## 3 Results and Discussion
### LCA Results  
The results per m\({}^{2}\) of living floor using the ReCiPe indicator are presented below. The total impact of the reference system is higher (109 impact points) than the innovative system (88 impact points) (Figure 4a). Moreover, in all damage categories (Figure 4b), the impact of the innovative system is lower than that of the reference system. When going to more detail (Figure 4c), the only category where the impact of the innovative system is higher than that of the reference is the metal depletion sub-category within the resources category; nevertheless, the other subcategory, fossil depletion, shows lower impact for the innovative system than for the reference system.  
Finally, when the life cycle stages are evaluated (Figure 4d), the impact of the innovative system in the manufacturing and disposal stages is higher than the reference one (22 impact points vs. 13 impact points). However, this is highly compensated during the operational stage, where the innovative system has 66 impact points vs. the 97 of the reference system.  
When the IPCC GWP indicator is considered (Figure 5), both for the 100-year and 20-year horizon, the reference system has higher impact than the innovative one (428 kg CO\({}_{2}\) eq. per m\({}^{2}\) vs. 312 kg CO\({}_{2}\) eq. per m\({}^{2}\) for GWP 100a; and 482 kg CO\({}_{2}\) eq. per m\({}^{2}\) vs. 343 kg CO\({}_{2}\) eq. per m\({}^{2}\) for GWP 20a).  
When the life cycle stages are considered (Figure 5b,d), the biggest difference is in the operational stage, where the reference system has higher impact due to the higher use of electricity from the grid vs. the use of renewable energy, both thermal and electrical, in the innovative system. On the other hand, in the manufacturing and disposal stage, the reference system has a lower impact than the innovative one (19 kg CO\({}_{2}\) eq. per m\({}^{2}\) vs.  
\begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Element**} & \multirow{2}{*}{**Total (kWh/Year)**} & \multicolumn{2}{c}{**ReCiPe**} & **GWP 100a** & **GWP 20a** \\ \cline{3-5}  & & **Impact/m\({}^{2}\) Floor** & **kgCO\({}_{2}\)-eq /m\({}^{2}\)** & **kgCO\({}_{2}\)-eq /m\({}^{2}\)** \\ \hline Heat pump & 6374 & 38.070 & 161.211 & 175.81 \\ \hline Domestic hot water tank with electric heater & 3654 & 21.824 & 92.417 & 100.78 \\ \hline Fan coil & 658 & 3.930 & 16.642 & 18.149 \\ \hline Circulating pumps & 392 & 2.341 & 9.914 & 10.812 \\ \hline Total & 11,078 & 66.166 & 280.184 & 305.55 \\ \hline \hline \end{tabular}
\end{table}
Table 10: LCIA of the innovative system during the operational stage for a 30-year lifespan.  
\begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Element**} & \multirow{2}{*}{**Total (kWh/Years)**} & **ReCiPe** & **GWP 100a** & **GWP 20a** \\ \cline{3-5}  & & **Impact/m\({}^{2}\) Floor** & **kgCO\({}_{2}\)-eq /m\({}^{2}\)** & **kgCO\({}_{2}\)-eq /m\({}^{2}\)** \\ \hline Heat pump & 15,769 & 94.18 & 398.83 & 434.94 \\ \hline Circulating pump DHW & 30 & 0.18 & 0.76 & 0.83 \\ \hline Circulating pump H\&C & 405 & 2.42 & 10.24 & 11.17 \\ \hline Total & 16,204 & 96.78 & 409.83 & 446.94 \\ \hline \hline \end{tabular}
\end{table}
Table 9: LCIA of the reference system during the operational stage for a 30-year lifespan.  
31 kg CO\({}_{2}\) eq. per m\({}^{2}\) for GWP 100a; and 36 kg CO\({}_{2}\) eq. per m\({}^{2}\) vs. 37 kg CO\({}_{2}\) eq. per m\({}^{2}\) for GWP 20a).  
Figure 4: LCA results using ReCiPe indicator: (**a**) total impact points; (**b**) total impact points of damage categories; (**c**) total impact categories towards ReCiPe endpoint single score; (**d**) impact points per life cycle stage.  
Figure 5: Results per m\({}^{2}\) of living floor using the indicator IPCC GWP–kgCO\({}_{2}\)-eq.: (**a**) GWP 100a per life cycle stage; (**b**) GWP 100a total; (**c**) GWP 20a per life cycle stage; (**d**) GWP 20a total.