Many people (builders, owners, designers, occupants, etc) have an interest in appraising the fire safety of existing or proposed buildings. Computers are playing an ever increasing role in fire safety analysis and in the technology transfer of fire science. In this report the concept of the Calculus of Fire Safety is developed as a declarative programming language. This calculus will enable users to specify what fire safety question is to be answered without specifying how the answer is to be obtained. Advances in Artifical Intelligence programming techniques will enable the implementation of the Calculus of Fire Safety on widely availabel workstations. This will provide a very powerful tool to anyone interested in determining the fire safety of buildings.