The Lighting Systems Division of the National Electrical Manufacturers Association (NEMA) recently published a white paper, “Outdoor Lighting and Human/Animal Factors: An Industry Evaluation,” available for download at the National Lighting Bureau, here.
The paper examines issues that can result in compromised outdoor-lighting quality when color issues are misunderstood and, therefore, misapplied. “Some proposals oversimplify the ecological tradeoffs that are inherent with any proposal to limit outdoor lighting to a certain correlated color temperature (CCT),” the paper states. “Such recommendations do not recognize the inconsistencies of such a spectrum choice, for instance, that long wavelength ‘red’ light purportedly may disturb certain bird migrations while short wavelength (i.e., blue) light distracts sea turtles. How is such a trade-off to be reconciled between species? The topic of lighting color is complex and involves many factors beyond CCT. Thus, promoting specific CCTs to advance a particular outdoor lighting policy may have unintended consequences on overall lighting quality and other concerns of public policy such as safety and security.”
In fact, Division members believe that existing data are insufficient to recommend that outdoor-lighting systems be limited to any CCT. The conclude: “A careful balance of controlling light pollution, excessive lighting infringing on residential property, and energy use while addressing issues of visual acuity and safety/security requires consideration of not only the lighting equipment installed but also the design and layout of the lighting equipment on a site.”