Many people only think of insulation as something you need in the winter to keep your home warm. This is especially the case for insulation in the attic since heat rises and you want to retain as much as possible in your living space.
But heat doesn’t just rise, it migrates. It basically seeks out cool zones to fill, so if that zone is lower than the source of the heat, the warmer air will travel down into that cooler area. This is the key to whether or not attic insulation can help keep your house cool in the summer. So in answer to that question, attic insulation is very important to keeping your house cool during a heat spell. In fact, it’s just as important for staying cool in the summer as it is in the winter, and here’s how.
How Hot and Cold Air Interact
Let’s take the common knowledge which stipulates that hot air rises and cool air falls and bring it indoors to the confines of your humble home. When it’s cold outside and you have the furnace running, warm air is blowing through your vents. This air is warmer than the air in your home so it fills the living space and rises through the house, making your entire home warmer than the winter air outside.
This warm air rising through your home is called the stack effect and it will continue to rise through to your attic and escape through any gaps it can find. So the more attic insulation the more warm air is retained, saving your furnace from running too often.
The Reverse Stack Effect
In the summer warm air will flow where the cool air is settled. This could be upward, downward, or sideways. That’s why when it’s hot outside and you have the air conditioning in Red Deer running, that outdoor heat is always trying to get in from any angle it can find. That includes your roof, which takes plenty of direct sun and gets very hot.
The one thing that can help prevent that heat from entering your cool home from above is attic insulation.
So many people who live in a two-story home complain of having a much hotter second floor that the rest of the house. While some of that may be attributed to the stack effect allowing the downstairs heat to rise and collect upstairs, the problem may be that the attic is poorly insulated allowing the very hot air to enter from your roof.
But you also have to consider sealing the air gaps, those places in your attic where the insulation appears dirty. That’s airflow carrying around dust to go along with the heat, and it will always look for the easiest points of entry.
So when combining the proper insulation in your attic with an air seal to stop the flow from getting through the gaps, you have the recipe for keeping your home cool in the summer and warm in the winter.