Controlling lighting with daylight sensors and presence detectors promises savings in terms of energy consumption. Dr. Sebastian Knoche, Research & Development department at TRILUX, was eager to find out for certain. Therefore, in the context of the European research project Repro-Light, he measured and analysed lighting data in the TRILUX training workshop over the period of one year. His results: presence detection reduced energy consumption by five percent, daylight sensors facilitated energy savings of up to 26 percent and extended the LEDs’ service life by up to 37,000 operating hours. And that is not even the full extent of the potential.
The luminaires in the Arnsberg training workshop were networked using the LiveLink light management system and equipped with sensors for presence detection and daylight control. To examine the influence of the sensors on energy consumption and service life, the luminaires were monitored over the course of one year using the TRILUX cloud service and data was recorded at 261,000 points in time. The goal: developing a mathematical model to predict or quantify savings achieved by sensors in a precise way. Based on these formulas, TRILUX customers can calculate the advantages provided to them by a sensor-controlled light management system very precisely, in advance.
The energy consumption of a lighting installation depends on the time of day, the day of the week and the course of the year. Daylight sensors regulate precisely the required amount of light to natural sunlight to achieve a certain level of lighting. The case study shows the dimming curve measured in the training workshop correlates to the elevation angle of the sun over the course of the year. The result is impacted, among other factors, by the geographical latitude (due to the deviating sun angle) and the time of use of the luminaires. In classic office applications in Germany with a working time from 9 a.m. to 5 p.m., the savings potential using daylight sensors alone is already up to 26 percent.
In addition, the presence detector switches off the lighting in the training workshop during working hours for an average of 21 minutes per day. This corresponds to added savings potential of about five percent. In areas with lower public use, savings are significantly greater.
Service life – extended by up to 37,000 h
Reduced power at the LED control gear unit means a lower average temperature at the LED chip. The case study proves that the daylight sensors increase the service life of an LED from 50,000 h to up to 87,000 h with this method. The scale of the effect – corresponding to the energy savings – depends on the use of the lighting installation. Even with around-the-clock operation, the LEDs’ service life will be extended by 18,000 hours using daylight sensors.
Research for a more sustainable society
Another research topic within which Dr. Sebastian Knoche is currently engaging, under the context of the Repro-Light project, is the improvement of material efficiency in LED luminaires for a comprehensive life cycle analysis. Besides energy resources, a responsible treatment of material resources is an important starting point for a more sustainable society. The Repro-Light project will continue until September of this year.
All results of the study regarding light management are available to interested readers here:
S. Knoche, Data Analytics in Connected Lighting Systems – case study, LpS 2019 conference proceedings