Greentips June 2012: Let There Be Light—But Only When You Need It
Turning off the lights saves energy, but an even better strategy can be switching to high-efficiency compact fluorescent lightbulbs (CFLs) and light-emitting diode bulbs (LEDs). According to our new book Cooler Smarter: Practical Steps for Low-Carbon Living, these bulbs are so good that you’d have to switch off an incandescent bulb for three of every four days to achieve comparable savings.
If you’ve already switched to CFLs or LEDs, don’t forget to turn them off when they’re not needed. Lighting’s share of residential electricity consumption has risen from 9 percent in 2001 to as much as 15 percent today due to increases in the total number of households and the size of homes being built, and leaving the lights on accounts for up to half of this consumption. Thankfully, a number of technologies can help make conservation more convenient, including:
Door–activated switches. These work best in closets, cabinets, and utility areas where light is only needed when the door is open. Some automatically turn the lights off after a certain period of time. Prices range from about $6 to $25.
Dimmers. These work best in rooms where lighting needs vary. Energy savings differ by the type of bulb in use: with incandescents, dimming tends to reduce the amount of light produced more than the power used, whereas the two variables adjust proportionally with CFLs (i.e., CFLs dimmed by 30 percent consume about 30 percent less energy). To maximize energy savings and bulb life, use CFLs and LEDs labeled as “dimmable.” Dimmers range in price from $5 (for incandescent bulbs) to $25 or more (for CFL and LED bulbs).
Occupancy/motion sensors. These turn lights on when someone enters a room (or approaches your house, if used outside) and turn off after a period of inactivity. The most common types are infrared (which detect motion and heat) and ultrasonic (which detect noise), and often come with photo sensors to prevent lights from turning on during the day. Interior sensors work best in rooms that are used infrequently or are prone to having the lights left on. Prices start around $20 for wall-mounted units and $60 for ceiling-mounted and outdoor models. Make sure the unit you choose is compatible with CFLs (or LEDs).
Timers. These can be effective when used for outdoor lighting, especially combined with a photo sensor that turns lights on at dusk. Timers attached to lamps can also enhance security by giving your home the appearance of being occupied at night.
