Good News or Bad?
By Mary Coolidge
Birdsafe Portland Campaign Coordinator
Audubon Society of Portland
If you live in Portland, you’ve probably noticed the replacement of our familiar soft yellow streetlights with bright blue-white bulbs. In 2012, Portland City Council approved the conversion of Portland’s streetlights from high pressure sodium (HPS) to light emitting diode (LED) technology. This is the largest energy efficiency project ever undertaken in Portland, and is expected to save the city $32 million over the anticipated 25-year lifespan of the new lights. LEDs consume less energy than the old bulbs, will last about four times longer, and have lower maintenance costs. Good news, right?
Well, yes & no. While the switch to LED technology will dramatically reduce greenhouse gas emissions and is prescribed in the City’s 2015 Climate Action Plan, the Plan also stipulates the use [of] Dark Skies best practices when possible to reduce light pollution and minimize bird strike hazards. The Portland Central City Plan and Draft Comprehensive Plan also call for bird friendly building and lighting design. Best practices in lighting design include: proper shielding to keep light focused where it is needed; careful setting of lighting levels (not over-lighting); and thoughtful consideration of the spectral composition of bulbs.
A large body of research shows that light pollution in our cities can have significant negative impacts on human health as well as birds, fish and wildlife. Most songbirds migrate at night and rely on the moon and stars to navigate. Light emanating from cities drowns out these natural cues disorienting migrating birds and attracting them into the city, where they face a variety of hazards including deadly and deceptive building glass. Reducing unnecessary overnight lighting can help reduce exposure to these hazards. Many major cities such are taking significant steps to address light pollution.
Unfortunately, the 4,000 Kelvin bulbs selected by the Portland Bureau of Transportation emit what is known as blue-rich white light--a spike in the blue wavelength portion of the light spectrum—and do not meet the current International Dark Sky Association’s Fixture Seal of Approval rating (<3,000 Kelvin). These lamps are likely to actually worsen light pollution in the Portland area. Although the new cobra head light fixtures are shielded, the diodes are not recessed into the cobra head mount. Furthermore, blue-rich white light scatters more readily in the atmosphere than longer wavelength light sources, and is known to impact circadian rhythms in humans, plants, and fish & wildlife. It creates significant glare and suppresses melatonin production, which interferes with sleep cycles and may be linked to serious human health problems.
Portland’s Bureau of Transportation claims that the city is rolling the conversion out slowly to allow for public input. Yet, only 2 LED pilot projects were ever developed in the city, with limited opportunity for public input; only 49 surveys were completed in response to pilot projects. Seventy-five percent of the city’s 45,000 cobra-head fixtures have already been converted, with an estimated project completion date of December 2016. Representatives at PBOT are eager to say that the 4,000 Kelvin LED fixtures may seem brighter than their HPS predecessors, but that they actually approximate moonlight. Not true! The spectral composition of moonlight is most closely approximated by a 2,200 Kelvin bulb. Furthermore, Portland’s 55,000 total streetlight fixtures will shine brighter than moonlight every night of the year! Darkness provides important habitat and is home to many nocturnal species that have long-evolved natural histories linked to darkness, which is rapidly vanishing across the globe.
Although PBOT is touting that the selected streetlights are dimmable, residential units are already set to their lowest output level of 29 watts, and can dim no further. PBOT is currently evaluating test fixtures with recessed diodes and with 3,000 Kelvin bulbs, but where and how these fixtures might be put to use remains unclear.
Public outcry about conversion to 4,000 Kelvin streetlights in the cities of Davis, Honolulu, and Phoenix have resulted in project adaptations that utilize lower Kelvin and/or lower wattage bulbs. Cities like Tucson, Boston and Cambridge have demonstrated interest in the evolving story around LED conversions, and have committed to dimmable technology and lower Kelvin lamps. LED is a rapidly advancing technology; comparably energy-efficient lamps designed to minimize blue light are now available at equivalent cost.
At a time when many major North American cities are taking steps to reduce light pollution, Portland is lagging behind and in some cases going the wrong direction altogether. Too many recent Portland Projects have suffered from garish lighting that blocks out the night sky and reduces the ecological health of our communities. Citywide conversion and update projects like this provide opportunities to think about ways that we design with nature as our region grows. Audubon Society of Portland is committed to working with the City of Portland and the development community to ensure that we are designing our built landscape for ecological resilience into the future. We urge our members to track local projects and insist upon ecologically responsible lighting and building design.
Reprinted by Permission