A dimming system reads the amount of daylight in the space and automatically adjusts light levels to meet a certain threshold for light that works for the activities in the space. Getting this type of system to perform properly requires experienced contractors, as well as guidance from the manufacturer on fixture and sensor placement. Daylight dimming response should be slow and imperceptible so it isn’t distracting to occupants. 

Stepping is a common approach to controlling lighting systems with daylight sensors. This systems works by turning off a group of fixtures (or ballasts within a group of fixtures) when the daylight in the space reaches a certain level. This system is usually cheaper than dimming, but the sudden switching of lights on and off can be disruptive for occupants.

Select glazing that allows enough daylight on as many days, and during as much of the year, as possible. Typically, the visible light transmittance of daylight glazing should be above 60%.  

Discuss with your project team the possibility of adding more windows. Windows of different sizes in various locations have different levels of daylight penetration. Skylights offer diffused light, clerestories can provide longer daylight hours, and vision glazing can be more suitable for desk work. Note that not all fenestrations are suitable for all space functions.

Sketch a lighting layout that incorporates daylight sensors for the fixture types that are the most numerous and look to minimize fixtures that use the most power. 

Work with your lighting designer, in collaboration with the architect, to determine the applicability of the credit requirements and their potential implementation to your project. 

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. 

ASHRAE-90.1 requires the installation of an automatic shut-off for spaces larger than 5,000 ft2. Both timers and occupancy sensors fulfill this requirement. 

Spaces with daylight can save more energy in a “manual-on/auto-off mode” by forcing the user to turn on the lights. Many people will prefer to keep the lights off if they have good daylight.

Some new sensors self-adjust and “learn” occupancy patterns in the space. Some systems allow the time-out delay to change depending on the time of day to adapt to changing occupancy patterns. This can save even more energy by providing short time delays at night for cleaning crews, and longer time delays during the day to avoid false “off” occurrences.