Image Source: Cool Roof Contractor
In much the same way that more ice/snow reflects UV rays instead of absorbing the heat the way the oceans do (think: feedback loop that results from melting polar ice caps), cities are now giving white roofs a second look as a way to cool cities and fight climate change. The Los Angeles Times reports that the Climate Change Research Conference, held this week, advised that if buildings and road surfaces in 100 of the largest cities in the US were covered with lighter and heat-reflective surfaces the savings could be massive. Roofs account for 25% and pavement account for 35% of surface area in cities.
California has required white roofs on commercial buildings since 2005, but starting next year, all "new and retrofitted residential and commercial buildings [in California], with both flat and sloped roofs, will have to install heat-reflecting roofing." Painting flat roofs white is fairly easy but sloped roofs are more difficult which is why they will be allowed to just install "lighter" roof surfaces. Lighter or metal roofs also help to lower electricity costs by reducing cooling needs. Authors of the study, published in the journal Climatic Change, also report that cooling a city will also reduce smog and offset carbon emissions. Lighter roofs themselves do not directly emit fewer emissions, but they do directly affect other things which emit carbon like the energy needed to cool your home under that dark roof.The technique is known as geo-engineering, meaning "the artificial manipulation of the environments of the Earth, especially as a means of counteracting global warming." Estimates for net annual energy savings in the US from increasing lighter roof surfaces could top $1 Billion USD.
These lighter roofs can be made from vinyl materials, acrylic paints, or even green roofs planted on the roof. This will mean more green jobs, though the exposure to these chemicals is not great. Residents can also choose to independently add white or metal roofs outside of city regulations in order to lower electric bills, particularly in desert conditions or climates that get high temperatures and lots of sun.
:White Roofs Cool the World:: Los Angeles Times
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