Abstract A total heat recovery system performances are analysed by monitoring building–plant system long term behaviour. Some of the installed chillers offer in fact the possibility of a total recovery of the heat rejected by condenser. The results are very satisfactory both in energy and economic–financial terms. The experimental test takes advantage of the supervisor just existing in the building. Therefore it is an example of how these control systems can be used not only for safety and management needs, but also for a detailed performance analysis able to permit an easy simulation of the effects of different design and control options.