Lighting design can be said to be optimum when it has taken account of the nature of the space, its purpose, the special features of the building and the intentions of the architect, and has treated light as an additional material and design element. Artificial lighting can be superior to natural lighting. It can help people find their way around the interior of a building. Light becomes the fourth dimension in architecture.
Space and function
The space to be lit is divided into functions and areas for the purpose of defining the lighting tasks. These areas may be workplaces, sales areas, counters and shelving, entrances and walkways. We talk about "zoning". The zones are defined according to the tasks to be performed in them, their functionality and their emotional impact.
Light shapes the space
Based on experience and intuition, lighting designers decide which lighting effects will best serve the intended purpose. In the various zones, light is used for background lighting, for accent lighting or for marking routes, for helping people find their way around and for highlighting architectural features. Light shapes the space and helps people perceive their surroundings. There is a virtually unlimited number of ways in which style elements, lights and lamps can be combined. Often it is a good idea to call in a competent partner.
Light and lamps
Depending on the task that the lighting has to perform, one or more different types of lamp may be needed. With the aid of initial estimates and computer programs, it is possible to define the number of light sources required, their wattage and other technical details. This goes hand in hand with selecting the luminaires.
Lighting designers often have to reconcile a number of conflicting requirements. They have to take into consideration overall design, luminaire technology, economy, energy savings and interaction with other equipment.
Quality features of lighting systems:
The following quality features are described below:
- lighting level
- luminance distribution
- glare reduction and directed light
- directed light and the effects of shadow
- light colors and colors rendering
The lighting level has a major influence of performance, productivity and safety at work. However, as the lighting level increases so too do the costs. Consequently, the recommended values for illuminance are generally compromises between visibility, comfort, cost and energy consumption.
|20||Corridors and service rooms|
|50||Production facilities with no manual intervention|
|100||Production facilities with occasional manual intervention|
|200||Minimum for work rooms that are constantly occupied|
|300||Work rooms for medium-fine work(e.g. locksmiths and plumbers)|
|300-500||Zones with computer terminals|
|500||Work rooms for normal and fine work(e.g. office work)|
|1000||Individual workplace lighting with additional general lighting for extremely fine work(e.g. assembly of small parts)|
For optimum vision, the German DIN 5035 standard recommends a luminance ratio of 3:1 between the close field and the ambient field. The close field is the work area and ambient field is the immediate environment of the work area. This ensures that the eye adapts properly.
When choosing and positioning lamps and luminaires the danger of glare must be taken into account. Thus an unfavorable positioning can lead to direct glare (looking directly into the lamp) or to reflected glare (across shiny or reflecting surfaces). This can impair the vision. In order to minimize reflected glare surfaces of workplaces should be mat. Furthermore the medium light density at the room boundaries should not be more than 200 cd/m2 sein.
Directed light and the effects of shadow
For right handed people the light should fall onto the work surface from the left side. Otherwise shadows could impair perception. Strong contrasts should be avoided.
Light colors and colors rendering
Only use lamps with good to very good colors rendering (like Lumilux fluorescent lamps or halogen lamps) in order to naturally represent furnishings and other materials.
The Kruithof comfort curve indicates which range of illuminance is seen as comfortable at which colors temperature.
This shows that lighting systems with low color temperatures of 2700° to 3000° K are seen as comfortable in the range from 50 to 100 lux, whereas higher illuminances are seen as unpleasant. At a color temperature of 6000° K, for example, illuminances of at least 500 lux have to be provided so that people in the room feel comfortable.