Abstract: Using windows with reflectors and roof elements with a triangular pyramidal structure, the natural sun rays of the entire spectral range from infra-red to ultra-violet are spread at least in a major part of the room in a controlled diffuse manner. Local excessive illumination and overheating of the room in the vicinity of the window are thereby prevented. In case of insufficient natural lighting, fluorescent lights permit a large-area, uniform overall room illumination. As regards rooms with flat roofs, additional light may be introduced in diffusely controlled manner into room by truncated pyramidal roof domes. The roof elements may comprise baffles by means of which acousting dampening openings can be adjusted individually for the purpose of additionally controlling the sound waves generated in the room. The invention allows creating conditions of optimal comfort in a room while simultaneously saving on auxiliary energy by using the natural energy of radiation in a controlled manner.