What is the principle of Constant Light Control regulation in KNX?
A — Maintain a fixed illuminance (e.g. 500 lux) by varying the artificial lighting in response to the natural daylight contribution
(A) is correct: Constant Light Control is a closed-loop combination of a lux meter and a dimming actuator. The controller compares the measured illuminance to the setpoint (e.g. 500 lux) and adjusts the artificial output to cover the gap left by natural daylight from the windows. Energy savings are typically 30-60% versus simple on/off switching, and the function is usually paired with presence detection to avoid lighting unoccupied zones. (B) describes a brute-force presence-on-full strategy with no light regulation. (C) describes a time-based daylight curve, not closed-loop regulation. (D) describes an absence time-out, which is a separate function.
Always combine Constant Light Control with presence detection: a perfectly regulated 500 lux on an empty room is still pure waste.
- A.Maintain a fixed illuminance (e.g. 500 lux) by varying the artificial lighting in response to the natural daylight contribution✓
- B.Switch every lamp to full power as soon as a presence sensor detects occupancy
- C.Dim linearly from 0 to 100% over the course of the day (sunrise to sunset)
- D.Switch lighting off automatically after X minutes of inactivity
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