In order to guarantee that the structure and its members can withstand a realistic fire exposure that is expected in some building compartments, which are contemporary office buildings, hospitals, libraries, etc., this paper presents a new framework for assessing the spatiotemporal temperature which can occur inside a building compartment. Achieving a fair balance between the complexity and variety of such fires and the practicability and simplicity required by a structural engineer in properly defining fire as a load, served as the main guiding concept in designing the proposed model for building compartments.