The short answer
Lighting controls switch or dim lights automatically. Presence (PIR) sensors turn lights off in empty spaces, daylight sensors dim fittings when there is enough natural light, and DALI gives each fitting a digital address for dimming, grouping and scenes. Controls only save energy when they cut output or hours.
Presence and absence detection
Presence detection switches lights on when someone enters and off after a set time without movement. Absence detection needs a manual switch-on but switches off automatically, which can save more in rooms with good daylight.
Daylight dimming
A daylight sensor measures light in the room and dims fittings near windows or roof lights when daylight is strong. It works best in perimeter zones and buildings with roof lights.
DALI
DALI (Digital Addressable Lighting Interface) is a standard that lets each fitting be addressed, dimmed and grouped, with scenes and fault reporting. It suits larger offices, retail and hospitality where flexibility matters.
Typical costs
| Control | Budget (ex VAT) |
|---|---|
| Presence (PIR) sensor | £40–£80 per sensor installed |
| Daylight sensor | £60–£120 per sensor installed |
| DALI control | £50–£150 per luminaire, on top of the fitting |
Questions
Where do sensors save most?
Meeting rooms, toilets, stores, plant rooms and warehouse aisles, where lights are often left on with nobody there.
Related services
Lighting controls
Presence detection, daylight dimming and DALI systems.
Office lighting
Glare-free LED lighting for desks, meeting rooms and receptions.
Warehouse lighting
LED high bays and aisle lighting for warehouses and distribution sites.
LED lighting upgrades
Swap fluorescent, halogen and metal halide fittings for efficient LED.
Last reviewed 9 November 2026. This guide is general information, not legal, tax or engineering advice for a specific site.