If every building made more energy than it uses, would all the world's power plants pack up and go home? Maybe education would be fully funded and the military would be forced to have a bake sale!
But really: There is a building in Bellenberg, Germany that produces more energy than it consumes, mostly by being super energy efficient in the first place. It also has solar panels for electricity and ground-source heat pumps for heating and cooling. It doesn't just produce a little more energy than it uses, either: It's making 80 percent more juice per year than it consumes.
If you think about it, there's nothing terribly magical or perpetual motion-machine-ish about this energy-positive building. We already know how to build houses that have no need for heating, so taking one of those and strapping some panels on the roof should do the trick.