The days of providing a simple wall switch to control lighting are gone. The last few revisions of the energy codes, whether the International Energy Conservation Code or ASHRAE 90.1, has continually increased lighting control complexity. However, with this complexity significant energy reduction, and thus lower operating costs, can be achieved resulting in relatively short return-on-invest times, typically between two to three years (depending on the type and quantity of lamps being controlled and their operating durations).
In addition to a manual means to control lighting in a room, most rooms are now required to have an automatic means to turn the lights off when the space is unoccupied, either by vacancy sensors (formally referred to as occupancy sensors), programmable circuit breakers or time switches. Depending on the automatic means, the room lighting controls may also require a means to reduce lighting levels. Additionally for larger rooms with lighting areas located adjacent to windows or under skylights, the lighting within these areas may be required to be separately switched from the room’s general area controlled lighting.
The following provides some of the options which need to be evaluated in selecting the appropriate lighting control scheme and components for each application:
- Switches – line-voltage, low-voltage or wireless
- Programmable circuit breakers
- Time clock versus vacancy sensing
- Occupancy sensor switches – line-voltage, low-voltage or wireless
- Occupancy sensors – line-voltage, low-voltage or wireless; wall or ceiling mounted passive infrared and/or ultrasonic/sound sensors
- Daylight sensors – open or closed loop
- Ballasts quantity and types – step-dimming, 10-100%, 1-100%, 10-volt dimming and DALI (digital addressable lighting interface).
Many options can be selected to meet the code requirements, but selecting the appropriate lighting control scheme for each room or area should be based on the space’s function, ease of use by the space’s occupants and project’s budget.
If you have any questions regarding the energy code requirements for your project or the appropriate lighting control options, please do not hesitate to contact Jon B. Slagel, PE at (717) 845-7654 or firstname.lastname@example.org.