École St. Anne School

Energy Simulation

École St. Anne School in Prince Albert, Saskatchewan, uses simple design along with smart use of renewable energy to achieve big energy savings and potentially become the first LEED school in Saskatchewan.

Service completion: Fall 2011

Scope of services: Enhanced and Fundamental Commissioning (EAp1, EAc3), Minimum and Optimize Energy Performance Simulation (EAp2, EAc1) for CaGBC LEED: New Construction 1.0 with addenda, Renewable Energy Simulation.

Size: $14,200,000 construction budget, 4950 sq.m.

Building systems: Stone/concrete and metal panel envelope, radiant heating with 100% outdoor air demand control ventilation and no centrallized cooling, efficient lighting with occupancy and daylight sensor control.

The design of École St. Anne School is simple: use hot water to heat the spaces with radiant panels, provide small air-conditioners in the daycare centre only (as it is only space regularly occupied in summer), and ventilate with 100% outdoor air from VAV boxes driven by occupancy sensors. Also, provide lighting that is controlled by occupancy and by daylight sensing, as opposed to manual control which can be forgotten in a chaotic classroom environment. A big, beneficial design feature was using a solar wall to preheat ventilation air to the gymnasium, which had a large, empty south-facing wall.

But even with good design comes implementation issues…that’s where commissioning comes in. Programming of the VAVs was not in accordance with the spec: there was no cooling in the building; however, there is a design cooling airflow for when outdoor temperature conditions can provide cool air. This was not programmed correctly when outdoor temperature conditions are too warm for cooling, as the boxes still go into max flow and dump very warm air into the space (heating it up even further). An outdoor air temperature cutoff point had to be programmed so that in these circumstances, the spaces would not be overheated. The other aspect of this is that the spaces were constantly calling for cooling, i.e. max airflow, so the supply and return fan variable speed drives were running at maximum speed. Other major commissioning verifications indicated that approximately 50% of the radiant panels were air locked and not providing heat, and the air conditioners for computer lab and daycare had refrigerant leaks and some wiring issues.

With efficient boilers, demand control ventilation, solar wall savings, and efficient lighting, the building model was reviewed to be 52% better than MNECB with respect to cost, equivalent to 7 points for EAc1.

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