## 4 Summary and Conclusions
### Conclusions Related to Economic Analysis  
A comprehensive analysis revealed that the optimal type of glazing system in the location of the reference building in Bialystok was triple-glazed windows. Financial indicators were the main determinant. This type of window was characterised by the lowest LCC value after the end of the 30-year life cycle, assuming that the discount rate would not exceed 5.2%. However, if this value were higher, then four-pane windows would have the lowest LCC value. However, one should hope that this is an unrealistic scenario for the development of the financial situation in the world.  
The balancing of cash inflows and costs was also performed in order to compare the case of replacing windows with a lesser number of panes with windows with one more panes. It turned out that only one situation, i.e., replacing double-glazed windows with triple-glazed ones, would be a profitable undertaking. This was evidenced by the positive value of the NPV indicator, equal to 2.95 EUR/m\({}^{2}\) for the Bialystok site and 29.35 EUR/m\({}^{2}\) for the Kiruna. The IRR value was equal to 5% after 26 years and 14 years for Bialystok and Kiruna, respectively.  
In the case of an annual increase in energy prices by 2% for the Bialystok site, triple and quadruple windows had a similar LCC value when the discount rate is lower than 2.5%. The house equipped with triple windows was characterised by the lowest LCC in the range \(r\) from 2.5% to 7.5%.  
In the case of a house site in a slightly colder climate (Kiruna), triple- and quadruple-glazed windows had similar LCC values when the discount rate was less than about 3%. When \(r\) values were greater, only the triple-glazed system had the lowest life cycle costs. Quadruple-glazed windows were the best choice when the discount rate was less than 5%, and a 2% increase in energy prices was taken into account.  
To summarise, assuming a stable financial situation and a small increase in energy prices, it is recommended to use triple-glazed windows in the location of the house in the climatic conditions of Northeastern Poland. Quadruple-glazed windows are suggested in more severe climatic conditions, for example similar to those prevailing in Northern Sweden.  
It is important to note that the high initial cost of quadruple-glazed windows currently results in very little interest from investors. However, it should be noted that the constant increase in energy prices, as well as rapidly developing technological progress, can reduce production costs and increase the profitability of this technology in the future.  
**Future works:** The author plans to perform a detailed experimental and CFD simulation analysis of thermal bridges occurring in houses made of a hybrid construction in order to precisely determine the heat transfer coefficients of individual building partitions. In addition, it is planned to carry out a similar analysis but for the location of a reference house in a warm climate zone, for example Southern Italy or Spain.  
This work was supported by the Bialystok University of Technology [grant number WZ/WB-IIS/8/2023] and financed by the Ministry of Science and Higher Education of the Republic of Poland.  
Not applicable.  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
The author thanks R&D Coordinating Engineer [PERSON] from Danwood SA for providing the reference house plans and information on the NEXT hybrid technology.  
The author declares no conflicts of interest.