Light management: giving priority to natural light

Planners seek to keep artificial lighting to a minimum

Light management is about regulating and controlling artificial lighting, combined with targeted use of daylight and automated blinds. Artificial lights are only switched on or boosted when daylight is not sufficient. Efficient light management therefore starts with the floor plan and window design. More natural light is better for people and for the environment.

Summary

Directing daylight to reduce artificial lighting

Energy costs for artificial light are strongly correlated with the daylight autonomy of a building. This figure indicates the percentage of working time that space will be adequately illuminated through the use of daylight alone. The use of daylight can be optimised by:

  • carefully zoning spaces to avoid shadows cast by neighbouring buildings,
  • positioning glass areas correctly and efficiently,
  • deploying an automated solar shading system that adapts to the incidence of light and allows diffuse daylight to flood the interior.

The daylight factor (DF) is used to describe the available amount of daylight in a room or building. For side lit spaces, for example, according to the international DIN 5034 standard there should be a daylight factor of 0.95% halfway into the area. In spaces with skylights, the DF should be between 4 and 10%.

Percentage of working time spent with daylight only
Based on Bauer/Mösle/Schwarz: Green Building. Guidebook for Sustainable Architecture

Failing to utilise daylight can increase energy costs by 30% as a result of having to switch on artificial lighting. In addition to the economic benefit and energy efficiency of good daylight autonomy, daylight and sunlight are proven to have a positive effect on people’s motivation and performance levels (visual comfort).

Using lighting technology to reduce CO2

Energy-efficient lighting is hugely important in the context of environmental protection. The German Electrical and Electronic Manufacturers’ Association (ZVEI) has calculated that switching entirely to energy-efficient lighting across industry and private households could save up to 13 million tonnes of carbon dioxide a year in Germany alone. By optimising existing lighting systems, it is possible to achieve energy savings of up to 50% in some office buildings.

The following offer high potential savings:

  • Long life energy-saving light bulbs with high luminous efficacy
  • Highly efficient lights and direct/indirect lighting design
  • Money-saving lighting ballasts such as electronic ballasts (EB)
  • Energy management systems with daylight and artificial lighting controlled and delivered as needed
  • Presence detectors that switch lights off when nobody is in the room
  • Dimming lighting systems to maintenance level

Achieving the biggest energy savings requires the right combination of different types of bulbs and the appropriate controls and ballasts, as well as making effective use of the lighting system on a daily basis (energy management).