## 4 Analysis of Zero Carbon Performance in Production Stage  
### A1-A3 ZCBI Calculation Method  
This study introduces the Zero Carbon Building Index in the production stage (A1-A3 ZCBI) to quantitatively represent carbon neutrality performance during the production phase. This index provides a comparable evaluation framework that enables the performance of various buildings to be assessed consistently and managed in an integrated manner. The A1-A3 ZCBI proposed in this study represents the percentage ratio of carbon emissions (CE\({}_{\text{LCI DB}}\)), calculated using Korea's national LCI database under the existing building LCA preparation guideline, to A1-A3 CR achieved through the use of EPD-certified products to minimize embodied carbon in buildings. An optimal A1-A3 ZCBI can be achieved in the initial planning stage by either reducing the denominator through efficient design \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Year** & **Authors** & **Main Contents** & **Differences in This Study** \\ \hline
2024 & [PERSON] et al. [40] & \
\begin{tabular}{c} Developed and improved an environmental impact database \\ for construction materials \\ in China. \\ \end{tabular} &
\begin{tabular}{c} Lacked the concept of a reference \\ building and evaluation \\ methodology, making it impossible \\ to estimate carbon reduction \\ (CR) potential. \\ \end{tabular} \\ \hline
2025 & [PERSON] et al. [41] & \
\begin{tabular}{c} Proposed an evaluation model for \\ managing whole-process carbon \\ emissions (CE) in buildings. \\ \end{tabular} &
\begin{tabular}{c} Did not present a structured database \\ or a quantitative method for \\ estimating carbon reduction \\ (CR) performance. \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._ \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Construction** & **Detail** & **Unit** & \begin{tabular}{c} **Carbon** \\ **Emissions** \\ **(CE)** \\ \end{tabular} & **Construction** & **Detail** & **Unit** & \begin{tabular}{c} **Carbon** \\ **Emissions** \\ **(CE)** \\ \end{tabular} \\ \hline \multirow{4}{*}{\begin{tabular}{c} Ready-mixed \\ concrete \\ \end{tabular} } & 18 MPa & m\({}^{3}\) & \(4.09\times 10^{2}\) & \begin{tabular}{c} Expanded \\ polystyrene (EPS) \\ Extruded polystyrene \\ (XPS) \\ \end{tabular} & kg & \(1.96\times 10^{0}\) \\  & 24 MPa & m\({}^{3}\) & \(4.14\times 10^{2}\) & \begin{tabular}{c} Diss wool \\ Cement \\ \end{tabular} & ton & \(1.90\times 10^{2}\) \\  & \begin{tabular}{c} Concrete brick \\ Autocleaved \\ lightweight concrete \\ (ALC) block \\ \end{tabular} & kg & \(6.57\times 10^{-1}\) & Cement & \begin{tabular}{c} White Portland \\ Cement \\ \end{tabular} & kg & \(1.22\times 10^{0}\) \\  & \begin{tabular}{c} Sand \\ gravel \\ \end{tabular} & m\({}^{3}\) & \(3.87\times 10^{0}\) & \begin{tabular}{c} Mortar \\ Square edge-type \\ board \\ \end{tabular} & ton & \(1.38\times 10^{2}\) \\  & \begin{tabular}{c} Rebar \\ Fine protection \\ \end{tabular} & ton & \(1.38\times 10^{3}\) \\  & \begin{tabular}{c} - \\ Fine \\ \end{tabular} & ton & \(1.38\times 10^{3}\) \\  & \
\begin{tabular}{c} Mobile-glazed Glass \\ \end{tabular} & m\({}^{2}\) & \(2.24\times 10^{1}\) \\  &
\begin{tabular}{c} Granite \\ Artificial marble \\ \end{tabular} & kg & \(1.64\times 10^{1}\) & Glass & Tempered Glass & m\({}^{2}\) & \(1.0\times 10^{0}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: CE (kgCO\({}_{2}\)e) of major construction materials from Korea’s Life Cycle Inventory (LCI) database. to minimize material input or increasing the numerator by incorporating EPD-certified products with low CE. Equation (1) presents the calculation of A1-A3 ZCBI, which indexes carbon neutrality performance in the production stage. \[\text{A1-A3}\text{ZCBI}\left(\%\right)=\text{A1-A3}\text{CR}\div\text{CE}_{ \text{LCI}\text{DB}}\times 100 \tag{1}\]  
\(\text{A1-A3}\text{ZCBI}\): Zero Carbon Building Index in production stage (kgCO2e/m2). \(\text{A1-A3}\text{CR}\): Amount of Carbon Reduction in production stage (kgCO2e/m2).