22 May 2008
The Dock Midfield is the new terminal E of the Zürich airport. A 630 kW heat pump
at S4W40 operative conditions is coupled to about 300 piles to contribute to the building
heating and cooling. Measurements of the energy pile system begun in October 2004 for a 2
years period. The results of the measurement campaign are presented. The global system
efficiency, defined as heating and cooling energy divided by all the electrical energy used to
operate the system, lies over 5. Cooling energy is provided by geocooling, i.e. by coupling
the cooling distribution to the pile flow loop with a flat plate heat exchanger, and the heat
pump used as a cooling machine. Simulations performed with PILESIM2 have shown that
cooling energy delivered at 16 – 17°C instead of 14°C would not require the use of the
cooling machine. The global system efficiency would increase from 5.1 to 5.7. From an
economical point of view, the pile system is more convenient than a conventional system.
The additional investment of the pile system is paid back in about 8 years.