If your facility uses T12 fluorescent lamps, relamping with modern T8 lamps and electronic ballasts can reduce your lighting energy consumption by 35 percent. Adding specular reflectors, new lenses, and occupancy sensors or timers can double the savings. Paybacks of one to three years are common.
Smart lighting design in parking lots
In its Lighting Handbook, the Illuminating Engineering Society of North America recommends parking lots be lit at an average of 1 foot-candle or less of light, but most parking lots are designed with far more lighting than that. Using lower-wattage bulbs can actually increase the safety of your lot: An over lit lot can be dangerous to drivers if their eyes cannot adjust quickly enough in the transition from highly lit to dark areas. When designing lighting for a new parking lot, consider using low-wattage metal halide lamps, instead of high-pressure sodium lamps, in fixtures that direct the light downward. Even with a lower wattage, an office building could safely use fewer lamps if this choice is made. Metal halide is less efficient than high-pressure sodium in conventional terms, but it puts out more light in the blue part of the spectrum, which turns out to be easier for our eyes to see under low-light conditions.
Light shelves, installed high on the inside of a window, will shade and prevent glare in the bottom 6 feet of a floor, which is where most occupants work. The shelves also reflect the daylight up onto the ceiling, which indirectly illuminates a room.