With a typical HID fixture, about 55 percent of the energy input is lost through heat, with another 9 percent going toward vibration. Conversely, with a typical T8 fluorescent setup, approximately 93 percent of the energy input is converted to light, with minimal heat and vibration.
HID lighting burns at 1,200 degrees Fahrenheit and has safety risks. There are NEMA and NFPA advisory warnings for fire and UV hazards due to possible rupture of the arc tube or cracked glass.
HID lamps take from 30 seconds to five minutes to reach full brightness when turned on. They can take between a minute (for high-pressure sodium) to 20 minutes (metal halide) to regain full brightness after even a momentary power loss. With fluorescents lighting, re-strike is immediate under all but the coldest conditions.