## 3 Results and Discussion  
### Thermal Behaviour of Dynamic PCM System  
Figure 4 shows the solar radiation and outdoor temperature evolution, and how the variation of the position of PCM layer (0 or 1) affects to the PCM temperature when implemented in ASHRAE envelope (Wall 2). As it can be seen, once the position of the system is set to 1 and PCM is located facing outdoors with respect to the insulation layer, its temperature starts to increase as solar radiation is stored through the melting process of PCM. After the sunny hours, the PCM is set back to its original position (facing indoors with respect to insulation, POS = 0) and discharges the stored heat to the indoor environment. In this period, the PCM layer remains inside the phase change range (21 to 25 \({}^{\circ}\)C) being warmer than indoor set point temperature (20 \({}^{\circ}\)C), that allows the system not only to be used as a thermal barrier to outdoor conditions, but to provide space heating due to stored solar energy. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Construct** & **Layer** & **Thickness (m)** & \begin{tabular}{c} **Thermal Conductivity** \\ **(W/m\(\cdot\)K)** \\ \end{tabular} & \begin{tabular}{c} **Heat Capacity** \\ **(J/kg\(\cdot\)K)** \\ \end{tabular} & \begin{tabular}{c} **Density** \\ **(kg/m\({}^{3}\))** \\ \end{tabular} \\ \hline Wall 1 & \begin{tabular}{c} Hollow Brick \\ PCM \\ \end{tabular} & 0.07 & 0.375 & 1000 & 930 \\  & \begin{tabular}{c} PCM \\ \end{tabular} & 0.007 & 0.2 & f(T) & 800 \\  & \begin{tabular}{c} Insulation \\ Plastic sheet \\ \end{tabular} & 0.05 & 0.05 & 1000 & 35 \\  & \begin{tabular}{c} Plastic sheet \\ \end{tabular} & 0.007 & 0.3 & 1250 & 900 \\  & \begin{tabular}{c} Perforated \\ brick \\ \end{tabular} & 0.14 & 0.543 & 1000 & 900 \\ \hline Wall 2 & \begin{tabular}{c} Wood siding \\ PCM \\ \end{tabular} & 0.01 & 0.14 & 900 & 530 \\  & \begin{tabular}{c} PCM \\ \end{tabular} & 0.007 & 0.2 & f(T) & 800 \\  & \begin{tabular}{c} Insulation \\ Plastic sheet \\ \end{tabular} & 0.0615 & 0.04 & 1400 & 40 \\  & \begin{tabular}{c} Plastic sheet \\ Concrete \\ block \\ \end{tabular} & 0.07 & 0.3 & 1250 & 900 \\ \hline Wall 3 & \
\begin{tabular}{c} PCM \\ \end{tabular} & 0.007 & 0.2 & f(T) & 800 \\  &
\begin{tabular}{c} Insulation \\ Plastic sheet \\ \end{tabular} & 0.072 & 0.05 & 1000 & 35 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Thermo-physical properties and constructive systems description (listed from outside to inside). Moreover, as it was previously discussed in the introduction, the current state of the art of passive PCM systems for heating purposes is limited as PCM cannot be melted unless it is directly exposed to solar energy coming from openings or windows. This issue can be clearly seen in Figure 5, which shows the thermal evolution of the polymeric layer (with or without PCM) in case it is implemented in a static or dynamic system. No significant differences were observed between the static system with or without PCM with temperatures below set point (20 \({}^{\circ}\)C) almost all the time. On the other hand, the dynamic system is able to charge the PCM partially six days (phase change range between 21 and 25 \({}^{\circ}\)C) out of ten, and to fully charge it three days. It is important to highlight, that the control of the system was optimized based on the average results of the ten analyzed days, meaning the optimal decision of positioning PCM facing outdoors and indoors is the same for all the analyzed days, therefore, a daily-based control would even increase the performance. These activations of the PCM result in a dramatic reduction of the heating load coming from the outer environment. Figure 6 presents the evolution of the heating load for static and dynamic systems, showing that the use of PCM does not reduce heating load unless it is implemented in the dynamic technology. When the PCM layer is able to move with respect to the insulation, it provides space heating to indoor environment (negative heating loads), specially during afternoons and night periods.