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Control office lighting with timers and motion sensors

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Give your fingers—and your memory—a break by automating your office’s lighting controls. No more worries about leaving the building’s lights on by mistake when you’ve got motion sensors and timers. These little devices give you stress-free control of your interior and exterior lighting, allowing you to cut your energy load while saving a bundle on your monthly electricity bill—one of the biggest business expenses around.

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) or T8s, office lighting controls may need to be set differently. Although you'll achieve energy savings by shutting off these lights just like you do by switching off incandescents, you need to consider bulb life expectancy. Unfortunately, every time you turn one of these bulbs on and off again, you can shorten its life, so in general, they're are best suited for areas where you're going to leave the lights on for 15 minutes or more: board rooms, individual offices, kitchen and break areas, etc. This will extend the life of the bulb, giving you longer-term energy savings so that you can get the biggest bang for your buck.

Installing timers or motion sensors on CFLs and T8s 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, storage rooms, parkades, and so on) should be fitted with light emitting diodes (LEDs) or incandescents with motions sensors or light timers.

How to automate your lighting controls

Many energy-saving lighting options exist for offices of all types. Consider that electric lighting is used for parking lots and outdoor spaces, doorways, foyers, halls, bathrooms, and storage areas, as well as individual offices and board rooms. Automating your office’s lighting with motion sensors and timers will take the thought out of shutting off unnecessary lights, while lightening your lighting budget’s load—by as much as 90 percent in some rooms!

Occupancy sensors

Office employees are busy and distracted, distracted by the work at hand—as they should be! Help them out by installing occupancy sensors—often called motion sensors—in less-used spaces (think conference rooms, storage closets, copy areas) throughout your office. 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 in small rooms, like individual offices, bathrooms, and copy 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 such as office cubicles. Best for spaces with few obstructions, such as smaller board rooms, offices, janitorial closets, storage rooms, and hallways.
  • 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 (such as partitions). However, they’re prone to being falsely triggered and they tend to be one of the more expensive options. Best for larger offices, storage areas, bathrooms, and rooms with unusual shapes.
  • 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, as well as for industrial facilities and warehouses.
  • 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. 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.

  • 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 and janitorial closets and individual bathrooms.
  • 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 in hallways and entrances.
  • 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! Best for outdoor lighting fixtures and most indoor office spaces, as well.

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 employee 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.

Lighting, both indoor and outdoor, is one of the biggest energy drains in office environments: it accounts for nearly 28 percent of total office energy consumption.[4][5] According to the US Department of Energy (DOE), 22 percent of the total electricity used in the US goes to lighting up our lives.[6] 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 yearly.[7]

Occupancy sensors and timers can significantly reduce an office’s 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.[8] The greatest potential for savings exists in bathrooms (up to 90 percent), corridors and storage areas (up to 80 percent), and conference or board rooms (up to 65 percent).[2] A Connecticut state-owned 188,000 square foot office building was retrofitted with dual-technology occupancy sensors (project costs: $51,000) that resulted in savings of $24,000 annually.[8]

Photocells and timers provide similar energy savings, and can result in energy cuts upwards of 10 percent. The Challengers Tennis Club for Boys and Girls in Los Angeles was built in 2002 with a variety of green features, including photocells and motion sensors. Combined with ENERGY STAR appliances and equipment, this facility realized savings of 60 percent over conventional buildings of similar design.[9]

Tax breaks and subsidies

Most states have at least one listing on the Database of State Incentives for Renewables & Efficiency. Choose the ‘Search by’ option, then ‘Technology,’ and then choose 'Lighting Controls/Sensors’ to find out if your business qualifies.

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