HVAC
District Heating for Schools Pre-insulated pipe enhanced installation speed and energy efficiency. By Ali Sajjadi
W
Going for gold The district sought to integrate the new schools into the existing landscape in an earth-friendly way. Its goals included optimizing energy efficiency and achieving the Canadian Green Building Council’s (CaGBC’s) Leadership in Environmental and Energy Design (LEED) v4 Gold certification. To do so, the project incorporated photovoltaic (PV) solar panels on the roofs, strategically positioned the windows and deployed geothermally boosted heating, ventilation and air conditioning (HVAC) systems, which would run heating and cooling water through the ground to extract or reject heat, as needed. The planners also decided to follow a district heating model, whereby a central plant would collect and distribute energy between the two schools, for greater flexibility in heating and cooling. Rather than running two separate mechanical rooms, the single heating/ cooling plant conditions water to accommodate the schools’ different energy cycles. This way, if one school requires less heat, the system can move excess heat to 6
CANADIAN CONSULTING ENGINEER
"The heat loss numbers were within tolerance and the pipe met all of the design criteria very well." — Michael Hladky, principal, SMcN Consulting
854
The project’s scope encompassed 854 m (2,800 ft) of underground energy transfer piping.
the other school. Heating and cooling can be produced simultaneously by a water source heat pump (WSHP), with additional heating provided by electric boilers if needed. The water is delivered through underground piping to the terminal units of each school, where it is then used in local HVAC systems to provide comfortable heating and cooling. Meeting the challenge The engineering firm behind the project was SMcN Consulting. According to its principal, Michael Hladky, the key to success in distribution piping or energy transfer piping applications is to prevent the heating or cooling energy from escaping while it travels. Only then could temperatures be maintained efficiently in both schools. To meet this challenge, SMcN’s team specified Rehau’s pre-insulated cross-linked polyethylene (PEX) pipe as the basis of its system design. The pipe is engineered to efficiently transfer hot or chilled fluid through buried pipelines, minimizing energy loss. The system uses 125-mm thick pipe to transfer energy November/ December 2023
PHOTOS COU RT E SY S O OK E S C HO OL DI ST R IC T.
ith many young families moving to Victoria’s Western Communities, Sooke School District 62 recently found itself with a need to quickly build more schools to accommodate approximately 1,200 elementary and middle school students. After seeking community input for the project, the district chose to build the new PEXSISEN Elementary School and Centre Mountain Lellum Middle School. (The former, named by the Songhees First Nation, refers to the opening of hands; while the latter, named by the Beecher Bay Nation, suggests ‘house’ or ‘the idea of community, where we raise our children.’) Designed by HCMA and built by Farmer Construction, both schools opened in 2022.
