Brentwood College School

The need

Located on Vancouver Island's eastern shore, Brentwood College School is an independent university preparatory school for some 425 students in Grades 9 through 12. A few years ago, the school was planning to build a new performing arts centre, including a 431-seat theatre with make-up and dressing rooms, storage rooms, orchestra pit, music and dance studios, lounge and catering facilities, and other areas.

Brentwood College School was seeking an economical heating and cooling solution for the arts centre. Lockhart Industries of Duncan, a plumbing, heating and air conditioning contractor, approached the school with the idea of using a geoexchange system to meet the theatre's heating and cooling needs. BC Hydro contributed funding for a feasibility study, which found that a geoexchange system using an ocean loop could provide significant energy savings compared with a conventional system. As well, because geothermal energy is a clean, renewable energy source, it would support Brentwood College School's commitment to sustainable energy.

The technology

Geoexchange systems take advantage of the sun's energy stored in the ground or in ocean water, where the temperature remains at about 12°C throughout the year. In the winter, heat pumps are used to extract heat from the ground or water and transfer it into buildings for space heating or hot water heating. In the summer, the heat pumps reverse the process, removing heat from the building and returning it to the ground or water, thus cooling the building. In other words, the ground or ocean acts as a heat source in winter and a heat sink in summer.

A geoexchange system consists of a series of pipes (called a "loop") lowered into the ocean or buried in the ground, a heat exchanger and ductwork into the building. The loop circulates a fluid (water, or a mixture of water and non-toxic antifreeze) that absorbs heat from, or relinquishes heat to, the ground or ocean water, depending on whether the ambient air is colder or warmer than the water.

The project

Lockhart Industries installed a geoexchange system in which a 70-ton loop was placed 70 metres offshore, weighted down and sunk at a depth of six metres at low tide. Permission was granted by Fisheries and Oceans Canada to place the loop on the sea floor. The loop combines with 12 water furnace heat pumps to heat and cool the theatre.

The benefits

Electricity savings

Operational costs for Brentwood College School's geoexchange system are among the lowest in Canada when compared with heating and cooling costs of similar institutions. The system uses 35% less energy to heat and cool the arts centre than would a conventional system, saving the school 130,000 kilowatt hours of electricity each year. This translates into $4,800 in annual energy cost savings. In addition, the school is saving on reduced maintenance costs. The projected payback for the project is 6.3 years.

Enhanced comfort

Customer comfort is typically very high with geothermal systems, since heating and cooling can be done simultaneously and the systems offer zone control of heating levels. Students, teachers and staff at the school have reported a high level of satisfaction.

Environmental and social benefits

An advantage of geoexchange systems is that they work by concentrating naturally existing heat, rather than by producing heat through the combustion of fossil fuels, thus reducing greenhouse gas emissions.

More efficient use of space

Because most of the school's geoexchange system is buried in the ocean, it requires only a small mechanical room inside the building.