Outdoor Lighting

• Overview

Bright Outside: Outdoor Lighting. Lighting isn’t just a consideration for indoors — it’s even more challenging outside, because there aren’t many walls and ceilings to reflect light back into the environment. A key strategy is to shine lights on buildings or other exterior surfaces. If the surfaces are lighter in color, lower wattage lamps can be used. Shining lights off low gloss or rough surfaces helps to minimize glare.

A Lighter Load: Efficient Bulbs & Lamps

CFLs enclosed in fixtures are good for porch lighting, post top lighting, or small area lighting, when lower light output is enough. For large areas, IR halogen PAR flood lamps are most effective. Halogen lamps can be up to 50% more efficient than standard incandescents. Halogen PAR floods are more efficient than standard PAR floods.

HID: Light With Might

High intensity discharge (HID) lamps are highly efficient lights that use 75% to 90% less energy than incandescents. They are commonly used in exterior lighting applications, because they produce a bright light, and last up to 24,000 hours. This class of lamps includes metal halide, high-pressure sodium, and mercury vapor. Metal halide lamps work well for lighting large areas for extended use. High-pressure sodium lamps are more efficient than metal halide, but emit a yellow light with poor color rendering. Mercury lamps are less efficient than metal halide lamps. These HID lamps must warm up before reaching full intensity, and require special ballasts.

Types of High-Intensity Discharge Lamps
	Efficacy (lumens per watt)	Lifetime (Hours)	Color Rendering Index	Color Temperature (K)
Mercury Vapor	25-60	16,000-24,000	50 (poor to fair)	3200-7000 (warm to cold)
Metal Halide	70-115	5,000-20,000	70 (fair)	3700 (cold)
High-pressure sodium	50-140	16,000-24,000	25 (poor)	2100 (warm)
*Source: Department of Energy, Energy Efficiency and Renewable Energy, “Energy Savers: High-Intensity Discharge Lighting.” (July 19, 2011), Content in part adapted from the Rensselaer Lighting Research Center, “Exterior Luminaires”.

Sunlight at Night: Solar-Powered Lights

Solar powered landscape and walk lights are convenient and attractive. They require no wiring for power, and install easily. But solar powered lights may not fully charge when it’s cloudy, so their light output may fade or disappear at night. Still, solar lights have been used for many years, even in cloudy conditions.

Take Aim: Floodlights

Floodlights mounted high on buildings provide wider light distribution. Use floodlights carefully to ensure they don’t shine into neighbors’ windows or property.

Smart Savings: Controls & Sensors

For more energy savings, use controls for outdoor lighting as you would for indoor lighting. Motion detectors for security lighting turn lamps on when motion is sensed. Integrated photocells that turn lights off in daylight are good for lights that operate all night.