Cool roofs reflect the sun’s rays and reduce heat build-up through a light-coloured or highly reflective roofing product such as a coating, new membrane, or shingles.

Most roofs in Canada are dark in colour and absorb heat from the sun’s rays transferring it into the rooms below. Because cool roofs are better at reflecting the sun’s energy, less heat is transferred inside your home. As a result, you may not have to use your air conditioner as much, saving you money and reducing greenhouse gas emissions. Cool roofs also increase the life expectancy of your roof because they reflect the heat and UV rays that damage and age roof materials.

Dark-coloured roofs in high-density areas also contribute to the urban heat island effect (significantly warmer temperatures in urban areas compared to rural areas). As a result of climate change, Ontario is expected to see dramatic increases in the number of extremely hot days due to continued global warming. Installing a cool roof is one way to help to offset this.

There are cool roof options for all types of roofs, including steep slopes (pitched roofs) and low slopes (flat roofs). Roofing products are tested for their reflectivity and given a Solar Reflective Index (SRI) value between 0-100. The higher the number, the more reflective it is.

If you want to convert an existing roof into a cool roof, you have the following options:

• Retrofit your existing roof: Apply a coating that is waterproof and has reflective properties.
• Replace your existing roof: Install a new cool roof using a reflective roof product.