Lighting the Way: Reclaiming Our Night Sky
By Don Brett,
Previous NatureSpeak columns have discussed the problem of light pollution and outlined some solutions. In this column and the next, I will examine light pollution in our local environment within the municipality of Whistler.
Light pollution threatens our connection with the natural world by robbing us of the night sky. For the first time in history, the majority of humans alive cannot see the full glory of the stars because of the artificial light pouring from our cities. This unnatural light may have a significant and as yet largely unstudied effect on human health and well-being, not to mention on nocturnal animals and insects, and in turn, the biosphere as a whole. The loss of this part of nature desensitizes us to other damage to the environment.
There are other reasons why we should care about light pollution:
Most light pollution is caused by misdirected light, that is, light that does not illuminate the intended target. This wasted light means wasted energy and money. Wasted energy means more hydroelectric dams and unnecessary CO 2 emissions from fossil fuel generation stations;
Misdirected light is often noticeable in the form of glare. Glare hinders our vision, reduces visibility and can increase nighttime travel hazards. Glare reduces effective illumination by making our eyes less sensitive to light and can create blind spots and dark areas. Glare creates a disagreeable and cluttered night environment;
Light trespass is a misdirected light that spills unwanted across property lines. Unpleasant and annoying, the most obvious example is the neighbours light that shines in your bedroom window. Less obvious, but perhaps more important, is the effect of the light that pours unnecessarily from homes, businesses and streetlights and spoils our enjoyment of the night environment.
The good news about light pollution is that it can be easily mitigated at relatively low cost. Since poorly shielded fixtures that spew light directly into the sky cause most light pollution (for instance, 50 per cent-75 per cent of sky glow), the installation of inexpensive shields can create a significant improvement. (The design of some fixtures makes retrofitting with shields impractical and the remedy replacement will be more expensive). The two most annoying forms of light pollution glare and light trespass can be virtually eliminated with good shielding with no loss of illumination.
To go beyond a 50 per cent-75 per cent improvement, light levels have to be reduced. Since night lighting is often a necessity for safety and security, for instance at intersections, careful engineering must be done to ensure that sufficient illumination is provided. This is not an impossible task and good fixture design can help. For instance, if glare from streetlamps is reduced, then lamp wattage can also be reduced, with no net change in the effective illumination level. The City of Calgary has recently commenced a major streetlight retrofit program with precisely this objective: improving shielding while reducing wattage with the capital costs to be recovered from energy savings.