Fit daylight-linked controls (photocells)

Capital cost is approximately £50 - £90 per sensor. The energy saving available is often around 40% in relatively bright rooms. Daylight sensors are used to adjust lighting levels according to the level of daylight the room is receiving. They come in two forms:

Switching: these automatically switch off the lights when the level of natural light is adequate, and switch them back on when it is not. They cost approximately £50 to install, and can usually be applied to fluorescent and filament lamps.

Dimming: these dim or brighten the lights according to the levels of natural light present. So, on a bright day the lights are dimmed right down (or even off), whilst on a dull day, the lights may be partially or fully on. Dimming sensors tend to be more expensive than switching ones, but, depending on the daylight distribution in an area, one sensor can often control a large bank of lights.

All fluorescent and filament lamps can be connected to switching photocells. However, not all types of lighting can be dimmed.

In areas of constant use, the dimming daylight linked controls are usually the best option, as lights switching on and off can distract ocupants, whilst lights dimming and brightening according to natural light levels tend to be imperceptible.