A motion sensor light switch turns lights on when the sensor detects motion, and turns lights off automatically after a set period of time after no motion is detected. In general, the cost of the motion sensor light has to be broken up over time to determine its savings. Additionally, its placement is important. A motion-activated light switch placed in the right environment, indoors or outdoors, can be a money saver.
Cost of the Sensor Light
Indoor sensor lights range from around $20 to $50. At the lower cost end, the sensor may be contained within a wall switch. At the higher cost end are kits with a separate sensor. With the kit, you can place its sensor where you want it to be. Basic outdoor sensor lights can cost under $20 for a simple floodlight. More powerful and decorative lights for outdoors can cost around $100.
Motion sensor switches have some phantom energy costs associated with their use. As an example, assume a motion sensor uses 1 watt of energy when it is on standby, and 5 watts when it is actively lighting. Next, assume the standby mode is on 23 hours and the active mode is on one hour every day. In an area with an energy cost of 11 cents cost per kilowatt-hour, the motion sensor would use .84 kilowatt-hours in a month. The phantom cost would be about nine cents per month.
Placement in the Home
Sensor lights can be most effective indoors when placed in a room that does not get frequent traffic, or a room where the likelihood of leaving a light on accidentally is high. As an example, a kitchen is seldom a candidate, since it is in frequent use. Bathrooms, on the other hand, are rooms that people tend to use and then leave. Closets, garages, storage rooms, laundry or utility rooms and guest rooms are also spaces where brief periods of activity may be followed by lengthy periods of inactivity — rooms where a light is easily turned on and then forgotten. These are rooms in which a motion sensor light has the opportunity to save energy, and thus save money.
Compact fluorescent light bulbs, called CFLs for short, are lighting products that save energy. CFLs can cut electricity costs, and last much longer than old-fashioned incandescent light bulbs. Many spiral CFLs can be placed in fixtures that enclose them for protection against weather out of doors. CFL floodlights are also available; however, some of these are not compatible with motion detectors. Home residents who want to save energy costs should look for motion sensor fixtures that are labeled as Energy Star qualified.
Consider the Overall Picture
Since the average household spends about 11 percent of its energy budget on lighting, improving your lighting is a fast way to trim your energy bills. Recent advances in lighting controls can contribute to energy savings because these technologies turn off lights when they are not being used. According the U.S. Department of Energy in its Energy Savers Booklet, "using new lighting technologies can reduce lighting energy use in your home by 50 percent to 75 percent."