Are White Roofs the New Green Roofs?

Is a can of white paint the answer to the “Heat Island Effect”? Apparently rooftops have become the new “untapped” resource towards curbing certain aspects of climate change.

white-roof

According to a report published by the Associated Press, painting rooftops white can reduce temperatures both inside and out. When the temperature on a white roof is measured, it can be 45 degrees cooler than conventional dark coloured roofs. A roof covered with solar reflective white paint can reflect up to 90% of sunlight, as opposed to 20% reflected by traditional black roofs. Thus, lowering indoor temperatures and reducing the need for air conditioning and the consumption of natural resources. Other research reports have also stated that white roofs can save 10 tons of carbon dioxide, which is the equivalent of emissions produced from one car for about 2 years.

These findings have led to the creation of  “cool roof” programs in cities across North America and beyond, especially in regions where the Heat Island Effect is in full force. For example, various neighbourhoods in New York city have implemented this program due to its effectiveness, low tech demand, and low cost.

Are white roof tops really the answer to all climate change problems?

Before canvasing your neighbourhood’s rooftops with white, put down that paint brush and take a minute to do some more research. New studies have shown that white roofs increase the average space heating use more than they decreased average air condition use in Northern climates. This leads to a spike in natural resource consumption. White roofs are also more prone to developing condensation build up, lowering wind resistance, insulation values, and to formation of mold. In areas that experience more than average rainfall, this might be a bad choice as well. A cooler surface will allow for stagnant water to accumulate on these white rooftops. When not drained properly, water can cause membrane soiling and algae growth.

Overall, white roofs are a great environmental initiative that certainly has its place, more likely in southern climates. However, in places like Canada where the climate tends to be colder and milder, painting our rooftops white might just not be that cool.

Are white rooftops the answer to climate change? Would you ever paint your rooftop white? Share your thoughts in the comment section below!

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