## 6 Conclusions  
This paper proposes the upgrading of a conventional Lightweight Steel Frame (LSF) structure, and presents a comprehensive assessment of the case study LSF building--the high-performance \"MUZA\" module, with a useful floor area of less than 50 m\({}^{2}\). Extensive analyses of the MUZA's performance were conducted, focusing on the effects of thermal bridging on energy performance and moisture condensation. Additional climate- and orientation-dependent analyses were performed in order to investigate how the module performed under different conditions. From the presented results, it can be concluded that the suitable evaluation of thermal performances of LSF walls requires more complex and detailed analysis than those required for reinforced concrete or masonry structures. This means using numerical methods for calculating heat losses, including all steel studs and other construction details. It was shown in this research that the heterogeneity of structural and insulation materials, as well  
Figure 14: MUZA energy needs in respect to the main facade orientation. as the high frequency of steel studs, lead to an underestimation of thermal transmittance if performing a \(U\)-value calculation for the case of one-dimensional heat flux. It was also shown that applying thermal insulation on the outside of the steel frame (warm construction type), makes the most of its performance, leading to the reduction in the influence of steel elements on effective \(U\)-value to the minimum. The superposition of thermal bridges along the entire building envelope certainly will create a considerable impact on the building's energy performance. In cases where an EU Member State's building code requires a default \(U\)-factor increase in buildings, for which calculations do not explicitly address thermal bridges, this value is usually found to be worse than if the thermal bridges had been explicitly calculated. That is, detailed calculation tends to predict a lower overall transmission heat loss for a building than does the addition of a default increment. This means that, because insulation improvements in the clear wall show diminishing returns, mitigating thermal bridges becomes the wiser investment. It was also shown in this research that the influence of the approach taken for including thermal bridges in the building's energy balance calculation also depends on the location of the building, where greater impact was shown on the heating energy need in the warmer climates. Furthermore, it was shown in this research that by using LSF, it is possible to meet the Croatian requirements for NZEB buildings even for a building with a very small useful floor area, as observed in the presented case study. This means that for larger buildings constructed using two or more modules, as shown in this paper, it would be somewhat easier to achieve NZEB requirements. It was shown in this paper that by using an air-to-water heat pump and a small PV system mounted on the roof of the building, one can achieve net-positive building. A picture of the energy consumption of the module in different climates of Croatia and different orientations was gained by studying the MUZA, based on which one can draw design conclusions about using the LSF system for different building uses (from temporary buildings to permanent buildings). In conclusion, the analysis presented in this paper broadens the knowledge about the possibilities and limitations of designing a LSF module by NZEB standards. The results indicate that the MUZA module is a promising solution for temporary (such as post-disaster housing) and permanent modular construction. However, this requires proof-of-concept. Hence, the future work will be focused on the constructed mobile pavilion MUZA and real-time monitoring of energy consumption, energy production, and different indoor air parameters (temperature, relative humidity, CO\({}_{2}\), and relative air quality), as well as hygrothermal performance of external walls.