The article is devoted to the determination of the patterns of joint influence exerted by the heating system and heat-protective envelope of a building on its energy consumption, taking into account the composition of the enclosing structures and the peculiarities of the course of thermodynamic processes in the enclosing structures and engineering equipment. The paper presents an overview of the literature on energy saving in the field of construction. It is concluded that it is necessary to form a new approach to optimizing the thermal insulation of buildings based on the method of thermoeconomics, which allows increasing the energy efficiency of buildings. A schematic diagram of the object under study is presented, for which a thermoeconomic model has been developed in the form of several zones connected in series. All cost components affecting the energy efficiency of buildings have been investigated, and the division of costs into energy and non-energy costs is substantiated. Dependences of the reduced costs on the variables to be optimized are given. The dependence of the reduced costs on the cost of the chosen enclosing structures (heat-shielding shell) of the building and engineering equipment is revealed. The analysis of the results obtained is carried out. It is concluded that it is possible to decrease the reduced costs by an average of 20–25 % in comparison with traditional approaches, and the energy consumption of the building by 30–34 %.