Throughout my lighting career I have always approached each new project with the question: “What am I lighting?” This simple question actually encompasses a lot; not only accenting objects, but illuminating the vertical and horizontal planes of the three-dimensional space. As lighting designers, we think about how we use light to model a space, which surfaces and materials should be highlighted and at what angle. Equally important to consider is how do we make people look and feel good in the space? In the past, as designers, our creative ideas were shaped by architectural style, and really, limited only by the project budget. But increasingly, over the past 10 years, as the designer responsible for the creation of the lighting scheme, I find myself asking a different question: “What can I light with the watts I'm allowed to use?” and a corollary “How little light can I afford to live with?”
AN ENERGY-EFFICIENT MINDSET Over the years, a consciousness among the general public and certainly the design community has grown about energy consumption. The need to conserve energy has gone from a virtue to an imperative. The last energy crisis in the early 1990s was a wake-up call, with energy rebate programs beginning to appear, and lamp manufacturers being spurred on to “build a better light bulb.” We have always used new energy-efficient sources in our work at Cline Bettridge Bernstein Lighting Design, and we are constantly looking for sources with longer life and greater output.
For me, part of the excitement of lighting design comes from using new light sources and fixtures in unexpected ways. The lure of new technology is irresistible because it solves problems, creates opportunity, and helps address energy issues, which have become more critical over the past 15 years. At our office, we like to think of ourselves as pioneers:
Using energy-efficient sources has become part of our basic vocabulary, as is the norm for many lighting design firms, but meeting the Leadership in Energy and Environmental Design (LEED) requirements has demanded further adjustment to our practice. One of our first LEED certified projects was the William J. Clinton Presidential Center in Little Rock, Arkansas. From the beginning of the design process, the former president expressed his real interest in energy conservation and wanted the center to be as sensitive to the environment as possible. We were introduced to the process of working with the LEED consultants and experienced expanded coordination time with the engineers and architects. We currently are working on One Bryant Park in New York City, the first office tower to seek a platinum LEED rating in the United States. Here, too, the clients are completely dedicated to investing the time and money necessary to achieve this goal. For a project this large—56 stories and 2.2 million square feet—and complex, I do not think we, as a firm, ever could have estimated the amount of time the certification process would consume. More to the point, I don't think there are many clients who are willing to invest in the extra work, time, and cost this process commands.
CODES AND CONTRADICTIONS The purpose of the various building energy and energy conservation codes—the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) 90.1, the International Energy Conservation Code (IECC), and California's Energy-Efficient Standards for Residential and Non-Residential Buildings (Title 24)—which are required, as well as LEED, which is voluntary but actively influencing the building process, now governing our practice locally, nationally, and internationally, is to limit energy consumption. They are well-meaning and necessary, coincidentally challenging designers to do more with less, and encouraging lamp and fixture manufacturers to make products that are more efficient. At the same time, we see inexplicable exemptions to the requirements and inherent contradictions in the rules. For example, in ASHRAE 90.1, why are “casino gaming areas” exempt? Signage is exempt from watts limitations, but why are there no restrictions on the mind-numbing brightness of LED signs that have taken over the pedestrian-level experience?
Sometimes we encounter seeming contradictions between recommended best practices and the new legislation. ASHRAE allows 1.3 watts per square foot for libraries, while at the same time the Illuminating Engineering Society (IES) recommends 30 footcandles at 30 inches above finished floor in the stacks. We can achieve this only by reducing the general light level in the circulation and public areas, and the contrast can result in an unbalanced composition. If an office design uses fixtures that comply with the IES office standard RP-1 we can take advantage of an additional .35 watts per square foot of energy allowed. The standard defines maximum average luminance allowed above a certain angle; this is intended to prevent glare on the CRT (computer) monitor in an office and was very valuable when written. However, given technological advances of computer screen technology, some of the reasons behind the RP-1 standards no longer apply, and taking advantage of the “watts bonus” further reduces fixture options. Fixtures with a wider distribution that put light high up on the wall do not comply, even if they contribute to better lighting solutions.
Exterior lighting is fraught with its own problems and contradictions. Under current ASHRAE requirements building façades are allowed .2 watts per square foot for each illuminated wall or 5 watts per linear foot for each wall or surface length. On a recent project, we calculated that we could floodlight the façade of the building but could not achieve an alternate scheme illuminating certain specific elements of the façade, even though we actually would use fewer watts overall. The IES acknowledges environmental context and recommends different light levels, while ASHRAE does not make a distinction with the allowable watts.
THE ROLE OF DIMMING While many of the energy codes and energy programs promote the use of daylight harvesting they do not give any consideration for the slightly higher wattage consumption of the dimming ballasts, the so-called “dimming penalty.” At the same time we are trying to convince clients to pay more for the dimming ballasts and control systems to better manage their electrical usage, we have fewer watts for the design. LEED certification programs give credit for dimming, but the dimming capabilities of metal halide sources is still very limited and the technology needs to mature. We have found that the metal halide lamp color loses stability after 50 percent dimming, a visual reduction, which is not significantly noticeable to the eye. It helps in the overall reduction of energy consumption, but while we are waiting for the technology to catch up with our needs, we are lacking the tools to further refine our designs. And although we are very active in speaking with the manufacturers explaining to them what we need, responsiveness varies from lighting company to lighting company.