In office rooms and other small rooms it is usually hard to justify investment in presence-controlled lighting on a purely financial basis. The investment cost of existing technology is too high in relation to the possible reduced energy consumption (saving). Detection in this type of premises uses IR detectors equipped with a high-resolution lens. To improve the results and increase the saving, wall sockets can also be connected to the presence control. This means that fittings for desk lights, point lighting, monitors etc. can be presence-controlled.

NB:

If the office room is planned with fittings with built-in presence detectors, the opportunity of presence-controlled wall sockets will be missed.

Other benefits such as environmental and convenience benefits can often be entered in a ‘calculation’, which can lead to justification of the investment. Future increased energy prices and more advanced and cheaper technology can also make it profitable to invest in presence-controlled lighting in office rooms.

Light sources

The fittings can use conventional 50 Hz operating devices or dimmable HF operating devices. In the latter case the lighting can be dimmed manually using a separate potentiometer that does not affect the presence control.

Control

In an installation for presence control of the lighting the user must be able to determine when the lighting is switched on. This requires a logic module (EX-11) that blocks the IR detector upon entry into the room. It is not energy-efficient to impose lighting on people every time they enter the room.

One will often only want local lighting of an area, or the natural light entering may be sufficient. Using a strap the EX-11 can be programmed for two separate areas with a lighting group in each. In this example the strap in the EX-11 must be in the ‘Two Areas’ mode.

The lighting is switched on and off using impulse push-buttons in the normal manner. However, if one forgets to switch off, the detector takes over and switches off when the room is empty.

If dimmable fittings are used the lighting can be dimmed manually using a potentiometer in each room. The simplest solution is analogue fittings using 1 – 10 V regulation.

Positioning of the detector

To achieve the optimum direction of detection and avoid the detector looking out through the door, the ideal positioning is in accordance with the design below. The mounting height must be 1.8 – 2.0 m.

It is also important to select a lens with as many fields of detection as possible, and for them to be as dense as possible. For areas involving sedentary work we recommend Lens 51 in the lens library for the PD-2200.

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