- Active. This SFPE engineering guide provides a methodology to define and quantify the fire development and ensuing conditions within the room of fire origin from the fire's incipient stage through its full development. The approach presented in this guide was developed using the framework set forth in the SFPE Engineering Guide to Performance-Based Fire Protection. It consists of three distinct parts: 1. Approach selection 2. Input definition and data collection 3. Results computation Specifically this guide was developed for use as a means to implement the requirements presented in Chapter 10 of the SFPE Engineering Guide to Performance-Based Fire Protection. However, the material within this guide has broader applicability and is therefore not limited to performance-based design applications.The room of origin is the volumetric space that encompasses the primary development of the source fire. The room of origin interacts with the source fire and the flow of combustion products and hear via the boundaries and the openings. This guide presents an approach for the selection of different analytical methods of varying complexity to quantify room of origin fire conditions and identifies useful source documentation available to fire protection engineers for consideration when conducting fire hazards analyses.