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State-of-the-art air handling systems

Centre Hospitalier de l’Université de Montréal (CHUM) is one of the largest P3 healthcare projects in North America. It replaces three existing hospitals that currently serve more than half a million patients every year. The CHUM project will increase the quality and accessibility of medical and hospital care, ensure quality training for the new generation of healthcare providers, and promote healthcare research and technology. Located on a downtown site in east Montreal, when complete, CHUM will occupy more than 2 ½ city blocks with over 334,000 m2 of floor space. The facility is being designed to target LEED® Silver.

The complex consists of a main 21-storey acute care block, with four additional levels underground. The upper floors will house 772 beds in single rooms, while the lower floors will contain diagnostic and treatment functions such as a large emergency department, 39 operating rooms, 7 MRIs and a full Cancer Centre with 12 bunkers. Distinct blocks house ambulatory care clinics, office space and logistics. The engineering design scope also includes a large Amphitheatre for conferences and large meetings.

HH Angus and Associates is responsible for the mechanical, electrical and security systems design, as well as commissioning management for CHUM.  The project is another example of HH Angus’ experience with the design of state-of-the-art healthcare centres as part of an integrated team, in this case, the Construction Santé Montréal consortium. (The full project team is listed below.)

Despite the challenges presented by CHUM’s enormous size, the project’s design was completed in Revit building information modelling software (BIM), resulting in enhanced coordination of building services and collaboration among the design team.

The project’s RFP mandated a standby air handling unit for each unit serving a critical care space. This solution would have required much higher capital and operating costs over the life of the building. HH Angus developed an alternative approach by manifolding together a number of air handling units to share the redundant capacity. This solution considerably increased the overall reliability of the systems while lowering operating costs.

Where the RFP required a distinct air handling unit for each department, HHA proposed the use of 100% outdoor air units serving multiple floors where the occupancy was similar, and demonstrated to the hospital the merits of this approach from the perspectives of infection control and future flexibility.  To mitigate the energy penalty of 100% fresh air systems, we proposed enthalpy heat recovery wheels. The RFP initially prohibited these wheels, but we used our 25+ years of successful experience with the technology to demonstrate to CHUM and their compliance team that their infection control concerns could be successfully mitigated with the right components and controls. The RFP was modified accordingly.

The operating suites posed particular challenges for the design mechanical and electrical design team. The 39 operating rooms had to be stacked over two floors, even with a floor plate the size of two football fields. HH Angus situated a main air handling plant room on the floor immediately above to enable direct servicing of the ORs. All of the supply and return terminal boxes, as well as the terminal humidifiers, are located in the plant room, which will reduce the need for maintenance personnel to enter the ceiling space of the sterile area. The final air delivery in to the operating rooms is via an array of ceiling mounted laminar flow diffusers equipped with HEPA filters to provide the cleanest possible air. 

The CHUM project is ongoing, with Phase 1 anticipated to be nearing completion at the end of this year.


Design, build, finance, maintain P3 consortium: Collectif Santé Montréal (Innisfree Canada, Obrascon Huarte Lain (OHL), Laing O’Rourke Corp., Dalkia Canada)

Design-build: Construction Santé Montréal (Laing O’Rourke/OHL)

Architects: Cannon Design and Neuf Architects

Structural engineers: Pasquin St-Jean et associés

Mechanical and electrical engineers: HH Angus & Associates (Nick Stark, P.Eng., Marianne Lee, ing., Anna Chan, ing., Bob Tibbs, ing., Phil Schuyler, ing., Mohamed Kamel, ing.)

Infrastructure and land-use planning: SM International Group

Acoustics, Vibration and Microclimate: RWDI

Building Code: Technorm


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