Painting your roof white might be one way you can help fight the 'urban heat island effect' according to a report by the National Centre for Atmospheric Research.
What Is The Urban Heat Island Effect?
Urban areas are generally several degrees warmer than nearby countryside. This is because dark man-made surfaces such as roofs and roads retain heat more efficiently than natural vegetation. Roofs and roads can comprise approximately 50% of a cityscape.
Light surfaces reflect ultra violet rays into the atmosphere and this keeps the surface cooler. On the other hand, dark surfaces absorb heat and then release the heat back into the air increasing the temperature.
Considerations If Painting Your Roof White
• If you paint your roof white, not only will you be helping to combat the urban heat island effect, but this will keep your roof cooler. A cooler roof means a cooler house and, if you live in a hot climate, this reduces air conditioning costs and energy.
• If painting your roof in any case, painting it white does not add any extra cost.
• Of course a white roof might not suit every house. But if lighter colours reflect more ultraviolet light back into the atmosphere rather than absorbing and releasing heat nearby as do darker colours, you will better serve the environment by painting your roof a lighter colour if not white, rather than a darker colour.
• You should heed the location and the type of roof; a steep roof may simply reflect heat in your neighbours direction rather than back into the atmosphere.
More About The Research
The National Centre for Atmospheric Research point out that their research is hypothetical, and they admit to reservations about the feasibility of entire cities painting their roofs white. But if all the roofs of an entire city were painted white, this would reduce urban heat by 33% according to their computer modelling.
You might wonder why a hotter urban environment is negative. Hotter temperatures can generate greater fossil fuel usage to run air conditioners, hot weather can exacerbate health problems, and can increase air pollution by encouraging the formation of smog. Smog is proportional to temperature: as temperature rises, smog increases.
The report points out that in cool climates, a cooler house may not be beneficial as the additional costs and energy for heating may outweigh the benefit of reducing urban heat.
If you are painting your house, why not go for a lighter rather than a darker colour? It can't hurt, and might sustain the environment. For more information on painting your roof, contact local companies such as iCoat Intelligent Roof Coatings.