Abstract: Described herein are systems and methods for building information modeling. An embodiment of the method includes: receiving a BIM; and transforming the BIM to flatten solid-volume geometry for space bounding elements into thin-walled boundaries of the thermal zones by: determining wall volumes from the BIM; collapsing the wall volumes to provide single surface walls; determining wall center surfaces and end points from the single surface walls; aligning, and trimming or extending, the single surface walls using the wall end points to create closed spaces; connecting the closed spaces vertically to generate a single water tight volume for the closed spaces; and creating interfaces between the single water tight volume for the closed spaces to generate thermal zones.