The TOBUS software has been developed to facilitate the implementation of the TOBUS building diagnosis and decision-making method for retrofit studies. This user-friendly software runs under the Windows(R) operating system and includes several modules, each of which addresses a particular aspect of the diagnosis including: building description, dimensions, cost coefficients, building diagnosis of current physical state and functional obsolescence, indoor environmental quality (IEQ), energy use, elaboration of retrofit scenarios, cost analysis, reporting results. The software also includes comprehensive databases on the physical state of degradation, including hundreds of illustrations, retrofit work details, cost, etc.