Utilities and Energy Codes Drive Changes in Lighting Systems
October 5, 2015
As lighting requirements have changed, so have electric rates and structures. Utilities have multiple rate schedules and programs designed to encourage efficiency. This is driven by ever increasing demand on the grid. Instead of building more and more capacity, there is more benefit to cutting energy waste out of the system.
In the last few years, many utilities and grid operators have begun to offer demand response (DR) programs that pay customers to drop load when wholesale power prices spike, or when there's a problem maintaining service. DR ballasts, run via powerline carrier controls, now allow facility managers to drop wattage and light output by about 30 percent, gradually enough to not tip off occupants, in return for potentially lucrative payments. The same units may also be used, at any time, to manage a facility's peak demand. In some areas, peak demand charges are now a major component of an electric bill.
Changing energy codes have fostered bi-level ballasts and switching systems in lighting schemes, as well as other changes. Technology improvements are also driving improvements.
Recent versions of the ASHRAE 90.1 energy standard
and some state energy codes are making bi-level lighting mandatory for new construction and major lighting renovations. The goal is to cut electricity use whenever natural light or tasks allow a lower light level.
Likewise, some codes now call for automatic lighting controls in relatively small spaces. In the past, once lighting wattages had been reduced, occupancy sensors were often not economical. Where they could not replace existing wall switches due to room layout or other reasons, labor for wiring to ceiling-mounted sensors was prohibitive or difficult. Enter wireless sensors that communicate by radio to relays built into new wall switches. Using one of several wireless standards (e.g., EnOcean), a variety of such products address such issues.
To cut kilowatt-hours when lighting stairwells facility managers can consider fixtures that contain their own sensors. When no occupancy is detected, they drop down to only a third of full light output and wattage. Stairwells never go dark, thus maintaining safety and security while greatly cutting operating cost.
Changing occupancy patterns and tasks suggest other ways to economize on lighting. The proliferation of computer-based tasks has greatly reduced the need for high ambient light levels. Low-cost LED task lights are now available to provide more light just where it's needed, instead of continually pumping it out of ceiling-mounted fixtures. When personnel are out of the office or working from home, task lights at the facility remain off, cutting wattage and consumption. In such locations, vacancy — as opposed to occupancy — sensors might make more sense. The former require occupants to manually turn lights on, but then shut them off when a room is empty. Doing so allows occupants to keep ceiling-mounted lights off when daylight or task light is preferred instead.
Addressable ballasts are available that may be controlled via low-voltage, wireless, or powerline carrier systems, allowing managers to adjust output of individual fixtures. Customization of light levels by location and task offers savings during cleaning, re-stocking, and maintenance, and in multi-use areas.
Outdoor lighting — long the sole turf of high intensity discharge (HID) systems — is also undergoing big changes. Both LED and high intensity fluorescents are fostering dimmable fixtures with instant re-start, unlike their predecessors. Marrying that capability with occupancy sensors may provide big savings when parking areas are empty or sparsely used.
For parking structures, bi-level LED fixtures and (where feasible) photosensor controls on perimeter lighting to take advantage of daylight are also options.
To learn more about the possibilities available with lighting retrofits, read this