AWARD OF MERIT: Burnaby Mountain School, B.C. Mechanical and Electrical Systems

Category: Buildings

STANTEC CONSULTING

The Burnaby Mountain Secondary School is the first school to be completed under the British Columbia government’s stricter cost guidelines. Occupied last fall, it is a 15,000 square metre facility built to accommodate up to 1,875 students and teachers.

As the mechanical and electrical engineers, Stantec designed a unique geothermal heating and cooling system using the school’s playing field. They took advantage of the efficient mechanical design to reduce the electrical service size and distribution system. At the same time, the team accommodated the challenges presented by an ecologically sensitive site.

The mechanical, plumbing and electrical systems consume less than 75% of the energy in a similar sized school, and also significantly reduce the school’s water consumption and CO2 emissions. Indoor air quality concerns were answered since the mechanical system supplies higher than the recommended quantities of outside air into the school, throughout the year.

The geothermal system either extracts heat from the ground or rejects heat into the ground through 20 kilometres of cross-linked polyethylene pipe buried in the playing field. During the winter, the system takes advantage of heat in the earth as well as solar heating on the surface. During summer, the geothermal field serves as a large heat rejection/condensing field. The system eliminates the need for a traditional cooling tower and the associated emissions and noise. And by providing cooling to all the teaching areas, the system also makes it possible to have heat recovery within the building during the shoulder seasons, which makes for operational flexibility.

The geothermal field was designed to ensure that it is easy to maintain and can be operated under seasonally dry conditions. The field irrigation system is used to wet the geothermal heat recovery surfaces. When it is raining, the rainwater is encouraged to flow through the geothermal trenches to increase the heat recovery/rejection efficiencies.

The site selected for the school is ecologically sensitive and was extremely difficult to build on. In addition to a designated salmon spawning stream running down one side, there are railway lines on one side of the property and a major highway on the other. The geothermal pipe trenches are designed to ensure that the playing field irrigation and rainwater is channeled away from the spawning stream into a lower retention/permanent biofiltration pond.

The mechanical system has a central heat recovery chiller and a 4-pipe fan coil distribution system. The modular chillers are used to boost the extracted ground energy to a temperature that can be used to heat the school in winter. They are high efficiency units with an operating coefficiency of energy performance (COP) in excess of 4.5 (i.e. for every kilowatt of energy used by the heat recovery chiller, 4.5 kilowatts of recovered energy is available for heating or cooling the school). High efficiency condensing boilers (95% operating efficiency) supplement the geothermal system.

The building management system is designed to integrate the control of all the mechanical system components, including the geothermal system, as well as the building’s lighting, power distribution systems and plumbing water conservation controls.

For the electrical systems, a 1,000 kVA substation distributes power to three sub-distribution transformers that serve the lighting, power and mechanical loads. Lighting uses less than 1.2 watts a square foot, well below the ASHRAE standard of 1.7 watts per square foot.

The construction budget for the school was $954 per square metre. This figure compares to $1,040 per square meter allowed by the B.C. government for the construction of a similar sized secondary school. A DOE2e hourly energy analysis indicates that the school will consume approximately 7,070 Gj per year as compared to 9,490 Gj per year for a comparable school. Incorporating the geothermal field into the overall mechanical system will save approximately $15,000 per year in energy operating costs based on 1999 price levels. The ground source heat pump system and high efficiency heating plant should emit 126,000 kilograms per year less CO2 than with a standard approach.

A fast track design and construction period of 26 months allowed students to move into the new building at the beginning of the 2000 year, instead of having to return to the portable classrooms they used before.CCE

Name of project: Burnaby Mountain School mechanical & electrical systems

Award winning firm: Stantec Consulting, Vancouver

Project team leaders: Paul Marmion, P.Eng., Joe Tai, P.Eng., Jimmy Ng., P.Eng., Dejan Radoicic, P.Eng., Dean Kaardal, P.Eng., Jim Jay

Owner: Burnaby School District #41

Client: The Learning Consortium (design-build)

Prime consultant: Hotson Bakker Architects, Cornerstone Architects

Other key players: Dominion Construction (construction manager), Fred Welsh (mechanical contractor), Status Electric (electrical contractor), B.C. Hydro (energy simulations), BKG Consulting (project manager).