Click here alt="LED street light life span chart" src="https://upload.wikimedia.org/wikipedia/commons/thumb/d/d4/LED_Street_Light_Life_Span-1.jpg/240px-LED_Street_Light_Life_Span-1.jpg" style="border-style:solid; border-width:1px; height:126px; width:240px" />
The life span of an LED as compared to other light sources
The primary appeal of LED street lighting is energy efficiency compared to conventional street lighting fixture technologies such as high pressure sodium (HPS) and metal halide (MH). Research continues to improve the efficiency of newer models of LED street lights.
An LED street light based on a 901-milliwatt output LED can normally produce the same amount of (or higher) luminance as a traditional light, but requires only half of the power consumption. LED lighting does not typically fail, but instead decreases in output until it needs to be replaced. It is estimated that installation of energy efficient street lighting in the 10 largest metropolitan areas in the U.S. could reduce annual carbon dioxide emissions by 1.2 million metric tons, the equivalent of taking 212,000 vehicles off the road, and save at least $90 million annually in electricity costs.
As LED lighting fixtures normally produce less illumination it is important to use a well-distributed illumination pattern in order to produce the same illumination as higher-lumen conventional fixtures. For example, different LEDs in one fixture can target different points on the street.