Energy savings

Figure 2.71: Energy savings potential of light management. The combination of switching-off in case of absence and daylight-dependent constant light control results in great savings potential.

Increased comfort, which used to be the most frequent reason to opt for light management, has long been replaced by energy savings. The multitude of applications which feature high potential for energy savings creates a great demand for suitable installations, which has led to a development spurt and drastic cost reductions in the most recent past, which in turn further accelerates the spread of light management systems.

As mentioned above in the example of the sports hall, in some applications it is possible to save energy merely by adjusting the artificial lighting level to the value required at the respective point in time instead of permanently operating at 100%. This used to be implemented in steps through series switching of several light sources or luminaires; however, the uniform dimming of all light sources, particularly LED luminaires, has proven to be the more rational and economic solution (see chapter "Dimming through operating current regulation and pulse-width modulation"). Any desired lighting level can be set and called up without negatively impacting other photometric quality criteria such as e.g. uniformity or glare.

Another advantage is the higher level of user acceptance of dimming. Switching in steps is often perceived to be irritating. Dimming processes happen unnoticed and do not impair visual comfort.

Fundamentally, only an additional sensor for detecting the current illuminance at the workstation is required at this point to factor in interfering light available at the visual task location and to further reduce the lighting installation's energy consumption by means of constant light control. At many workstations, daylight is readily available, which means great energy savings potentials can be utilised (see also chapter "Daylight utilisation").

When measuring power consumption in dimmed operation, it should be considered that a reduced power factor (see chapter might manifest. The absence of people in rooms, which can be made useful be means of sensors, also presents potential for further savings (see below, section 2.4.2). In many applications, the lighting can be switched off or operated in a highly dimmed state during times of absence. However, energy-saving switching-off in case of absence requires reliable presence detection to avoid risks regarding occupational safety. When selecting and arranging sensors expertly, both aspects can be combined excellently with the means available today.

Available sensor technologies and essential framework conditions to be observed for presence detection concepts and daylight-dependent regulation are outlined in the following technical sections of this chapter.

Information on the energy savings potential of presence detection and daylight-dependent regulation (see figure) can be found in the chapter "Light and the environment", section "German standard DIN V 18599".