An Investigation of the Impact of Floor Setting on Airflow and Smoke Extraction in Designated Refuge Floor

Refuge floor is used as a temporary place for evacuees residing in high-rise buildings to take a short rest before taking further evacuation under fire case. It is specified as a prescriptive requirement in the Fire Code of Hong Kong to provide designated refuge floors for high-rise buildings. To fulfill its functions, a refuge floor must be a safe place for the evacuees. However, the safety of refuge floors under fire situations may be impaired if the floor is affected by smoke ingress from lower levels. The code prescribes that cross-ventilation should be provided in refuge floor so as to prevent smoke logging. Even with sufficient cross-ventilation, the prevention and/or extraction of smoke logging into the refuge floor cannot be guaranteed. In fact, the airflow pattern and smoke extraction/dilution largely depend on the floor planning in designated refuge floor. A study of the impact of refuge floor settings on the airflow around and inside the refuge floor is required and expected to provide some insight on the smoke movement pattern. In this paper, the Computational Fluid Dynamics (CFD) method is employed to predict and analyze the air movement around and inside designated refuge floor within a high-rise building under different floor plans. The study shows that the floor planning does affect airflow patterns and further the smoke dispersion in the refuge floor.