Lighting Control and BAS
There have been tremendous improvements in the efficiency of lighting over the last 20 years. The movement from older technologies such as incandescent, halogen, CFL, and fluorescent with magnetic ballasts has given way to the use of LED and high-performance T8 fluorescent options. As a result, new office building projects are being designed with lighting power densities that are around .5 watts/ft, a dramatic drop from what was possible even a few years ago. Still, lighting, in most buildings, remains the second highest energy user, and lighting controls remain one of the best options to improve efficiency.
Of course, there are also additional benefits to lighting controls including improved occupant support (i.e. comfort) by helping to provide the desired lighting levels. As states move to adopt the latest energy codes, the use of lighting control will become a requirement and no longer just a “nice to have.”
Ideally, we like to see a lighting control system that is integrated with the BAS. Having an integrated solution has many benefits, including the ability to set up and modify schedules for zones or areas of the building that include both lights and HVAC. Designing an integrated system is not without its challenges, though. Usually, lighting control is included with electrical design (division 26), however, BAS is often part of mechanical (Division 25). There are several ways to proceed with this integration, including moving BAS into Division 25 (Integrated Automation Facility Controls), then developing the needed coordination with all other sections and designers. Alternatively, BAS can stay in Division 23 and the designers and trades can then be coordinate as needed. Key items to watch for are protocols support, lists of data to be shared, and contractor responsibilities (i.e. who programs or does the integration).
While it is desirable to have an integrated system, it is very viable to have a lighting control system that is standalone from the BAS. The options vary from traditional lighting control systems that have the ability to switch at a central panel or out in the zone to newer systems that allow for dimming and occupancy control at every fixture. We are even starting to see lighting fixture companies beginning to offer wireless lighting control as an option for the fixture.
When selecting a lighting control product, be sure to look closely at not just the functionality of the system, but at how well it can be supported and modified as needed. Keep in mind that it is fairly typical for space usage to change, and ideally the lighting control system can readily be modified to keep up with these changes.
LIGHTING CONTROL BASICS
With the design of any lighting control system, it is important to remember the basics.
- Scheduling. Schedule lights to be on based upon anticipated building or zone occupancy. This can readily be shared with HVAC zone schedules. Scheduling often works best when occupancy sensing is not practical for areas such as lobbies, corridors, and open office areas.
- Occupancy control. Use a motion sensor to bring lights on or off based upon occupancy or vacancy. Occupancy sensors have traditionally been used in areas with intermittent usage such as conference rooms, private offices, and restrooms.
- Daylight harvesting. Use sensors that turn off or dim lights when daylight is available.
- Occupant based control. Use switches or other methods so that occupants can readily turn on or off lights or adjust light levels.