Lighting the Way
Reclaiming the Whistler night sky, part 2
By Don Brett,
This is the second NatureSpeak column to examine light pollution within the Resort Municipality of Whistler. In this column, well look at commercial and residential lighting within the municipality and provide a checklist for assessing lighting needs.
As we saw last week, light pollution is an under-rated environmental hazard that may have a negative effect on humans emotional and physical health, as well as other parts of the biosphere. Poor light design and usage wastes energy and creates an annoying and dangerous night environment. Light pollution is perhaps not the biggest environmental threat but it is often the most noticeable (think of the sky glow above big cities). The good news is that reducing light pollution is easy and inexpensive.
We are so accustomed to glaring and inefficient night time lighting that we are hardly conscious of it. (Similarly, it is not long ago that smoking in public places was so much the norm that neither non-smokers nor smokers gave it much thought.) Starting with architects and designers and through to businesses and homeowners, we need to be conscious of good lighting. As a local architect said to me: "Lighting is often an afterthought in the design process the lighting is often specified by the engineer, not all of whom have expertise in lighting design"
To help you become more conscious of lighting issues, here are the key questions to ask of any light design or installation:
Why is the lighting needed?
Night lighting around homes and commercial buildings has one or more purposes: convenience (e.g. being able to find the keyhole); safety (e.g. being able to see the stairs); security (to discourage crime); decoration ; or advertising (to attract customers). If the light does not serve any of these purposes, then there is no need to install a light (and there will be one more victory for the forces of darkness). The purpose of the lighting will dictate answers to the remaining questions.
When do you need the light?
It is rare that a light needs to be on all the time. For convenience or safety, a motion sensor-triggered light is best: the light will only go on when the presence of a person triggers the light. The best infrared sensors are calibrated to trigger on the movement of people-sized objects, not animals or cars.
As far as security is concerned, consider that there is little evidence, despite considerable research, that more light deters crime such as assault and break-ins. Several U.S. school districts have reported a reduction in vandalism when school exterior lights were turned off apparently the vandals were afraid of the dark! Current wisdom is that motion detector-triggered lights offer the best deterrence as they create a sudden change in the environment that may disconcert a malicious individual.
How much light do you need?
We are so accustomed to brilliant lights that we think we "need" brightly lit areas to see well. In fact, the human eye can adapt within a few seconds to low levels of light. For convenience and safety around the home, low wattage lights are more than adequate (think of the low voltage "garden lights" sold in hardware stores). A 40 or even 25 watt bulb will be sufficient for most of your exterior house lights. Even security lighting may be more effective if less bright bright lights create dark shadows that can hide a person. The amount of light produced by the floodlights so common on homes (Photo 9) is rarely necessary. If you are tempted to install a brighter bulb to "throw" light further out, consider instead installing another, low wattage light, close to where you need the illumination.
Where do you need the illumination?
Since light pollution is largely caused by misdirected light, controlling the emitted light to within the targeted area is the core of the light pollution fight. It seems obvious that the light should be pointed at rather than out from the target area but look at all of the violations of this principal in the accompanying photos. Point the lights down at a steep angle (straight down if possible) since all unshielded lights produce a very broad beam. (Figure A)
Most important, however, is to have properly shielded fixtures. The shields should be installed so that the emitted light is contained within the target area. In all cases, you should keep the light from your building inside your property lines. (See Figure B). There is no excuse for light trespass.
In future columns we will keep you abreast of the growing movement within Whistler to reclaim our night sky.
Wednesday, May 22 Nature Walk; Shadow Lake Interpretive Forest. Meet at 7 p.m. at the forest service parking area, 1 km north of the Green River railway crossing, on the east side. Call Mitch Sulkers at 604-932-3707 for details.
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