Protecting Homes Against Overheating

As Canada s climate warms, extended heat periods in summers may cause homes to overheat, which poses health risks to occupants. There are several reasons influencing overheating:

• Outdoor Environment: 
       A mix of high temperatures, humidity, and solar radiation.
• Building Factors: 
       Air leakage, unshaded windows, poor ventilation, (lack of) air conditioning, and low or high insulation levels.
• Internal Gains
       Appliances, lighting, and occupants increase indoor temperatures.

What Builders, Renovators and Homeowners can do

Homeowners can reduce the risk of their home overheating by implementing these measures:

• Planting trees along the south, east, and west side of their home to help create shade.
• Installing weather stripping around doors and windows to reduce loss of cool air.

Builders and Renovators can suggest active and passive cooling measures to their clients:

• Installing windows with integrated exterior blinds or shutters and awnings
• Selecting low solar heat gain coefficient (SHGC) glazing for windows and doors.
• Installing reflective roofing materials or vegetation roofing.
• Installing mechanical cooling or an energy recovery ventilator (ERV) to reduce humidity
• Where possible, enhancing natural ventilation by placing windows on opposite sides of the house to promote natural air flow 

How do I know if overheating is a concern for the homes I build?

While HOT2000 is not suitable for a cooling load analysis, other building energy modeling tools can calculate hourly loads in zones or spaces and could model the effect of passive cooling devices.

How do I know if overheating is a concern in my area?

The Climate Atlas of Canada features a map that shows the number of very hot days and average temperatures, based on historical data from the 1970s and projections extending to 2080. The map is updated as new data becomes available.

Where can I find more information?

More information can be found in NRC s overheating guide and this one-page heat protection guide from the Intact Centre for Climate Adaptation.