Energy-saving sensors get smart

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Occupancy sensors are widely used to control lighting as well as heating, ventilating and air conditioning (HVAC) in buildings. A new smart sensor developed by the smart people at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) may soon change the way we think about this decades-old technology. While occupancy sensors are useful for saving energy, this next-generation version dramatically increases sensor accuracy and capabilities. 


The Image Processing Occupancy Sensor (IPOS for short) raises the accuracy of detecting people from about 75 percent for currently available sensors to the upper 90 percent range. This greatly increases the level of control and the potential for energy savings. The IPOS was recognized by R&D Magazine in 2014 as one of the top 100 technology developments of the year.


How did NREL researchers achieve this breakthrough? They borrowed from a technology used by millions of people every day—the smartphone. The IPOS combines an inexpensive camera with a high-speed microprocessor and algorithms to detect the presence of people in a room. By adding optics to what had previously been only motion detection, it marks the first fundamental change in occupancy sensors in decades, according to researchers.


In addition to increasing accuracy, the IPOS can do a lot of smart things to help save energy. It can count the number of people in a room, document their location and tell you whether they are sitting down or moving around. "All functions are combined in a single sensor, and it's done in a way that is more robust than current sensor technology," according to NREL section manager Larry Brackney.

Combined with controls, the IPOS can dim or switch off lights based on need, or make instantaneous decisions on the amount of airflow necessary based on the number of people and activity in a space. A U.S. Department of Energy report found that, when used to control lighting and airflow, advanced occupancy sensors such as the IPOS can reduce building energy consumption by 18 percent.


Because the IPOS is made from mass-produced technology already available on the market, it can be made cheaply. Although still in development, researchers project that it will cost less than $200 when it becomes available commercially.


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