Evaluation of FDS scaling-pyrolysis model in predicting ignition, self-extinguishment and heat release contribution in timber compartments

Predicting fire behavior in compartments with exposed timber surfaces is of critical importance to the fire safety community, given the widespread use of timber in modern buildings as both a structural and valuated for environmental aspect and the overall quality of space it creates when exposed. Fire safety engineers are particularly interested in understanding fire initiation and growth, heat release contribution, self-extinguishment conditions, and the charring behavior of wood. This study evaluates the predictive performance of Fire Dynamics Simulator (FDS) and its recently integrated pyrolysis model, S-Pyro, with respect to these key parameters. Experimental tests were conducted in medium- and large-scale compartments with exposed timber elements. A parameter sensitivity analysis was first performed on one medium-scale configuration. The results demonstrate that FDS provides accurate predictions of ignition times, fire growth rates, and heat release rates across both scales. The model also reproduced char layer thickness qualitatively at the end of the experiments. However, FDS exhibited limitations in predicting self-extinguishment in certain scenarios, highlighting the need for further investigation into this complex phenomenon in future studies.