The University of British Columbia (UBC) has found a way to use Wi-Fi technology to reduce its energy costs by using proprietary software that determines the number of people in a building then adjusts ventilation accordingly.
The system was first installed at the Irving K. Barber Learning Centre library more than a year ago. Finding that it reduced energy consumption by five per cent over a 12-month period, the school decided to have the system installed in nine more buildings.
The system makes use of the fact that almost everyone who uses the building has a Wi-Fi connection in their phone, laptop or tablet. So all of those devices are connected by way of the campus Wi-Fi network.
Based on the savings achieved in the Barber library, the school expects, when the new installations are complete later this year, to be able to save about $100,000 annually.
David Woodson is UBC’s managing director for energy and water services. He said he is delighted with the results.
"The best savings in the world are in the energy that you no longer consume," he said in a recent interview. "And to a certain degree, we are being conservative. We’ve learned a couple of things along the way. The buildings where we have more lecture theatres — those seem to represent the ones with the greatest opportunity for savings."
Initially, Woodson said, the focus was simply on turning systems off when there was no one in the space. With later installations there will be more emphasis placed on adjusting the system to fit larger or smaller crowds in a room.
If there are only 10 or 15 people in a room, "the system needs to be on, but it doesn’t need to be fully on."
That means that there might be additional savings achieved by tweaking the system.
The idea for the system originated with Stefan Storey, who was conducting research on ways to improve indoor air comfort as part of his doctoral work. That led him to found Sensible Building Science, to develop the system presently being installed at UBC.
"Every day, thousands of smartphones, laptops and tablets connect to the Wi-Fi network at UBC," he said. "Our software anonymously counts the number of wireless devices in each room and passes the count on to UBC’s building control system, which then adjusts airflow through the relative building."
Installing the system is relatively easy with no expensive hardware or sensors needed, he said. Customers simply install software that reuses the existing, anonymous data from a building’s Wi-Fi system. That reduces retrofit costs for older buildings.
The success of the system thus far has encouraged the university to branch out. It’s now in the process of installing the system in some buildings on its campus in Kelowna.
When the present work in Vancouver and Kelowna is complete, there’s likely to be a pause in the work, Woodson said.
"We will sort of take a step back, review how that has gone and then decide from there how we move forward in doing the rest of the campus buildings," he said.
There are more than 200 buildings on campus, but, given their different uses, not all are candidates to receive the system.
As building managers everywhere have tried to reduce energy costs there have been other attempts to keep track of the number of people in the building, Woodson said.
There are systems that use motion sensors for example and systems that use "counters," that sit above a doorway and count the number of people that come into a room. There are systems that use carbon dioxide sensors that sit in the return air duct. As more people enter a the room, the carbon dioxide level builds and the sensors pick that up.
"But the problem with all those attempts…is that they all rely on a device or a sensor that works great on day one," Woodson said. "But at some point they’ll need to be replaced, the service loses its calibration and that will throw off the occupant counts.
"What’s neat about what we’ve done is that we are actually not adding any new physical device. We’re leaning on the existing Wi-Fi infrastructure."
That means obtaining an accurate count depends upon everyone in the building having a phone in their pocket.
"That’s our only limitation," Woodson said. "That’s why the system works really, really well in a lecture theatre, but not so much in an office block where you have people sitting in an office but perhaps not having a phone in their pocket."
Storey said that as far as he knows, "this is the first technology in North America to use Wi-Fi access points as a sensor network and as a way to communicate with building control systems.
"As we continue to develop it, we can help many more buildings become much more responsive to occupant needs."
Woodson said there has already been interest shown on a couple of university campuses in the United States.
"I have colleagues at the University of Texas who were very excited to learn more about how we were going about doing this," he said. "And I mentioned it to a colleague from Caltech, who is very interested in our system."
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