The Basics of LED Lighting
LED lighting technology has come a long way in the past decade and manufacturing efficiencies have driven down the cost so that LED streetlight fixtures are, in most cases, less expensive to purchase than traditional Low or High Pressure Sodium Vapor fixtures that have been used for decades.
Many people associate LED lights with glaring, blue hued lights that are hard on the eyes. Fortunately, LED technology has changed significantly in the past few years. LED streetlights can be ordered in a wide variety of specifications, including different color temperatures, different wattage which relates to the intensity of the light, different distribution patterns and have a much higher color rendering index (CRI) than High and Low Pressure Sodium lights that cast an orange glow.
The City has selected fixtures with a warm color temperature of 2,700 Kelvin, which is a temperature similar to an incandescent light bulb, and also conforms with the American Medical Association's recommendation that jurisdictions select fixtures with a color temperature no greater than 3,000 Kelvin. 2,700 Kelvin is a temperature that filters out much of the blue color of the spectrum, which has been linked to interfering with the circadian rhythms of mammals.
The goal when providing street lighting to residential neighborhoods is to provide a level of public safety and balance the brightness of fixtures so that streets are illuminated but light is not cast onto the front of homes or through windows. The City has selected a 14-watt fixture which provides a more ambient quality light and will save a significant amount of energy over the current 55-watt Low Pressure Sodium (LPS) fixtures commonly found in Murrieta residential neighborhoods today. The streetlights on major roadways in the City will be retrofitted with 83-watt LED fixtures.
The distribution pattern for all these lights have been selected so that the lights don't cast light backwards onto yards and only cast light out far enough to cover the road surface.
Provided are some side by side photo comparisons of an actual residential street in Murrieta where test fixtures were installed and allowed City staff to see LED lights deployed in the field prior to finalizing our fixture selection. You can see the typical orange glow from the LPS fixture on the left which spills over onto the adjacent properties. There is less light intrusion from the LED fixtures, and you can clearly see more colors of the spectrum and a more natural light.