An analysis made by the Japanese Institute of Energy Economics points out that office buildings, wholesale, department stores and supermarkets have the highest electricity consumption among all the others (40%).
Sanyo Electric Co., in an initiative to reduce their carbon footprint and at the same time to save money, is experimenting with a system composed of cameras that assess how many persons are in a certain room and regulates air conditioning and lighting according to the results.
“Reduce energy consumption in the office.” The goal is pretty easy to state, but a lot harder to achieve. It is difficult to optimize air conditioning or lighting in busy offices where people are constantly coming and going, but Sanyo Electric Co., Ltd. of Japan is challenging the problem with cameras. The firm’s approach uses cameras to continually monitor the office, automatically adjusting air conditioning and lighting as needed where people are present. Estimates indicate the technology could save 1.3 million yen annually in energy costs for an office of 12,000 square meters.
Sanyo used a technology already present in the automotive industry that involves four wide-angle cameras mounted on the vehicle. An image processor corrects the distortions and displays a moving picture of the car seen from above. The system helps the driver in tight parking spaces.
The room is divided into 20-meter square section, each having its own camera, each determining how many people are located and where. It then transmits the images to the Sanyo Total Air-conditioning Intelligent Management Systems (STAIMS), which coordinates the air conditioning units. The system is based on motion detection rather than on other more sophisticated imaging techniques. Experiments have shown that there is a negligible difference in power saving compared to the case in which more complicated face recognition was involved, for example.
The system can turn off air conditioning a minute after there’s no person in the room, and turn it back on a minute after someone arrives. The same goes with controlling the lighting, only that works by coordinating the light’s intensity by taking into account the persons’ positions and the natural lighting present, with camera-mounted sensors.
Sanyo Electric investigated air conditioning on/off times over a 2-day period (Monday and Tuesday) in the winter, from 8:00 to 20:00 (a total of 720 minutes). Normally the air conditioning is on throughout this entire period, so total off time is zero. The system was set to turn air conditioning off one minute after zero people were detected, and restart within one minute after detecting presence. Experimental results showed that within that 720-minute period, the off ratio was 72.5% (Fig.6), reaching a maximum of 59.3% for the 2-day period. Total stop time for all 16 air conditioning units was 3722 minutes over two days, for an average off ratio of 16.2%.
An estimation shows that an office building can save approximately $15,000 per year if using this system.