Challenges When Deploying LED Lighting Retrofits

Transcription

1 Challenges When Deploying LED Retrofits With many of the opportunities afforded by new lighting technology, such as LED lighting, come new issues. New technology can sometimes create new, unforeseen challenges, which then need to be dealt with. Calculating savings with care and the variance in the quality of LED systems are additional issues. Some SSL systems may create new glare sources when their intense points of light reflect off specular surfaces such as telephones, windows, polished tables, and glass-covered artwork. Fixtures or kits that use lenses, diffusers, or indirect lighting may be essential to mitigate that problem. Many SSL devices cannot be dimmed using existing controls without causing visible flicker. New dimmers chosen from lists of equipment known to be compatible with SSL units are often the answer, potentially adding unplanned cost to an upgrade. While SSL devices may eliminate the need to regularly re-lamp, they don't eliminate the need to clean fixtures. Significant lumen depreciation may occur due to buildup of dirt that would otherwise be removed during the re-lamping process. Claimed labor savings due to avoided re-lamping should not be exaggerated by assuming zero attention to fixtures for many years. The quality of LED systems varies widely. Also points the compatibility of controls is an ongoing issue, especially with outdoor lighting. Look for devices listed with the DesignLights Consortium (DLC) or having a DOE Facts label. Each means that an independent lab has tested samples to verify manufacturer claims for efficiency, color, etc. A sharper pencil may also be needed when calculating savings. Once high-efficiency lamps and ballasts are installed, potential savings from adding controls may be greatly reduced, making their incremental payback too long to be acceptable. Regardless of the technology, experts recommend doing several mockups to assess ease of installation and occupant acceptance, before committing to a major purchase. Keep the mockups in place for several weeks to ensure there are no glare or other issues that might only become apparent as conditions vary. When pursuing any cutting edge or high-tech opportunities, don't skimp on the expertise.

2 Energy Codes Drive Changes in Systems 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 ceilingmounted 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.

3 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) photo sensor controls on perimeter lighting to take advantage of daylight are also options.

4 New Generation of LEDs Make Good Case for Retrofit The biggest development in the last decade of lighting has been white LED lamps. Several thousand solid-state lighting (SSL) products using white LED lamps are now available to fit almost any socket. Pricing continues to drop, even as efficiency and quality continue to rise. Unlike their CFL predecessors, screw-in LED units come to full brightness immediately, maintain light output for decades instead of years, are happy being cycled thousands of times, and love cold environments, all while cutting wattage by 20 to 40 percent (60 to 80 percent when compared to incandescent). In many cases, power quality and color rendering are also better, mercury is no longer an issue, and fragility is a thing of the past. Color temperature and beam spread options exist to satisfy even lovers of incandescent. Infrared and ultraviolet emissions are so low that museums are switching to them. The same attributes apply to most LED replacements for tubular fluorescents. Care is needed with regard to maintaining similar light distribution, color temperature, and glare control. Some retrofit kits or replacement lamps may compromise a fixture's UL listing, but many are available that do not do so. While most presently involve ballast disconnection and minor fixture re-wiring, some replacement LED tubes are designed to work with existing electronic ballasts. Not only does SSL offer additional savings but unlike all earlier options it offers the ability to "tune" color temperature. Some LED systems are designed to change it across time to mimic daylight, which might be desirable for its positive human health effects, and productivity. The fluorescent lighting industry has responded to the SSL challenge, offering T8 lamps that last more than 50,000 hours, with wattages (for a 4-foot lamp) as low as 25 (instead of the standard 32), emitting only slightly fewer lumens. Electronic ballasts with a wide range of ballast factors (BF) are available that offer higher or lower light output commensurate with their wattage. Some high-performance two-lamp units with standard BFs save about 5 watts. When combined with appropriate lamps, a room's light level may be altered by about 35 percent merely by changing lamps and ballasts. Doing so may, at low cost, adjust lighting to accommodate changes in tasks while keeping the same fixtures and layout.

