Lights out. It's a simple directive, but hard to follow in some environments, particularly in office buildings where the switches can be inconveniently located or you think somebody else might be coming any minute now. But in commercial buildings lighting accounts for about 29% of electrical energy use, a huge emitter of greenhouse gases. Motion and occupancy sensors can cut this use by about a third to almost half, depending on office rhythms. Motion sensors are obviously useful in restrooms and storage areas and lesser traveled hallways, where a light left on might go unnoticed for hours or days. In conference rooms they can save 65%, while even offices can register a savings of as much as 50%.
Studies have shown that effectiveness depends on previous lighting patterns and proper placement of the sensors, so it will pay to hire a professional to maximize your greenhouse gas reductions.
Curiously, sensors at work can change behavior at home, and not always for the better. One interesting study compared people who had sensors in their office to those who didn't. People who had sensors to do the work for them were only half as likely to switch the lights off when they left a room. If this behavioral change carries to your home it would offset some of the benefits. So, don't become lazy at home if your company installs sensors in the office. Use the change as an opportunity to talk about energy efficiency and how lighting choices and behaviors make a difference.
Check with your local utility to see if they offer rebates to help businesses upgrade to more efficient lighting systems. The federal government also offers tax deductions for new buildings if the lighting substantially exceeds standards.
