An Ambitious Experiment
An initial vision becomes a lasting foundation
Nestled along the coastline of Vancouver Island, Canada, overlooking the Saanich Bay lies Brentwood College School. A private institution for high school children in grades 9 though 12, Brentwood is home to 350 boarder students and 110 day students. Brentwood is a leader among boarding schools, boasting a co-educational university preparatory curriculum for students from more than 30 different countries.
The 49-acre campus includes eight dormitories, several modern classroom buildings, a new 28,000-square-foot performing arts center with a 431-seat performance auditorium and a beautiful student services building housing the cafeteria, classrooms and laundry, called Crook’s Hall, a LEED Gold Standard Building. A new Visual Arts and Global Studies building opened in May 2012 and combines the latest technology and sustainable designs available.
Nearly a decade ago, Gord Bilsten, who oversees the school’s heating, ventilation and air conditioning (HVAC) systems, decided to try using geothermal energy to heat Crook’s Hall. With his initial experiment, Bilsten began a journey that would make Brentwood College School one of the most energy-efficient educational campuses in North America.
Harnessing Energy from the Bay
Team creates innovative solutions to overcome challenges
The initial geothermal loop, located in Saanich Bay, grew to become three loops, which work together with several other innovations Bilsten implemented, to heat and cool key campus buildings. By his own admission, Bilsten cobbled together the first loop, designed initially to provide heat only to Crook’s Hall.
When I saw all the energy wasted at Crook’s Hall, I knew there had to be a way to capture it and put it to use. The only thing we don’t capture now is the heat from the dryer vents. I’m working on that.
Once the energy savings became apparent, he installed two additional loops with stainless steel plate exchangers, equipped with specially designed cathodic protectors to prevent corrosion. Bilsten worked with Doug Lockhart of Lockhart Industries, a geoexchange heating and cooling expert, to design and implement the subsequent expansion. The loops lie 30 feet deep in the bay, covering a surface of about 1,000 square feet. The unconventional stainless steel exchangers provided a $250,000 savings compared to the cost of traditional exchangers.
“The most difficult challenge was obtaining the government approvals,” said Lockhart. “But we met all the requirements and even bring out a marine biologist regularly to ensure we’re not disrupting marine life in the bay.”
Recapturing discharged heat
Water from the ocean loop enters the primary pump room manifold and is redistributed through three internal loops within Crook’s Hall and to the performing arts center and the new visual arts building. The mechanical room housed in Crook’s Hall further distributes the heat to specific zones in each of the larger buildings, as well as zones within a couple of the dormitories connected to the system. It houses three heat pumps for heating the buildings, as well as six heat pumps for the domestic hot water supply and a solution for recovering heat from the grey water, refrigeration and exhaust output from Crook’s Hall. Cooling is provided directly from the chilled water in the main loop.
Realizing Crook’s Hall uses the most energy of any building on campus, Bilsten and Lockhart focused on how to recapture the energy and redistribute it to other buildings. They added a grey water heat recovery tank that captures water from the dishwashers and clothes washers, and a heat recovery storage tank for storing excess energy to use in heating water for the kitchen and laundry.
Keeping water moving through the main system requires numerous pumps. A smaller pump room houses four pumps, two used for the ocean loop, which provide water to the three connected buildings—Crook’s Hall, the performing arts center and the Visual Arts and Global Studies building—and two used for the dining hall. A second mechanical room in Crook’s Hall contains 10 pumps for heating and air conditioning, and seven more for heat recovery/hot water production. The performing arts center uses two pumps with variable speed drives to supply 16 individual heat pumps while the Visual Arts Center uses 15 pumps supplying heating, heat recovery and air conditioning loads. Pumps are optimized for best performance and reduced energy consumption.
Complete Building Management
Automated monitoring and control maximizes flexibility and cost savings
The entire system is controlled by a Siemens APOGEE Building Automation Software system, which automatically controls and regulates heating or cooling to each zone in the buildings. Bilsten can easily track the temperature in all the zones, whether doors or windows are opened or closed, the outside air temperature, ambient sunlight, ocean water temperatures, relative humidity and carbon monoxide, as well as water and power usage. He can then remotely adjust various components as needed to heat or cool rooms. For example, if the temperature in the dining room in Cook’s Hall rises by more than a couple degrees celsius, he can open select windows using air from outside to help cool the room and minimize the need for air conditioning. Essentially, the heat from any of the zones being cooled can be transferred to any of the zones requiring heat automatically through the building control system. By carefully managing the system, Bilsten achieves a constant COP (Coefficient of performance) of about 10.
Achieving maximum sustainability and savings
The more buildings you have on the system, the more efficient it becomes. Then you have the flexibility to shift energy from one building to another, rather than just from one zone to another, gaining maximum efficiency.
Bilsten says the buildings on the geothermal system use 25 percent of the energy required by campus buildings still heated by conventional means. “Heat pumps take about 13 months to pay for themselves,” Bilsten said. He expects the entire system to pay for itself within five years. It also dramatically reduced CO2 emissions because the carbon footprint of the heat pumps is very small compared to traditional fossil fuel systems.