These days, there is an increasing emphasis on making everything we do sustainable. Competition in the marketplace has taken us well beyond LEED, and in order to be “greener” than one's rivals, it helps to be able to embrace as many life cycle and environmental issues as one can. Architect William McDonough and chemist Michael Braungart's “cradle-to-cradle” philosophy, which advocates a “reduce, reuse, recycle” approach to the environment and our consumption of materials, is a starting point for how involved in this we, as both designers and citizens of the planet, have to be.
When it comes to lighting, it's important to remember that first and foremost, the greatest impact to the environment is energy consumption. Unless the energy source is totally sustainable, such as wind or solar, the greenhouse gases and air pollution resulting from electrical energy generation are by far the most significant impact caused by electric lighting. Moreover, even with sustainable sources of power, using light needlessly or inefficiently is depriving the nation's electrical grid of valuable watts that could be used for more-pressing demands. Conservation through the use of daylighting, lighting controls, and efficient sources still remains lighting's principal sustainability consideration.
The next largest consideration is mercury. High efficacy light sources including fluorescent and metal halide rely upon it. And while significant reductions in mercury have occurred in mainstream T8 and T5 lighting systems, the mercury content in compact fluorescent lamps and metal halide remains a lot higher. Recycling of spent lamps is essential. However, until there is a more efficacious choice, remember that the mercury emissions of coal burning power plants, which place mercury throughout the environment, are a bigger threat, so don't start a “Ban the Bulb” campaign just yet. Instead, emphasize low-mercury T5 and T8 lamps in as much of your design as possible. And, of course, make sure mercury is not part of any control system or component.
Once these issues are resolved, it's time to focus on the details of the lighting system. There are a number of things you can do to make your design even greener, as follows.Material Considerations
When evaluating the sustainability of a luminaire, it helps to address every material, with specific attention to the following key issues:Is the material renewable or depletable?How much energy is expended acquiring and processing the raw material?How much environmental damage is done obtaining the material?How far does the material need to be transported?When the material is mined, processed, or finished, does it require the use of heavy metals or volatile chemicals? If so, are they thoroughly and environmentally contained?When the life of the luminaire ends, what happens to the material?
To assess these issues well, it will take a lot of homework. As an example, gold is used to make critical connectors for, among other things, lighting and control systems. When mined, gold is often amalgamated with mercury to form solid nuggets. For every gram of gold obtained using this technique, 1 to 3 grams of mercury are washed into the watershed, in turn becoming the neurotoxin methyl mercury and accumulating in the flesh of carnivorous fish. As with many resources, this illegal process remains widely practiced because it is more profitable than more environmentally responsible methods.The Anatomy of a Luminaire
Almost every luminaire uses a metal housing. The most common material is steel, and because lighting is seldom structural, using thin gauge and/or recycled material is a good start. The side effects of iron mining and processing are substantial. Aluminum is another popular choice, but in addition to the impacts of mining, aluminum has an extremely high-embedded electrical energy use. Recycled aluminum is available and represents a moderately responsible choice. But for all forms of metal processing, about 12 percent of the cost is for oil-based solvents and chemicals. You might consider wood luminaires, but be sure to employ rapidly renewable wood and non-volatile organic compound (VOC) finishes. Perhaps the best advice is to use smaller, lighter weight fixtures—the less material, the better.