## 5 Attained Results and Discussion
### Thermal Behaviour Improvement: PCM Position Optimisation in the Construction Solution (Step 3)  
At this step, the goal is the cumulative improvement of the results attained in Step 2. Thus, the strategy was the optimisation of the PCM position into construction solutions.  
[PERSON] [54] proposes a distribution of the PCM into the constructive solutions to take advantage of the full capacity of the charge-discharge cycles of PCM during a daily amplitude temperature (Figure 6).  
\begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**\#id**} & \multirow{2}{*}{**Ventilation Rate 1 (\(\text{h}^{-1}\))**} & \multirow{2}{*}{**BioPCM Type**} & \multicolumn{2}{c}{**Indoor 2 (\({}^{\circ}\)C)**} & \multicolumn{2}{c}{**Outdoor 3 (\({}^{\circ}\)C)**} \\ \cline{3-5}  & & & **Controller for Window Opening** \\ \hline
7069 & 0.91 & BioPCM® M91/Q23\_0.037 & 25 & 28 \\
3250 & 0.71 & BioPCM® M91/Q21\_0.037 & 27 & 27 \\
8986 & 0.92 & BioPCM® M51/Q25\_0.021 & 23 & 27 \\ \hline \hline \end{tabular}  
* Notes: 1 average of all thermal zones; 2 indoor temperature below which windows are closed; 3 outdoor temperature above which windows are closed.  
\end{table}
Table 3: Parameters results for Step 2.  
Figure 5: Pareto front using all simulated results: Steps 1 and 2.  
Thus, to develop this issue, the simulations were carried out considering the PCM layers in different positions (1 to 3) according to Figure 7.  
Figure 6: Constructive solution with enhanced PCM (adapted from [54]).  
Figure 7: Cont.  
To assess the impact and the optimised PCM position, a new set of parameters and strings were added to Table 2 (see Table 4).  
The objective functions listed in Step 2 were maintained.  
Figure 8 shows that the PCM position has a significant impact on overheating reduction of about 2%. Regarding the heating demand, similar results were attained with a small difference of about 1%.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{3}{c}{**Continuous Variables**} \\ \hline
**Parameter id.** & **Designation** & **Box Constraints** \\ \hline a11–a14 [FOOTNOTE:]Footnote : [[https://github.com/gypsum/research/](https://github.com/gypsum/research/)]([https://github.com/gypsum/research/](https://github.com/gypsum/research/))  
\end{tabular}
\end{table}
Table 4: New set of parameters and strings.  
Figure 7: Constructive solutions details including PCM and positioning into the construction solutions: (**a**) cross-sections identification; (**b**,**e**) position 1: inner surface layer; (**c**,**f**) position 2: behind the double gypsum plasterboard; (**d**,**g**) position 3: behind the acoustic layer.  
Solely targeting the reduction in the overheating rate, the best solution was attained with BioPCM(r) M27/Q27_0.011 in position 2 for the walls and BioPCM(r) M27/Q27_0.011 in position 1 (see Figure 6) for the roof. Thus, the PCM positioning into the construction solution, walls and ceiling is not a straightforward decision. Regarding the scenario with the PCM layer positioned after the acoustic insulation layer (id2), the zone considered to have low heat transfer (Figure 5) was never chosen by the optimiser. Therefore, a detailed analysis was performed changing the PCM only in position 1 and 2, and it was possible to conclude that small differences were attained for the overheating rate reduction (less than 1%). Thus, the use of the PCM layer as the most inner layer is recommended. Additionally, the increase in the wall surface heat coefficient, due to the increase in the air velocity, promotes the PCM charge and discharge process.