Reflectivity

The reflectance indicates what percentage of the luminous flux is reflected by a surface. Generally speaking, light-colored surfaces—such as white walls—have a very high reflectance, which means that a lot of light is reflected back into the room. Dark surfaces, on the other hand, have a very low reflectance and, so to speak, “absorb” a large portion of the light. As a general rule, the darker a room is painted or decorated, the more light is ultimately needed to achieve the same illuminance on a surface as in a bright room. The reflectance coefficient is therefore particularly important to consider for visual tasks, such as at workstations, where good lighting plays a very important role. Typical reflectance coefficients that can serve as a guide include, among others:

• White walls have a reflectance of up to 85%
• Light-colored wood paneling has a reflectance of approximately 35%
• Red bricks have a reflectance of only about 15%

When lighting a room, it is therefore always important to take into account its characteristics and color scheme. To create a balanced impression of brightness, ceilings and walls should have higher reflectance levels and therefore should not be painted too dark. For furniture or work surfaces, the reflectance depends heavily on the specific requirements or activities taking place in the room. The floor, on the other hand, does not play a particularly significant role, which is why a reflectance of approximately 20% to 40% is sufficient here.