This paper adopts the simplest numerical procedure for solving the multi-dimensional nonlinear transient heat conduction model, which "occasionally" is used to simulate fire endurance and related fire engineering problems. Due to its superb simplicity, average fire professionals can easily implement this relatively user-friendly algorithm customized for the rarely published fire (convective or Robin) boundary conditions. Further, the danger of constant incident (Neumann) flux is discussed. This paper also discusses the cogent investigation of converging solutions, numerical difficulties, comparisons of analytical solutions of a simple benchmark case, and nonlinear problems arising from thermophysical properties, temporal fire including variable combined heat transfer coefficient, and a heat source or sink. Language: en