A discussion on estimating the heat release rate of design fires in Hong Kong

Many big construction projects in Hong Kong have difficulties to comply with prescriptive fire codes. Fire safety provisions have to go through Fire Engineering Approach (FEA) or performance-based design (PBD). The heat release rate of a design fire is the most important parameter in fire safety assessment. However, a very low design fire less than 5 MW is usually assumed, even in large crowded spaces, such as public transport terminals and shopping malls. Surveys indicated that local buildings usually store combustibles exceeding the upper limit imposed by the codes. A post-flashover fire due to whatever reason would give even higher heat release rate. As data for local combustible products is not yet available, heat release rate in most of the FEA/PBD projects were estimated by crude methods not supported by full-scale burning tests. Three methods commonly adopted to estimate the heat release rate will be discussed in this article. Some calculations were even wrong in taking average heat release rate as the peak heat release rate. Correct calculation on heat release rate by burning combustibles is necessary with support of full-scale burning tests.