It's Complicated...

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Last week the Nature Museum completed a major lighting upgrade which will reduce our electricity bills and lower our carbon footprint significantly in the years to come. The project was spearheaded and primarily funded by a board member (with additional financial support from two of her colleagues) with a passion for clean energy projects. The Nature Museum’s operating expenses will be reduced and our planet will be better off with the upgrade, so big thanks to the three board members who made it happen. You rock!

But as the saying goes, no good deed goes unpunished. And in the case of our lighting upgrade our punishment came in the form of increased sky glow (a fancy way of saying light pollution) from the two outdoor lamps illuminating our parking area at the Outdoor Discovery Center.  A major reason homeowners, companies and municipalities are rapidly switching to LEDs is because they are highly energy efficient. LEDs produce more light (lumens) with less electricity (watts) than incandescent or sodium vapor lights.

And that’s good … mostly. But as with many things in life, it’s complicated.

The spectrum of visible light spans a range of wavelengths that, when separated into a single wavelength are seen by the human eye as red, orange, yellow, green, blue, indigo and violet (think rainbows). Different types of lighting systems and bulbs emit light at different wavelengths. Some light bulbs are described as cold or cool, meaning they emit more blue-indigo-violet wavelengths, others are described as warm, meaning they emit more red-orange-yellow wavelengths. Additionally, light bulbs are rated for brightness or intensity which is reported as lumens. The combination of these features determines how we experience electrically generated light.

For these reasons changing out exterior incandescent or sodium vapor bulbs with LEDs can be problematic when the color (wavelengths) and brightness (lumens) cause substantially more sky glow.  Because white LEDs emit more short wavelength light than conventional bulbs, increased blue and green wavelengths cause substantially more light pollution when the wattage is not adequately stepped down and the lamps are not properly designed or positioned.  Nighttime light pollution can negatively impact insect and animal behavior, and may affect human health by disrupting circadian rhythms, messing with melatonin levels and creating other sleep disorders.

So, are we giving up on our lighting upgrade because of these problems? Not at all.

But we have begun an assessment and will quickly implement one or more of the following steps to address the light pollution issue head on; 1) install motion detectors to greatly reduce the amount of time the lights are illuminated, 2) swap out the new bulbs with lower wattage LEDs to reduce the intensity when they are on, and 3) install hoods on the lamps to direct the light downward and reduce omnidirectional light. These modest adjustments will allow us to save energy, lower our electrical costs, reduce our carbon footprint and preserve our dark skies too.

See you in the dark!!!

                              By Tom Bregman

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