## 3 Discussion and Results
### GWP Indicator (CO\({}_{2}\) Operational + CO\({}_{2}\) Embedded)
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Materials**} & \multirow{2}{*}{\
\begin{tabular}{c} **kg CO\({}_{2}\) eq.** \\ **(A4)** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **63.8\% Recycled** \\ **\% Recycled** \\ \end{tabular} } & \multicolumn{2}{c}{**24.1\% Recycled**} & \multicolumn{2}{c}{**0\% Recycled**} \\  & & & **kg CO\({}_{2}\) eq.** & \multicolumn{1}{c}{**\% Recycled**} & \multicolumn{1}{c}{**kg CO\({}_{2}\) eq.**} \\  & & & **(A1–A3)** & \multicolumn{1}{c}{**(A1–A3)**} & \multicolumn{1}{c}{**(A1–A3)**} \\ \hline Stones and Soils & 1900.21 & 100 & 0 & 0 & 20,140.14 & 20,140.14 \\ Steels & 4385.1 & 80 & 449,690.03 & 20 & 1,798,760.12 & 2,248,450.15 \\ Aluminum & 15,128.60 & 80 & 1,716,983.05 & 20 & 6,867,932.19 & 8,584,915.24 \\ Bronze and Zinc & 365.43 & 0 & 13,451.76 & 0 & 13,451.76 & 13,451.76 \\ Ceramics and & 501.81 & 30 & 51,828.3 & 30 & 51,828.3 & 58,362.62 \\ Stoneware & & & & & & \\ Wood & 1461.7 & 0.2 & 68,288.39 & 0 & 68,393.73 & 68,393.73 \\ Plasterboard & 5393.67 & 100 & 0 & 0 & 226,209.32 & 226,209.32 \\ Concrete & 33,114.81 & 15 & 4,527,117.24 & 15 & 4,527,117.24 & 5,581,992.36 \\ Expanded clay & 88.23 & 100 & 0 & 50 & 2086.13 & 4172.26 \\ Sand and gravel & 13,309.69 & 100 & 0 & 30 & 18,334.3 & 26,191.85 \\ Mineral Wool & 418.05 & 29 & 770.92 & 29 & 770.92 & 1085.81 \\ Extruded & 287.22 & 29 & 1623.42 & 29 & 1623.42 & 2286.51 \\ Polystyrene & & & & & & \\ Glass & 438.51 & 0 & 105,498.54 & 0 & 105,498.54 & 105,498.54 \\ PVC & 73.09 & 0 & 179,620.2 & 50 & 89,810.10 & 179,620.2 \\ PV Panels & 51.16 & 0 & 133,008 & 0 & 133,008 & 133,008 \\ \hline
**TOTAL** & **76,917.28** & **63.8** & **7,247,879.85** & **24.1** & **13,924,964.18** & **17,253,778.49** \\
**GWP (kg CO\({}_{2}\)** & & & & & \\
**eq./m2)** & **13.88** & & **1308.35** & & **2513.66** & **3114.56** \\ \hline \hline \end{tabular}
\end{table} 
Table 3: CO\({}_{2}\) Emissions during construction (A1–A3) and transportation (A4) for each recycling scenario. Therefore, for the current recycling scenario (63.8%), the CO\({}_{2}\) impact in the construction phase (A1-A3) results to 1308.35 kg of CO\({}_{2}\) eq/m\({}^{2}\), which is the unit of measurement for GWP. The transport phase (A4) adds 13.88 kg of CO\({}_{2}\) eq/m\({}^{2}\) to this figure. Consequently, the total embodied carbon impact (A1-A3 + A4) constitutes a release to the atmosphere of 1322.23 kg of CO\({}_{2}\) eq/m\({}^{2}\). As a summary, the impact in terms of kg CO\({}_{2}\) eq/m\({}^{2}\) for each recycling scenario is shown in Table 4.  
The results show that in an nZEB building, embodied carbon emissions are much higher than operational emissions (except for the ideal case of 100% recycling). In addition, it is also observed that a higher quantity of recycled materials results in a lower environmental impact. In short, the application of circular economy principles is environmentally beneficial. The results of the above table are plotted in Figure 5 below. It is evident from analyzing the results that operational carbon emissions are significantly lower when dealing with a high-energy-efficiency building. On the other hand, the percentage of embodied carbon is notably high for a building with these characteristics. To further decrease life cycle emissions, a greater contribution of energy generation in the building and increased use of materials with low emissions are required. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**GWP** & **100\% Recycled** & **63.8\% Recycled** & **24.1\% Recycled** & **0\% Recycled** \\ \hline
**Embedded GWP** & & & & \\
**(kg CO\({}_{2}\) eq./m\({}^{2}\))** & & & & \\
**Operational GWP** & & & & \\
**(kg CO\({}_{2}\) eq./m\({}^{2}\))** & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Embedded and operational GWP for each recycling scenario at IndUVa nZEB.