## 3 Studies of PCMs Incorporated in Passive Systems
### Experimental Studies
#### 3.1.1 At the Composite Scale
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{1}{c}{**Composites**} & \multicolumn{2}{c}{**Temperature of Fusion**} & \multicolumn{1}{c}{**Heat of Fusion**} & \multicolumn{1}{c}{**References**} \\  & & (\({}^{\circ}\)C) & **(J g\({}^{-1}\))** & **References** \\ \hline \multirow{3}{*}{Support materials} & PCM & & & \\  & (wt\%) & & & \\ \hline \multirow{4}{*}{Diatomite} & Paraffin & \multirow{2}{*}{41.11} & \multirow{2}{*}{70.51} & \multirow{2}{*}{[71]} \\  & (47.4) & & & \\ \cline{2-4}  & PEG & & & \\  & (50) & & & \\ \cline{2-4}  & Capric-lauric acid & \multirow{2}{*}{23.61} & \multirow{2}{*}{87.33} & \multirow{2}{*}{[73]} \\  & (CA-LA) & & & \\ \hline \multirow{4}{*}{Kaolin} & Lauric alcohol & \multirow{2}{*}{19.14} & \multirow{2}{*}{48.08} & \multirow{2}{*}{[74]} \\  & (24) & & & \\ \cline{2-4}  & Capric acid & \multirow{2}{*}{30.71} & \multirow{2}{*}{27.23} & \multirow{2}{*}{[75]} \\  & (17.5) & & & \\ \cline{2-4}  & PEG600 & \multirow{2}{*}{5.16} & \multirow{2}{*}{32.80} & \multirow{2}{*}{[75]} \\  & (21) & & & \\ \cline{2-4}  & Heptadecane & \multirow{2}{*}{22.08} & \multirow{2}{*}{34.63} & \multirow{2}{*}{[75]} \\  & (16.5) & & & \\ \cline{2-4}  & Stearic acid & \multirow{2}{*}{60.1} & \multirow{2}{*}{149.5} & \multirow{2}{*}{[76]} \\  & (75) & & & \\ \hline \multirow{4}{*}{Expanded Vermiculite} & n-octadec & \multirow{2}{*}{26.1} & \multirow{2}{*}{142} & \multirow{2}{*}{[77]} \\  & (80) & & & \\ \cline{2-4}  & Lauric acid & \multirow{2}{*}{41.88} & \multirow{2}{*}{126.8} & \multirow{2}{*}{[78]} \\  & (70) & & & \\ \cline{2-4}  & CA-PA-SA & \multirow{2}{*}{19.3} & \multirow{2}{*}{117.6} & \multirow{2}{*}{[79]} \\  & (70) & & & \\ \cline{2-4}  & CA-LA (40) & & & \\ \cline{2-4}  & CA-PA (40) & & & \\ \cline{2-4}  & CA-SA (40) & & & \\ \hline \multirow{4}{*}{Expanded Graphite} & Heptadecane & \multirow{2}{*}{13.8} & \multirow{2}{*}{195.9} & \multirow{2}{*}{[80]} \\  & LA-MA-SA & \multirow{2}{*}{29.05} & \multirow{2}{*}{137.1} & \multirow{2}{*}{[81]} \\  & (92.3) & & & \\ \cline{2-4}  & PEG & \multirow{2}{*}{18.89} & \multirow{2}{*}{98.59} & \multirow{2}{*}{[82]} \\  & (90) & & & \\ \cline{2-4}  & SA & \multirow{2}{*}{52.74} & \multirow{2}{*}{169.9} & \multirow{2}{*}{[83]} \\  & (90) & & & \\ \hline \multirow{4}{*}{Biochar} & Heptadecane & \multirow{2}{*}{13.9} & \multirow{2}{*}{53,3} & \multirow{2}{*}{[80]} \\  & (25.7) & & & \\ \cline{2-4}  & Paraffin & \multirow{2}{*}{57.67} & \multirow{2}{*}{179.4} & \multirow{2}{*}{[84]} \\  & (60) & & & \\ \cline{2-4}  & LA-SA & \multirow{2}{*}{35.1} & \multirow{2}{*}{148.3} & \multirow{2}{*}{[68]} \\  & (77.9) & & & \\ \cline{2-4} \cline{2-4}  & Methyl palmitate (43-55) & & & \\ \cline{2-4}  & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Various experimental studies using naturally occurring support materials for the fabrication of shape-stabilized PCMs. In addition to their biological origin, these materials have a very good porous structure, which justifies the very high value of the impregnation rate approaching 100%. Shape stabilization is therefore considered as a promising way to take advantage of the latent storage capacity of PCMs. The list of bio-sourced materials that can be used to shape-stabilize PCMs is very large, so we focus on insulating materials that are already in use or are promising for application in buildings (Table 5). These are vegetable fibers, such as flax or hemp. Another advantage of these materials is their ability to regulate humidity, which ensures good indoor air quality. Finally, the cost of these bio-sourced insulators is very attractive. Fatty acids and their eutectic mixtures have melting temperatures suitable for thermal comfort application (15 to 30 \({}^{\circ}\)C, T) and are commonly used. In addition, they are renewable and have similar or better characteristics than paraffin waves used in actual systems. Fatty acids of interest for the targeted application are reported in Table 6.