## 4 Results and Discussion
### General Application of the Methodology and Obtaining the Optimal Solution Package  
The following graphs shows the result of the combinations assessed:  
Each of the points on the figure represents the possible combination of renovation measures that can be applied to renovate the building (set of renovation measures). Therefore, each point represents the status of the building after renovation. Finally, a set of renovation measures was selected for the renovation of the building, specifically the red dot at the right on the \"pareto front\" in Figure 7. This pareto front is the curve that represents the locus of points with the minimum LCC achievable with the defined set of renovation measures for each primary energy consumption value. This minimum LCC was reached with a specific combination of the renovation measures. It is important to highlight that the vertical reference lines in Figure 7 contain the points at which the primary energy consumption was the same but the LCC was different. In practice, they represent different combinations of measures where the building would have the same primary energy consumption but a different LCC. It is noteworthy that the LCC could vary by up to 67% for two situations with the same primary energy consumption, meaning that the investment costs plus the operating and maintenance costs may have been 1.67 times higher in one building than in another whose renovation measures were selected with a lower LCC, and, therefore, with a better criterion. Since the primary energy consumption was the same, the operating energy cost was approximately the same, except for the different prices for different energy sources, and this implies that the fundamental difference was in the cost of the renovation measures, in other words the initial investment costs. In short, if the set of renovation measures were not properly chosen, the investment costs to renovate a building could have been 1.67 times higher than another set of renovation measures that provided similar results. This is what the HAPPEN project aims to prevent, particularly with this case study, given that this could be one of the obstacles to the energy renovation of buildings. A high investment cost can, as shown, be the result of the incorrect choice of a set of renovation measures for a building. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Air Tightness**} & \multirow{2}{*}{**System**} & **Infiltration Rate** & \multirow{2}{*}{**Cost (\(\upxi\)/linear m)**} \\  & & **(\(  
Other point of view is that several variants in fact had the same cost, but very different primary energy consumption. Thus, the election of the variant with the lowest primary energy would mean that the building was environmentally-friendlier than the others. If the LCC of the renovated building was better than that of the original, it might be a win-win situation for both the users and the environment. Table 5 summarizes the different packages of optimal solutions for the pilot building. The code in each cell corresponds to the number given in the tables of the appendix or Section 3.2 for the description of different renovation measures collected in the list. For instance, a 7 in the facade solution corresponds to the solution with this code in Table 15 in Appendix A.