Poorly calibrated daylight sensors can result in little or no energy savings—and can also annoy occupants, so it’s worth it to calibrate the sensor settings regularly and confirm that the occupants are satisfied with the performance of the system.
Sensors can reduce the lighting energy use of infrequently used spaces by more than 50%. Places like bathrooms, pantries, and storage areas do not need constant lighting and automatic devices can save a lot of energy. Infrequently used stairways and hallways need only minimum safety-oriented lighting and should have occupancy sensors installed to avoid wasting energy when they are unoccupied.
As each sensor costs $30–$150, develop a lighting layout that strategically combines similar tasks and exposure to daylight to reduce the number of sensors required.
Although integrated control strategies have additional cost up front, these systems can also tie into mechanical systems to significantly reduce energy use.
Make sure that the owner knows about ongoing maintenance requirements for controls. Daylight sensors should be calibrated every 3–5 years to maintain the performance of the lighting control system.
Dimming systems often cost more than stepped systems, but also have better performance and are less distracting to occupants when the amount of daylight in the space changes.
According to the New Buildings Institute, occupancy sensors produce 25%-45% energy savings. Adding occupancy sensors is often a low-cost upgrade with payback period of less than one year.
If concerned about costs, do a payback analysis. Although some efficient fixtures cost more than typical ones, efficient fixtures significantly reduce energy use and operating costs and often have a payback of 1–3 years. Consider this payback analysis before eliminating any installed lighting power reduction strategies from the final construction plan.
