doi:10.3850/978-981-08-7724-8_16-05

ABSTRACT

Smoke and Heat Exhaust Ventilation Systems (SHEVS) are often designed to limit the temperature of smoke spill plume within atria to temperatures that can be tolerated by non fire-resisting glazing. This work uses computational fluid dynamics, CFD, package FDS4 to determine whether the temperature within an atrium can be controlled using a fixed amount of ventilation, thus providing a general temperature control design for a number of building geometries. Further, the results from the CFD modelling are compared to results derived from the SHEVS formulae. The CFD results show that a general temperature control design can be achieved for common atrium geometries in office buildings where the heat release rate is limited to below 3.6 MW (e.g. by sprinklers). It requires ventilation in the atrium roof with an effective free area of 2m², with an equal amount of make-up air provided in the base of the atrium. This solution is valid for atria within the range of simulated geometries, and is it is reasonable to assume that it would also be valid for atria larger than those simulated. It is also shown that the temperatures calculated using the SHEVS formulae do not vary greatly with opening width, whereas the results from the simulations suggest that opening width is an important variable with much higher temperatures than SHEVS predicted by the CFD simulations. These results therefore suggest that the current trend to assume that the highest temperature (and therefore worst-case design scenario) occurs when the opening width is narrow may be unsafe.

Keywords: Atria, Spill plume, Temperature, Glazing.

© 2011 CPD Unit, University of Leeds