I was planning to continue writing my IBS columns on how to integrate the various building technologies, but my visit to this year’s LightCongress in New York exposed me to so many good ideas that I just have to talk about them. I’ll get back to my plan next month.
Dr. Mark Rea, director of the Lighting Research Center at Rensselaer Polytechnic Institute in Troy, N.Y., gave the keynote address on sustainable lighting. He outlined ways of looking at lighting and energy savings, which would be useful for anyone involved in lighting design and installation. His strategic view is based on the reality of how people actually use lighting, rather than being based on a rigid formula.
Rea distinguished between the price of lighting and the cost of lighting. Price is dollars per square meter-hour, and is at its lowest level in the 100-year history of the light bulb. But cost has to include such items as the problem of disposing of fluorescent bulbs that will reach their end of life roughly five years after the present surge in their usage. Cost also takes into account the quality of the desired lighting function. For example, a ceiling-mounted fluorescent fixture would not be an acceptable light source in the center of a formal living room. Fluorescent light in a bedroom would throw off a body’s circadian rhythm, which requires warmer colors as night approaches.
We can minimize the cost of lighting, including its environmental impact, by the intelligence with which we apply our lighting strategies. For example:
• Consider whether we have to light everything in a given space or whether we need to project the light on a given task area. Fluorescent may not be the best choice for task lighting because its light spreads in all directions. The real cost here would involve comparing the watts for illuminating the task area of various light sources. Or as Rea put it, “High source efficacy does not guarantee high application efficacy.”
• Use motion sensing to keep lighting on only when an area is occupied.
• Use daylighting to take advantage of natural ambient light to minimize the use of electrical energy.
• Electric utilities need to have the ability to generate enough energy to meet peak demand. So, if on a hot summer afternoon, there is a large increase in the amount of power used, the utility must be able to supply that, even if most of the time the load is much less. For this reason, utilities charge commercial customers for peak demand over some defined time period. However, if usage could be cut back during periods of high demand, it would reduce the users’ electricity bill, allow the utility to generate power at more constant levels and safeguard against the threat of blackouts. Rea described a load-shedding ballast developed by Osram Sylvania, which can replace a standard T8 fluorescent ballast and reduce lamp power by 33 percent in response to a command signal, while still retaining reasonably adequate levels of illumination—and there is no control wiring to add. It was introduced at LightFair ’08.
In summary, “Light what you want when you want to.”
Rea introduced an interesting way to say this. For lighting efficacy, instead of lumens per watt, the measure should be benefit per watt. For example, “Sparkle per Watt” would be appropriate for an elegant ballroom, where the lighting is designed to convey a certain sense of style, rather than just providing illumination. He illustrated “Excitement per Watt” with a photograph of the Basketball Hall of Fame.
Bill Warren, of the consulting firm Warren Associates, defined sustainability as doing the least damage to the planet and made the very important point that designing green for sustainability should apply as much to renovation as to new construction, especially since less than 1 percent of existing buildings are replaced each year. This makes me think of a great sales pitch for contractors: Renovate green to save both dollars and the planet.
Warren also described the concept of volumetric lighting, which is the opposite of task lighting. This type of lighting, for venues such as offices or sales floors, is designed to light an entire space evenly. According to Warren, this type of lighting can be greatly improved by replacing standard three-bulb luminaires with special two-lamp luminaires with built-in optics designed for optimum volumetric lighting.
Cheryl English of Acuity Brands spoke about the tax incentives for energy-efficient lighting systems, which are available to owners through the end of 2008 for new construction and renovation, as a provision of the Federal Energy Policy Act of 2005. (If congress votes on it, the closing date for these incentives could be extended.) Contractors can use this as one more selling point. Not only will owners save on energy costs by building in light-conserving techniques, your customers could qualify for a tax deduction as well.
I can sum up much of what I learned with two thoughts: 1. The most energy-efficient lighting systems require taking into account the desired function of the lighting, and 2. Much electrical energy can be saved by shutting off lights when and where they are not needed.
The PowerPoint presentations are available at www.lightcongress.com/wrapup.asp.
BROWN is an electrical engineer, technical writer and editor. He serves as managing editor for SECURITY + LIFE SAFETY SYSTEMS magazine. For many years, he designed high-power electronics systems for industry, research laboratories and government. Reach him at email@example.com.