The use of surface-mounted lights is often determined by practical considerations. Diffused lighting is ideal for tasks. It generates even light dispersion, lighting up every corners effortlessly. They all share a common guiding design principle of efficient visual comfort. For example, there might not be sufficient room to install recessed downlights in the ceiling. The decision to use surface-mounted lights in a lighting concept can considerably reduce installation costs, as in buildings with solid ceilings or in existing buildings.