The Greenburgh Town Board will vote tonight to replace the town street lighting system with LED energy efficient lights. We expect that this will provide energy savings from the reduced electrical demands of the new fixtures at nearly $350,000 annually. We are going to award a bid to Lumen Light Solutions, LLC for a cost not to exceed $1,384,448.88. This is a cooperative relations with the New Rochelle department of Public Works which also selected this company.
This summer Matt Rabito interned with the Greenburgh Conservation Advisory Council and came up with a report on light pollution which recommended that the town convert our street lights to LED lights (something we are now doing). I was impressed with the quality of Matt’s report and am forwarding a copy for your review. Funding for LED lighting has been included in previous capital budgets. Fortunately, the costs of the lights has gone done in recent years.
To the Town of Greenburgh Conservation Advisory Council
From Matt Rabito
RE: Light Pollution
- Artificial light pollution harms human health and damages ecosystems
- Good lighting strategy has three components:
o Determine where and when light is necessary
o Choosing the right light fixture
o Choosing the right light source
- Many of Greenburgh’s neighboring municipalities have addressed the issue of light pollution by switching to LED lights and shaded streetlights. They’re saving money and protecting public wellbeing.
Life on Earth is dictated by the diurnal pattern of night and day, a pattern humans are disrupting with artificial light. Artificial light is a necessity of modern life. It extends the productive part of the day and it keeps us safe—on the roads and on the streets. However, excessive artificial light has negative impacts on human health and the environment, and it blocks our view of the night sky.
Types of light pollution:
We live in the most light-polluted part of the country—Westchester never experiences what astronomers call “true dark.”
The biggest form of light pollution in Westchester is sky glow from New York City. Sky glow occurs when artificial light shines into the night sky from one source, and then dust and air pollution in the atmosphere scatter the light so that it glows over a larger area.
We also experience point-source light pollution, which refers to unwanted light from individual sources, i.e. a streetlight that shines all night into someone’s bedroom window
A third form of light pollution in Westchester is glare, the sensation produced by luminance that is greater than the human eye can handle. Streetlights and headlights are common sources of glare, and they can temporarily blind drivers.
- Disrupts circadian rhythms. If you wake up during the night, unless you have blackout shades, some electric light will come in through your window. This immediately starts to wake you up, by decreasing your body’s level of the sleep hormone melatonin. Going back to sleep with decreased melatonin means your sleep will be less restful, and you’re more likely to wake up again—vicious cycle.
- Melatonin, a hormone produced by the pineal gland, is secreted at night and is known for helping to regulate the body’s biologic clock. Melatonin triggers a host of biologic activities, including a nocturnal reduction in the body’s production of estrogen. The body produces melatonin at night, and melatonin levels drop precipitously in the presence of artificial or natural light. Numerous studies suggest that decreasing nocturnal melatonin production levels increases an individual’s risk of developing cancer, particularly breast cancer in women 1
- Disruption of the circadian clock is linked to several medical disorders in humans, including depression, insomnia, cardiovascular disease, and cancer. Paolo Sassone-Corsi, chairman of the Pharmacology Department at the University of California, Irvine, says: “Studies show that the circadian cycle controls from ten to fifteen percent of our genes. So the disruption of the circadian cycle can cause a lot of health problems”
- There is a consistent association between exposure to indoor artificial nighttime light and health problems such as breast cancer, says George Brainard, a professor of neurology at Jefferson Medical College, Thomas Jefferson University in Philadelphia. “That association does not prove that artificial light causes the problem. On the other hand, controlled laboratory studies do show that exposure to light during the night can disrupt circadian and neuroendocrine physiology, thereby accelerating tumor growth.”
- Infants are particularly susceptible. Researchers at Vanderbilt University exposed newborn mice (comparable in development to 13-week-old human fetuses) to constant artificial light for several weeks.2 The exposed mice were unable to maintain a coherent circadian cycle at age 3 weeks (comparable to a full-term human neonate). Mice exposed for an additional 4 weeks were unable to establish a regular activity cycle. The researchers concluded that excessive artificial light exposure early in life might contribute to an increased risk of depression and other mood disorders in humans. Lead researcher Douglas McMahon notes, “All this is speculative at this time, but certainly the data would indicate that human infants benefit from the synchronizing effect of a normal light/dark cycle.”
