Modern building systems can be exceedingly complex. In this research we develop a computational framework for the parametric modeling and architecture-energy assessment of building floorplans. Parametric representations of floorplans are formulated as multi-layer hierarchies, with adjacent layers coupled by dependency relationships. Software is developed for two approaches to floorplan specification: (1) scripting, and (2) interactive graphical techniques. Computational procedures are developed for assessment of building code regulations, electricity cost assessment, and simplified HVAC component selection and architecture-energy sensitivity analysis. A case study analysis of a two-apartment building system is presented.