How it’s done

Light sources

Various light sources are used in outdoor areas. They differ in many respects, such as efficiency, light spectrum and colour rendition.

Light emitting diode (LED):

LED technology is comparatively new and continues to develop rapidly. The positive features of LEDs include energy efficiency, precision light control, variable light colours and dimming from 0 to 100 percent.

For aesthetic, health and ecological reasons, warm white and amber LEDs are recommended.

Due to the residual emission in the blue range of some warm-white LEDs, the Austrian Outdoor Lighting Guideline recommends the use of a filter, also to counteract the age-related drift of light emission into the short-wave range.

Boomerang effect
The cold- and warm-white LED dilemma
Contents of LEDs

High-pressure sodium lamp:

The positive features include a warm-white colour temperature, energy efficiency and good contrast vision. On the other hand, high-pressure sodium lamps offer only limited colour rendering.

Metal-halide lamp:

These discharge lamps are often employed for street lighting, and thanks to their compact design they are also used in floodlights. Some brands emit a relatively high proportion of short-wave and ultraviolet light. Since this light has impacts on human health and the environment, the use of metal halide lamps often attracts criticism.

Light colour and spectrum

In the interest of health and many animal species, light in the short-wave range below 480 nm should be avoided. Amber LEDs (below 2200 kelvin), many warm white LEDs (below 3000 kelvin) and high-pressure sodium lamps satisfy this requirement.

Light colour is the colour of light as it appears to the human eye.

Targeted lighting

Great importance must be attached to the use of fully shielded luminaires for controlled lighting that does not extend beyond the target area.

Targeted light control is also dependent on such factors as correct installation (parallel alignment of the light emission surface to the ground), intelligent optic design (reflectors or lenses) and flat luminaire diffusers.

A lower mounting height can be selected to reduce the range of the light emitted.That reduces illumination of the surrounding area and the resulting negative impacts on the nocturnal landscape and living creatures. Street lighting masts should not be more than 6 metres high.

On slopes, the street lighting is best located on the lower side so as to avoid unnecessary illumination of the surrounding area.

Such fully shielded luminaires have a maximum beam angle of 70° for optimum light distribution.

Enclosed housings are important so that insects and spiders cannot get inside the fittings. The luminaires should have a IP 60 protection rating at least.

Theodore Roosvelt NP – Light Pollution: The Solution Is Easy!

Operation

True lighting needs

Artificial light should only be available at the times and in the intensities in which it is needed. Through night-time set back or switch off and the use of intelligent control systems, lighting can be provided on the basis of true need.

Intensity

The human eye can adapt to low levels of illumination. Uniform, glare-free lighting that provides orientation offers increased safety. Experience shows that many lighting systems are much too bright. It is important to adjust luminous intensity to match visual requirements.

Good lighting design

The installation of all types of lighting systems (street lighting, sports facilities, facades, etc.) calls for individual solutions and the expertise of professional lighting planners, not least because of the wide range of products available on the market.

It is also important to invest in durable, high-quality lighting systems with easily replaceable components.

How it's done