|Considerable energy savings can be achieved by replacing incandescent lamps with high-intensity discharge (HID) fixtures for outdoor lighting and display lighting. High-pressure sodium lamps (which have a golden color) are the most efficient lamps you can buy. The lamps offer a variety of outputs from 35 to 1,000 watts and have approximately 24,000 hours of life. Typical payback time is 2 years. Metal halide lamps (which appear bluish white) offer significant energy savings over standard incandescent lamps.
As an example, consider that a 32-watt metal halide lamp can replace an incandescent bulb in the range of 100 to 150 watts, thus saving over 50% in outdoor lighting costs.