- A study team used satellite photos to gauge the level of nighttime artificial light in 147 communities in Israel, then overlaid the photos with a map detailing the distribution of breast cancer cases. The results showed a statistically significant correlation between outdoor artificial light at night and breast cancer, even when controlling for population density, affluence, and air pollution. Women living in neighborhoods where it was bright enough to read a book outside at midnight had a 73% higher risk of developing breast cancer than those residing in areas with the least outdoor artificial lighting.3
- Lose sight of night sky, milky way
- 2/3 of American population cannot see Milky Way with naked eye.4
- Prevents trees from adjusting to seasons, causing them to die sooner. 5
- This, in turn, has implications for the wildlife that depend on trees for their natural habitat.
- Research on insects, turtles, birds, fish, reptiles, and other wildlife species shows that light pollution can alter behaviors, foraging areas, and breeding cycles, in urban centers and rural areas as well.
- Bright lights disorient migratory birds--Michael Mesure, executive director of the Toronto-based Fatal Light Awareness Program (FLAP):
“It is a serious situation because many species that collide [with light sources] frequently are known to be in long-term decline and some are already designated officially as threatened.”
- Bat feeding behavior is altered, especially New York’s native Northern Bat. Little Brown Bats are also affected, since they nest in trees.6
- North American moth population decline.6
- Almost all small rodents and carnivores are nocturnal. “We are just now understanding the nocturnality of many creatures,” says Chad Moore, Night Sky Program manager with the National Park Service. “Not protecting the night will destroy the habitat of many animals.”
- On the roads—nighttime glare can temporarily blind drivers and cause accidents.
- Home security—using an outdoor light for safety’s sake is only beneficial if you are constantly watching the lit area. Otherwise, the light gives an intruder information about the property. Outdoor lights with motion sensors do not make your property safer, since they typically light up for any passerby, and thus they get ignored—just another source of unnecessary light. Glare and bright lights create deeper shadows, and they make it harder for us to see darker areas where criminals hide.
- On the other hand a lack of outdoor light forces an intruder to reveal him/herself by using a flashlight.
From 2004 to 2013, the majority of burglaries actually occurred during the daytime. Burglars use light to their advantage, by locating valuables or planning escape routes. Light at night does not necessarily make your property safer.7
LEDs vs Incandescent:
Avg. Lifespan 50,000-100,000 hours 1,200 hours
Average Annual operating cost $32.85/year $328.59/year
CO2 Emissions, burning coal to light 30 bulbs 451 pounds/year 4500 pounds/year
Sensitive to humidity? No Slight
Sensitive to low temperature? No Slight
Heat emitted 3.4 btu/hr 85 btu/hr
To emit 800 lumens of light: ~6 Watts 60 Watts
Proportional energy usage 1:10 – LEDs use 1/10th of the power of incandescent
LEDs also easier to maintain because they have no filament and each bulb lasts longer—less maintenance required
What can we do?
1) Fix our Fixtures
WHAT we should do:
Some municipalities have already seen the light and installed shades on their streetlights. Ardsley Square, for example, has streetlights that look like the above, which is beneficial because the shade prevents up-light. However, most of Greenburgh’s streetlights still look like the diagram below on the left
a. Change light fixtures to “full cutoff” or “full focus” design
b. Install shades on our current streetlights to focus light downward, or mandate a new design for new construction.
WHY we should do this:
In addition to shining downward on the street, our current streetlights emit light ABOVE the horizontal plane of the fixture. Producing this upward light wastes energy, causes glare for drivers, and contributes to sky glow. If we invested in fixtures that shine light only where we need it—on the road—we could save money, limit our environmental impact, and protect human health.
2) Brighter does not mean safer.
WHAT we should do:
The best lighting is dim and even over an area. We should install lower wattage bulbs in public light fixtures, or mandate a dimmer bulb for new construction. We can also change the color of our lights. Of all colors of light, bluish light, with wavelength under 500nm, diffracts the most throughout the atmosphere, so it travels the farthest. For this reason, bluish light contributes the most to light pollution. On the other end of the spectrum is red light, with wavelength around 700nm. Red light diffracts the least, so it has the smallest environmental impact of all light colors.
WHY we should do this:
For safety—brighter lights create deeper shadows, and can make it easier for a criminal to sneak up on a pedestrian. Brighter lights on the road contribute to glare. Reddish light preserves humans’ natural night vision, improving visibility even in unlit areas.
To save money—running lower wattage bulbs uses less electricity.
And, obviously, dimmer lights would have less of an impact on human health and local ecosystems.
3) Get rid of vanity lighting
WHAT we should do:
Encourage residents to abandon vanity lights—wasteful lights that illuminate shrubbery, trees, driveways and homes for show. Similarly, people should lower the sensitivities of motion-sensor lights in driveways, or get rid of them completely.
WHY we should do this:
Vanity lights waste energy and money, they’re a health hazard, and they damage local ecosystems.
