SAVING ENERGY WITH AN OFFSET

Use energy only when it is really needed: that is the principle behind demand-driven building automation. In terms of light control, presence and daylight dependent constant light control implements this premise particularly well through its energy-efficient use of daylight — although this can be improved even further using a simple concept.

Central perspectives, parallel perspectives and colour perspectives — just like in art, things in buildings can also often be seen from completely different points of view. One example of this is the use of daylight, which has become very important in architecture today. Daylight systems direct diffuse, natural daylight into the depths of buildings to help people in that building feel better and work more healthily. To achieve this, the architect calculates the ratio between the strength of indoor and outdoor lighting, also known as the daylight quotient.

A SIMPLE SOLUTION TO ENSURE MAXIMUM USE OF DAYLIGHT: OFFSET WITH JUST ONE REGULATING PRESENCE DETECTOR

The presence detector achieves constant lighting control using an integral light sensor. This also means that at least one detector is always required to control the light in a specific room zone. On the one hand, of course it would be ideal to do this in as many zones as possible to optimise the use of daylight. However on the other hand, it makes little sense to increase the number of detectors simply to achieve this.

So what do we do? This is the question that automation experts were also faced with — and they found a simple but effective solution: an offset between multiple lighting groups controlled by a presence detector. In other words, an offset that improves the use of daylight even if there is only one detector installed in a room. A first example of how it works is provided by the DUO DALI presence detectors in the COMPACT series from ESYLUX, which control two light channels in broadcast mode.

The following now occurs when the lights are used: As the daylight entering the classroom increases during the morning, the detector initially dims only the lights near the window. The zone away from the window still needs 100 % light output. When the light output from the lights near the window falls to 70 %, the offset of 30 % has been reached. The detector then starts to dim the lights away from the window. Once the daylight is sufficient in both zones, it switches all the lights off.

If it gets darker outside again due to the weather or the time of day, this sequence is reversed. The detector first increases the light output from the lights away from the window while the offset delays the same process for those near the window. Only when the lights away from the window have reached 100 % and the daylight continues to fade does the detector finally also set the lights near the window to full light output. The offset therefore improves energy efficiency through the earlier reduction or delayed increase in light output from the lights near the window as the daylight fades or brightens.

DUO-DALI-Präsenzmelder und APC-Präsenzmelder für DALI-2 zeigen so auf unterschiedliche Weise, wie sich durch einfache Offsets die Tageslichtnutzung der Konstantlichtregelung weiter verbessern lässt. Und das bei nur einem Melder und damit nur einem Lichtsensor im Raum. Es ist ein einfaches, aber wirksames Konzept, das die Energieeffizienz zusätzlich verbessert, dennoch eine normgerechte Ausleuchtung aller Zonen gewährleistet – und sich insbesondere bei den APC-Präsenzmeldern mit ihren vielfachen Gruppen übrigens ohne Weiteres auch für Räume mit mehreren Fensterseiten einsetzen lässt.