This type is defined by two- to four-level residential buildings with about three to ten residential units. The most ancient ones came from the adaptation of medieval buildings, made higher and deeper in order to adapt them to new usesand family's changfs. In the Wilhelminian era, they used to build city mansions for multigenerational living. Mostly the very prestigious facades were organized by an impressive entrance and bay zones, facades were decorated by stuck ornamentation. Although the structural thermal protection was hardly taken into account, due to the very large masonry the heating demand of buildings of this construction period is often lower than in the following periods. Multi-family houses from the interwar and postwar years have a high energy consumption due to the usually thin and uninsulated walls. In the 1970s and particularly in the 1980s, the insulation of the whole external building envelope spreaded out, resulting in a decreasing heating energy consumption.