In the article a method of the failures search formalizing by efficiency indicators of energy resources in heating, ventilation and air conditioning of buildings and structures is proposed. The main feature of this method is the combination of the educational process and the procedure of selecting a minimal set of controlled parameters. In the framework of the method a way of training patterns grouping and groups ranking in order to accelerate the convergence of the learning process, as well as the modification of training procedures at low volume and lack of a priori information about the system is considered. The solution of the problem of choosing a minimal set of controlled parameters is based on the properties of orthogonal vector systems.