Ever burn your foot walking on hot asphalt in the summer? That’s because black absorbs heat—while white reflects it. Well, in case you haven’t noticed, modern cities are covered in the black stuff. Dutch construction firm Ooms is now heading its headquarters by running water pipes under the street. Some of them collect heat in the summer and run deep into the ground where they heat water via a heat exchanger. That heated water is stored for winter—a sort of battery, if you will. In fact to take it a step further, the water is returned to the ground after heating the building, by passing under the street again. The residual heat in the water, now only a few degrees above freezing, melts any snow or ice on the road surface. The water is then stored—used cold to cool the building—before being run under the asphalt again to prepare for winter. Brilliant!