On Time, On Budget

According to Nigel High, lead engineer with McKee Engineering, Ottawa, a primary goal of the project was to complete it on time and on budget. The passenger terminal opened six months ahead of schedule, on budget, and without help from government subsidies. An airport improvement fee administered over the last four years covered the cost.

"The job was bid to a number of suppliers, but in the final analysis, McQuay had the features as well as being cost effective," said High. McQuay custom modular Vision units allow specifiers to select from a variety of factory-installed components and configurations to fit the exact requirements. For the airport, these included stainless steel interior lining options, polished aluminum diamond plate floors, marine lights, windows in access doors, and a painted finish.

A custom dimension specified between the fresh air and exhaust air connections provided more space for the insulation contractor to install insulation on the fresh air duct to the unit. "The custom modular construction gave us features generally only available in a custom unit, but without the expense. That meant we could install the kind of equipment we wanted at a cost-effective price," said High.

Besides hiding the mechanical services, engineers designed the air-handling units to accommodate a variety of spaces, including the open check-in level on the third floor, the three-story-high baggage claim area, and individual offices.

All of the 18 departure gates, with their floor-to-ceiling, west-facing windows, are served by an individual air-handling unit.

"This is not a cookie cutter project," said High. "Every area has specific requirements in terms of ventilation, cooling, heating, and air distribution. Probably our biggest challenge was to economically distribute air throughout the space, while at the same time hiding these services in the architectural features."

The solution proved to be both innovative and economical.

Air Stratification

"It's not like a typical office building, which generally requires one air-handling system because each floor has the same service requirements," said Sylvain Chenier, project engineer with McKee Engineering. "And it's different from many other airports and large spaces such as gymnasiums because those spaces often have exposed ductwork."

Standard HVAC systems supply air from above with air diffusers that push conditioned air down toward floor level, which can be 20 feet away. That requires conditioning a relatively large volume of air. The solution at the airport was to stratify the air: Air is brought in at ground level at low velocity, and returned about eight feet above the floor. That requires conditioning only the first eight feet of air.

"Stratification is not a common feature in most buildings, but we had great success with it at the Ottawa airport," said High. "Reducing the cooling requirements helps to boost energy efficiency in the facility."

Architectural Features

At the third-floor check-in area, 10 freestanding service tables offer travelers a convenient surface for placing their bags or writing a note. The real purpose of the tables is to hide ventilation grilles, located in the cavities below the tables, and served by ductwork hidden underneath the floor. The grilles are hidden behind perforated stainless steel.

"The tables serve as an architectural feature to accommodate the air displacement units," said Chenier. "Low-velocity air is supplied from underneath the tables at just a few degrees cooler than ambient temperature. This stratifies the air, providing conditioned air for the space up to eight feet or so above the floor. It's very economical because, when cooling is required, it conditions air at a fraction of the volume of the space, and pushes the warmer air up. We don't need the typical fan power to blow air down from above."

A similar system was installed behind the 25 ticketing desks, which also hide the displacement units. "The challenge here was to avoid blowing cold drafts on the ticketing agents. We provided conditioned air at extremely low velocity, and added dampers so that airflow can be easily adjusted," said Chenier.

To boost energy efficiency further, engineers incorporated variable-speed drives throughout the project on both variable- and constant-volume systems. The variable-frequency drives help save energy by reducing air change rates during those hours when the airport is not busy. In addition, ventilation rates are adjusted based on a CO2 demand ventilation strategy.

More than just a passenger terminal, the airport is "our national gateway to the world," said Paul Benoit, the airport authority's chief operating officer, during commissioning ceremonies.

Modern conveniences include climate-controlled covered walkways and a giant video wall displaying national news. Local touches include a water fountain representing the confluence of the region's three rivers, and copper and limestone from nearby sources. These and other amenities, including the ones no one notices, make it a pleasure to visit this airport.

Publication date: 06/28/2004