To optimise energy efficiency, buildings need to reflect radiation (infra rad, visible light, ultraviolet, etc) when they are at or above their intended temperature, and absorb radiation when they are below their intended temperature.
The tiles of the roof of the building would have a hinged panel in the middle of them. One side of the panel and the corresponding side of the underlying tile would be painted with a high albedo paint, the other side of the panel would and the other side of the tile would be painted with a low albedo paint. A small motor in the panel would flip the panel between the two states. The motor would be powered by a small solar panel and battery, and controlled remotely.
The panel and hinge attachment could either be attached to existing tiles, or built into new tiles.
The diagrams below illustrate:
It is noted that it may be better solution to cover the roof in solar cells and solar water heaters.