Cooling Your Home… Passively

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Cooling Your Home… Passively

Hats, fans, sprinklers, and pools. We all look for ways to keep cool in the summer, so why not do the same for your home? Typically we crank the AC or plug in a fan, which both get the job done, but consume a considerable amount of energy while doing so. The demand that air conditioners put on the electricity grid is actually a major concern during the summer months in Ontario. Fortunately, you can help alleviate this issue by relying on one – or all – of the following energy-saving strategies.

1. Find Some Shade

Although windows provide a great view of the outdoors, they also serve as a mechanism for solar heat gains. These are beneficial in the winter, but a detriment in the summer. In the warmer months, try shielding your indoor space from the sun by covering windows with blinds, shades, or even exterior window covers. The latter provides more coverage, and can range from simple covers to more sophisticated systems that can be programmed to mechanically open or close depending on the time of day and outdoor temperature.

Still want a view of the outside? You don’t have to cover all of your windows to still see the benefits. The most critical windows to target are those in the south and west facing directions. Windows facing south experience the highest solar heat gains over the course of a day. Windows facing west are a slightly different story. Towards the early evening (think around 5pm), your house has absorbed heat over the course of the day and is likely at its highest indoor temperature. Since the sun sets in the west, it is also around this time (i.e. the early evening) that the sun’s rays hit west-facing glass at a more direct angle (i.e. one that is perpendicular to the window). Since the sun’s path is more direct, a greater amount of heat will enter the indoors (this is because less light has been scattered and/or refracted while travelling to the window). Shielding these windows is an easy way to block unwanted heat and keep you and your house cool.

2. Veg Out

We’ve all heard that a plant-based diet can do wonders for your health, so could some extra plants do some good for your home? With some strategic gardening, the answer to that question is yes! Planting deciduous trees around your house’s perimeter can help create a pleasing indoor climate. In the summer, the leaves help block out the sun’s UV rays and consequently shield your home from unwanted heat. In the winter, these trees shed their leaves, which allows for maximum solar heat to enter your home, thereby creating a toasty indoor temperature.

3. Put on a Hat

Try a new hat… for your home! When it’s time to invest in a new roof, try a greener option such as a white or green roof that will help keep things cool in the summer. A green roof is covered in vegetation and will help moderate your indoor temperature and better manage storm water and precipitation. A white roof is typically a flat roof that has been painted white. This allows the sun’s rays to be reflected, instead of absorbed. Both of these roofs do come with their challenges though. Green roofs can be difficult to maintain and often leak, while white roofs can peel and lose their effectiveness over time. If you still prefer a more traditional option (and one that requires less maintenance), choose a lighter shade of shingles so that less of the sun’s energy is absorbed.

These are only a few of the many ways to passively cool your home. Hopefully at least one will appeal to every homeowner so that we can collectively cut down on our consumption this summer.


Sandra Dedesko is a recent graduate of Civil Engineering at the University of Toronto. She has a high interest in energy efficient buildings and sustainable urban development. She's currently working towards a Masters degree and industry career in this area.

  • Cheriel Jensen

    There is a white acrylic roofing coating for flat or slightly sloping white roofs that lasts a very long time. I have had my most recent white roof for more than 20 years and it is still in good shape. I designed the roof originally to hold about 1 1/2 inches of water to keep it passively cooled in the summer, but with the white acrylic there is no need for the water as the roof stays cool. The house also has a south facing sloping roof designed for when solar panels would become available. Since I built the house in 1973, many trees now shade that high portion of roof. We are able to keep our summer inside temperature cool with deep overhangs on the south and these trees. I began the process to install solar panels, but my electricity use is so small, less than $30 per month, two contractors said there was no point in adding panels. (I hang my laundry in the sun, saving about half the electricity I would otherwise use. The dryer adds heat to the house so it’s non-use also helps keep the house cool.) The house also has many high windows making daytime use of lights unnecessary. This also saves the heat the lights would produce. There are many other design solutions that add to my passive solar house.

    • Sandra Dedesko

      Thanks for sharing your strategies! I hope your success will motivate others!