**6. Summary and Conclusions**

The current regulations define the rules for calculating the heat demand for heating based on the difference between the maximum and minimum outside air temperature for the climate zone. The calculations do not take into account the thermal inertia of building partitions.

The main aim of the article is to determine the influence of the thermal inertia of building partitions on the building's heating system, taking into account changing climatic conditions.

The process of heat transfer through the partitions is described in the literature, and the novelty in this respect is the use of boundary conditions appropriate for the nature of the partition, i.e., variable outside air temperature and solar radiation intensity. These conditions are taken into account in the literature—also in standards—, but in a simplified way through indicators covering longer periods (usually monthly). This variability is not considered when constructing an ordered diagram of heat loads, which affects the determination of the heating season time.

The thermal power of heating devices is assumed on the basis of calculations made for the steady state with extreme parameters, without taking into account the thermal inertia. In the presented study, the influence of the thermal inertia of the external building partition on the heat exchange between the building's interior and its surroundings was analyzed. Different thicknesses of the insulation of the outer partition were considered. The ongoing dynamic processes were analyzed computationally using the finite difference method (FDM).

Based on the obtained calculation and measurement results, the following conclusions can be drawn:


The development of issues related to the dynamics of heat transfer, taking into account the variability of weather conditions and thermal inertia in buildings, will be the subject of future research conducted by the authors of this article.

**Author Contributions:** Conceptualization, W.S. and B.B., methodology, W.S. and B.B; writing—original draft preparation, B.B. and W.S.; writing—review and editing, B.B. and W.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
