By Chris Brown
Lighting used to be about lumens, foot candles, color temperature, CRI and, oh yes, energy efficiency. Today we talk about sensors, controls, connectivity, IoT, IoE, data mining, Smart Lighting, Intelligent Lighting, Lighting as a Service, etc. And who knows what new word or phrase we will hear tomorrow? But still, lighting has to be about light, and not just any lighting, but about quality of lighting appropriate to the specific applications.
Defining what lighting qualities are appropriate is primarily subjective, but let’s try to get our arms around the broader concepts of quality lighting. From a very simplistic retrofitting point of view, what lighting products and strategies are appropriate for the application and what are the client preferences for color temperature and lighting levels? The client probably knows the answers to those questions already. But is the client aware of the other questions (and answers) that should be part of the conversation? For that matter is the lighting distributor aware of the potential upsell opportunities that come with identifying the values and benefits of quality lighting?
A good example is safety and security enhancements that come with uniform lighting in parking lots. Mark Rea is the Director of the Lighting Research Center at RPI, and the author of Value Metrics for Better Lighting. I asked Mark to briefly discuss the Parking Lot study, and then to comment on his proposition that “our society undervalues light because we do not properly measure the benefits of light, in terms of both the lighting system and how it is applied.”
“Yes, LEDs and their controls have created possibilities for lighting, but how does a specifier know if those possibilities can become a reality? One way to “know” is simply to believe all the hype about the possible benefits in marketing materials. The other way is to have the tools to engineer those benefits consistently and reliably.
To engineer benefits, one has to write a specification. What the LRC has been doing over the last 15 years or so is to help make a bridge from meaningful design goals like productivity, health and safety to specifications of the amount, spectrum, distribution, and timing of light needed to deliver those design goals. Benefit metrics are that bridge.
Benefit metrics bridge the measureable dimensions of light to physiological or behavioral responses that correlate well with the meaningful design goals that clients care about. For example, our research into the reasons why people do or do not feel safe in a parking lot at night has revealed two important factors, each represented by a benefit metric—the uniformity of the illumination, meaning eliminating dark or dim areas where someone might hide, and the brightness of the illumination, meaning how the retina actually perceives different wavelength combinations.
Specifications based upon benefit metrics are guaranteed to deliver greater value to our customers than current illuminance level recommendations. You can read about the details of these studies at the following links:
Parking Lot Lighting with Improved Uniformity
Toward a model of outdoor lighting scene brightness
Spectral considerations for outdoor lighting: Designing for perceived scene brightness
A more complete discussion of benefit metrics can be found in my recent book, Value Metrics for Better Lighting, but the bottom line is this—the old ways of specifying illuminance levels by a committee consensus process are essentially over. We don’t have to just talk, talk, talk about the potential of LEDs and their controls. We can now engineer those benefits.”
Mark S. Rea, PhD
Professor and Director
Lighting Research Center
Rensselaer Polytechnic Institute
Troy, NY 12180
Brown is the CEO of Wiedenbach-Brown. Find him on Twitter at @illumigeddon.
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