Attic AC Units: How to Cool Your Attic in Summer

As the uppermost level of your home, the attic is one of the first spaces in the house to get hot in the summer. Even in winter, the attic tends to remain warm as heat tends to rise.

This can be a problem if you use your attic for storage, or more crucially, as a living space. Soaring temperatures can cause discomfort, and damage the stored items in your attic, and even your very home. 

In this guide, we explore ways of keeping your attic cool, and discuss the pros and cons of each cooling method so you can choose the best one for your attic.

Why Cool Your Attic?

Extra living space

The average attic can be between 1,600 sq. ft to 1,800 sq. ft. That is a lot of valuable living space potentially lying unused. Without sufficient cooling, the attic is too warm to comfortably stay in during the spring and summer season, as it lies directly under the baking heat of the roof. This makes it unusable for half of the year, or more in some places.

Proper temperature for storage

Even when used as a storage area, your attic needs proper cooling and regulated humidity. An attic that is too hot and humid can damage your stored items, especially those made of paper. Even cardboard boxes can suffer moisture damage and affect the contents inside.

Less risk of structural damage

Excessive heat can damage more than just your stored valuables – it can potentially affect your home itself. High heat and humidity can lead to the formation of mold and mildew, which can damage walls, ceilings, and even structural support.

Wooden beams and support rafters are also at risk of damage when temperatures fluctuate wildly, such as when the oven heat of summer gives way to the freezing cold of winter.

The Different Types of Attic AC Units

There are various heating options to choose from when considering how to heat your attic. Each type has its advantages and disadvantages, and the choice depends on your specific needs and budget.

Portable Air Conditioners

Portable AC units are standalone devices with an exhaust hose that can be placed in the attic. As the name suggests, their main benefit is their portability: they are easy to move around and do not require permanent installation. However, their smaller size means they can’t cool larger spaces as effectively as bigger and more permanent AC solutions.

Pros:

• Portable
• No professional installation required
• Least expensive attic cooling option

Cons:

• Limited cooling capacity
• May require a window or vent for the exhaust hose
• Not very efficient
• Not ideal for long-term cooling

Best for: 

Smaller attics, or attics that are occasionally used and don’t require a permanent cooling solution and have a window that the exhaust vent can be placed through.

Recommended portable AC for attic:

Friedrich ZCP12DB 11000 BTU Class ZoneAire Dual Hose Portable Air Conditioner with Built-In WiFi – R32 Refrigerant

This 3-in-1 portable air conditioner gives you all the power and functionality of a Friedrich Window unit in a compact portable package, plus dehumidification and fan functions. It has a capacity of 11,000 BTUs and can service a space up to 400 sq. ft.

Its highlight feature is its smart connectivity. This smart portable AC supports both Amazon Alexa and Google Home, and can be controlled via voice and app. It can also integrate with your smart home routines via the FriedrichGo app. With built-in WiFi, you can easily set your preferences for cooling as well as change from virtually anywhere so no matter when you can walk in the door, your space is ready for you!

This unit also has a sleep control function that increases the temperature by 2° every 4 hours for comfort while you sleep. Another feature is a self-evaporative condensate system, so there is no bucket to empty, as well as a condensate overflow protection that shuts the unit off to prevent overflow if the tank becomes full. 

The included window slider installation kit allows for horizontal or vertical window openings from 26″ to 46″. The window kit can also be trimmed to fit smaller windows. It plugs into a standard 115-volt HH outlet with a 6-ft long power cord.

Also check out our complete lineup of portable air conditioners for different applications.

Window Air Conditioners

Window air conditioners are self-contained units that are mounted in a window. They provide cooling for a single room or a small area. They provide more cooling capacity than portable ACs, but are fixed in place.

Pros:

• Low cost cooling
• Does not require ductwork

Cons:

• Limited cooling capacity.
• Requires window installation
• May obstruct the view from the window
• Unsightly if placed in front of the house

Best for: 

Attics used as a single bedroom or a home office, or small attic spaces.

Recommended window AC for attic:

Friedrich CCV12A10A 12000 BTU Chill Premier Inverter Smart Window Air Conditioner – 115V – Energy Star – R32 Refrigerant

The new Chill Premier Inverter Series is Friedrich’s Premium Line of “smart” room air conditioners now with variable comfort / inverter technology. The Premier Inverter units allow for the compressor to operate at the capacity needed at any given time.

This particular model has a 12,000 BTU cooling capacity and boasts a CEER rating of 15.0. It uses the new R32 refrigerant mandated by the EPA for new AC units produced after 2023, making it future-proof. R32 is up to 12% more efficient than the older R410A refrigerant, as well as being safer, less toxic, and more eco-friendly.

It comes with a window installation kit with solid side flaps (vs accordion-style). Designed with the homeowner in mind, the SimpleSill Design allows the window to be opened and closed after the unit is installed. The three-step installation kit includes a one-piece frame, included hardware and expandable side panels to lock the unit in place.

See our complete line of window air conditioners.

Ductless Mini Splits

Ductless mini-splits are a highly efficient and versatile option. They are much more efficient than ducted cooling as well as window ACs, while providing both cooling and heating functions.

They can also be combined with other indoor units to provide zoned heating and cooling for different rooms, all connected to one outdoor compressor.

