From Wai Wong, Melbourne, Australia
While John Tons’s idea of painting every roof white is effective at cooling the home and reducing the urban heat island effect, it has a negligible effect on a global scale, because the total area of roofs of buildings is minute compared with Earth’s surface area (Letters, 29 November).
Antarctica’s surface area alone is equivalent to the roofs of about 100 billion medium-sized homes, far more than the number of roofs that can potentially be painted white. That is why the drawback of photovoltaic solar panels’ dark colour is dwarfed by their benefit in reducing fossil fuel consumption. On the other hand, road surfaces cover a much larger area than roofs, and trials of light-coloured road surfaces are happening around the world.
