Last month, we covered regulations covering fluorescent ballasts that have essentially eliminated the magnetic T12 ballast with few exceptions, including F40T12, F96T12 and F96T12HO ballasts for both full-wattage and energy-saving versions of these lamps.
Two years later, in 2012, additional regulations will take effect, creating new energy standards for selected linear T5, T8 and T12 lamps. The net result, with few exceptions, is a majority of 4-ft. linear and 2-ft. U-shaped T12, many 8-ft. T12 and T12HO, and some low-color-rendering 4-ft. T8 lamps will be eliminated.
Based on these facts, one could make a simple argument that it is now time to upgrade existing lighting and control systems to improve energy efficiency and lighting quality.
Replace individually or in a planned upgrade?
A basic choice will be whether to replace the existing T12 lighting system all at once in a planned upgrade or replace individual components as they fail.
At first glance, replacing individual components as they fail appears to be the easiest path forward as it avoids the upfront cost of equipment and installation labor and potential disruption of a renovation.
However, a planned upgrade presents several major advantages:
- good lighting performance, uniformity and space appearance by switching from T12 to T8 all at once, avoiding confusion resulting from maintaining two incompatibility lamp and ballast types in inventory; and most importantly:
- higher energy savings and greater lighting quality resulting from reevaluating the existing lighting system and upgrading it to current best practices. Once a decision is made to upgrade the lighting system, the owner has taken control of the situation and can maximize the benefit of the new lighting.
The biggest energy-saving and lighting quality opportunities are in:
- older, overlighted buildings that use older technologies such as T12 systems
- where utility costs are very high; and
- where lighting is uncontrolled and left ON all night.
T12 systems, for example, can be upgraded to realize energy savings as high as 50% or more in offices, classrooms and other applications, according to the National Lighting Bureau.
Retrofit or redesign?
The next basic choice facing the facility manager is whether to retrofit or redesign. In a retrofit, new lamps and ballasts are installed in existing fixtures and existing controls replaced. In a redesign, the fixtures themselves may be replaced or moved.
Good lighting quality accounts for factors such as visual comfort, glare, uniformity, color rendering, lighting on walls and ceilings, and harsh patterns, shadows and flicker. If the building’s primary spaces have been retasked to new purposes for which the existing lighting system provides insufficient lighting conditions, or uniformity is poor, or there is little light on walls and ceilings, or there are obvious, unaddressed sources of glare, and if occupants are unhappy with their lighting, then the space may benefit from a redesign.
The owner may benefit prior to the upgrade by simply asking occupants—the people who use the lighting regularly—whether they are satisfied with their lighting, what their lighting problems are, and what they want.
Lamps and ballasts
Energy-efficient lighting technologies have had decades to develop and so 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 dimmable general 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.
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 older ballasts and controls for new controls.
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. If LEED (for existing buildings) is used as a model path or actual requirement for the upgrade, this will be essential, as LEED requires that buildings meet the ASHRAE 90.1 energy standard as a prerequisite to gaining points for transcending it.
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? If so, consider upgrading the existing lighting panelboard to an intelligent lighting control panel that offers programmable scheduling. Be sure to give local users override capability with a maximum 2- to 4-hour override.
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. These sensors install anywhere within range of the receiver switch, which replaces the wall switch, and present no wiring requirements, although wireless technology is presently a premium option. Similarly, wireless photosensors are also available.
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.
Light levels can be stepped using a single ballast called a step dimming or light level switching ballast. If the existing space is already circuited for bilevel switching, step-dimming ballasts can be installed to ensure light levels are reduced uniformly, without a checkerboard pattern. These ballasts can operate without low-voltage wiring. Most products are programmed-start T8 ballasts, which may experience a loss of efficacy during light level reduction; dimming to 50%, for example, may reduce wattage by 40%. Instant-start step-dimming ballasts are available that offer proportional reductions in light output and input watts, although instant-start operation is not recommended by some manufacturers for applications with five or more ON/OFF cycles per day. Other hi/lo switching opportunities include corridors that receive a lot of daylight (with a photosensor) and stairwells (with an occupancy sensor).
Continuous-dimming ballast costs have been falling for years, putting this control method within reach of many upgrade projects. Efficiency has also improved such that dimmable ballasts are available that are as efficacious as standard instant-start fixed-output ballasts. Look for the NEMA Premium label for the most efficient ballasts.
Some dimming ballasts are available that communicate with lighting controls using existing line-voltage wiring. Two-wire phase-control dimming ballasts use existing line-voltage lines for both power and communication and are suitable for any application where greater flexibility is desired, such as conference rooms, boardrooms and private offices. A dimming range of 100-5% is available for T8 lamps and CFLs, and 100-1% for T5HO lamps. The lighting is typically controlled via local controls accessible to occupants.
Line-voltage stepped dimming (“load shedding” or “demand response”) ballasts may be combined with specialized energy management systems enabling a preset light level reduction, with a fade transition between light levels, in response to a variety of control inputs such as photosensors and schedules. The ballast may be combined with a signal transmitter that initiates load shedding in response to some type of demand response program. While demand response is still emerging as a trend, it will likely play a larger role in lighting in the future.
The ultimate control upgrade involves creating a fully realized lighting control system combining multiple strategies. In spaces where stationary tasks are performed, dimming will be preferable to switching while the space is occupied. If the ballasts will be replaced with dimmable ballasts, then multiple strategies should be enacted to make this installation more economical. When wiring a control system enacting multiple strategies around a dimmable ballast, one should consider a digital communication architecture, which eliminates multiple home runs and produces installation savings. If a digital architecture is chosen, one can consider creating a system out of DALI-compatible components, or specifying a proprietary system built around relays in distributed power packs and occupancy sensors, or digital dimming ballasts.
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 and, in some cases, improving flexibility.