Canadian Consulting Engineer

Pearson International: New Terminal 1 Mechanical Systems

August 1, 2003
By John Lowden, P.Eng.

Airport terminals are some of the largest and busiest multifunctional buildings in the world. They all have elements in common that affect the mechanical design, but the new Pearson terminal was a spe...

Airport terminals are some of the largest and busiest multifunctional buildings in the world. They all have elements in common that affect the mechanical design, but the new Pearson terminal was a special challenge.

Size. The building’s large size affected the distances for mechanical services (ducts and piping), ventilation efficiency, energy consumption and temperature control accuracy. In T1 New there are 200 air-handling units varying in size from 700 to 29,000 L/s (1,500 to 60,000 cfm). At peak they use approximately 7,500 tons of cooling in summer and 47,000 kW of heat in winter. The hot or cold energy is supplied hydronically from the remote Central Utilities Plant, which serves most of the buildings at the airport.

Most of the hydronic pumping and air handling equipment is located in the basement service level with distribution through numerous vertical shafts to the upper levels. Integrating these service shafts into the building’s structural, electrical and baggage systems was a challenge for the designers due to the sheer size and quantity of services required.

The voluminous Departures Hall at Level 3, as well as some of the high ceiling circulation spaces, called for an approach to air-conditioning using stratification. The environment in the occupied space — up to about three metres off the floor — was controlled through the strategic placement and selection of supply air diffusers. The space temperature above three metres was left to vary to avoid large air circulation requirements and to conserve energy. Each of the skylights above the main Ticketing Hall, however, is equipped with a ventilation fan that is thermostatically controlled to limit temperatures and prevent the failure of construction materials such as caulking and sealants.

Variety of occupancies. Within the terminal, there are many different uses and occupancies: public assembly, private office space, back-of-house facility service space, secure and non-secure areas and even police and detention areas. The mechanical systems are therefore selected to suit a variety of zones and conditions. And because the airport operates over extended hours seven days a week, the systems are selected with a built-in quality to minimize the need for maintenance and for redundancy.

The mechanical systems must be flexible enough to accommodate large swings in population in different locations. At times some areas have crowds of people who are relatively stationary (at check-in counters, security checkpoints, baggage claim and gates), and in other places people are in continuous flux (in circulation corridors). Such occupancy swings, which occur hourly, daily and seasonally, have an impact on the size of air handling units as well as the thermostatic zone control. The building automation system is integrated with the airport gate management system to allow the environmental systems serving gates to be run at reduced capacity or shut down when they are not in use.

Renovation and expansion. Air terminal buildings require frequent upgrades, not just to renovate the heavily used public areas, but also for replanning the back-of-house operational spaces, for relocating airlines and retail tenants. In planning the mechanical systems, the designers took care to avoid interfering with future expansions and renovations. Primary pumping and piping were provided to serve future piers, and future requirements for shafts and duct rights-of-way were taken into account.

Security. Although electronic security systems have the highest profile in these facilities, security considerations have an impact on the mechanical systems as well. Ductwork is of particular concern as it may provide a pathway across security walls. In T1 New, special consideration was given to routing ducts around security areas. In some cases ducts are fitted with security screens to prevent the passage of humans and materials.

Consultant: The Mitchell Partnership/Smith and Andersen Consulting Engineers, in joint venture (John Lowden, P.Eng., Douglas Smith, P.Eng., David Campbell, P.Eng., Raymond Niepage, P.Eng., David MacKeracher, P.Eng.)

Contractor: Sayers and Associates


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