Aesthetically pleasing as they may be, windows are typically a drain on a buildings energy efficiency. Enter Smart Energy Glass, a new innovation from Dutch Peer+ that turns windows into solar energy collectors with a customisable appearance.Not only are Smart Energy Glass windows available in several colours, but they can switch between three modes: dark, bright and privacy, which scatters the light passing through. Even better, the glass serves to collect solar energy, which can then be used directly or fed back to the grid.