A New Study Finds that White Or Reflective Roofs are More Effective in Controlling Urban Heat Than Green Roofs

A new study led by UCL researchers found that cool roofs, like painting them white is more effective than green roofs, solar panels or street level vegetation. The researchers used a three dimensional urban climate model of London to find out how different urban heat management systems can impact the thermal levels of this place. Different heat management systems like green roofs, air conditioning, painted cool roofs, solar panel roofs and ground level tree vegetation were used.

Air conditioning in London homes doesn’t have much impact on warming the outside. The study found out that having cool roofs inside homes can decrease the outside weather of the city. The average temperature outside can be reduced by 1.2 degrees while in some areas, it can even be reduced by 2 degrees. The other systems like solar panels or street level vegetation can also reduce warm temperature but not to the same extent. The impact of green roofs was almost nonexistent on the environment.

Air conditioning which can lower the inside environment, can warm the outside environment by 0.15 degrees and 1 degree overall in Central London. The team of researchers studied each method on housing, industrial and commercial buildings throughout London. The lead author of the study said that cool roofs are the best way to keep temperature a little cool on extremely hot days in London. Other methods have various side benefits but they are not good enough to reduce outside urban heat.

As the climate is changing, the heat in London has become almost unbearable which leads to discomfort and even rise in mortality. The study also offered many insights on urban heat management and other forms of heat management systems. Green roofs were found to have no effects on a warm environment because their effect on the environment changes throughout the day. Even though it can reduce some heat in the night, it can increase the humidity levels at day time which could affect thermal levels of the area.

Image: Unsplash / Derek Thomson

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