Most daylight harvesting schemes fall short of performance goals, says study
A new study by the Energy Center of Wisconsin shows the importance of commissioning when implementing automatic daylighting control programs.
Analysis of daylighting control systems in 20 office and public spaces in Minnesota and Wisconsin shows that while the automatic daylight harvesting schemes are helping to reduce lighting energy in the buildings, most are not achieving optimal performance, according to a new study by the Energy Center of Wisconsin (ECW).
According to ECW, the median daylighting control system studied was saving 23% of lighting energy, including impacts on heating and cooling. This translated to 915 kWh saved for every kW of lighting controlled. But the average effectiveness (the energy saved versus energy saved with ideal control) of the controls was only 51%. This meant that almost half of the potential savings from these controls was not captured due to imperfect controls operation. Even worse, four of the 20 spaces studied had zero savings.
The low level of effectiveness, says ECW, is evidence of a lack of controls execution. The findings show that successful implementation of automatic daylighting control requires a significant commissioning effort to reach full energy-savings potential.
As part of the report, ECW developed a tip sheet on commissioning and calibration and function testing of lighting controls. Recommendations include assigning a single person of the construction team to be responsible for verifying completion of all steps in the daylighting commissioning process, and proper training of the building owner/operator on the controls equipment and systems. Download the tip sheet (PDF)