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energy efficiency, a double-glazed window, low-e glass, payback period, thermal energy.

The article is devoted to the further development and implementation of technologies that allow some considerable reducing energy consumption and, as a result, reduce greenhouse gas emissions. In Ukraine and abroad, a huge amount of heat is lost through the external enclosing structures of buildings. The largest specific heat losses occur through translucent enclosures, in particular, windows, the main elements of which are double-glazed windows. Today, manufacturers offer double-glazed windows, which are characterized by different costs and energy efficiency. The buyer does not know which double-glazed window to choose. We have proposed a clear and understandable method of solving this issue. For example, two different double-glazed windows were considered and a comparison was made on their cost, thermal resistance of heat transfer, and the ability to save certain amounts of heat and money for its purchase during operation. A feasibility study of additional capital investments in double-glazed windows with improved characteristics instead of conventional double-glazed ones has been carried out. Its results show that, at the current stage of the society development, the use of double-glazed windows with improved characteristics, despite their higher cost, is economically more appropriate than conventional double-glazed windows. This applies to external translucent fences of buildings of any purpose and form of ownership - both residential and industrial, public, which are on the balance sheets of local and state budgets, etc. The results of all calculations are explained in detail and presented in the form of a table. In addition, a simple and clear scheme of technical and economic substantiation of additional capital investments in a double-glazed window with improved characteristics is presented instead of an ordinary one, which can be used at the design stages of new construction or thermal renovation of existing buildings to ensure the selection of the most rational structural solutions. The materials of the article can be generalized to any other cases of technical and economic substantiation of the choice of options for technical solutions in energy-efficient projects.