Upgrading Existing Lighting and Control Systems
Last month, we covered making decisions about updating T-12 lighting systems for energy savings. Here is a some information on lighting controls you may want to consider for your project as well. And don’t forget to check out page three of this edition of the highline headlines for commercial rebate information on lighting efficiency improvements.
LAMPS AND BALLASTS
Energy-efficient lighting technologies have had decades to develop and many good, reliable solutions are now available from manufacturers.
Regarding lamps and ballasts, consider T8 systems. There are now 23W, 25W, 28W, 32W (normal output) and 32W (high output, or “Super T8”) T8 lamps available offering a choice of power and light output.
There are also electronic ballasts available with a range of efficiencies and ballast factors enabling further tuning of light output. The most efficient ballasts carry the NEMA Premium mark on the ballast label. Dimmable ballasts are becoming more efficient, versatile and affordable, making general dimmable lighting a reality.
Regarding fixtures, consider T5 systems, direct/indirect lighting and, if recessed, volumetric-distribution fixtures that place some light on walls to eliminate the “cave effect” common with some parabolic fixtures. LED lighting offers exciting opportunities to dramatically improve efficiency but as the overall technology is still relatively new, owners should proceed with caution, particularly when confronted by options such as LED T8 lamp replacements, which have not faired well in independent product testing at the Department of Energy.
LIGHT CONTROLS
According to the New Buildings Institute, advanced lighting controls can generate up to 50% lighting energy savings in existing buildings. Effective strategies include automatic shutoff, light reduction control, daylight harvesting and demand response.
The biggest challenge to incorporating advanced control strategies to an existing building is adding low-voltage control wiring, generally limiting opportunities for installation of sophisticated control systems. As a result, the simplest upgrade options involve the least amount of rewiring or simply swapping out of older ballasts and controls for new controls.
The easiest controls retrofit involves replacing components with the least amount of rewiring. While this often leads to occupancy sensors and lighting panelboard upgrades, new wireless controls and the falling cost of dimming ballasts are expanding the potential role for lighting control in building upgrades. The first lighting control strategy to consider is automatic shutoff. It is considered the easiest, lowest-risk path to energy savings and is relatively simple to set up and commission.
Start at the lighting panel. Are there large, open spaces in the building with predictable hours of operation? Are there public spaces where the lights must stay ON even when a space is unoccupied? Next, consider replacing the wall switch. Are there smaller, enclosed spaces in the building that are intermittently occupied during the day and are lighted with instant-ON light sources? If so, consider replacing toggle wall switches with occupancy sensors. If there is a clear line of sight between the switch and the primary task area, PIR sensors can present a cost-effective option. If greater sensitivity is needed for small levels of motion or if there are obstacles between the wall switch and the task, consider ultrasonic. For the ultimate in reliability, consider dual-technology sensors.
If the space is a private office already circuited for bilevel switching, consider replacing the manual switches with a manual-ON/auto-OFF occupancy sensor for the highest positive energy savings and some flexibility. If the space requires an occupancy sensor be installed in a location other than at the wall switch, consider wireless occupancy sensors that run on batteries or ambient light in the space harvested using an integral solar cell.
If the upgrade involves replacing light fixtures, consider integral controls. In a workstation-specific open office lighting layout, for example, direct/indirect fixtures can be installed that include an integral occupancy sensor and/or, if placed in a daylight zone, a photosensor and dimmable ballast, with the control wiring located inside the fixture. If the space is a hibay lighting application where metal halide is being replaced by fluorescent fixtures, consider fixture-integrated or mounted line-voltage occupancy sensors, which can be an economical addition to a new fluorescent fixture or separate add-on that is field installed. Photosensors could be similarly added for control of fixtures mounted over spaces that receive ample daylight from skylights.
Finally, if the existing installation already includes automatic lighting controls that will be retained after the upgrade, ensure these controls are working properly by re-commissioning them as part of the project. The system may have been improperly designed, installed or commissioned when first put in place, or its operating parameters may have drifted out of sync with the space and how its lighting is used. Re-commissioning can therefore become a source of energy savings by itself.
The bottom line is that in most spaces, simple control strategies can be economically incorporated into lamp/ballast upgrades and fixture replacement projects, accelerating energy savings.