## 4 Conclusions and Further Work  
The article presents the results of experimental, numerical and analytical simulations of an IGU with dimensions of 500 mm \(\times\) 500 mm built with two 6 mm toughened glass panes and a 16 mm wide spacer. The analysis aimed to experimentally determine the values of the pressure difference in the gap, deflection of the panes, and stress in the glass in the IGU model. This was carried out using a rarely used method of simulating climatic loads, allowing research to be conducted without a climatic chamber. Subsequently, analytical and numerical models of the tested IGU were developed, and the results were compared with the results of the experimental studies. The following conclusions were drawn from the conducted research:  
* The results obtained from the analytical and numerical models are in good agreement; they do not differ by more than 12% (mostly much less), which proves the correctness of the assumptions for the analyses. The differences result from different ways of defining the gas input parameters in the gap;
* During the tests, it was found that the rapid injection/withdrawal of gas causes a sudden increase (in absolute value) of the pressure difference, which decreases and stabilizes almost instantly. The difference is, on average 7%. This is due to adiabatic effects resulting from the high rate of gas transformation. We plan to analyze it in more detail in future work;
* The results from the numerical and analytical models, in terms of the pressure difference, underestimate the values obtained in the tests by an average of 8%, while for deflections and stresses, they overestimate them by 16% and 32%, respectively. This indicates a rotational stiffness at the edges of the panes resulting from the properties of the connection of the glass pane with the spacer, seal and support rod. As part of the research in the near future, we plan to improve these models, considering the rotational stiffness of the panes' edges. * Simulating climatic loads in IGUs by the controlled change of pressure in the gap is inexpensive and can be used by other researchers or company laboratories. IGUs with different types of spacers and different methods of their installation in window frames or facade systems can be tested. It is also possible to define a specific amount \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Test Series** & \(p_{\text{stab}}\) & \(w_{\text{stab}}\) & \(\sigma_{\text{stab}}\) \\ \hline \multicolumn{5}{c}{\(-100\) mL} \\ FEM/EXP & \(-7.5\%\) & & 17.6\% & 32.3\% \\ ANA/EXP & 1.0\% & & 17.1\% & 35.8\% \\ ANA/FEM & 9.1\% & & \(-0.4\%\) & 2.6\% \\ \hline \multicolumn{5}{c}{\(+150\) mL} \\ FEM/EXP & \(-8.2\%\) & & 53.0\% & 30.2\% \\ ANA/EXP & 1.6\% & & 55.2\% & 33.6\% \\ ANA/FEM & 10.7\% & & 1.4\% & 2.6\% \\ \hline \multicolumn{5}{c}{\(-150\) mL} \\ FEM/EXP & \(-5.4\%\) & & 14.6\% & 33.0\% \\ ANA/EXP & 2.7\% & & 14.3\% & 36.5\% \\ ANA/FEM & 8.6\% & & \(-0.3\%\) & 2.7\% \\ \hline \multicolumn{5}{c}{\(+200\) mL} \\ FEM/EXP & \(-6.9\%\) & & 9.3\% & 32.2\% \\ ANA/EXP & 2.9\% & & 11.1\% & 35.0\% \\ ANA/FEM & 10.4\% & & 1.7\% & 2.1\% \\ \hline \multicolumn{5}{c}{\(-200\) mL} \\ FEM/EXP & \(-3.1\%\) & & 12.0\% & 34.3\% \\ ANA/EXP & 4.1\% & & 10.9\% & 37.0\% \\ ANA/FEM & 7.5\% & & \(-1.0\%\) & 2.0\% \\ \hline \hline \end{tabular}
\end{table} 
Table 4: _Cont._of injected/extracted air to model specific climatic loading for assumed locations and operating conditions. * The experience gained from this research will be used in planned tests with curved IGUs in the near future. This particularly applies to the use of the methodology of experimental research that proved its applicability in the case of the tested flat glass. Experimental tests with curved IGUs are expensive to carry out for a large number of samples; therefore, a validated numerical model is actually the only way to analyze their mechanical behavior under climatic loads. Conceptualization, M.K. and Z.R. ; methodology M.K. and Z.R. ; software, M.K., M.W. and K.Z. ; validation, M.K., Z.R. and K.Z.