## 4 Discussion  
The results presented in the previous subsections demonstrated that heat flux measurements in buildings need to reflect specific requirements given by the experimental conditions. Besides the changing environment, which might be typical for \"free-running\" buildings, the selection of appropriate heat flux probes is crucial for obtaining accurate data. However, the results reported in this paper showed that even such issues can be effectively addressed if a proper approach is chosen.  
The analysis of the experimental data underlined the necessity of sensor re-calibration as the heat flow rate between the indoor environment and building walls may dramatically change during the measurement as a consequence of changing environmental conditions. The adaptive sensitivity adjustment proved that the heat transfer coefficient \(\alpha\) was changed during the measurement which could be attributed to different conditions during model initialization [38; 39]. Therefore, careful monitoring of environmental conditions as well as field variables should be done to provide sufficient data for a decision on whether re-initializations and/or re-adjustments are required and what is the recommended time span for performing the individual procedural steps.  
A periodic calibration is often required in the building sector to ensure reliable quality of measured quantities. The conventional approach of calibration, on the other hand, may be exceptionally difficult to perform as the sensors might be difficult to reach or can't be removed from the construction due to ongoing measurement. There have been limited studies published in the literature focusing on addressing those issues [40; 41; 42]. The novel approaches are mostly called virtual experiments, online calibrations, self-calibrations, or various combinations using these or similar other terms. However, most of the research published in the literature tends to prefer the traditional ways of sensor calibrations, which depend primarily on the type of used sensors [43; 44; 45]. The importance of heat flux monitoring and analysis in the field of building and civil engineering can be documented by reference to numerous works that have been published recently [46; 47; 48; 49; 50; 51; 52; 53; 54; 55]. Also, the variety of those applications proves the importance of heat flux analysis that spans across multiple disciplines. Heat flux measurement is a key part of practically any thermal performance analysis [46; 52; 53; 55], experimental validation of thermal properties of novel materials or building components [47; 49; 54], monitoring of thermal performances of buildings or their parts [48; 50; 51], etc. Therefore, the quality and accuracy of heat flux measurement should be always maintained at a high level, especially when long-term monitoring and observations are required [49; 50; 51]. In the field of heat flux monitoring, the producers brought new types of sensors with self-calibration capability, which clearly documents the awareness of the necessity for sensor recalibration during experimental measurement. The proposed method may contribute to the state-of-the art in this respect with the utilization of standard probes without advanced features, thus, providing high-tech solutions at standard costs. Also, the proposed approach can be applied \"ex-post\" to existing experimental data if some discrepancy is detected and appropriate environmental data are available along with heat flux variations. The accuracy of the proposed technique depends mostly on the selected re-adjustment period. Shorter periods bring higher accuracy to the heat flux measurement as the approach may efficiently reflect and address the changing environmental conditions. Basically, the readjustment can be triggered by user-defined values describing the change of environmental conditions or scheduled in regular periods. Consequently, a novel time-saving solution for maintenance-free application may be proposed as an alternative to traditional laboratory techniques.