The existing international terminal building used artesian water in a pre-cooling application, pumping water directly through pre-cooling coils and, at the start of the project, it was envisaged that the new terminal building would use a similar system.
Beca believed the artesian water had more to offer and more could be done to make better use of this sustainable resource. Thinking further, we found the artesian water, which has a fairly constant year-round temperature of 12°C, would lend itself well to a heat pump-type system. With such a system we could not only reject heat energy to the aquifer, but also take heat energy for heating.
Once extracted, the artesian water passes through heat exchangers that increase or decrease the water's temperature to extract or reject heat energy. Cooling the water provides heating to the building (by extracting heat energy), while heating the water provides cooling to the building (by rejecting heat energy). The work is done by relatively standard air-conditioning equipment. When conditions suit, this equipment can be bypassed to further enhance performance.
The heat exchangers create a physical separation between the artesian water and the building's water supply to eliminate the risk of contamination of the artesian water. Afterwards, the water is returned in the same condition it was taken (with only the temperature altered).
Every aspect of the system's design was analysed, challenged and developed to maximise energy efficiency and sustainability, with the end result dramatically reducing Christchurch Airport's energy consumption, carbon emissions, operational costs and dependency on fossil fuels.