It is a Light Emitting Diode. Diodes are semiconductors that, in this case, convert electricity into light. A main factor that makes LED lights energy efficient is the small amount of heat that they emit compared to an incandescent bulb that release 90% of their energy in heat. For more information about LED lights visit the Department of Energy’s web page.
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The Town will convert all town-owned streetlights to LEDs which includes 1,800 streetlights and some park and parking lot lights that aren’t already LEDs.
The proposed project will result in a 50-80% reduction in energy usage from the current technology and significant utility and maintenance savings annually. Between the purchase of our lights and the retrofit to LED, the Town stands to save roughly $100,000 per year in maintenance and energy use. LED lights are more expensive, but can last 20 years, so the investment will be paid back by these savings and reduced maintenance costs in under 5 years
In addition to the extended lifecycle and lower replacement costs, LEDs result in reduced light pollution at night and improved and more uniform light quality. Because they use less energy, LEDs also help to reduce carbon emissions. LEDs also make colors look brighter and more “true” to natural color. Due to the improved color rendition things appear brighter and sharper under LEDs which is why police and other safety personnel prefer LEDs.
Approximately 60% of our streetlights are currently High Pressure Sodium (HPS), 30% Mercury Vapor (MV), and 10% Incandescent cobrahead fixtures.
Color temperature of lighting is measured in Kelvin (K) units. When LED streetlights first came out most applications used 5,000 Kelvin, very cool or white. These were very harsh and almost bluish. Applications then moved to using 4,000K which is called “moonlight.” Several credible sources have issued opinions about the detrimental effects of 4,000K lighting, regarding its negative affect on human sleep patterns, nocturnal animal behavior, and light pollution. The Town has chosen 3,000 kelvin LED lights due to its softened yet effective color.
No, the new lights will reduce unwanted spill light into homes and properties as most of the light is directed downward to the street and sidewalk. However, if a homeowner reports that there is too much light coming into their home from the new LEDs, the Town can install a houseshield on the streetlight to control unwanted light.
National Grid owns the street lights in areas, such as North Main Street, where electricity is fed underground. There are a few privately owned street lights that the Town also doesn’t own and therefore cannot convert.
Yes. The Town has already converted all the antique post top lighting on Main St., in the Shawsheen Village, and by the Town Offices.
A system of street classification (arterial, connector, and residential) was developed to determine appropriate light levels for each street. The criteria are in accordance with guidelines used by the Federal Highway Administration, MassDOT, and the Illuminating Engineering Society. However, as the scope of this project does not include moving light poles, the Town was limited to using existing pole locations throughout the Town.
Yes but dimming controls are not included in the project. The current cost of wireless controls added 30-40% to the overall project cost. In addition, the National Grid streetlight tariff does not yet reflect savings from dimming so the Town wouldn’t save additional money on utility bills from dimming. However the Town is adding components to each fixture that will make the streetlights dimming control-ready so we can take advantage of the technology when the prices come down and the utility savings are guaranteed to show up on our electric bills.