## 5 Conclusions  
In this work, the influence of surface thermal resistance (\(R_{\rm{s}}\)) on the conductive thermal resistance (\(R_{\rm{cond}}\)) of LSF walls was evaluated. To this end, four finite elements' numerical simulation tools were used to model the four assessed LSF walls, showing different levels of thermal conductivity inhomogeneity: (1) partition, cold frame LSF wall; (2) facade, hybrid LSF wall; (3) simplified homogeneous partition LSF wall, and (4) simplified homogeneous facade LSF wall. Moreover, six external thermal surface resistances (\(R_{\rm{se}}\)) were modeled, ranging from 0.00 up to 0.20 m\({}^{2}\)-K/W. The average temperature of the partition LSF walls is 15 \({}^{\circ}\)C, while for the facade LSF walls it is 10 \({}^{\circ}\)C.  
Notice that the accuracy of the implemented numerical models used in this study was verified, taking as a reference the ISO 10211 test cases and the ISO 6946 analytical calculation rules for homogeneous layered simplified walls, as well as by comparing the results provided by the four evaluated computational tools. Moreover, the precision of the employed models was also validated by comparison to measurements under controlled lab conditions.  
The main conclusions of this research work can be listed as follows:  
* The accuracy of all evaluated computational tools was very high and similar;  
Figure 11: Average computed conductive thermal resistances, with temperature showing colour distribution predicted by THERM models for the two extreme surface thermal resistances (\(R_{\rm{se}}\)) and for different wall configurations: (**a**) partition LSF wall; (**b**) facade LSF wall; (**c**) simplified facade wall with homogenous layers (without steel studs).  
* The \(R_{\text{cond}}\) value is nearly uniform for walls with homogeneous layers, as expected;
* The variation of the \(R_{\text{cond}}\) values depends on the level of inhomogeneity in the LSF wall layers;
* For the assessed \(R_{\text{se}}\) values, the conductive thermal resistances increased up to 8.1%, i.e., +0.123 m\({}^{2}\cdot\)K/W, for the partition cold frame LSF wall;
* However, the variation in \(R_{\text{cond}}\) values was almost negligible (only up to +0.2%) for the facade hybrid LSF wall with a continuous thermal insulation layer (50 mm thick);
* When removing the steel frames, the \(R_{\text{cond}}\) values of this simplified facade wall do not change, regardless of the \(R_{\text{se}}\) values;
* However, when compared to the original LSF facade wall, the conductive thermal resistance values increased significantly (+34%);
* Numerical modelling and laboratory measurements are complementary methods, and the combination of them boosts the accuracy and the practical relevance of thermal performance analyses.  
Conceptualization, P.S. and L.M.; methodology, P.S. and L.M.; software, P.S., D.A., P.L. and L.M.; validation, P.S., D.A., P.L. and L.M.; formal analysis, P.S. and L.M.; investigation, P.S.; resources, P.S.; writing--original draft preparation, P.S. and L.M.; writing--review and editing, P.S. and L.M.; visualization, P.S.; supervision, P.S.; project administration, P.S. and L.M.; funding acquisition, P.S. and L.M. All authors have read and agreed to the published version of the manuscript.  
This work was funded using FEDER funds from the Competitivity Factors Operational Programme--COMPETE and national funds form FCT--Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-032061. This work was also supported by a grant of the Ministry of Research, Innovation and Digitization, CCCDI--UEFISCDI, project number PN-III-P2-2.1-PED-2021-4137, within PNCDI III--CT 714 PED/2022.  
Not applicable.  
The data presented in this study are available in article.  
The authors declare no conflicts of interest.