Cooler Roofs Reduce CO2 Emissions

As cool as a shiny new black sports car is there is wisdom in choosing one with a white paint job. With the sun bombarding the cars body the black paint will naturally absorb more of that energy and the white car will reflect it. This for some is a matter of life and death in the middle of summer as the inside of their cars transform into state of the art pizza ovens while they’re parked.

Slowly a similar and common theme is becoming apparent with in the building construction industry. More and more new buildings are having light coloured roofs installed instead of the standard darker colours.

Common sense seems to be prevailing at last and now also backed up with research. Lighter coloured roofs reflect more sunlight there fore keeping the building interior cooler. Coupled with ceiling and wall insulation, blinds and properly treated windows the air-conditioner will be under less stress in the middle of summer thereby cutting down usage leading to the drop in CO2 emissions. In fact white coloured roofs are possibly the quickest and cheapest way to start reducing house hold CO2 emissions. Along with cooling the interior of the building by reflecting heat radiation they also reduce what is called the urban heat island effect. This effect can be caused by such things as darker coloured roofs absorbing heat and retaining it through out the day and slowly releasing that energy into the air thereby raising the ambient temperature of that area. Entire cities can become heated this way and this can be detrimental for the energy efficiency of the city as a hole.

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Aerial Thermal images showing the cooler roofs in shades of blue reflecting the heat. Note that most other house roofs are almost as hot as the road surface which is by far the hottest.

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Same as above, the houses with the lighter coloured roofs reflect more heat than those with darker colours.

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Not as many light coloured roofs in this area. Although coolour matters most, material is also a vital factor. Metal roofs will reflect more than tile or slate.

Extensive studies, especially in the United States, have now caused governments to act. For instance in the US Energy Secretary Steven Chu announced a series of initiatives at the Department of Energy to more broadly implement cool roof technologies on DOE facilities and buildings across the federal government. Other governments have also taken action and have started encouraging local builders to start installing white roofs along with light coloured exterior finishes.

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The people of the Island of Santorini have the idea.