Luminaires for providing general illumination to an area are well known and often used in outdoor lighting applications including roadway and sidewalk lighting, parking lot lighting, and residential area lighting. In order to increase luminaire efficiency, light emitting diodes have been incorporated into luminaire designs as a light source. Light emitting diodes offer several advantages including high lighting efficiency, long lifetimes that can exceed 50,000 hours of operation, resistance to physical or mechanical shock and rapid lighting response time.
Conversely, light emitting diodes additionally exhibit several disadvantages which challenge their use in luminaire constructions, including luminaires used for general outdoor illumination. The performance of a light emitting diode, for example, is largely dependent on the temperature of the operating environment. Operating a light emitting diode in high ambient temperatures can lead to overheating and device failure. Moreover, light emitting diodes are generally offered in relatively low lumen packages, necessitating large numbers to create the required lighting levels. As a result, it is difficult to produce a light emitting diode luminaire having the size, shape and light output of existing high intensity discharge (HID) luminaires.