5 Benefits to Upgrades, Even in Relatively Recent System While upgrades in the 1990s and 2000s cut lighting power densities from 2.5 to 4 watts per square foot (W/SF) down to 1.5 to 1.8 W/SF, some of today's options may cut that to.7 W/SF, or even lower. Where electric rates and financial incentives are high, even reduction of only 10 watts per fixture may be costeffective. Many upgrades may be pursued as part of routine maintenance. For example, in some facilities early model T8 ballasts installed over 10 years ago may be starting to fail. Instead of replacing in kind, the time might be right to switch to a more efficient technology, such as LEDs. Once a fixture must be accessed and opened for maintenance, the labor to do so becomes a sunk cost. The value of that investment is maximized by instead deploying whatever cost-effective options are available. Payback calculations then include only the costs of new equipment and any additional incremental labor. Such work may involve replacing both lamps and ballasts with an LED retrofit kit that includes a "driver" (works like a ballast) and a device (shaped like a flat strip or fluorescent tube) containing many LEDs. Not only has re-lamping then been essentially eliminated for a long time, but the energy cost of lighting may be cut by 20 percent or more. Some early upgrades maintained the parabolic louvers found in fixtures from the 1980s and 1990s. A variety of new kits and lenses are now available that provide a more modern look while eliminating the "cave effect" (darkened ceilings and upper walls) those louvers created. Not yet ready to make the leap to LEDs? Just change lamp and ballast specs so the facility buys only super T8s that provide about the same lumens, using fewer watts, while lasting almost as long as LEDs. While more expensive than standard T8s, the ROI, when accounting for both reduced energy and maintenance costs, may be acceptable.

6 Review a Sample Fixture to Ensure Quality retrofits to improve energy efficiency are fairly common in facilities. When lighting is being upgraded, it's important to ensure that the space will also look good after the upgrade is complete. That means paying attention to lighting quality. One important consideration is the quantity of light. Facility managers know that there has to be enough light to allow occupants to complete tasks that are to be performed in a space. But having an adequate quantity of light is also important from an aesthetic standpoint. If a lobby feels gloomy, it's not going to have a very welcoming quality. Note that this can also be a function of fixture performance. Not all downlights are the same. They come in all sorts of sizes, shapes, and light distributions, incorporate varying qualities of ballasts, and utilize different lamps altogether. Some are glary. Some trap as much as 70 percent of the light within the fixture. The same factors affect up lights as well. Some potential problems will be obvious when photometric calculations are run, but some of them can only be confirmed with a fully functioning fixture sample. In general, a working sample of any fixture (with cord and plug and specified lamp) should be physically reviewed to confirm that it meets the desired aesthetic of the space and that there are no flaws such as glare, visible lamps or poor light distribution, which cannot be determined merely from a picture of the product. Keep in mind that fixture appearance is generally related to cost - it's always easy to find a cheaper replacement, but if it isn't truly suitable for the space that's intended to be created, it's no bargain.

7 Retrofits: Look Closely at Controls Most managers considering lighting retrofits consider only the lighting equipment when, in fact, some of the greatest potential for energy savings comes from controls. At the most basic level, occupancy sensors can save percent of a space's lighting energy use if the space has intermittent use throughout the day. Occupancy sensors can be simple replacements for wall switches, and wireless versions are available that eliminate the need for an electrician to rewire the space. In rooms with daylight, photocells that automatically dim the lights in conjunction with daylight can save an additional percent of energy use. By making the leap from devices to systems, managers can tie lighting controls to room schedules, give users individual control of the fixtures in their immediate area, shed load to avoid peak-demand charges from the utility, and set a high-end trim if light levels are higher than needed. To analyze the opportunities a retrofit presents to an organization, managers will need to plan in advance. A lighting designer can guide managers through the many available options and prioritize the highest-yield returns. A salesperson associated with a manufacturer or distributor primarily is interested in selling their products, so managers need to be aware they will slant their sales pitches to achieve that goal. By comparison, an independent lighting designer who is knowledgeable about current technologies is more likely to look at all potential options. The designer will learn about the organization and its operations to understand the level of feasible change. They do not have a financial interest in the final equipment selected, so they can make recommendations with the organization's best interest in mind.

8 Sustainable Interiors and Productivity Green The link between sustainable workplaces and employee productivity is getting stronger as more research is being done. A recent study, "Effects of Green Buildings on Employee Health and Productivity," from the School of Planning, Design, and Construction at Michigan State University surveyed two groups of employees who had moved from conventional office buildings to LEED-certified buildings. Among the findings: The mean number of hours per month that respondents reported being absent due to allergies and asthma dropped from over an hour pre-move to about one-half hour post-move. Similarly, the mean number of hours survey participants reported being affected by allergies and asthma decreased 60 percent. The mean number of hours per month respondents reported being absent due to depression and stress dropped from almost an hour pre-move to a little under half an hour post-move. The mean number of work hours affected by depression and stress decreased 30 percent.