Pressure losses in an air-intake plenum in relation to fire-safety systems: comparing variants to guarantee the regulatory flow rates.
The major restructuring of office buildings at La Défense entails the reconfiguration of a plenum acting as an air collector, which feeds numerous air-handling units (AHUs). These supply air to the fire-safety systems.
The EOLIOS studies made it possible to compare the different pressure-loss levels across the variants devised by the architects.
The challenge: to rule out the configurations that degrade the performance of the plenum, ensuring the selected configurations remain compliant with fire-safety requirements.
As part of the restructuring of office buildings at La Défense, the AF1 plenum acts as an air collector: it distributes air to the units feeding the smoke-control and pressurisation devices. A controlled pressure loss in this plenum is essential so that the safety fans deliver the regulatory flow rates in the event of fire.
The AF1 plenum is one of the project's main air intakes; its geometry and the layout of its grilles directly determine the pressure loss seen by the smoke-control fans.
The entire plenum was modelled from on-site surveys. The air-intake grilles were “sub-modelled” from the manufacturer's datasheets, in order to reproduce their pressure loss faithfully without needlessly increasing the mesh.
This approach makes it possible to simulate precisely the air velocities and pressure fields inside the collector, and to locate the turbulence and restriction zones responsible for the pressure losses.
Several layout variants devised by the architects were simulated and compared on the pressure-loss criterion. The studies made it possible to rule out the configurations that degrade the plenum's performance.
The selected configurations ensure the required fire-safety flow rates are maintained, while remaining compliant with regulatory requirements. CFD asserts itself here as a decision-support tool to reconcile architectural constraints with the performance of safety systems.
Savoir-faire : l'ingénierie du smoke controlCFD pressure-loss study of the AF1 air-intake plenum (office restructuring at La Défense): full 3D modelling from surveys, grilles sub-modelled from manufacturer datasheets, and comparison of architectural variants to rule out penalising configurations and guarantee the compliance of the fire-safety systems.
OfficesISI — Offices — Grande Armée
RestaurantSmoke control engineering — Restaurant Type N
TheatreSmoke control engineering — Theatre
EventsFire engineering — Fashion show
HospitalSmoke control — Pontoise hospital
Data CenterSmoke control — Data Center (GAZ NOVEC)
PlenumSmoke extraction plenum — AF2
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