In the fire growth stage, there is sufficient oxygen for combustion and the fire is so-called fuel-controlled. The
characteristics, distribution and arrangement of the fuel dominate the heat release by the fire.
After initiation of a fire, whether the surrounding items will be ignited depends on the radiation heat flux received
by the exposed items and how easily they can be ignited [21]. For example, the fire spread might be considerably
affected by the location of the ignition source, as experimentally demonstrated in ref [22]. When the fire load is
close to each other, the fire may become intense more quickly; otherwise it may self-extinguish due to burn up of
the fire source. Types of combustible materials will typically be of primary concern. Heavy wooden furniture might
be difficult to ignite, but once ignited, it lasts a relatively long time. On the other hand, a vertically hanging curtain
can be ignited with ease and pose a rapid flame spread, burning very shortly.
The consequence of the combustibles being ignited plays an important role in the determination of heat release
rate. There are many experimental data for heat release rate of single items. How to obtain the total heat release rate
of burning more than one item needs to be investigated. The principle of superposition [23] is sometimes used to
combine heat release rate of combustibles. The ignition temperature or critical heat flux are usually taken as ignition
criterion. Where practical, full-scale burning tests [24] should be conducted for typical arrangement of combustibles
items found in the fire load survey. The heat release rate and other parameters measured can be used for a design fire