ANSWER: Revolving doors serve as an airlock, which keeps cold air out, thereby reducing heating costs. Revolving doors cut off the air path between the outside of the building and the inside.

When news breaks, you need to understand what actually matters — and what to do about it. At Vox, our mission to help you make sense of the world has never been more vital. But we can’t do it on our ...

Darmstadt and Dubai present the extreme possibilities of contemporary living. In the first, a small town south of Frankfurt, you find the Passivhaus Institut. Since 1996, it has been experimenting ...

Starting in February 2014, he plans to take season 4 of the show weekly; you can support his Kickstarter campaign here. His most recent show—about revolving doors—can be played below. Or keep reading ...