Linear fluorescent lighting consisting of tubular fluorescent lamps operated by electrical devices called ballasts, which provide the proper starting voltage and then regulate current flowing through the lamps during operation, is common in commercial buildings. For decades, T12 lamps powered by magnetic ballasts served as the workhorse lighting system in commercial buildings until the Energy Crisis of the 1970s spurred development of more efficient alternatives such as T8 lamps and electronic ballasts.
Upgrading to T8 lighting, for example, can reduce lighting energy costs by up to half in typical applications such as offices and classrooms. The T8 family now includes 23W, 25W, 28W, 32W (standard) and 32W (high output or Super T8) lamps and electronic ballasts. These are available with a range of efficiencies and ballast factors that enable tuning of light output for additional energy savings in existing spaces that may be overly lighted. The most efficient electronic fluorescent ballasts carry the NEMA Premium mark on the ballast label. Dimmable ballasts are becoming more efficient, versatile and affordable, making dimmable general lighting a reality.
Throughout the 1990s and 2000s, demand steadily shifted to T8 lighting as the new standard in new construction, as building owners acted to minimize their energy costs and to respond to more restrictive commercial building energy codes. At least 20 percent of floorspace in the existing commercial building stock built before 1980 was also upgraded.
Then, July 2010 marked the end of an era in the lighting industry. The final phase of energy regulations created by the Department of Energy and the Energy Policy Act of 2005 virtually eliminated the manufacturing and importing of fluorescent magnetic ballasts designed to operate full-wattage and energy-saving T12 lamps, including replacement ballasts, with few exceptions.
What’s more, beginning in July 2012, fluorescent lamp energy standards recently enacted by the Department of Energy eliminated most 4-foot linear and 2-foot U-shaped T12, many 8-foot T12 and T12HO and some low-color-rendering 4-foot T8 lamps.
Millions of linear T12 lamps and magnetic ballasts are still in operation and will require replacement, presenting a massive retrofit opportunity that is now being compelled by legislation. Owners of T12 lighting systems should consider upgrading to more-efficient alternatives if they have not done so already. There are at least three major options.
First, building owners could replace their ballasts with electronic T12 ballasts and replace their lamps with compliant T12 lamps (which may be offered with limited availability) as their existing inventory fails. While this would improve efficiency while avoiding a mass retrofit, it could be confusing from a maintenance standpoint because it leaves energy savings and does not avoid higher lighting costs due to a premium imposed by the compliant system.
A second option for owners would be to keep the existing light fixtures and upgrade to T8 lamps powered by electronic ballasts. In some cases, reflector kits can be installed to adapt the optical performance of the fixture to a new lamp type and fewer lamps. Mixing T8 and T12 lamps and ballasts in the same lighting system can negatively affect lighting quality. Since mixing lamps can be confusing for maintenance, a systematic upgrade from T12 to T8 across the lighting system is recommended. This option imposes the cost of the upgrade and requires disposal of equipment that may still be operating. It does, however, maximize energy savings and enable other benefits, such as economies of volume purchasing and incentives such as the Commercial Buildings Deduction and utility rebates. Obviously, the biggest opportunities for upgrading are in older, over-lighted buildings where utility costs are high and lighting is uncontrolled and left on all night.
As a third option, owners can replace the light fixtures, potentially improving lighting quality and reducing the total number of light fixtures in the space. This may involve a redesign of the system that addresses issues of quality such as visual comfort, uniformity, color rendering, spatial definition, shadows, flicker and glare. Source options include T8, T5 and LED general lighting; fixture options include direct/indirect and volumetric-distribution recessed fixtures. If the building’s primary spaces have been re-tasked to new purposes for which the existing lighting system is insufficient, uniformity is poor, light on walls and ceilings is inadequate or has obvious unaddressed sources of glare and if occupants are unhappy about their lighting, then the space may benefit from a deeper redesign rather than simple lamp and ballast replacement.
Regardless of which option is chosen, lighting controls can be added to enhance energy savings and flexibility. According to the New Buildings Institute based in Vancouver, Wash., automatic lighting controls can generate up to 50 percent 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 into an existing building is adding low-voltage wiring, generally limiting opportunities for installation of sophisticated control systems that involve networking of components. As a result, the simplest upgrade options involve the least amount of rewiring or simply swapping out older ballasts and controls for new controls. Options include wallbox occupancy sensors, intelligent low-voltage relay panels, line-voltage dimming ballasts and wireless RF controls (switches, occupancy sensors, photosensors).
Regardless of what the best path forward might be, the workhorse magnetic T12 lighting system is gracefully retiring. Owners of systems will have to upgrade now or later. The questions now are how does the owner wish to manage the process, and how much energy savings and flexibility does the owner want from the new lighting system.