Is It Possible?
High electricity costs in Alberta may have a silver lining for astronomers
by Bob King
Light pollution is everywhere — or so it seems. Sometimes it's as obvious as the yellowish dome of light above a distant city. Or it can be as nearby and annoying as your neighbour's porch light. Either way, our natural heritage of a view of the starry night sky has become so eroded that an informal survey of schoolchildren in Toronto recently revealed that two-thirds of them have never seen the Milky Way.
Light lighting is now so commonplace that most people don't even question the wastefulness of illuminating shopping-centre parking lots all night when the cars are gone by 10 p.m. Also largely unnoticed are the thousands of streetlights that beam a portion of their light directly up into the night sky (individual streetlamps are actually visible from airplane windows). But now, something is happening that may reverse at least some of the crucial streetlight component of light pollution.
Astronomers at the Rothney Astrophysical Observatory (Canada's third largest observatory), located 25 kilometres from Calgary, amateur astronomers and others who abhor light pollution were thrilled to learn that the City of Calgary is proposing to retrofit residential streetlights with full-cutoff luminaires and lower-wattage lamps. The desire to reduce carbon-dioxide emissions from power plants and the sharp increase in the price of electricity in Alberta have caused Calgary to consider using lighting more wisely.
We anticipate an "operating-cost saving of approximately $3 million per year for the City and a reduction of 17 kilotonnes of carbon-dioxide emissions per year," said Arne Andreasen, general manager of Calgary Roads, when he recently accepted a Responsible Lighting Award from the Calgary Centre of The Royal Astronomical Society of Canada. A helpful catalyst for the project is that the Infrastructure Canada/Alberta Program has offered $3 million toward the retrofit. The balance of the $7.2 million project will be financed by the proposed annual energy savings.
Calgary has suffered very bad light pollution for many decades, making it readily visible on the "Earth at Night" satellite photo. A significant portion of the light pollution is caused by its 68,600 streetlights, but this has begun to change. Calgary Roads now requires that all new streetlights have full-cutoff fixtures (no light emitted above horizontal). More important, 49,000 existing residential streetlights will be retrofitted over the next few years with full-cutoff, high-pressure sodium lamps reduced from 200 watts to 100 watts.
The remaining 20,000 streetlights, however, are problematic. They are decorative lights, such as historic-style and post-top luminaires, as well as several thousand high-mast, 400- and 1,000-watt streetlights that illuminate Calgary's expressways and freeways. Although Calgary Roads has no plans to replace the decorative streetlights, it will retrofit the 400- and 1,000-watt streetlights when suitable full-cutoff fixtures are found.
Calgary Roads tested the new lighting last year in several communities. The luminaires were installed along a few roads and at two new interchanges, while the lamps in several residential areas were reduced to 100 watts. There were no complaints about the revamped lighting, although before the lights were installed, some residents had expressed their concern that crime would increase because the streets would be dimmer and the yards darker.
The remaining light pollution in Calgary arises from industrial, commercial and residential misuse of light. Correcting that situation will require a bylaw, although there are increasing numbers of new, good lighting installations. Recently, lighting bylaws have been enacted in the towns of Cochrane and Okotoks, which are just outside of Calgary. Since the mid-1990s, the town of Canmore, located just east of Banff, has required full-cutoff streetlights. Alberta Transportation has been using cutoff luminaires or low-pressure sodium lamps at rural intersections since the mid-1990s.
Awareness of the detrimental effects of light pollution is increasing in Alberta and elsewhere in Canada. Coupled with the rising demand for and cost of electricity, that awareness is forcing communities to begin to use night lighting more wisely. Taxpayers, environmentalists and astronomers — take heart.
Image credits: Two Calgary street shots: Roland Dechesne. Western hemisphere satellite image: NASA/JPL.