NUMERICAL STUDIES ON SMOKE SPREAD IN THE CAVITY OF A DOUBLE-SKIN FACADE

Double-skin facade (DSF) is an environmental friendly architectural feature. However, fire hazard is a concern. A scenario of having a flashover room fire adjacent to the facade was identified. Heat and mass would be trapped in the facade cavity. This paper examines air flow driven out of a flashover room fire to the cavity of a DSF by Computational Fluid Dynamics. The software Fire Dynamics Simulator developed at the Building and Fire Research laboratory, National Institute of Standards and Technology, USA was selected as the simulation tool. Three DSF features labeled as DSF1, DSF2 and DSF3 were considered. Detailed simulations were carried out to understand the fire-induced aerodynamics in a 5-level model DSF1 with a fire room at the third level. Hot gas spreading out to the facade cavity was simulated under two heat release rates of 1 MW and 5 MW. Air cavity depths of 0.5 m, 1 m, 1.5 m and 2 m were considered. Three stages of flame spreading out to a DSF with a wide air cavity depth were identified. Results suggested that wider air cavity depths would be more dangerous, with higher risk of the upper interior glass pane's breaking. To study spreading of heat and mass up the facade cavity as vertical channel flow, two taller DSF facade features DSF2 and DSF3 with differing air cavity depths were simulated. Both features were of height 24 m but of differing fire room height. Vertical temperature profiles with and without the DSF feature were compared.