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Connecting People to Buildings: Virtual Occupancy Metering

Author: Stefan Storey, Director & Co-Founder, Sensible Bldg Science, UBC

The key to realizing the potential of smart buildings is well known. Solutions must connect people to the building control systems to meet their needs for comfort: supply fresh air, maintain optimum temperature and provide high quality lighting. The cornerstone of any solution is the need to accurately detect and locate building occupants in real-time.

Once you know where people are located, the building controls can target comfort, ventilation and lighting services. But why is occupancy detection so hard to attain at an affordable price? In part, this is due to the reliance on physical sensors to detect the location and presence of occupants. Deploying a fleet of sensors such as CO2 detectors, PIR, or video analytics requires dedicated hardware and supporting infrastructure. The good news is that virtual solutions have arrived, meaning that occupancy sensing hardware is no longer the only option.

Sensible Building Science (Sensible) has invented an entirely new method of virtual occupancy metering (VOM). Through partnership with Cisco Systems, existing Wi-Fi activity data can be made available to provide feedback to building control systems on occupancy as well as number of people in a space, without the need for physical sensors. This solution is called Bridge, and it uses existing Wi-Fi activity data to generate VOM data and enable occupant-demand control of building HVAC systems, without the need to install new equipment such as motion detectors, video cameras, or physical sensors. It’s like Google Traffic, but for indoor environments.



This solution finds energy savings and improves comfort from optimized automation of heating, ventilation and air-conditioning (HVAC) control, by directly communicating occupancy changes to the building control system. When people arrive in a room with their cell phones, or other Wi-Fi enabled devices, the virtual solution tells the building controls to provide fresh air along with heating or cooling to match the occupancy need. With over 90% accuracy and a response time of less than three minutes, it is potentially faster and more precise than CO2 sensor response. The solution has been tested successfully at the University of British Columbia, where Cisco provided the location data with their CMX product and Sensible’s Bridge provided the occupancy intelligence and integration with HVAC. UBC’s one million square meter campus supports approximately 70,000 concurrent clients using the network on 130,000 unique devices, supported by 5500 access points. UBC paved the way in digitizing their network to glean data analytics on traffic patterns to improve and adapt their campus buildings. With Cisco CMX, UBC is now able to dynamically adapt to building occupancy rates (Source: Cisco Blogs).

The advantages of virtual solutions really come into their own when it comes to facility management. They are low maintenance, as they use existing Wi-Fi infrastructure—which means there is no sensor calibration or maintenance. The solution can also reduce facility ‘trouble-calls’ by detecting unscheduled occupancy. HVAC response is automated and responds wherever people gather, making sure people have optimal comfort, and reducing the number of comfort complaints.

Virtual solutions have a distinctive advantage for getting fast returns on investment for organizations and institutions with sustainability mandates. Municipalities, universities and the health care sector all have stringent ‘green’ targets to reduce energy and lower their buildings’ impact on the environment. The low capital expenditure required for virtual solutions results in fast payback times. Extensive testing at three different university campuses attained energy savings of 5% annually with a payback of under five years. Most of these savings have been gained in building zones with rooms that have low occupancy for extended periods of time. In lecture halls with periodic classes, the Bridge reduced fan run-time hours by 20-40%.

Implementing virtual solutions can be accelerated by excellent partnerships. Integrating between systems to ensure uninterrupted data communication can be challenging. Bridging Wi-Fi data to building controls was advanced with partnerships with Cisco Systems, along with control vendors and energy management consultation partners Prism Engineering and SES Consulting. With the support and innovation possible with the right partners, the future is looking bright for virtualized smart building solutions.


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Next Week: Intelligent Buildings