Sustainable lighting design offers various well-being and environmental benefits in addition to economic advantages for clients and users. Although daylight provides a free lighting source, for most spaces the amount and time of daylight is not sufficient and electrical lighting is necessary. A focus on sustainability becomes essential for minimizing energy consumption and improving the quality of life. Even though efficiency has significantly increased with LED technology, electrical lighting is still more widely used. Often the ambition for renovations or new applications goes along with a higher quantity of lighting instead of finding a better lighting quality with an adequate amount of energy.
Read on after the break for Light Matters’ 7 fundamental steps to achieve sustainable lighting.
1. Select an efficient light source
The search for efficient lighting starts with the right light source and its luminous efficacy as a key indicator. The higher the visible light output is in relation to the consumed energy, the more efficient your light source is. Due to the fact that incandescent lamps emit a large amount of infrared radiation, they offer only a very low luminous efficacy. In contrast, contemporary white LEDs enable a much higher luminous efficacy. The functional life is another important factor for light sources: the longer the functional life, the lower your maintenance costs will be.
2. Choose efficient and appropriate luminaires
The optical system within a luminaire should feature minimal light loss in order to accomplish a high light output ratio. However, a high light output ratio is often accompanied by a lower visual comfort. The right balance between efficiency and visual comfort is crucial for achieving sustainable lighting solutions. The lighting distribution should also fit the specific application. While a floodlight might be highly efficient for realizing a focal glow for a small sculpture it would not be the right tool as it would create a lot of glare.
3. Turn lights off if unnecessary
A small, but very effective way to improve sustainability is to switch off the lighting when it is not necessary. And, if only a low level of general light is required the lighting could alternatively be dimmed down to a minimum level in order to save energy.
4. Include smart lighting control
Sensors combined with lighting control systems enable considerable automatic energy savings. At daytime, light sensors can take natural lighting into account to reduce artificial lighting. With the help of presence detectors, low frequented areas like corridors, outdoor areas at night or vacant offices could be dimmed to a minimum level or switched off when not required. For regular events, time-dependant lighting systems are suitable to optimise energy consumption, for example, in relation to office hours. An ergonomic interface facilitates an easy adaption for individual needs.
5. Design individual zones for expected activities
A huge amount of energy is wasted by planning high uniform illuminance levels to cover numerous possible requirements. Defining functional zones within large spaces and individually analyzing the expected activities offers an enormous potential for reducing electrical power. For drawing attention and separating important from unimportant areas, a proper ratio between accent and ambient lighting is beneficial. Low ambient lighting levels help to decrease the energy amount for effective accents.
6. Work with bright interior surfaces
Plan your interior surfaces with high reflectance to enhance the reflection of light in the space, but be careful with shiny or very bright surfaces that could cause glare. It is best to use matte light colours to improve the visual comfort. For a bright room impression, keep away from dark surfaces. Creating walls of light are another effective method for increasing the apparent brightness of a space.
7. Avoid glare and spill light
Glare interferes significantly with visual tasks and pleasant surroundings. Direct glare comes from luminaires, whereas indirect glare originates from reflections on surfaces. Specifically, fixtures with wide beam angles and not precisely defined beam angles cause critical glare situations. In this situation, multiple small beams could lead to a much higher visual comfort than a few wide beam floodlights. Additionally, accurate lighting distributions without spill light are essential for minimizing glare. For example, in outdoor lighting the negative effect of spill light becomes apparent when the dark sky with its stars is not visible any more.
The second form of glare, the indirect type, occurs when the lighting is reflected from shiny surfaces like computer screens or glossy images on walls. A well-designed luminaire layout with adequate fixture positions and directions prevent indirect glare.
Lighting beyond energy
An exclusive focus on energy optimization could lead to weird lighting solutions. Pure technical driven installations might demonstrate a minimum power consumption, but if architecture, aesthetic and health is ignored users will not likely stay at these sites and all energy efforts would be unsuccessful. Therefore, lighting qualities need to incorporate the individual well-being, architecture and economics, as Jennifer Veitch, researcher at the National Research Council of Canada, has pointed out. However, the first step for good light should really begin with sustainable daylight architecture.
Light matters, a monthly column on light and space, is written by Thomas Schielke. Based in Germany, he is fascinated by architectural lighting and works for the lighting company and academy DIAL. He has published numerous articles and co-authored the book "Light Perspectives." For more information check www.arclighting.de or follow him @arcspaces