Pros:

• Highly energy-efficient
• Zoned cooling for customized comfort
• Quiet operation

Cons:

• Higher upfront cost
• Professional installation required

Best used for: 

Attics with multiple rooms or areas, especially if you need precise temperature control.

Attics without existing ductwork or when duct installation is impractical. Great when energy efficiency is a priority. 

Recommended mini split for attic:

Friedrich FSHW183 18000 BTU, 17.0 SEER2 Floating Air Select Series Single Zone Mini Split – Heat and Cool – 230V

This single zone mini split system includes both the FSHSW18A3A wall unit and the FSHSR18A3A outdoor compressor. It has 18,000 BTUs of cooling and a 19,800 BTU heat pump. It also boasts high efficiency ratings of 18.0 SEER and 9.89 EER.

This is achieved using Friedrich’s inverter technology, which reduces energy costs while reaching the desired set temperature more quickly. With its low ambient heating capacity, it can continue to provide heat even with temperatures down to -13°F. If you need to cool your attic year round, this unit’s low ambient cooling features make it a great choice.

The outdoor unit is pre-charged with R410A refrigerant for 25 feet of line. Additionally, the line sets can be as long as 66 feet between the compressor and the indoor unit with a 65 foot height difference. Line sets are sold separately.

Check out our wide range of ductless mini splits, for your attic as well as different areas of the house.

Evaporative Coolers

Also known as swamp coolers, these use water to cool the air through evaporation. They are an energy-efficient and eco-friendly option, but they work best in dry climates.

Pros:

• Energy-efficient with low operating cost
• Environmentally friendly
• Effective in dry climates

Cons:

• Ineffective in areas with high humidity
• Limited cooling capacity

Best for: 

Dry and hot attic spaces in arid regions.

Central Air Conditioning

Central AC systems use ductwork to distribute cooled air throughout the entire home. This requires ducts to already be installed in the attic. Depending on your system design, you may or may not be able to use your existing central air conditioner. If it was not sized and planned for use in the attic, adding an extra vent may do more harm to your total home comfort than good.

Pros:

• Provides even cooling throughout the house
• High cooling capacity
• Can be integrated with existing ductwork

Cons:

• High upfront and operating costs
• Requires professional installation and maintenance

Best for: 

Larger homes with existing ductwork or those seeking whole-house cooling.

Factors That Affect Attic Cooling

Insulation

Whether or not the attic was intended to be used for storage or a living space to begin with, it needs to have been properly insulated. Insulation provides a barrier between your home and the outside world and influences so much surrounding the regulation of temperature. 

Make sure you have the proper amount of attic insulation for your region. Calculating how much insulation you need will involve making sure you know the zone where you live. The United States is divided into 8 zones, and each zone requires a different thickness of insulation.

See our guide to insulation installation here.

Ventilation

Ventilation also plays a huge role in the regulation of your home’s temperature. A properly ventilated attic will automatically move hot air through and out, not keep it trapped inside. Attic ventilation systems also work together with your insulation. The type of ventilation, or roof vent, that you’ll need depends on your home’s construction and the details surrounding your attic.

Roofing

In the case of warmer climates, keeping your attic cool also helps protect your roof, saves you energy, and affects your ability to manage the temperature in the rest of your home. A possible way of preventing a build-up of hot air in your attic is installing reflective roofing. It won’t solve the issue, but it can go a long way towards improving the attic temperature. Dark roofing material absorbs light energy and increases the temperature, while lighter, more reflective roofing materials will deflect more of the heat and prevent high attic temperatures.

Practical Tips to Keep Your Attic Cool

Here are a few different options to explore when trying to figure out how to cool your attic:

1. Cover windows

Windows play a part in regulating the temperature of your attic space. Keeping them covered in the summer will block sunlight and excess heat, while allowing the sun to stream through in the winter will provide heat. Make sure the windows are properly sealed and caulked so that no drafts get through.

2. Install an attic fan

Attic fans are a great place to start to cool your attic. Fans work by pulling the hot air out of your home and transferring it to the outside, but you need to make sure the attic is airtight to prevent cooled air from also being pulled from the rest of your home. 

There are two types of attic fans. Roof fans are installed much like a skylight, and gabled wall fans work best for roofing with existing gable vents. If no gable vents exist, you can easily have a professional come out and cut the properly-sized hole. 

Professional installation for any attic fan type is recommended, as using extension cords to provide attic fans with power is not a good idea. If you’d prefer not to use electricity, solar attic fans that are powered from solar panels are another option.

3. Install ridge and soffit vents

Ridge and soffit vents are also helpful for venting hot air and keeping an attic cool, but you’ll need a little extra help as this method alone probably won’t remove enough heat to keep the space comfortable enough to live in. 

Ridge vents are a small opening in the ridge of the roof and a soffit vent is a small vent installed under the roof eaves.

4. Use a dehumidifier

High humidity can cause a space to feel warmer. This can pose a problem for your comfort and health, as well as the safety of your long-term stored items. A dehumidifier helps absorb the excess humidity from the air, lowering the temperature and minimizing the risk of moisture damage. 

At Total Home Supply, we carry all types of AC solutions to suit your attic, covering different price points, air conditioner types and models, and all kinds of attic sizes and layouts. Give us a call today and see what we can do to keep your attic cool and your utilities low in the heat of summer!