Stephen Chu, Barack Obama's secretary for energy, proposes as a solution to climate change to paint all the roofs of the houses white, reviving a centuries-old idea to have cooler houses.
He is about to end up run over, his mother saves himPut one Climate change conference, organized by none other than from Prince of Galles (well-known champion of the environment): the Nobel Laureate Symposium which sees gathered around the same table a large group of nobel prizes in various disciplines together with the greatest experts of global warming. Who knows what new and incredible solutions to environmental problems one would expect to hear emerging. Instead it arrives Stephen Chu, guest of honor and secretary for energy of Barack Obama and leaves everyone speechless by presenting a solution as simple as it is effective to actively fight environmental heating at low, very low cost: paint the roofs white. That's all. But not one or two, all of them!
The simplest things are easily mistaken for useless, but it is enough for someone important to bring them to the attention and then everyone is there to beat the palm on the forehead: how could we have forgotten the teachings of our ancestors?
The idea is certainly not the most original: the villages entirely made up of white houses they are a usual panorama for those accustomed to travel along the coasts of the Mediterranean: from Greece to Morocco throughout the Mare Nostrum basin painting houses white to reflect the sun and keep cool has been a widely practiced solution for centuries.
Mr Chu does not speak "empty-handed": California, the US state most attentive to the environment, has already enacted a law requiring all new commercial buildings to have a white roof following a study of the California Energy Commission - quoted by Chu - which demonstrates how a white roof under the California sun is enough on its own save 15% of the electricity used by that building's air conditioner.
An article appeared last January on New Scientist pushed this reasoning much further. The author of the article, Catherine Brahic, starting from the observation that the earth has an albedo - that is the fraction of light or, more generally, of incident radiation that is reflected back from a surface - of 0.29 while cities, on average , of 0.1 therefore reflect less and absorb and heat up more.
A white roof, on the other hand, has an albedo of 0.3, even lower than that of the "natural" territory, where the completely white areas are very few. At this point, considering the total urbanized surface of the planet, if every roof were painted white - according to a very simplifying mechanistic reasoning - this would be enough to lower the global temperature by 1 °!
While these estimates cannot be taken as perfectly reliable, as climate models are extremely multidimensional, it appears that thecenturies old idea to have cool houses simply painting them white can quickly come back into vogue.
However, the climate does not live by albedo alone and the roof could be occupied more profitably by plants - the so-called green roof we have already told you about - that in addition to reflecting heat, they contain rainwater, produce oxygen and embellish the landscape, or even better from solar panels capable of producing clean energy. Compared to these two very valid alternatives, white roofs have the immense advantage of being cheap and easily achievable with small investments. Their very cheapness makes them applicable on a large scale in industrialized countries but also in developing countries that still do not have access to the latest technological advances, but whose inhabitants often experience the consequences of climate change harder.
Michele Clausi
