Choosing new technology over old, a University of Pittsburgh study recommends that Pittsburgh replace its 40,000 streetlights with LED lighting.
The 72-page study, "Life Cycle Assessment of Streetlight Technologies," by Pitt's Mascaro Center for Sustainable Innovation, says electricity savings from light-emitting-diode -- or LED -- lighting would offset negative environmental impacts of the LED manufacturing process by a factor of 10.
That means the city, which spends $4.2 million annually on electricity and streetlight maintenance, could save $1 million each year in energy costs and $700,000 in maintenance costs with LED lighting.
For now, induction lighting holds a slight edge over LED lighting in environmental issues, costs and other factors. But anticipated boosts in efficiency in coming months and years, along with expected cost reductions, flick the switch in LED's favor.
LED uses solid-state electronics to convert electricity into light waves, which then strike a phosphorus coating and transform the ultraviolet light into white light. Older lighting technologies excite gas or gases with electricity that energize coatings to produce light. Such gas technologies include induction, high-pressure sodium and metal-halides lighting.
Currently 90 percent of the nation's lighting is high-pressure sodium, including most of Pittsburgh's streetlights. Only 1 percent of the nation's streetlights are LED lighting, the study says.
In the study led by Melissa Bilec and Joe Marriott, Pitt reviewed manufacturing, use and disposal of housings, plus raw materials, bulbs and power in evaluating the four technologies. While LED contains fewer harmful materials than the others, its manufacturing process is more energy intensive. The study's evaluation also included recycling issues and disposal of used bulbs, known as lamps.
"The University of Pittsburgh looked at what is the best product from cradle to grave approach on the environmental impact, and one of the first studies done on urban lighting," city Councilman William Peduto said. "The report clearly demonstrates with all the technology out there that LED has the best impact from an environmental point of view."
Induction lighting, an older technology and LED's chief competitor, already has reached its peak of efficiency. The study compared LED lighting with computer chips in projecting increases in efficiency and cost reductions for years to come.
"Our recommendation is that the city of Pittsburgh use LED lighting," the study states. "This will allow the city to realize immediate electricity savings and complete its retrofit with a single technology."
Last February, City Council formed six subcommittees to lead a Pittsburgh Streetlight Conversion Task Force in evaluating various issues regarding streetlight replacement citywide. Hoping to make decisions based on science, the city drew in Pitt, CMU, lighting experts and the Clinton Climate Initiative to do the analysis.
The Remaking Cities Institute in Carnegie Mellon University's School of Architecture is completing an urban planning analysis to develop a better streetlight network, among other issues.
The Clinton Climate Initiative, based in Little Rock, Ark., New York City and Boston, is studying costs, financing and funding. One of the initiative's missions is resolving problems leading to climate change by improving energy efficiency in outdoor urban lighting.
Michael A. Cherock, founder of Powerhouse Design Architects and Engineers Ltd. of Pittsburgh, is putting final touches on a proposed Pittsburgh Lighting Code. Pittsburgh is one of the few cities without a lighting code, which is necessary to set lighting standards and give the city a basis for enforcement, he said.
Mr. Cherock also is completing a light-quality analysis with assistance from researchers at Penn State and Virginia Tech universities that he expects to complete in March.
"I'm doing this as a resident," he said, noting he's receiving no fee for his efforts. "We will establish a lighting code, then we will have lighting equality.
"Without a lighting code, you have nothing."
Mr. Peduto and Lindsay Baxter, sustainability coordinator in Mayor Luke Ravenstahl's office, said the task force studies will serve as a standard tool for municipalities worldwide to evaluate streetlight technologies.
With completion of the Pitt study, Ms. Baxter said she and the mayor's office now are leaning toward LED lighting. But a final decision will await completion of all the task-force studies.
The hope is to seek bids in June and begin streetlight construction in late summer, Ms. Baxter said. The project will progress in phases to allow the technology to mature and costs to decline.
"This really is a good and useful tool for us," Ms. Baxter said of the study. "It provides information that we do not have the technical ability to realize."
The ultimate goal, she said, is "how to make Pittsburgh a nicer place."
Still, it's no surprise that Pitt's study identified LED lighting as the brightest option. Already Los Angeles and Anchorage, Alaska, have chosen LED lighting, but without comprehensive analyses to back up their decisions.
Pittsburgh has installed LED streetlights on one side of Shadyside's Walnut Street, between South Aiken Avenue and Bellefonte Street, with lights of other technologies used along the other side of the street. Mr. Peduto said the superior quality of LED lighting is obvious.
The city also has been analyzing energy usage, longevity of lamps, light quality and environmental impacts of all four lighting technologies in 150 streetlights on the South Side. Early results were used in the Pitt study.
The 131 million streetlights in the United States produce 128 million metric tons of carbon dioxide pollution. With LED lighting, Pittsburgh would reduce CO2 emissions by 6,818 metric tons per year, the study says.
The downside of LED lighting, Mr. Cherock said, is light quality.
LED lighting has a bluish cast, which does not allow an accurate view of colors. LED lighting makes it look as though the moon rather than the sun is the light source.
Still, there's every expectation that LED light quality will improve.
Mr. Cherock who has been working with Mr. Peduto for five years on streetlight issues, said the task-force approach is necessary for the city to develop a position of knowledge.
While LED "is not the silver bullet," due to light-quality issues, he said he's not opposed to the Pitt recommendation.
"The whole package is a complex machine," Mr. Cherock said. "We will have to buy a progressive technology that's still in its infancy. But there are so many potential rewards that make it enticing."
David Templeton can be reached at firstname.lastname@example.org or 412-263-1578.