Abstract: The present invention relates to a device for utilizing a surface, such as the surface of a floor, outside wall or roof, for a variable function, comprising a first functional element with an active surface area the size of at least a part of the surface, at least a second functional element with an active surface area the size of at least a part of the surface, and means for varying, on at least a part of the surface, the functional element with which the surface is utilized. The invention also relates to a method for utilizing a surface for a variable function.