Turn off HID lights when not needed for a half hour or more
Turning off unneeded equipment is one of the easiest ways to save energy.
High Intensity Discharge (HID) lamps (Mercury Vapor, Metal Halide, and High Pressure Sodium) are not designed for frequently switching. A general rule is to shut them off if not needed for a half hour or more.
Mercury vapor and metal halide lamps require a 5 to 15 minute warm-up to achieve full intensity. In addition, they need 10 to 15 minutes of cool-down time prior to restarting; high pressure sodium only requires 1 minute. Some types of metal halide lamps with electronic ballasts may be suitable for instant restart.
Some rooms with HID lighting also have some fluorescent or incandescent fixtures, which are intended for short-term use to avoid starting up HID lamps. These lamps should be turned off once the HID lamps warm up.
Create additional savings (and simpler operation) by upgrading to LED lighting.