White Roofs: A Solution to Urban Heat Islands

Did you know that installing white roofs can help combat heat islands in urban areas? Certain neighborhoods, such as Rosemont-Petite-Patrie in Montreal, have even required new flat roofs to use white roofing. Which makes sense, given that it’s an affordable solution with many advantages for both homeowners and the general population.

In this article, our flat roof membrane experts will give you plenty of important information on white roofs. Read on to learn how white roofs reduce heat buildup and why they are a great roofing solution.

What Are Urban Heat Islands and How Do They Form?

First let’s go over how and why heat islands form.

It’s important to know that this phenomenon mainly occurs in urban areas, where you find large amounts of concrete, brick and asphalt. In zones where these materials are widely used, their surfaces absorb the heat from thermal radiation instead of reflecting it.

At night, the solar-heated material radiates this stored heat, leading to much higher temperatures. It is common for some urban heat islands to be more than 10°C warmer than their more rural surroundings!

Also, it is important to note that some materials used to install or repair roofs, especially those in darker colours, can lead to heat islands because they absorb heat rather than reflecting it.

The Negative Impact of Heat Islands

It is clear that urban heat islands do not have any positive effect on the areas where they develop.

For example, heat islands speed up smog formation, which poses a major problem. They are also to blame when city-dwellers experience heat exhaustion, weakness or other kinds of heat-related discomfort.

How Can White Roofs Help Offset Heat Islands?

Unlike other types of roofing like asphalt or gravel, white roofs reflect the sun’s rays instead of absorbing its heat. This is why some see it as the ultimate way to combat heat islands.

White roof design uses EPDM elastomeric roofing membranes, whichcontain grains of white porcelain that better reflect solar heat.This thermal property protects the roof coating and preventsheat buildup on the roof and its membrane.

When flat roofs absorb less heat the surrounding temperature is reduced dramatically, making everyone in the neighborhood more comfortable.

Are Certain Membranes Better Against Heat Islands?

Absolutely. For example, the Soprastar GR membrane stands out from other white roofs because it is incredibly energy efficient.It has an SRI (solar reflectance index) of 90. Very impressive given that the Canada Green Building Council recommends installing membranes with a minimum SRI of 29.

White roof installers regard this membrane highly and often recommend it to building owners to reduce urban heat islands.

Other Benefits of White Roofs

White roofs are not only good for controlling heat islands. They are also efficient, durable, and environmentally-friendly.

White Roofs Cut Energy Costs

A roof absorbs heat from the sun, and it then passes into the building via thermal conduction. The temperature inside the building increases, and more energy is required to cool its interior.

White roofs reflect sunlight and prevent heat buildup and prevent its spread. The building is cooler, you need less air conditioning and your energy costs are lower. White roofs save energy…and money!

White Roofs Last a Long Time

Don’t forget that the main role of a roof is to protect a building from the elements. White roofs are very effective at this AND for a very long time.

The white colour prevents overheating and extends a roof’s lifespan. White roof membranes also stay very flexible during the winter. They maintain an elasticity coefficient of 300% at -40°C. The membrane is also well-protected against leak-causing tears.

White Roofs Are an Excellent Foundation for Green Roofs

Some white roofing membranes make great foundations for installing a green roof. Of course, you should always make sure that the roof structure is sound enough to support the increased load.

White Roofs Are Recyclable and Limit Waste

Unlike many other types of roof coverings, certain kinds of white roof membranes can be recycled.

White roof membranes often last much longer than asphalt and gravel membranes. This means fewer end up in landfills and leads to less waste overall.

To Sum Up: White Roofs Work Against Urban Heat Islands

Installing white roofs can greatly reduce urban heat islands. This makes them an excellent solution in a time when concern for the environment and individual well-being is sky-rocketing.

It is for all these reasons that some areas in large cities, including Montreal, are beginning to require white roofs on new flat-roofed buildings. While this type of roofing is not yet required across the province or the country, its popularity is growing. Just take a look at their energy performance to understand why homeowners are investing in white roofs! Want to learn more about white roofs and the other green roofing options that Duro-Toit offers? Looking for a quote on white roofs? Contact our installation experts today!


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