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Insulation | Does It Help in the Summer?

When most people hear the word “insulation”, they think of keeping things warm in cold weather. However, insulation can also be important to keep things cool in warm weather.

Here, we explain why this is the case, and how you can enhance the benefits of insulation during the hot summer months.

Insulation does help in summer. It prevents hot outside air from transferring into the house and heating the interior, which has been cooled by ACs, HVACs, etc.

How Does Insulation Work?

Heat moves naturally from an area of higher temperature to an area of lower temperature, down a temperature gradient.

It does this by passing through solid materials in contact with one another via conduction, or by moving through air or liquids via convection.

The purpose of insulation is to prevent the conductive flow of heat down a temperature gradient, keeping heat where it already is.

Materials that are used as insulation do not conduct heat well, so even though heat may come into contact with these materials, it does not move through them easily via conduction.

Spray foam insulation on the roof frame

Air is a poor conductor, so insulating materials will often have small pockets of air.

A high ratio of void or air to solid material means that fewer materials will come into contact with each other and transfer heat, thereby minimizing conduction.

Small pockets of air also minimize convection, as air movement is restricted. However, heat is more likely to be lost through insulation via convection.

Insulation Prevents Inflow of Heat in Summer

A common misconception about insulation is that it prevents the loss of cold air from a building during the summer months.

“Cold”, however, is simply considered to be an absence or low amount of thermal energy or heat.

Since insulation works by keeping heat where it is and preventing it from moving down a temperature gradient, in winter, it will maintain the warmth produced by heaters and appliances within the house instead of allowing it to move to the colder outside air.

During summer, insulation will work in a similar way, except that it will prevent hot air from the outside from moving down the temperature gradient to reach the inside.

Hence, insulation works to keep a cool house cool by minimizing the flow of hot air inward.

Benefits of Insulation in Summer

  • Lower energy costs since you won’t need to keep cooling down hot air that has moved inside.
  • Reduced energy usage not only for air conditioners but also for refrigerators and other cooling appliances.
  • Lower emission of pollutants through air conditioning.
  • Reduced noise levels as you don’t have to run the air conditioning so high.
  • Improved comfort.
  • May help to reduce condensation caused by air conditioners running at high capacity.

Enhance the Benefits of Insulation in Summer

Installing insulation is the first step to keeping your home cool in the summer, but there are other tricks that can help you to maximize the benefits.

Man installing fiberglass insulation for the roof

Keep Windows and Doors Closed

During hot weather, it may seem logical to open doors and windows to cool down the house interior. However, if it is hotter outside than inside, warm air will simply move down the temperature gradient into the house.

So, if your home is insulated, you can further ensure that the warm air stays outside by keeping windows and doors closed.

The effects of this strategy may also depend on the time of day, though as you can pull cooler night air into the house, which will provide a cooling effect.

Install Weatherstripping and Double-Glazing

Along the same lines of logic, installing weatherstipping in your home will work to seal air leaks around doors and windows.

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With air leaks sealed, this will prevent warm air from moving into cooler rooms in your home.

Installing double-glazed windows will also help to better insulate your home, keeping it cool in summer and warm in winter.

Double-glazed windows or doors are made up of two panes of glass, with a small layer of air trapped between the glass.

As mentioned previously, this means that heat conduction will be reduced, so hot air from the outside is less likely to warm the inside.

Minimize Use of Heat-Generating Devices/Appliances

While heat emitted from appliances may seem negligible on its own, this can build up quickly and make a big difference when it comes to keeping a house cool.

Reducing the use of electronics and appliances such as tumble-dryers and water heaters will minimize the amount of heat produced within the house interior.

Hanging wet clothing out on a washing line instead of putting them in the dryer will help with this, or alternatively using appliances in the evening when outside air is cooler.

Insulate Attic and Crawl Spaces

Attics and crawl spaces can hold warm air, which will move to other parts of a building where it is cooler.

Heat from the sun quickly warms roofs, meaning that attics will easily become hot if they are not insulated.

Insulating these spaces in particular minimizes the amount of heat that moves into them, which, in turn, prevents the movement of heat into other rooms.

Insulate Ducts and Pipes

Pipes and ducts can also be sources of heat in the summer.

Insulating ducts and pipes will prevent heat transfer from these into living spaces and have the added benefits of helping to minimize condensation and increasing their lifespan by reducing expansion and contraction.

Man wearing a PPE installing an insulation for ducts

Limit Bathroom Fan and Range Hood Use

Bathroom fans and range hoods can be useful to suck out warm humid air from the rooms in which they are installed.

However, if they are left on longer than necessary, the motors can be a source of unwanted heat. They will also take all your conditioned air and put it outside.

Using these devices briefly and only when necessary, will thus help to maximize the cooling benefits in your home.


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