Lamp Efficency

Efficiency of Different Lamp Types
The job of a lamp is to convert electrical power (Watts) into light (lumens). Different lamps do this with varying efficiencies.

Lamp Type	Conversion Efficency (Lumens per Watt)	Life (Hours)
GLS	10	1000
Low Voltage Halogen	20	2000 to 5000
Mercury Vapour	40 to 60	22000
Fluorescent	64 t0 90	7000 +
Metal Halide	70 to 90	12000 +
High Pressure Sodium	90 to 125	25000
Low Pressure Sodium	120 to 200	20000

The customer should be made aware of lamp efficiencies and operational life in situations where a lamp is to be left on for long periods of time or is not easily accessible for replacement. The energy consumption of a large lighting system is considerable. For example in a commercial building the energy costs of the lighting system may be 30 to 50% of the total energy costs.