With many young families moving to the western communities of Greater Victoria, the local Sooke School District found themselves with a need to quickly build more schools for some 1,200 elementary- and middle-school age students.
Seeking community input for the projects at every juncture, the district would ultimately name the new schools PEXSISEN Elementary — meaning “the opening of hands,” as named by the Songhees First Nation, and Centre Mountain Lellum Middle School — meaning “house” and “the idea of community, where we raise our children” as named by the Beecher Bay Nation.
In addition to fitting into the culture of an inclusive and respectful community, it was also important for the new schools to be seamlessly integrated into the existing landscape and be earth-friendly in every way. This included optimizing energy efficiency by targeting LEED v4 Gold certification. To achieve this goal, the project incorporated elements such as photovoltaic panels on the roof, strategically positioned and designed windows and a geothermally-boosted HVAC system that runs heating and cooling water through the ground to extract or reject heat as needed for added efficiency.
Of significant note in this regard, the planners also decided upon a district heating model, in which a central plant collects and distributes energy between the two schools for flexible heating and cooling. Rather than having two mechanical rooms, water is conditioned at a single heating/cooling plant to easily accommodate different energy cycles between the schools. If one building requires less heat, the excess heat can be moved to the other building. Heating and cooling can be produced simultaneously by the water source heat pump, with additional heating provided by electric boilers as needed. The water is then delivered through underground piping to the terminal units of each school, where it is used by local HVAC systems to provide comfortable heating and cooling.
According to Michael Hladky, principal of engineering firm SMcN Consulting Inc., the key in these distribution piping or energy transfer piping applications is to keep the heating or cooling energy from escaping while it travels to the schools, maintaining temperatures. To meet the challenge, the team specified REHAU INSULPEX pre-insulated PEXa pipe as the basis of design. INSULPEX pipe is specially designed to efficiently transfer hot or chilled fluid through buried pipelines, minimizing energy loss.
Transferring energy from the central plant to each school is 125 mm INSULPEX pipe. The middle school uses 671 m (2,200 ft) of INSULPEX, while the elementary school uses 183 m (600 ft). In both cases, the flexible pipe is supplied in coil lengths of 40 m (130 ft) or greater and consists of PEXa O2 barrier pipe surrounded by foam insulation and a durable corrugated PE outer jacket. REHAU O2 barrier pipe has a co-extruded oxygen diffusion layer that prevents corrosion of any cast iron components within the heating system in compliance with DIN 4726.