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Green Goes Underground: Canada's largest geothermal system lies beneath the country's newest university

Canada's largest geothermal system lies beneath the country's newest university.

February 26, 2007 |

Canada's largest geothermal system (and the second largest in North America) sits inconspicuously beneath a beautifully landscaped, 80,730-sf quad at the center of the University of Ontario Institute of Technology, in Oshawa.

Founded in 2002, UOIT is Canada's newest university, and its 42-acre campus and academic village are being hailed as a model of sustainability, with the massive, 2,000-ton BTESS (Borehole Thermal Energy Storage System) heating and cooling system at its center.

The idea to integrate BTESS into the UOIT master plan came from Toronto-based Diamond + Schmitt Architects, which was commissioned by the university to design a site plan and academic facilities that would achieve Canadian Green Building Council LEED Gold certification. Many of the green features proposed by Diamond + Schmitt seemed like no-brainers—green roofs on all of the nine planned academic buildings (five buildings totaling about 440,000 sf have been built so far); a 65,000-gallon cistern for rainwater collection and storage; metal oxide-coated window glazing that blocks 99.5% of UV rays; and generous amounts of open space throughout the greenfield site.

The firm's proposal of the BTESS system, however, was less conventional and had the Building Team, including consultant Brian Beatty & Associates and mechanical engineers Keen Engineering, both of Toronto, excited and nervous. The geothermal system would provide the university with a 100% renewable energy source, but its upfront costs were approximately five to six times higher than that of a conventional heating and cooling system.

“The price can scare off a lot of people,” says Don Schmitt, principal at Diamond + Schmitt. “Many institutions would be cautious about it, but [UOIT] understood immediately. For them, it made good business sense to do it.”

University officials were presented with calculations that showed a payback period of around six years for the BTESS, and that, along with the fact that the system fit with the school's sustainability ideals, enabled them to sign off on the proposal. Their decision proved doubly wise in light of recent spikes in energy costs. New calculations indicate that the system is more likely to now have a payback period of about four years.

Building the geothermal field, at times, became a logistical nightmare. For one thing, the BTESS construction site was in the middle of the campus, which itself was experiencing a construction frenzy—and completing both the BTESS and the surrounding academic buildings was equally important. UOIT was on a fast-track schedule because Canada had recently passed legislation that eliminated grade 13, which resulted in an influx of high school students pouring into the country's colleges and universities.

UOIT's first building opened in only 10 months, just in time for the fall 2003 semester. The BTESS system, however, wasn't up and running until the following fall, so the first facility was forced to tap into an existing central plant at neighboring Durham College.

Another logistical problem involved difficulty in finding local contractors capable of drilling the very deep BTESS bore holes. Those working in the Ontario market were used to drilling wells for drinking water, not the 600-feet-deep wells the geothermal system required.

“We had to bring in special crews from Alberta,” says Mike Szabo, project architect with Diamond + Schmitt. “We had to get crews who normally drill oil wells to come to Ontario to tackle the project.” Those special crews—at peak there were seven drill rigs—worked virtually 24/7 from June to December 2003 drilling a total of 392 wells (each well accounts for about five tons) through terra firma consisting mostly of limestone.

The geothermal system has been on line for just over two years, and with UOIT's steady construction schedule, new academic facilities are being hooked into the system on a regular basis. It's just a matter of time before the BTESS will be operating at full capacity, providing heating and cooling to the university's planned one million sf of academic space—all the while realizing approximately 30% savings in operating costs.

Geothermal Technology 101

There are two types of geothermal technologies: BTESS and ATESS. BTESS, or Borehole Thermal Energy Storage System, is a closed system that circulates glycol as its heat-transfer fluid. ATESS, or Aquifer Thermal Energy Storage System, is an open system that uses water as its heat-transfer fluid.

The BTESS system operating at UOIT links all academic buildings to the central plant, which is located in the basement of one of the academic buildings. Fluid circulating through the tubes in the wells work in two ways: During the summer months, the system pulls heat from all the buildings and stores it in the ground. In the winter months, the heat is collected from the earth and delivered back to the buildings to provide warmth.

Geothermal systems are considered low-tech, low-maintenance heating and cooling systems, but they do require consistent monitoring to ensure their systems are balanced. If systems aren't properly managed, the ground temperature around the wells can gradually increase, which can then dramatically decrease the geothermal system's efficiency.
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