At a façade height of 32m, the heat losses in winter can reduce the thermal comfort in the occupied zone. Therefore the ventilation system uses jet nozzles to bring warm air to the façade. At a distance of 8 and 12 m from the façade, it was not evident that the system design was sufficient to shield the façade.
The façade system was tested in the Caverion laboratory using a full scale model. While the room height of the lab was only 13m, a numerical model was set up to show the air flow pattern for the final situation. The results of the lab tests were used to validate the numerical results.
In the terminal, nozzle groups of two and four nozzles are used for the ventilation. While the air flow pattern of je nozzles is generally well known, the effects of the nozzle grouping cannot be calculated exactly. The combination of laboratory tests and numerical simulation provides a good way to create reliable solutions for the building.
As a result of the tests, the nozzle system turned out to be not sufficient to shield the façade. The lower 10m of the façade is nearly not affected by the warm air, so cold air draft will reduce the comfort for passengers. An additional perimeter heating of 1 kW per m was necessary to keep comfort during cold winter days.
Requirements of the ventilation system:
Comfort in the occupied zone
Caverion was asked to evaluate a ventilation situation in a very unconventional building. The decision had to be made in a very serious way, because the results had substantial financial effects. The tests were performed as a combination of engineering work, laboratory tests and numerical simulation to provide the highest possible reliability for the results.
Terminal 5B measures
442 metres (1,450 ft) long
52 metres (171 ft) wide and
19.5 metres (64 ft) high
40 m roof height
Cost £4.2 billion
It contains 37 lifts and 29 escalators.