The part of artificial and outdoor lighting from the electricity consumption

Rebound effect - when light becomes cheaper, many users will increase illumination, and some previously unlit areas may become lit.

3 Ways to reduce energy consumption in street lighting systems:

1. use light only when and where it is needed (using motion sensors for example).
2. Defining maximum permitted illuminances for roadway lighting.
3. Defining and following street lighting system efficiency in terms of kilowatt hours per kilometer per year.

Fig. 1 In only a few human generations, the nighttime environment radically changed.

Fig. 2 - Aerial photograph of newly installed lighting in Rathenow, Germany, This is far brighter than is needed, for Pedestrian crossing.

LEDs Advantages

• Can be instantaneously dimmed to 10% or turned off entirely
• Allow directed light, precision, and control over color