The concept of parametric fires provides a rather simple design method to approximate post-flashover compartment fire. It is assumed that the temperature is uniform within the fire compartment. A parametric fire curve takes into account the compartment size, fuel load, ventilation conditions and the thermal properties of compartment walls and ceilings. Parametric fires will give more realistic estimates of the fire severity, for a given compartment, compared to the standard fires.

Annex A (informative) of BSEN1991-1-2 provides the most validated approach for determining parametric fires of compartments which will be described as follows.