International Journal on Engineering Performance-Based Fire Codes, Volume 10, Number 3, p.58-62, 2011 58 FIRE SAFETY CONCERN ON OPEN KITCHEN IN SMALL RESIDENTIAL UNITS OF TALL BUILDINGS W.K. Chow Research Centre for Fire Engineering, Department of Building Services Engineering The Hong Kong Polytechnic University, Hong Kong, China (Received 3 May 2011; Accepted 8 July 2011) ABSTRACT Open kitchens have been designed for many small residential units in tall buildings in Southeast Asia. This open design, without enclosing the kitchen with fire resisting walls has failed to comply with building fire safety codes in places like Hong Kong. Performance-based design was adopted to determine fire safety provisions. Gas cookers with flames are not allowed. Additional fire protection systems such as water mist suppression or dry powder systems have to be provided above the stoves, though studies on kitchen fire physical hazards with and without fire resisting walls were not reported in the literature. A survey on fire load density indicated that large amounts of combustibles are stored in small residential units. Experiments with electric induction cookers indicated that the cooking oil in a frying pan can be ignited within ten minutes. Fire would spread out from the open kitchen to burn up all stored combustibles in the residential unit to give a big fire. There are queries on whether such open kitchens in tall buildings are really safe when there is an accidental fire. Aspects of big open kitchen fires both with and without fire resisting walls in small residential units of tall buildings should be further explored. Fire dynamics must be applied to study the possibility of onsetting flashover upon igniting the cooking oil and burning adjacent combustibles. There might be new fire phenomena such as the air pumping effect of the plume and flame whirling motion in an open kitchen to give big disasters. Full-scale burning tests should be carried out to confirm identified scenarios; to justify the model predictions; and to observe any new physical fire phenomena. Performance of the specified suppression systems including water mist and dry powder suppression systems in big fires must be evaluated. 1. INTRODUCTION Many tall residential buildings over 200 m in height with small units of floor area less than 30 m 2 have been built in dense urban areas in Southeast Asia [1,2]. Fire resisting walls are required to enclose the kitchens. To utilize space more effectively in such a small residential unit, open kitchens have been designed. Although this design failed to comply with the usual building fire safety codes, some projects have been approved by virtue of a performance-based design (PBD) [3,4], known as fire engineering approach in Hong Kong [5]. Three conditions are commonly imposed in the associated PBD design for open kitchens. Firstly, gas cookers cannot be used, and only flameless electric induction cookers are allowed. Secondly, additional fire suppression systems including water mist [6] or dry powder [7] systems are specified for installation. The systems are supposed to act on the stove fire and prevent it from growing large. The residential unit owner cannot take out the system, nor change the cooking stove without approval from the government. Thirdly, the estate management office has to sign an undertaking to implement the approved fire safety management procedures [4,8] specified in the performance- based design report. Open kitchen is included in the new code [9] with additional fire safety provisions on fire detectors, sprinklers and fire resistance walls proposed by the Authorities. However, the performance of open kitchen fires in small units of tall buildings were not studied in detail using fire dynamics tools. Kitchen fire physical hazards with and without fire resisting walls were not even compared [10]. Only the spread of smoke from the open kitchen to areas outside the residential unit was predicted by fire models [11,12]. Results on carbon monoxide concentration, heat flux and visibility were used to justify the available and required safe egress times only as far as the staircase. The provision of additional water mist suppression or dry powder systems targeted to suppress small fires at an early stage might not work as expected if the fire grows big. No experimental data from full-scale burning tests has been made available to support the above specifications.