|
|
IALD’s Sustainability Committee has adopted a working definition for sustainable lighting design, which is somewhat loose: “Sustainable lighting design meets the qualitative needs of the visual environment with the least impact on the physical environment.”
“Sustainable” really means something that can be supported long term—indeed, forever. As long as electrical energy, product processes and transportation continue to rely on fossil fuels, and lighting products are produced using new (unrecycled) raw materials, only “less unsustainable” lighting is possible. (That is why throughout this article the word “sustainability,” is enclosed in quotation marks.)
In practice, designers seek to meet various energy codes or look at lighting guidelines presented in LEED (www.usgbc.org), Energy Star Buildings (www.energystar.gov) or Green Globes (www.greenglobes.com). Most have adopted watts per sq ft as the de facto measure of environmental impact. LEED has an additional measure called “picograms of mercury per lumen-hour.” Credit is often given for the presence (but not necessarily the use) of lighting controls for daylight harvesting and occupancy sensing.
The lighting community has passively accepted these strictures while weakly protesting that lighting quality must be maintained. Simplistically, the cry has become: let us maintain footcandles while reducing watts per sq ft.
FLAWED METRICS
Neither watts per sq ft nor picograms per lumen-hour, however, are impacted by turning off lights—an obvious act of environmental responsiveness. This is akin to applauding people who own cars with high fuel efficiency while giving them no credit for living close to work, or even leaving the cars in the garage and bicycling to work.
Even if there was a good measure of environmental impact and everyone chose lighting based on it, what about all the other factors that represent good lighting? If everyone is pushing to cut watts per sq ft or kWh, who is going to ensure that vision requirements are met and that people’s need to see is taken care of? There is more to seeing than average footcandles. We need something like “benefits per kilowatt-hour” to counter the users’ myopic obsession with costs.
I am reminded of an old story the Sufis tell about Mulla Nasruddin (a fictitious character present in many of their tales) who was on his hands and knees searching for something in the roadway just under a light pole. His friends joined him and after a fruitless hour, questioning brought out the fact that he had lost his keys somewhere else: in the fields.
“So why are we looking here?” the friends asked.
“Oh, the lighting is much better here!” replied the Mulla.
Like Mulla, the lighting industry is focusing on obvious areas which are easy to measure while ignoring the murky regions where the real key might lie.
The lighting community has abrogated its responsibility to the consumers of lighting by refusing to tell them Sustainable Design what constitutes “good” lighting. We say, “Oh that is too complex to explain, why don’t you hire a good lighting designer?” So we have changed the mission to measuring the “goodness” of a lighting designer rather than the “goodness” of the lighting itself.
Sure, some high-end lighting designs cannot be evaluated numerically, but interior lighting jobs in industrial and office settings are the bread-and-butter of lighting and will benefit from such scrutiny.
The 9th edition of the IES Lighting Handbook has a chapter on Quality of the Visual Environment, which identifies 16 design issues and indicates which are important in different interiors, but it does not propose a measure or metric. Without a metric, the only thing driving lighting design will be the movement to reduce watts per sq ft, and the perennial financial pressure to keep investment dollars low. Unless a balance is struck, lighting will deteriorate.
POINT SYSTEM
 Just as LEED came up with a quantifiable point system for measuring its view of “sustainability,” IES should be able to present a point system for “lighting quality and sustainability” through a “Goodness of Lighting” index (Figure 1).
I am proposing a checklist and point system that will allow someone with a decent knowledge of lighting to go into a simple commercial or industrial space and come out with a rough measure of “how good is the lighting?” While no awards are given out based on this measure, it will, at least, provide a basis for the end user to understand where the lighting falls short and what opportunities exist for improvement. This measure will have criteria along three fundamental axes: Right Design, Right Equipment and Right Practices.
Right Design awards points for things like meeting or exceeding light levels, architectural compatibility, good uniformity (where desirable), color and contrast, low glare, etc. If indirect lighting is superior, then we should award bonus points for it.
Similarly, Right Equipment checks to make sure that the right lamps, ballasts and fixtures are being used. Points would be awarded for using (say) premium T8 systems vs. standard, and using premium ballasts, improved CRI lamps, higher efficiency and longer life products, etc.
Finally, the Right Practices portion could include measures like watts per sq ft and picograms of mercury per lumen hour. There would be additional points for RoHS compliance, use of controls, etc., and even bonus points related to energy used per year per employee based on standards derived for various industries and functions.
We should be able to walk into a space and based on eight to 12 considerations for each, obtain a numerical rank for how good the lighting is for the function being carried out in that space. Sure, it will take effort to develop such a measurement system and two people evaluating the same space may differ, but at least we will have a starting point to answer the question: How good is the lighting?
|
