New Lighting Choices
- By Chin Lin
- December 1st, 2012
Imagine the day when you don’t need to change a light bulb. With a number of manufacturers introducing 100,000-hour LED fixtures as well as some with a projected life of more than 150,000 hours, replacing light bulbs may soon be a thing of the past.
The lighting industry is currently going through a revolution, as new legislation requires light bulbs (or lamps, as the industry calls them) to meet minimum efficiency standards. Advances in light fixture design and technology have progressed so rapidly that what was unthinkable only a few years ago is now reality. It seems that every three to six months another major advance in lighting technology is announced. Even the popular compact fluorescent lamps (CFLs) are losing favor as LEDs become more affordable. For most of today’s lighting designers CFLs are now an outdated technology, and it’s a matter of time before LEDs replace them altogether.
Light fixtures have also become so efficient that utilities are providing incentives to retrofit buildings completed as recently as five years ago as a way to reduce energy consumption. Colleges and universities would do well to understand these developments and how to leverage them to their facilities’ advantage.
Two of the most notable innovations in lighting technology include high-efficiency linear fluorescent fixtures and advancements in LED fixtures. Both lighting options provide high-quality light in an array of lighting designs while consuming significantly less energy. Paired with sophisticated control systems behind the scenes, a college or university can reduce its energy consumption and maintenance costs through smart lighting design.
High-Efficiency Fluorescent Lighting: Not Your Parents’ Light Bulb
Through the last few years, high-efficiency linear fluorescent fixtures have been developed by several manufacturers, achieving 90 to 95 percent efficacy rate with extremely good distribution patterns that allow for more flexibility in layout and design. This technology, along with the advances made in linear fluorescent lamps, may reduce the number of fixtures required in a given space, as well as reduce the light power density for a building. Using high-efficiency linear fluorescent fixtures instead of conventional linear fluorescent fixtures could save up to 30 percent in the total connected wattage of lights in a typical academic building. Combined with good daylighting design and a well-integrated control package with vacancy/occupancy sensors and daylight harvesting, institutions can realize up to 70 percent savings in energy use for lighting.
Efficient lighting can have a ripple effect in overall energy savings in a building and indeed, across a campus. We know that light bulbs generate heat, and in fact, the heat generated by a 60-watt standard light bulb is equivalent to the heat generated by the average person. By using fewer (and more efficient) light fixtures throughout a space, less heat is generated, thus requiring less energy to cool the building — and perhaps a smaller air conditioning unit. The reduction in electricity used for lights can translate into significant savings for campus buildings with air conditioning.
High-efficiency linear fluorescent lamps can also now achieve up to 60,000 hours of lamp life, reducing maintenance costs with less need to replace lamps (or relamping). It should be noted that the lamp-life rating system for fluorescent lamps is the hour when 50 percent of the lamps fail. In other words, 50 percent of the lamps would need to be changed during the rated life of the fluorescent fixture. While high-efficiency linear fluorescent lamps are inexpensive (especially when compared to their LED counterparts), lamp-life and mortality rates are a prime disadvantage when compared to LED light sources.
LED Lighting Technology: Leading the Industry
LED lighting technology has come a long way, and can now achieve light output, color quality, color rendering, and energy efficiency that rivals or surpasses fluorescent sources. LED light sources are more efficient than CFLs, contain no mercury, and offer a level of flexibility and control that no other type of light source can match. Moreover, LED lighting systems support a full range of indoor and outdoor lighting applications for an array of uses.
Among the differences between fluorescent and LED lighting sources are the different lamp-life rating systems. The LED life rating is determined when the LED light output (or lumen) falls below a set percentage of the original light output. For example, a 100,000-hour “L/90” rated LED will maintain 90 percent of the original light output at the end of the 100,000 hours. (Note that LED lamp failure rate is also very small; almost none after the initial six months.) LED manufacturers use different life-rating systems though, which make comparisons of lamp-life somewhat difficult. In general, however, a college or university can expect to replace only five to 10 percent of its 100,000-hour LED lamps.
Today, a number of major manufacturers are marketing 100,000-hour L/90 LED lamps with a 10-year warranty. For classroom and office use, assuming a 50-hour/week usage, 100,000 hours of lamp life translates into 38.5 years of life for the fixture, making the need to relamp for these spaces almost unnecessary. The long life and low rate of failure for LED fixtures are the principal reasons for colleges and universities around the country to replace their interior lights with LED fixtures, reducing the need to stock lamps and the staff necessary to check and replace lamps. Even in spaces where light is left on continuously, such as corridors, the 100,000 hours in a LED lamp translates into 11.5 years of service before replacement, saving two lamp changes compared to a typical standard 30,000-hour linear fluorescent, or nine lamp changes compared to a 10,000-hour compact fluorescent lamp (CFL) fixture. That is a significant savings in facility management manpower for a university with thousands of light bulbs throughout a campus!
In addition to long life, LED lights are easily adaptable to a wide range of control options with minimum added cost. Dimming, daylight harvesting, time clock, and demand response control can be incorporated into the LED power supply unit. Fluorescent fixtures, on the other hand, would require additional cost for dimming ballast and communicable devices to accept these control options.
However, LED lighting is not without its disadvantages. While the failure rate is low, it is not zero. When an LED light goes out, replacement is a complicated affair, requiring a replacement lamp from the original manufacturer. For now, LED lamps are uniquely designed to fit in a fixture, and manufacturers have proprietary lamp and fixture styles. Until the LED industry standardizes the lamps, colleges should consider the balance between the benefits of LEDs and the challenges of lamp replacement in lighting design.
What’s Next in Lighting?
High-efficiency linear fluorescent lights are still the most energy-efficient technology and the easiest to replace because the lamps are readily available. However, these lamps, while inexpensive, require greater maintenance due to more frequent replacement.
LED lights, on the other hand, feature more expensive lamps that last far longer. For colleges and universities, the advantage to switching to LED today is reducing the long-term manpower required to change lamps. Standardization of LED lamp technology will come, drawing down the cost, but we’re not there yet. Because the capital costs of buying and installing both technologies are similar, facility management costs become the deciding factor.
As LED becomes more competitive with fluorescent technology, we’ll see LED fixtures replacing other lighting choices for all applications in higher education. LED technology can’t replace everything yet, but the lighting industry is moving that way. It could happen in the near future.
Chin Lin, AIA, LEED-AP, is a senior associate at HMFH Architects, an architecture firm focused on the design of student learning and living environments. He is also on the Board of Managers of IES Boston, a section of The Illuminating Engineering Society of North America (IESNA).