Reducing the consumption of heat resources in construction and housing and communal services is one of the key tasks solved by design engineers. The increase in the thermal protection of buildings is determined by regulatory documents, but construction customers often require it to be strengthened without any feasibility study. The objective of the study is to develop a graphical-analytical model, the analysis of which allows you to choose the most optimal combination of heat resistances of the coating (walls) and translucent structures of a particular building object.

Keywords: energy-saving project, thermal protection of buildings, "indifference" curves, the method of the fastest descent

Reducing energy consumption in the design, installation and operation of engineering networks is implemented in the process of implementing investment construction projects. An energy service contract, like any economic agreement, requires a feasibility study. When strengthening the thermal protection of a building, it is necessary to determine both the design of the fences and translucent structures, and the payback period of the investment. The objective of the research is to develop and analyze a mathematical model of heat losses depending on the characteristics of the resistance to heat transfer of walls, windows and balcony doors. Classical dependencies do not allow applying standard mathematical analysis procedures. It is proposed to use a power function that assumes the availability of differentiation. The paper substantiates the form of such a function and provides an extended analysis of the effect of changes in the resistance to heat transfer of building structures on the transmission heat losses of a building, which allows arguing for the adoption of optimal technical and economic decisions.

Keywords: energy-saving construction project, thermal protection of buildings, indifference curves, mathematical model of heat loss