SOMETIMES, the simplest ideas are the best. To absorb heat from the sun efficiently—to use it, for example, to heat water—you need large, flat, black surfaces. One way to do that is to construct those surfaces specially, on the roofs of buildings. But why go to all that trouble when cities are full of black surfaces already, in the form of asphalted roads?
This was the thought that occurred ten years ago to Arian de Bondt, an engineer who works for a Dutch building company called Ooms. Eventually, Dr de Bondt persuaded his employers to follow it up. The result is that their headquarters in Scharwoude is now heated in winter—and also cooled in summer—by a system that relies on the surface of the road outside....MORE