The infrastructure of a building starts already in front of the entrance. Is the entrance clearly recognizable? Is there transparency from the outside in, that makes the building appear inviting and suggests security? Or is the sky reflected so strongly in the glass facade, that everything behind it appears dark?
Our evolution has made it so that we humans don’t like to go towards the darkness. That hasn’t changed since we were Neanderthals. With brightly illuminated wall surfaces in the interior or sun-like points of light on the ground, lighting designers can ensure that users already from outside see where the way leads behind the door.
Show the way
Also behind the entrance and heading into the building the light level should not drop substantially. Accent lights in important positions lead the user through the building and provide a feeling of security for him. The rules for security lighting (DIN EN 1838) also offer good advice for the general lighting design. Especially if planned for older users, since then, basically every way is regarded as security-sensitive area and potential point of an accident.Especially bright accents on doors, stairs, any level changes on the ground, intersections and changes of direction in the hall, form the basic elements for the path finding by light.
When distributing the remaining general lighting lighting designers strive for uniformity. Avoiding large differences in brightness is key, as otherwise the high intensities in accent lights lead to large light-to-dark contrasts. Our eyes can adapt to both very bright and very dark situations. Coming from a dark level into a bright one, this works very fast; in a reversed situation the eye adapts very slowly. Very fast changes of the light levels, such as in one very unevenly lit hallway or in flickering light, our eyes can therefore not provide their best performance.
Security through light
Glare should generally be avoided. This is another important point from the rulebook for emergency lighting, which gains significance in the general lighting, the older the users are. The vitreous in the aging eye is often clouded and scatters directly incoming light, resulting in glare. The light in the eye is then behaving similar to light in a smoke-filled room: the smoke scatters a small open light source and it is hard to perceive anything else than the blinding light. A narrow beam, well screened off light source, however, would produce only a light beam down into the smoke and not so massively disrupt the vision. For this reason, glare-free luminaires in areas of path finding are a good choice. All luminaires designed for Office workplaces comply with these criteria.
The right lighting dramaturgy
For the illumination in corridors and access areas, different standards recommend 150 lx and more. But at the time of implementation, two things are more important than the proper Lux Level: Who are the users? and: What materials and colours are being used?
Will people over 60 be using these corridors? Then, we should raise the light intensity by 100% due to diminishing eyesight, to ensure safe seeing and walking. Are the materials very dark? Very bright? Very high in contrast? Then, they affect the perception of brightness of the room regardless of the illuminance. A black wall will appear darker than a white one – no matter how much light you throw on it. The choice of material and color can thus be critical to health and safety. Using the reflection factors of surfaces (ρ) we can calculate and plan the luminance in the room and include it into the guidance dramaturgy of the building.
Self-evidently the light on all paths leading into the building should be available quickly to 100% when switched on. Nobody wants to step onto an unknown hallway, having to walk a few steps before the light slowly turns on and dims up. Orientation and safety must be a given at any time of day or night. At the same time, we want to save power and take advantage of natural light, therefore, the use of intelligent control systems is necessary.If you want to make life easy for the Neanderthal in all of us, then give him islands of light, where along he can find his way through the unknown building.
This article first appeared in Architektur und Bau Forum magazine.