From idea to implementation, changes in lighting system design, management, and operation can show big benefits to the bottom line. From the simplest solutions to the most complex retrofit options, Buildings puts lighting under the microscope and gives you a glimpse at the savings to be had by reducing energy consumption.
According to Spencer Abraham, U.S. Secretary of Energy, “Nationwide lighting consumes 7 quadrillion BTUs or more in a given year, which is about 7 percent of our entire energy usage in this country.” Abraham’s comment during the 13th Annual Energy Efficiency Forum last June is representative of the HUGE utilities costs associated with lighting in commercial buildings. Contrary to what many believe, reducing energy doesn’t have to mean reducing the quality or quantity of light.
1. Look for wasted light.
Chances are good that your facility is wasting light somewhere at some time. “We have estimates that vary on how much lighting is wasted in facilities, but the estimates range up to 50 percent in a typical office building,” says Russell P. Leslie, professor and acting director of the Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY.
Viewing skyscrapers at night may be beautiful when office lights are left on, but it’s these same lights that are causing a large number of BTUs to be wasted each year. “A simple process of ensuring that the lamps are off at night is a great way to reduce your energy,” explains Chris Forti, market development manager, Commercial Real Estate, GE Lighting, Cleveland.
Outdoor light fixtures that spray light off the property or send it gleaming up into the night sky may be another culprit of wasted light. Remedy the problem with full cut-off fixtures and help from a qualified lighting professional. Poorly directed or poorly located indoor fixtures may also be using light inefficiently.
Do a quick check of how many employees have brought in desk lamps from home. If the numbers are high, so is the likelihood that they’re using incandescent lamps. Provide more efficient task lighting (fixtures that use lamps such as compact fluorescent or halogen), group relamp before too many lamps expire, and make sure that fixtures are cleaned periodically to ensure the optimal amount of light output. “You lose some of the light through the dirt. Some people will then overcompensate and start adding lamps to try and gain more light on the surface. That’s defeating the purpose of the original installation,” explains Steve Goldmacher, director, Corporate Communications, Philips Lighting Co., Somerset, NJ.
2. Replace inefficient lighting equipment.
If T12 fluorescent lamps and magnetic ballasts are plentiful at your facility, you haven’t tapped the potential savings offered from the lighting industry’s technological advancements. “If you’re using a current T12 system, there are up to 16 different options you can do. Some might make sense. Some might not make sense,” Forti says. Among these options is the opportunity to reduce energy by 35 to 40 percent by relamping to standard T8 lamps and electronic ballasts.
If you’ve retrofitted in the last three or four years and already have T8 lamps and electronic ballasts, you may be under the mistaken assumption that you’ve maxed out your energy savings. Next-generation T8 lamps, such as GE Lighting’s T8 Watt-Miser®, can provide even greater efficiency and often offer longer lamp life, which can reduce the time and cost of labor.
Mercury lamps can be switched to metal halide or high pressure sodium. Exit signs that use compact fluorescents can be retrofitted with Light Emitting Diodes (LEDs) for improved efficiency and visibility. “Exit signs may seem like a small thing but they are on 24 hours, seven days a week, and it’s surprising how many exit signs are in buildings,” comments Leslie. Look for exit signs that carry the EnergyStar® label to ensure that you’re getting an efficient product.
3. Get control over your lighting system.
Installation of lighting controls can be as simple as an occupancy sensor, as extensive as the Digital Addressable Lighting Interface (DALI), or as comprehensive as tying in your lighting system to building controls. According to Leslie, when installing lighting controls you can expect up to a 30-percent reduction in energy usage.
“The occupancy sensor for private offices is fairly easy to implement on a retrofit basis if you have a wall switch that has a clear view of the rest of the office. But even easier, if you have a building that works on predictable scheduling (such as everyone leaves at six or seven o’clock), you can garner a large part of the savings by just having a time clock on your lighting circuit that automatically shuts the lights off and allows people an override,” Leslie explains.
More intricate solutions such as DALI involve a 2-wire communication bus that allows devices like light switches, ballasts, and even curtain controls to communicate between themselves and with a central server. Hard-wired switch zones and central control panels are gone. Bus wires are run either in or outside the power conduit using standard materials and methods. For retrofit applications, lighting power is left as-is while the DALI bus is free-run using snap-in connectors and plug-in jumpers.
The advantages of a networked DALI system are plentiful: easy reconfiguration of lighting zones, individual workstation control, dimming and scene control, peak shaving, sweeps with local override, energy monitoring, tenant billing, and more. “With DALI, energy management is just part of the package right along with incredible flexibility, installation simplicity, and individual user control. Right off the bat, you’re on a platform that can meet [ASHRAE] 90.1-1999 and [Calfornia’s] Title 24 requirements while concurrently serving the needs of owners, designers, and users alike,” says Wayne Morrow, president, Starfield Controls Inc., Louisville, CO.
Tying your lighting system into your building controls can offer many similar benefits, such as scheduling and energy monitoring. Lighting can even be used to increase HVAC efficiency. “Even the occupancy sensor function can tie into the HVAC system,” says Leslie, “to set back temperatures when cooling or heating isn’t needed because people are out.”
4. Harness the power of the sun.
Take advantage of sunlight. It provides excellent color rendering, is often preferred by employees, and – the best part – it’s free. A word of warning, however: Without glare control, daylight can be a nuisance. “If you give people a manual dimmer, some of our research has shown that approximately a third of the energy could be saved – by people just dimming [lights] down to the levels they want when they’re near windows,” Leslie says.
Coupled with lighting controls, the use of daylight can greatly reduce energy consumption. However, use of photosensor controls to automatically dim lights requires extensive calibration by an expert. To provide manual dimming, expect to pay a greater initial cost for ballasts with this capability.
5. Look for load curtailment opportunities.
Many utility companies are offering energy conservation incentive programs. When power is at a premium, load curtailment within commercial buildings can help utilities reduce generation capacity while benefiting building owners and facilities professionals. “It’s typical in areas of New York, California, southwestern Connecticut, and increasingly in other areas where utilities will pay large premiums to building owners if they’ll sign an agreement to curtail load for certain periods of time,” explains Leslie.
By dimming lights, energy levels can be reduced – often times during peak hours when daylighting can be advantageous. Building controls and DALI can likewise help you control your energy load by monitoring the lighting in your facilities.
If you’re unsure about the amount of savings you can reap, look online. Several manufacturers provide the opportunity to quickly survey the retrofit potential in your facility through online audit tools. If you’re looking to bone up on the basics, participate in courses offered by major manufacturers. When in doubt about finding ways to decrease energy consumption while increasing safety and productivity, look to the experts – manufacturers, lighting designers, and energy service companies – to provide an energy audit of your facilities.
Jana J. Madsen (firstname.lastname@example.org) is senior editor at Buildings magazine.