Gan tower: no possible return for effluents!

The Foncière des régions 4 company asked CSTB to carry out a rather unusual study, to check that the effluents from the future Gan tower in the La Défense district could not return into the ventilation systems through intakes. "We are more and more frequently asked to do this type of work for buildings with unusual configurations," says the engineer, Marc Dufresne de Virel.  "Architects and design offices must be absolutely certain that no « loopback » can disturb the comfort and health of building occupants."

CSTB made a 1:50 scale model of the top 10 floors and the roof of the Gan tower.  A series of tests on this model was then carried out in the Eiffel wind tunnel in Paris.  A large number of sensors fitted on the model were used to monitor the diffusion of a tracer gas, for which the concentration at the time of its ejection was known.   Different wind configurations (speed, direction, etc.) were simulated and the probabilities of gas re-entering through the building air conditioning intakes were evaluated.

The research done on the Gan tower is an example of the application field of these effluent diffusion measurements.  They are helpful to assure that air intakes are well positioned and to modify them, or even to install special systems to eliminate any risk.  The slightest risk of any toxic substance such as foul air, fire smoke, combustion gases being drawn into air intakes must be controlled.  CSTB is watching this carefully!