High intensity discharge (HID) lamps include mercury vapor, metal halide, and high-pressure sodium lamps. They are electric-discharge lamps in which: (1) the light-producing arc is stabilized by bulb wall temperature; and (2) the arc tube has a bulb wall loading in excess of 3 Watts/cm2. These lamps are commonly used outdoors in parking areas and on roadways and indoors in high ceiling applications such as factories, gymnasiums and big-box retail stores. Some types of metal halide lamps are also used in low ceiling applications.
There are currently no standards for HID lamps. In July 2010, DOE published a positive determination noting that a potential standard level that eliminates inefficient probe-start metal halide lamps (with a savings of approximately 15%) would likely prove technically feasible, cost-effective and would yield significant energy savings. However, in December 2015, after conducting research and analysis and receiving comments and input from stakeholders, DOE determined that standards for high pressure sodium lamps (HPS) were not technologically feasible, and that standards for mercury vapor (MV) and metal halide (MH) lamps were not economically justified. HPS, MV, and MH lamps are types of HID lamps.
Annual shipments of HID lamps are approximately 7 million but are expected to decline.