Metal halide lighting is a type of high-intensity discharge (HID) lamp that produces light by passing an electric arc through a gas mixture containing metal halide salts, giving a whiter light than the high-pressure sodium lamps it often replaced.
For decades metal halide was a standard choice for parking lots, garage roofs and pole lighting. Today it is largely obsolete in new parking work. LED fixtures use far less energy, last longer, turn on instantly and can be dimmed, which metal halide cannot do well.
Drawbacks
- Warm-up of several minutes to full output, and a cool-down delay before restrike after a power interruption.
- Significant lumen depreciation and color shift over lamp life.
- A ballast is required, adding losses and a failure point.
- Limited ability to dim, which rules out most energy-saving controls.
Retrofitting
- Most metal halide parking lighting can be replaced with LED fixtures or retrofit kits, usually with substantial energy savings and lower maintenance. See LED lighting.
The Parkonomics view
If a facility still runs metal halide, the LED retrofit is usually one of the fastest paybacks available, and it brings better light and controls with it.
Related terms: LED Lighting, Ballast, Ballast Factor, Lighting Power Density