An important project for southwest Saskatchewan health care and residents, Weyburn General Hospital design was a large team effort from all of trades, consultants, client and multiple provinces.
Service completion: Early 2024
Scope of services: NECB Performance Path energy modeling, NECB Coordinating Design Professional
Size: $160,000,000 construction budget; 114,000 sq.ft.
Building systems: Metal structure with rigid insulation, curtainwall, multiple HVAC systems including dedicated outdoor air and dual-fan dual-duct VAV, radiant heating, boiler system, chiller system with heat recovery, high efficiency LED lighting with automation.
The Design-Build project was headed by Wright Construction, with a multi-province design team. The Client also had a multi-province consultant team to provide specific direction and requirements on the design and build, which included energy and greenhouse gas targets tied to the contract. As such, TES energy modeling was tasked with providing timely energy code interpretations and results to ensure all requirements of all parties were being met. For much of the project, construction was being permitted and completed while other design details were still being refined, which added to the complexity of the modeling.
TES had notable and early contribution in immediately questioning the energy, greenhouse gas, and system efficiency targets as they are applied in the prairies. The initial requirements were defined by consultants in eastern Canada, unbeknownst of the difficulty in Zone 7A prescriptive envelope requirements (with bridging), Saskatchewan’s large greenhouse gas intensity in electricity that makes it difficult to balance both energy targets and greenhouse gas targets, and the new NECB 2020 difficulty in meeting targets when restricted on the mechanical systems (the Client mandated variable air volume systems, with boiler heat). TES presented these difficulties to the Design-Build and the Client teams, getting a refinement of targets that all could be happy with.
While initially the envelope was to meet NECB Prescriptive Requirements, this is difficult and costly in Zone 7A as it can require effective R40 walls (which may require R45-R60 insulation, depending on insulation configuration) when a standard, unavoidable thermal bridging loss is also applied. Further, investing this much into envelope when the air-changes are so large, for a hospital building type, is misguided. As such, requirements were refined such that envelope had to meet energy code in its clearfield R-values, and had to minimize thermal bridging to no more than 30% additional loss (wall). TES worked closely with the envelope designer to meet these R-values, and performed the extensive thermal bridging calculations. TES was further consulted on durability concerns at the loading dock, and the roof insulation application given the cold season in the construction schedule making adhesives ineffective.
The mechanical system was a complex mix of dedicated outdoor air system with a dual-fan dual-duct variable air volume (VAV) and a standard VAV system, along with zonal unit heaters and make-up air units for ambulance bays. Hot water is circulated to all air-handling units and in various ways in the zones (VAV reheat, perimeter radiant panels, unit heaters, and forceflows), and chilled water had a heat recovery loop that dumped heat into domestic hot water preheat for year-round benefit. Humidification and process loads were modeled in detail, and all done with IES-Virtual Environment software. Lighting is simpler modeling, applying control credits as defined by NECB.
After much testing and iterations, the final design was modeled to exceed NECB 2020 by 14% in energy use, 12% in greenhouse gas emissions, and 10% in annual cost. This is without a fenestration-to-wall credit, which was not permitted by the Client. Overall, the project was an arduous success.
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