4) Switch to LED
WHAT we should do:
Install LED lights in streetlights and other public fixtures, like walk signs and stoplights.
WHY we should do this:
To save money—LEDs are cheaper to operate than incandescent. See table on Page 4. LED lights now have a dimming feature, so we can save even more money by dimming streetlights in the dead of night when there is little traffic.
To save time—LEDs last longer, so maintenance crews will have to make fewer replacements
For the environment—LEDs take less electricity, which means we burn less coal
Yes, it’s an investment in the short term, but it’s cheaper in the long term.
And HOW do we do all this?
There are 3 major resources available to help municipalities make the switch to more efficient lights.
1) Government initiatives, like the Department of Energy’s LED Lighting Facts program, help consumers by enforcing strict accuracy and quality standards among LED products. There are also grant programs available for switching our streetlights. We could be eligible for funds from a program like the DOE’s Energy Efficiency and Conservation Block Grant, which has already helped 25 cities and towns install energy efficient light. And we don’t have to be a big city to get attention from the government: from 2011-2014, the DOE installed 5,700 energy-efficient lights in communities with populations of less than 35,000 people. The DOE also published a survey on specific brands of LEDs, investigating manufacturers’ inflated claims and recommending the best LED products.
2) The International Dark-Sky Association (IDA) is a group of scientists who study the effects of light pollution on ecosystems and human health. The IDA has a Fixture Seal of Approval program in which it recommends certain standards on energy usage and fixture design to minimize pollution and save users money. Their resources are easily accessible online.
3) In an effort to reduce its carbon footprint, the City of San Jose overhauled its streetlights and installed more efficient LED lights. Based on their experience, the city published a detailed instructional report in 2011—a Public Streetlight Design Guide—explaining how to make such a switch.
So, by improving our light fixtures, adjusting light positioning and upgrading to LEDs, Greenburgh can save money, mitigate damage to the environment, and protect its residents’ health.
This has all been done before! Here are three success stories compiled by NHSaves, a consortium of New Hampshire’s electric and gas utilities, working with the NH Public Utilities Commission to provide NH customers with information, incentives, and support designed to save energy, reduce costs, and protect our environment statewide.
• Abington Township (Montgomery County, Pennsylvania) converted the incandescent lights in its 104 signaled intersections to LEDs. In total, over 2,500 lamps were retrofitted including red, green and yellow traffic signals and pedestrian signals. The payback was only three years at a total cost of $120,000, or roughly $50 per lamp replacement. The township saw a 90 percent reduction in energy costs for traffic signals, significantly less maintenance and positive responses from residents because of the brighter light that was emitted.
• With the installation of LED traffic lights at 2,900 intersections, Chicago is saving $2.55 million in energy costs and $100,000 in materials, annually. Carbon emissions have also been reduced by 23,000 tonnes. The total cost of the project was $32 million, which is being funded, in part, by city bond money. Complete battery backup systems were also installed at 800 traffic signal intersections to maintain operations during power outages.
• Maryland Transportation Authority is converting lane-use signals at the Bay Bridge, Harbor and Fort McHenry tunnels to LED-type signals to take advantage of their superior vibration resistance, resulting in less maintenance costs.
1. “Benefits of Sunlight: A Bright Spot for Human Health,” EHP 116:A160–A167 (2008)
2. McMahon et. al. Pediatric Research. Aug. 2006.
3. Kloog, Itai et. al. “Light at Night Co-distributes with Incident Breast but not Lung Cancer in the Female Population of Israel.” Chronobiology International. Jan 2008, Vol. 25, No. 1:65-81
4. “The First World Atlas of the Artificial Night Sky Brightness,” a report on global light pollution published in volume 328, issue 3 (2001) of the Monthly Notices of the Royal Astronomical Society
5. Brigg, Winslow. Ecological Consequences of Artificial Night Lighting
6. Ecological Consequences of Artificial Night Lighting.
7. FBI Residential Burglary Crime Statistics: 2004-2013. Web. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2627884/
Comprehensive facts, published by the DOE:
- On the Block Grant: http://energy.gov/eere/articles/small-towns-achieve-big-savings-lighting-upgrades
- LED Fact Sheet: http://energy.gov/eere/ssl/led-lighting-facts
Links to fact sheets, archived web seminars, technology reports, and finance analysis tools: http://energy.gov/eere/ssl/outdoor-lighting-resources
The IDA: http://darksky.org/fsa/
City of San Jose Public Streetlight Design Guide: www.sanjoseca.gov/DocumentCenter/Home/View/242