Building re-tuning is a systematic process to identify and correct building operational problems that lead to energy waste. It is implemented at no or low cost other than labor required to perform the re-tuning process. Re-tuning may include adjusting thermostats for actual occupancy patterns, changing set points in building automation systems or small, low-cost repairs such as replacing faulty sensors or caulking openings in the building envelope. By proactively utilizing the energy savings opportunities taught in the re-tuning training, operations staff can save between 5 and 25 percent of all energy used in the buliding. The training is a blend of in-class instruction and discussion and building investigation (building "walkdown"). The training is most efficient when the classroom portion of the training takes place in a building that is also the subject of the experiential walkdown.