## 5 Conclusions  
* This study examined the relationship between the input and output of LCC calculations for a pre-selected renovation case of a residential building in Denmark.
* The study sheds light on the currently available data and sources for the inputs required for LCC calculations, focused on renovation expenditures.
* The applied approach consists of one-at-a-time (OAT) and Monte Carlo (MC) methods for the variation of the inputs. A simple first-order sensitivity index was calculated for all the model inputs variated with the OAT method to compare the sensitivity of the parameters and select the most influential ones for further variation with the MC method. The investigation of the interactive effects of the variated parameters on the output was quantified using linear regression and the analysis of the standardized regression coefficients for the selected parameters.
* Performing OAT variation on the boundary conditions and building-related inputs enabled the comparison of the individual effects of the three boundary conditions: the discount rate (DR) type, price development (PD), and calculation period. Based on the results, it can be concluded that the DR type and PD for electricity and district heat have approximately the same effect. At the same time, the variation in the calculation period showed greater sensitivity indexes for the studied scenarios. However, these results should be taken with caution, as they represent the individual effect of each input on the output and not the interactive effects of all inputs.
* The OAT method's results implied a linear relationship between the input and outputs, which was verified by the high R2 values resulting from a regression analysis of the MC  
Figure 10: Comparison of the number of simulations.  
results for all studied models. Furthermore, the applied regression method (Sensitivity-Ranked Regression Coefficients) ranked each of the five variated parameters with respect to the output's sensitivity to each one.
* The financial parameters and calculation period in Denmark can be considered deterministic, as their values are determined by legislation.
* Given that specific values are determined concerning the investigated building type, the variation applied in this paper is aimed at quantifying the expected variance when a different set of boundary condition assumptions is used in the selected baseline. The applied OAT approach to building-related model inputs showed that energy demand-related inputs are the most influential.
* The global sensitivity analysis shows that the calculation models with District Heating (DH) and gas reveal that the most influential inputs are about twice as sensitive as the next most influential ones. In those cases, the relative importance of the parameters of DH and gas is nearly equal, with a slight variation between the ranking in the two cases. On the contrary, for a scenario with a Heat Pump (HP), the lifetime of the HP is determined as the most sensitive. Moreover, the relative difference in the regression coefficient values (importance) for the different parameters in the HP case is much smaller than the DH and gas cases.
* This study adds to the understanding of the relationship between the inputs and output for LCC calculations, considering a cost-effective renovation package combined with three energy supply systems for heating and DHW production.  
Conceptualization, Y.I.A.; methodology, Y.I.A. and M.Z.P.; software, K.T.J.; validation, Y.I.A. and M.Z.P.; formal analysis, Y.I.A.; investigation, Y.I.A.; resources, P.H. and M.Z.P.; data curation, Y.I.A.; writing--original draft preparation, Y.I.A.; writing--review and editing, Y.I.A.; visualization, Y.I.A.; supervision, M.Z.P. and P.H.; project administration, M.Z.P. and P.H.; funding acquisition, P.H. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The authors declare no conflict of interest.