Outdoor lighting makes our streets safe for travel and supports commerce, socializing, night activities, and work tasks. Recent improvements in outdoor lighting systems use considerably less energy, while meeting energy requirements and providing better light quality. Energy costs can be dramatically reduced by a) strategically addressing lighting needs, b) selecting energy-efficient equipment, and c) controlling lighting appropriately.
Address lighting needs
The first step is to identify and prioritize the main objectives for a particular lighting project (e.g., way-finding, safety, shopping, or highlighting activities). Different outdoor lighting applications can have very different performance requirements. Next, review guidelines from the Illuminating Engineering Society of North America (IESNA) for recommended light levels (illuminance, measured in footcandles) and acceptable variations in brightness (uniformity, measured as a ratio).
Select energy efficient equipment
Meet lighting needs with a low lighting power density (Watts per square foot) well below the maximum allowed by code. Select, space, align, and place fixtures to direct light only where it is needed. The complete lighting assembly, combined with the support assembly (pole or mounting bracket), mounting position, and spacing, will impact energy performance as much or more than the specific lamp technology.
Control lighting appropriately
Strategic use of lighting controls can result in significant energy savings for outdoor lighting. For instance, you can reduce run hours and lower light levels after curfew. Options include astronomical time clocks, photocells, motion sensors, dimmers, bi-level switching, partial-night lighting, or a combination of strategies. Be sure lamp types are compatible with planned controls strategy (or vice versa). For example, if dimming is planned be sure lamp type can be dimmed.
Download pdf to read more.