Informal settlement fire load density: Survey outcomes from Western Cape, South Africa

Fire load density is fundamental to modelling compartment fire dynamics. In the context of informal settlements (IS) – residential areas which develop organically, without authorisation or regulatory oversight from the state – it represents a first step towards understanding the extent and rate of fire spread, thus characterising fire hazard and enabling development of mitigation strategies. Quantification of fire load for informal settlements is almost entirely absent from the literature. This paper presents estimates of fire load density from an ensemble of survey responses from 433 dwellings across 9 distinct settlements close to Cape Town, South Africa. Conditional on the assumption of a Gumbel distribution, fire load density was estimated between 247–947 MJ/m 2 (mean) and 354–1360 MJ/m 2 (80% fractile), depending on the assumed calorific value of movable furniture items and the inclusion or exclusion of non-movable combustibles. These outcomes are compared to the limited prior literature and code recommendations. The large variation in estimated fire load density highlights the requirement for greater understanding of contextual variation in fire load and modelling of fire dynamics in IS to support risk assessment for more than 1 billion people living in these settlements worldwide.