# A Sustainable Polygeneration System for a Residential Building
## 3 Results  
### End Design for Each Option  
Given the complexity of supplying five demands at 100%, the optimal configuration for each site (1-3) and technology selection (A-D) imply a different final design. Most of them correspond to the _Var._ values included in Table 5, which also contains the technical data of each technology. The following table summarizes the final design required for each case, the objective being to cover all demands at around 100%. However, in the case of electricity, this is done through an approximated annual net balance with the grid. For cooling, the buffer tank also prevents covering precisely 100% of the demand (see Table 8). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Item** & **Reference** & **Capacity** & **Unit** & **km Truck** & **km Ship** \\ \hline PV & [45] & 320 & W\({}_{\text{P}}\) & 300 & 16,500 \\ PVT & [45] & 320 & W\({}_{\text{P}}\) & 20 & – \\ Aerotherm & [50] & 24 & kW\({}_{\text{th}}\) & 150 & – \\ Inverter & [45] & 2.5 & kW\({}_{\text{e}}\) & 1892 & – \\ Water tanks & [50] & 2000 & L & 100 & – \\ Water pumps & [48] & 40 & W & 20 & – \\ Heat Pump & [48] & 10 & kW\({}_{\text{cl}}\) & 1500 & – \\ SEAC & [50] & 19 & kW\({}_{\text{cl}}\) & 2500 & 200 \\ MED & [51] & 2.8 & m\({}^{3}\)/d & 50 & – \\ RO & [40] & 35 & L/h & 500 & 1000 \\ Piping & [45] & 5 & kW\({}_{\text{P}}\) & 300 & – \\ Wiring & [50] & 3 & kW\({}_{\text{P}}\) & 1500 & – \\ Expansion vessel & [48] & 80 & L & 150 & – \\ Foundations (solar field) & [48] & 260 & W\({}_{\text{P}}\) & 80 & – \\ Biomass boiler & [48] & 50 & kW\({}_{\text{th}}\) & 50 & – \\ \hline Natural gas boiler & [47] & 300 & kW\({}_{\text{th}}\) & 900 & – \\ LV Electricity, Spanish grid & [48] & 1 & kW\({}_{\text{e}}\) & – & – \\ Heat demand (to a DH) & [47] & 1 & MJ & – & – \\ De-ionized water by RO & [48] & 1 & L & – & – \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Reference items to perform the LCI of the four options and the conventional supply. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Item** & **Location** & **A** & **B** & **C** & **D** \\ \hline \multirow{3}{*}{Number of PV panels} & 1 & 210 & 320 & 270 & 210 \\  & 2 & 210 & 320 & 270 & 210 \\  & 3 & 300 & 430 & 370 & 325 \\ \hline \multirow{3}{*}{Number of PVT panels} & 1 & 180 & 60 & 140 & 160 \\  & 2 & 190 & 70 & 140 & 160 \\  & 3 & 300 & 90 & 200 & 200 \\ \hline \multirow{3}{*}{TEG capacity (kW\({}_{\text{P}}\))} & 1 & 1,20 & 0.40 & 1.06 & 1.13 \\  & 2 & 1.23 & 0.44 & 1.07 & 1.13 \\ \cline{1-1}  & 3 & 2.00 & 0.92 & 1.67 & 1.67 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: The final design for each proposed configuration (A-D) and site (1–3). The comparative analysis by configuration and location of the results presented in the table above is summarised below. * The solar field required for Zaragoza (3) is higher than Almeria and Valencia (see annex A for details) to cover its higher electricity and DHW demand. Moreover, its heating demand is also higher due to its continental climate. * A much larger solar field with PVT, a boiler, and hot water tanks is necessary when the desalination technology is the MED, and to a lesser extent, when the cold production comes through the SEAC. That is, options D and A require a higher dimension of the thermal supply side than the others. * In that case, the share of PV and PVT is reduced for the first technology to complete the electricity demand. * The PVT required in configuration A (HP and MED) is higher than the theoretical maximum one (configuration D) for each location. This is mainly due to the lower setpoint temperature of the BB, which was adjusted only to activate the MED. * Rapidly following thermal demand sometimes forces a biomass boiler to upsize. However, the BB is a modulable device, and the equivalent number of operating hours may differ significantly for the same capacity. Especially in the spring and autumn periods where cooling is unnecessary, it is really underutilised. * The heat demand required by the SEAC matches better with the solar resource in summer.