AutomatedBuildings.com Article - I Know You’re There but I’m Not Watching: Smart Lighting Reconsidered

“If I sit at my desk and I don’t move, after 15 minutes the lights go out. Some offices are like that,” says Thomas Little, a BU professor of electrical and computer engineering and associate director of the Lighting Enabled Systems & Applications Engineering Research Center (LESA ERC). In another annoying scenario, if Little was to leave his office it would take 15 minutes of wasted energy before the lights go out.

Motion sensing doesn’t cut it when it comes to occupant tracking. It must leave an inefficient amount of time between the last sensed movement and turning the lights off in order to account for ‘stillness.’ Even then it will inevitably plunge you into darkness if you are too still for too long. There is no right amount of time for lights to stay on to suit every situation, nor can we rely on motion to recognize occupancy.

The smart solution is occupancy tracking with surveillance cameras, but this raises privacy fears, is simply not appropriate in many situations, and comes at a significantly greater cost. While waving your arms around every 15 minutes is quite annoying, it’s not annoying enough to install surveillance cameras throughout an office, library or in a bathroom. The lighting sector needs a low cost, efficient occupancy tracking solution that does not invade privacy. Professor Little and his team might just have the answer.

LESA ERC is a combined effort of Boston University, the University of New Mexico, Thomas Jefferson University, and Rensselaer Polytechnic Institute, funded primarily by the National Science Foundation.

The center researches and designs smart lighting: lights, sensors, and controls that can adapt to better support human productivity, energy efficiency, and wellness. In September last year, the team was awarded a US patent titled “Sensory Lighting System and Method for Characterizing an Illumination Space” for a system of LED lights and sensors that can detect the location and even the poses, of occupants in a room without using cameras.

“The lights in a space are strategically located,” says Little, “they’re in a good position in these indoor environments to interact with us.” Little sees no reason to revamp the entire lighting system but instead, wants to make it just intelligent enough for its purpose. He and his colleagues have been working on a system of responsive LED lights called ‘luminaires,’ embedded with ‘time-of-flight’ sensors.

These sensors can detect people and objects in a room based on reflected light, then switch lights on or off, change lighting intensity, and even adjust the LED’s color to suit a situation.

By emitting a brief pulse of light and timing its reflective response, similar to radar and sonar systems, the Sensory Lighting System can differentiate between people, pets, and furniture, and identify actions such as sitting, standing, talking or knitting. Once identified, the system can choose the appropriate lighting response, providing high functionality with the limited invasion of privacy. The system is also proving its useful in recognizing hand gestures, opening it up to other potential applications.

Furthermore, the low cost of such sensors means the technology could be more readily installed in more places, creating greater efficiency and unlocking significant health benefits for occupants. For example, the human body has naturally tuned itself to wake up in response to the blue light produced by the sun, but exposure to blue light after dark can disrupt sleep. By adapting mimicking natural light throughout artificially illuminated environments, we can limit such disruption.

“The increasing body of clinical evidence suggests that blue light is critical for maintaining the human circadian rhythm,” says Little. In fact, certain kinds of depression, such as seasonal affective disorder, and circadian rhythm disorders can improve with exposure to different levels of light, according to the Mayo Clinic. There are even blue light filters emerging for computer screens that seek to improve mood and sleep for after dark computer users.

What at first may seem like annoying little problems are in fact significant due to their ubiquity. The efficiency gains created by replacing one motion sensor with Little’s system are small, but it has the cost and privacy characteristics to replace many more motion sensors than cameras ever could. Similarly, the health benefits of a subtle change in light color might be easily dismissed, but even slightly improving the sleep and mood of an entire company’s workforce is likely to be much more attractive.

The Sensory Lighting System appears to be an elegant solution to a little problem with huge implications. By not being smarter than it needs, it reduces cost and alleviates privacy concerns, making it feasible for wide-scale deployment.

It seems that sometimes smart can be too smart, and sometimes smart can be too expensive, so maybe sometimes it’s smarter to consider less smart solutions to our annoying little big problems.

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