Windows - diverse large, round or angular glass panes in lead frames provided daylight for the illumination of interiors. Depending on the quantity of glass, the size of the frame and the number of lead braces, the brighter became the interiors. Glass windows offered protection against the weather, but only limited protection against heat and cold. Huts and simple farmhouses had no, or only few, small windows that bathed the interior of the house in a dim semi-darkness. Only the dwellings of the social elites had several and larger windows. Natural sunlight structured everyday life. The more light protruded into the house, the less artificial light sources and, thus, costs were necessary and the more activities could be carried out inside the house. Glass windows gradually shifted social life from outside the house to the inside of the house. The nobility had entire buildings made of leaded windows to create greenhouses, in which delicate plants could spend the winter in northern Europe.