Street Lighting

Ambient street lighting provides necessary light for pedestrians, motorists and public safety services. Currently several high intensity discharge technologies dominate the market place. The primarily technologies used to illuminate freeways, city streets, sidewalks and parking lots are low pressure sodium, high pressure sodium, and mercury vapor lights. Although these technologies (minus mercury vapor) are relatively efficacious when they are new, they have steep lumen depreciation curves. Lumen depreciation means that over time the technology will produce less light for the same amount of energy consumed. The technologies mentioned earlier are marked by poor color rendering properties and low correlated color temperature (CCT). Poor color rendering means that the color identified under the light source will not be the same as seen under day light. Having a low CCT means that the light output will have more red mixed in.

Street lighting fixtures vary in shape and wattage. The most common types of fixtures are cobra heads, shoe-boxes and acorn (decorative) heads. Most are mounted high on metal posts or wooden poles. System wattage often depends on location, fixture, mounting height and desired light levels at the street level. However, common wattages range between 75w and 400w.

Updating existing street lighting offers a great way to reduce electricity consumption and maintenance costs while increasing overall light quality. Advances in light emitting diode (LED) technologies have made cities across the United States and the world excited about addressing and retrofitting their existing street lighting. New LED street lights offer significant energy savings by reducing overall system wattage. LED street lighting also has much better color rendering properties and color temperature than previous lighting technologies.

LED fixtures offer several other advantages over current technologies. LED fixtures can be manufactured with specific photometric properties that overall light trespass. This is particularly useful in neighborhoods where residents don't want area lighting coming in their windows. Although not unique to LED fixtures, new cobra heads, shoe boxes and acorns can easily be dark sky compliant. Lastly, LED fixtures can reduce the number of dark spots on city streets, decreasing the likelihood of vandalism in those areas.

Several case studies have been conducted that indicate replacing traditional street lights with LED technologies offers significant energy and maintenance savings. For instance, the city of Los Angeles, in cooperation with the Clinton Climate Initiative, plans on replacing 140,000 street light fixtures with LED fixtures and installing a remote monitoring system. The city expects to save over $10 million a year and offset over 68 million kilowatt hours. The project should pay for itself within seven years. This and other case studies are provided as hot links below.

Advances in LED street lighting can offer businesses great savings as well. If you own a facility with a large parking lot and exterior area lighting, you may benefit from this technology. We recommend visiting our Small Business Direct Install page for more information on how to get one of our Energy Specialists to your site.

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