Climate hazards: Extreme heat

Extreme heat

Calgary’s temperatures are increasing, and local temperatures will continue to get hotter due to climate change. High heat days – days that reach or exceed 29°C – are projected to increase from an average of six days per year today, to an average of 28 days per year by the 2050s. Our hottest days will become much hotter (36°C by the 2050s) than what Calgarians have experienced in the past (32°C).

Extreme heat can make your indoor living environment unbearable and uncomfortable, and can lead to:

  • lethargy;
  • reduced productivity;
  • heat-related illnesses; and
  • in extreme cases, fatalities.

High temperatures, and large variations in temperature, can damage building materials (e.g., roofing and siding) over time, causing buckling, bowing, cracking, and sometimes breakage. Some chemical processes are accelerated by an increase in temperature, which can degrade and damage concrete, asphalt and steel structures over time.

For more information about staying safe before, during, and after an extreme heat event, visit What to do during extreme heat.

Extreme heat vulnerability

Consider the following questions. The more questions you answer as YES, the more vulnerable you and your home may be to extreme heat:

Question Yes/No
Do you live close to the downtown core, or in a more densely populated area with minimal vegetation?
Does the interior of your home get uncomfortably hot in the summertime?
Do you have older, single-pane or low-quality windows?
Are most of your windows fixed and non-opening?
Do you have air leaks in your windows and doors?
Do you have walls or an attic that is poorly insulated?
Does your property lack trees or other forms of shading (awning, covered porch, etc.) to direct sunlight?
Do you have dark coloured materials on your roof, exterior walls, deck and landscaping that absorb heat?

How to reduce extreme heat impacts

Below are some of the most impactful  measures to reduce extreme heat impacts to you and your home.

Roof and Attic

  • Consider using lighter colours for your roof  that absorb less heat.
  • If you have a flat or moderately-sloped roof (1:12 to 3:12 rise over run slope), consider a vegetated (living) roof
  • Consider adding insulation  to your attic space to help stabilize the temperature of your home in both hot and cold conditions.

Exterior walls and siding

  • Ensure your walls are well-insulated. If replacing your siding, consider installing exterior insulation  and siding options  with a higher R-value. The higher the R-value, the better the material is at preventing heat from entering or leaving your home.

Windows and doors

  • If replacing your windows , go with triple pane windows, and windows with a low solar heat gain coefficient. 
  • Ensure you have at least some windows that can open, preferably to the prevailing wind direction (south-west), to provide ventilation.
  • Install shading devices, such as roller shades or awnings.

Landscaping and yard

  • Plant deciduous trees on the south, east and west exposures of your home. They provide shade in the summer and shed leaves in the winter to let sunlight in. 
  • In general, planting trees and other vegetation in place of hard surfaces will lower surface and air temperatures around your home. Avoid using artificial turf, which tends to get hot.

Ventilation and cooling

  • You can install a window air conditioner unit in rooms that cannot be cross-ventilated effectively. 
  • For new homes, installing central air conditioning  may also provide opportunities to filter outside air that may be contaminated with pollen, dust or wildfire smoke. 
  • Remember that air conditioning units are energy intensive and running them contributes to climate change, so ideally, we should choose energy efficient A/C systems, and only use them after applying passive cooling measures, such as the ones listed above.

For more information about protecting your home and property from extreme heat, refer to the Institute for Catastrophic Loss Reduction’s Homeowner Guide: Protect Your Home From Extreme Heat.

Disclaimer:  The content of the Climate Ready Home Guide is for informational purposes only and cannot be construed as technical advice with respect to any particular building(s) or construction project(s). The Climate Ready Home Guide does not recommend or endorse specific products or companies. All products and measures should be installed by a professional contractor, according to manufacturer specifications and following all City Bylaws and codes.