When The Calgary Airport Authority began planning for the $1.4-billion terminal expansion at Calgary International Airport (YYC), it developed a mechanical and electrical master plan focused on sustainability and low operating costs. Geothermal heating and cooling became a key component of that plan, but it relies upon many other progressive design elements.
“The geothermal system in and of itself is a run-of-the-mill system with nothing fancy about it,” says John Munroe, vice-president, western Canada for AECOM, who engineered the expansion’s HVAC system. “How it ties into the holistic approach of this entire project is what makes it unique.”
Munroe explains that without a good building envelope (in this case, a triple-glazed double curtain wall separated by a 30-inch air space fitted with adjustable louvres and venting at both the bottom and top of the curtain wall’s space) and without good lighting (light-emitting diodes, or LEDs, throughout most of the terminal), a low-grade ground-sourced heating and cooling solution wouldn’t work.
“You have to look at the building as a whole,” he says. “Without the LED lighting, the double curtain wall and shading, you would have either tremendous heat gain or heat loss.”
Lacking these temperature extremes, the heating and cooling system can operate at lower temperatures, which improves operating efficiencies.
“Rather than heating your water up to 200 degrees [Fahrenheit], this system is operated at about 90–100 degrees [Fahrenheit],” Munroe says.
The latest YYC expansion includes a parallel runway that will be Canada’s longest commercial runway, and a new international concourse with 22 aircraft gates and almost two million square feet of space over five stories, including a 300-room hotel with spectacular views of downtown Calgary, the Rocky Mountains and airport activity.
To appreciate just how important sustainability is to the terminal’s design, Bruce McFarlane, director of air terminal development for The Calgary Airport Authority, lists just a few of the expansion’s other green features:
- A roof that harvests and stores half a million litres of rainwater for flushing its low-flow washroom fixtures;
- A new baggage handling system that requires only 30 per cent of the energy a traditional baggage system uses (its first installation in North America, although it’s already in use in Europe and Asia);
- Motion sensor occupancy controls for HVAC and lighting; and
- Finishes with low-volatile organic compounds.
“We went through a study that identified five levels of sustainability,” McFarlane says. “The first level [V1] is status quo, which isn’t an option today.... We’ve ended up at level V4.”
The only thing that separates the project from a level V5 sustainability rating is that it won’t generate its electric power through photovoltaic panels. The necessary rough-ins, however, have been included so that this option is available in the future.
The end result is a facility at the very forefront of emerging airport design in North America.
The YYC’s terminal facility geothermal system comprises 581 holes drilled vertically below the building footprint to a depth of up to 400 feet.
“We’re using a distributed heat/cool plant system in the building, so there are actually four mechanical rooms serving the terminal and each has a geothermal plant in it,” Munroe says.
Continuous 1.25-inch plastic piping loops with no joints were fed into the five-inch drilled hole and secured in place with thermal grout.
“The loops are all pre-made with built-in spacers to keep the pipes separated as to go down the hole,” Munroe notes.
A mixture of ethylene and water was the chosen circulation fluid over the more standard glycol mixture because of its superior thermal characteristics and ease of pumping.
Heat pumps, which are essentially refrigeration devices that extract or inject heat from the ground-source fluid, transfer that energy to a closed-loop plastic tubing system embedded in concrete radiant floors.
“The system accomplishes about 60 per cent of the heating load and all of the cooling load in the building,” Munroe says. “We have supplementary gas-fired condensing boilers to accommodate the additional 40 per cent of the heating when required.”
Fluid is moved through the tubing by electric pumps. Small natural gas–fired cogeneration units in each of the four mechanical rooms generate power. The heat from those generators is also utilized as heat in the building.
“So it’s a cascaded approach,” Munroe notes. “You use your most efficient, cleanest source first, then move down the line.”
Since the radiant floor handles heating and cooling functions, the terminal’s ventilation system can be decoupled from its typical twin duty of temperature control and fresh-air delivery.
“When the air system only has to handle the ventilation component, you reduce the air volumes significantly,” Munroe explains. “We’re using a displacement ventilation system. It’s been around for a while, just not used in the commercial world very much. It was a technique developed for the industrial world to get rid of air contaminants.”
Displacement ventilation fills interior spaces with fresh air from the ground up, making it quieter and more efficient, especially in a terminal building with 50-foot ceilings in some places.
“You get numbers in the range of 50 per cent less energy consumption than you would normally use along with better indoor comfort,” Munroe says.
Laying it down
The new YYC expansion is a good example of the sort of innovation an integrated design approach can yield. Integrated design requires extensive front-end collaboration among all the teams, including the owner, designers and contractors.
Collaboration on the YYC project also paid dividends in the construction process. Despite the general contractor’s unfamiliarity with geothermal and having to tiptoe around some 660 kilometres of radiant floor plastic tubing without damaging it before it was set in concrete, the geothermal installation actually turned out to be one of the least challenging aspects on site.
“Clean Energy [Technologies, Inc.] drilled the holes and did the installation, and it went exceptionally well,” says Marvin Messner, project director, EllisDon Construction Services Inc. “It came down to getting to know the process and understanding its sequencing, so we could work around their work and install everything correctly.”
YYC’s green side
The Calgary International Airport expansion incorporates several sustainability features, including:
- Geothermal heating and cooling, including reuse of heat created by airport generators
- A triple-glazed double curtain wall
- LED lighting throughout
- Low-flow washroom fixtures that reuse rainwater
- A reduced-energy baggage system
- Motion sensor-controlled HVAC and lighting
- Finishes that use low-volatile organic compounds
- A ground-up displacement ventilation system