Estimating the consequences of fire is a core problem in Lethality- and Vulnerability simulations. A fire is, however, a complex phenomenon which cannot generally be simplified to fit into the overall vulnerability simulation. This report gives a review of the problems associated with fire simulation and addresses questions including the choise of model in a specific scenario and how to use a CFD analysis of fire as a complement to the toolkit AVAL. The analysis results in recommendations on both short- and long-term actions as well as a hands-on instruction in converting a target description from AVAL into a simple CFD-input file.