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Install light timers and motion sensors

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Do you have trouble remembering to switch off the lights? Get ready to put an end to wasted energy worries—lighting automation is on the way! No more arguments over lights left on when you’ve got motion sensors and timers. These little devices give you stress-free control of interior and exterior lighting at home, school, office, or in your dorm room, saving you money on your electricity bills and producing fewer greenhouse gas emissions, too.

When to automate lights

Some argue that repeatedly turning lights on and off uses more energy because of the surge of electricity consumed at the start-up of any bulb. In the case of incandescent bulbs, this simply isn't true. And since only 10 to 15 percent of the energy consumed by incandescents is actually turned into light (the rest is turned into heat), shutting them off will always save you energy (and money!), both in electricity and air conditioning (these bulbs can actually increase a room's temperature).[1]

However, if you're using compact fluorescents (CFLs), your habits may need to be slightly different. Although you'll achieve energy savings by shutting off CFLs just like you do by switching off incandescents, you need to consider bulb life expectancy. Unfortunately, every time you turn a CFL on and off again, you can shorten its life, so in general, these bulbs are best suited for areas where you're going to leave the lights on for 15 minutes or more: your family room, living room, kitchen, office, bedroom, or back porch. This will extend the life of the bulb, giving you longer-term energy savings so that you can get the biggest bang for your CFL-buck.

Installing timers or motion sensors on CFLs set to stay on for 15 minutes or more provides a good balance of light life expectancy and energy savings. However, rooms that are occupied for shorter periods of time (bathrooms, closets, garages, and so on) should be fitted with light emitting diodes (LEDs) or incandescents with motions sensors or light timers. And if you're not able to afford a light timer or motion sensor, just adjust your light-using habits. A good rule of thumb is to turn off the lights if you're going to be out of a room for more than five minutes.

How to automate your lighting controls

Many automatic lighting options exist for your indoor and outdoor spaces. Automating your lighting with motion sensors and timers will take the thought out of shutting off unnecessary lights, potentially saving you as much as 90 percent in some areas!

Occupancy sensors

For those less-used spaces, check out occupancy sensors—often called motion sensors—which give you a worry-free way to control when your lights are on and when they turn off. These simple devices detect a person’s presence in a room, turning on the lights only as needed, and then shutting them off when the room becomes vacant again. Potential savings? Between 15 percent and 90 percent, depending on the room, how frequently it’s used, and the bulbs chosen.[2]

Occupancy sensors generally come as either wall- or ceiling-mounted models. Wall sensors work well for most residential and dorm room applications since they’re designed for small rooms. Ceiling sensors, on the other hand, are better suited for large spaces or wherever the lighting load is higher.

There are four main types of occupancy sensors (the first two being the big players, the others less common and difficult to find).

  • Infrared or Passive Infrared (PIR) sensors: Designed to see infrared radiation, or heat (from humans, for instance), these sensors detect the motion of heat from one area to another. They’re virtually immune to false triggering and are relatively inexpensive. However because they operate on a line-of-sight mechanism, they don’t work well over long distances (over 15 feet) or in rooms with obstructions. Best for most residential spaces, including front and back entrances, closets, and hallways, as long as the lines of site are 15 feet or less.
  • Ultrasonic or Ultra Sound (US) sensors: Using ultrasound technology, these devices emit sound waves. Motion of any kind will disrupt the reflected frequency, allowing the sensor to detect movement. These devices are very sensitive to motion and generally work when there are obstructions. However, they’re prone to being falsely triggered and they tend to be one of the more expensive options. Best for larger rooms, like family rooms and community spaces.
  • Audio sensors: Using a microphone, these sensors listen for sounds, such as voices or movement. They’re relatively inexpensive and work well in obstructed spaces, however they’re not great at distinguishing between the noise made by air conditioners and your voice, and are therefore prone to false alarms. Best for rooms of unusual shape.
  • Microwave sensors: This technology is most commonly used for automatic door openers, but it’s somewhat new and less tested in occupancy sensors. These devices function by sending out microwaves and then sensing the reflected frequency with a receiver. Like US sensors, any movements in the area will be detected by changes in the reflected frequency. They’re relatively sensitive, but their reliability has yet to be rigorously examined and they're hard to come by, too. Best for specialized applications.

Timers and photo sensors

From the truly simple to the ultra-sophisticated, there are many timer types now available. You set the timer to begin, which turns the lights on and keeps them illuminating until the set time has elapsed.

  • Simple timers: The most basic possible option, these little units generally come with small pegs that you insert into the desired “on” and “off” time slots. They sometimes allow you to program different times over the 7-day week, but usually accommodate only one lamp or appliance. Best for individual lamps, Christmas lights, and small appliances (think coffeemaker, crock pot, etc.).
  • Pre-set switch timers: These timers usually consist of a simple wall switch connected to specific fixtures. By clicking the appropriate button (usually something like 5-, 10-, 30-, and 45-minute options) you’ll turn the light on for the specified period of time. Best for storage rooms, bathrooms, garages, or under-cabinet lighting.
  • Programmable timers: Want to fine-tune your light timer? Then choose one of these more advanced programmable devices that let you set several unique time intervals for each day of the week. One downside to these: the further away you are from the equator, the greater the light differences throughout the year, making somewhat frequent reprogramming necessary (although some units come with intuitive seasonal programming). Best for lights that should be turned on and off at similar times most days of the year, such as those used for decorations and front or back outdoor fixtures.
  • Photo or Photocell timers: Get even more fine-tuned timing control with a photo sensitive device. By sensing changes in sunlight levels, the timer turns lights on and off only as needed, and can even function with dimmable bulbs, making minute adjustments to a bulb’s intensity. No programming required! Can be used with indoor and outdoor lighting fixtures.

Find it! Motion sensors and light timers

Many automatic lighting control devices combine two or more technologies to take advantage of complementary strengths. PIRs and USs are often combined, as are motion sensors with photocell technologies.

Before you buy

Avoid frustration by ensuring automatic light controls come with manual override systems, too. This way, users can switch the lights on when the sensor is malfunctioning and/or when they need long-term illumination.

Also, keep in mind that frequently switching a CFL light bulb on and off will shorten its life. Therefore, if you’re installing timers or occupancy sensors with “on” times shorter than 15 minutes, you may want to opt for non-CFL bulbs.[3]

Light timers and motion sensors help you go green because…

  • A light off equals energy savings and fewer greenhouse gas emissions. Motion sensors and timers make switching off easy and automatic.

According to the US Department of Energy (DOE), lighting accounts for about 22 percent of the electricity used in the United States.[4] This adds up to about $55 billion worth of electricity, roughly equivalent to the output of 100 large power plants emitting 450 million tons of carbon dioxide and 3 million tons of smog-generating nitrogen oxides and sulfur dioxide.[5]

Occupancy sensors and timers can significantly reduce lighting energy consumption. Although energy savings depend on the size of the area, occupancy pattern, and type of lighting used, the average overall reduction ranges from 35 percent to 45 percent.[6] The greatest potential for savings exists in bathrooms (up to 90 percent), as well as in corridors and storage areas (up to 80 percent).[2] Photocells and timers provide similar energy savings, and can result in energy cuts upwards of 10 percent.[7]

Tax breaks and subsidies

Most states have at least one listing on the Database of State Incentives for Renewables & Efficiency, many of which pertain to energy efficient lighting options. Choose the ‘Search by’ option, then ‘Technology,’ and then choose 'Lighting Controls/Sensors’ to find out if you qualify.

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