Mechanical systems at vancouver international

KEEN ENGINEERING

Keen Engineering’s mechanical design for the international terminal at Vancouver airport challenged the way that mechanical design is traditionally done in large buildings. Their design also has saved the airport authority more than $200,000 a year and netted them the largest B.C. Hydro “Power Smart” rebate (over $600,000) in the history of the program.

A ground water cooling system, incorporating direct ground-water cooling and very high efficiency chillers, reduces the energy consumption for cooling the 105,000-m2 building by 40 per cent. Because the airport sits on a very high water table, surrounded by the Fraser River and the Georgia Strait, Keen Engineering and R.D. Erdman first had to do extensive research and environmental reviews to determine whether a ground water cooling system would work.

Water is drawn from the ground using up to 23 wells. First it passes through a heat exchanger and directly cools return chilled water, taking 25 per cent of the cooling load during peak periods. The ground water then passes through heat exchangers that absorb the rejected heat from the three centrifugal chillers, and is finally discharged to surface ditches for return to the river. The high permeability of the ground makes recharge wells unnecessary.

The naturally pre-cooled well water improves the overall efficiency of the cooling system: with a 2,000-ton cooling load, the electrical consumption of the chillers is 500 to 600 kW lower than with a conventional chiller. The system also adjusts to the weather. In winter months, for instance, the ground water is cold enough that, coupled with the reduced flow requirements, it needs no mechanical help to cool the airport’s retail areas.

Another advantage of this system is that there is no need for a cooling tower. Cooling towers often generate a plume of water vapour that can reduce visibility for the pilots, and are therefore a major concern at airports.

Stack effect

Another innovative feature is the use of air stratification. The concourse areas on Level 3 and the Customs and Immigration area on Level 2 have very high ceilings with suspended walkways. Conventional mechanical systems would condition the upper volume of the atrium, and yet most of this area is unoccupied.

Instead, the designers chose to air condition only the lower occupied levels and let the air warmed by lights, equipment, people and the sun rise to the ceiling. In summer, this warm air is allowed to escape out of louvered openings. In winter, it is re-circulated to reduce the heating load.

The suspended walkways, with their 2.5 metre high glass walls, are cooled using fan coil units suspended under the walkway. The cool air pools in the U-shaped walkways, which are surrounded by warm stratified air.

Modular air-handling units were built into free-standing service pods or “totems.” These cost-effective components also contain the flight arrival and departure monitors.

Since many of the fan rooms in the airport are located next to public areas, noise was a concern. Keen addressed it by using Vane axial type fans with shaped silencer pods. They recover a significant amount of energy from the air as it goes from high to lower velocity, resulting in savings of 200 kW for the building’s nine fan systems. There are also no return air fans, which saves costs and energy.

Large differential temperature, chilled-water piping systems were installed to reduce the size of piping and energy costs. Capitalizing on the large scale of the facility and the high level of repetition, Keen also developed efficient modular equipment strategies that further reduced costs and construction time.

The first phase of work described above was finished on budget and on schedule in May 1996. However, Keen’s work is ongoing as development of the international terminal takes place. A concourse has been completed, and a baggage hall expansion and addition with holding areas for seven gates are under way. The mechanical cooling and heating systems have been designed to accommodate the additions. Looped chilled and heating water piping systems are designed for yet one more large building addition, while the physical plant equipment, chiller, boiler and pump stations, have spaces allocated for future equipment to be installed. The totem modular air handling units are provided for each new building entity and connected to the piping loops as required.CCE

Owner: Vancouver International Airport Authority

Building mechanical systems: Keen Engineering (Phil Rempel, P.Eng., Blair McCarry, P.Eng., Peter Hughes, Ray Miller, Dean Cumberbirch)

Other consultants: Architectura/Waisman Dewar Grout Carter (architect), Robert Freundlich (electrical), Bush Bohlman (structural) Acres International (structural)