is because it helps prevent cool, dehumidified air from escaping your garage space. If you’re looking to lighten the load on your garage air conditioner and reduce energy bills, adding new insulation is a great way to accomplish that.

Reach out to your HVAC technician to determine whether or not your home is a good candidate for an attic insulation update.

Contact Us for the Best Garage Air Conditioners

Island Comfort has been providing excellent HVAC services to Oahu and Kauai. Most importantly, our dedicated team of professionals understands the unique demands on AC systems in these humid conditions.

Find out today how we can help you install air conditioning for your garage! We will go above and beyond to transform it into a more comfortable room.

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