## 2 Research Methodology
### Description of the Case Study  
The case study in this study demonstrated the aforementioned process-based quantification method for the carbon dioxide emissions, and a comparative study amongst the three different types of slab systems in a building. Table 3 summarises the profile of the studied building. The floor area of the typical storey is 963 m\({}^{2}\), and the total floor area is 13,487 m\({}^{2}\).  
The evaluated case of this study is a commercial building located in Yeosu-si, South Korea, whose construction period was from 2017 to 2019. The building is a rigid-frame structure that has 10 storeys above ground, and four storeys underground for parking. The model was designed in compliance with Structural Concrete Design Code and Commentary by the Korea Concrete Institute [49] and ACI 318-05 [50]. Table 4 summarises the factors of seismic and wind loads that were applied to this building project:  
The slabs of the studied building were designed according to three different slab systems, which were the ordinary reinforced concrete slab (i.e., slab-column fames), flat plate slab, and voided slab systems. The slab thickness of 300 mm was selected for the three slab systems in this study. The slab reinforcement consisted of 12.70, 15.90, and 19.10 mm diameter deformed bars with a yield stress of 400 MPa. The 12.70 and 15.90 mm diameter reinforcing bars were placed for upper reinforcement, while the 15.90 and 19.10 mm diameter rebars were placed for lower reinforcement of the slabs. Various types of slab systems would be applied for different types of building, such as residential, office, and apartment. The selection of an adequate and economic slab system might depend upon the type of building, architectural layout, and the span length between columns. During the value analysis process in this project, both the flat plate slab and voided slab systems were suggested as alternative  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Seismic Load**} & \multicolumn{3}{c}{**Wind Load**} \\ \cline{2-7}
**Type** & **Site** & **Importance** & **Ground** & **Response** & **Terrain** & **Design Wind** & **Gust Influence** \\  & **Coefficient** & **Factor** & **Coefficient** & **Category** & **Speed (m/s)** & **Factor** \\ \hline Office & & & & & & & \\ building & A & 1.5 & Sc & 5.0 & B & 30 & 2.2 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Load factors of the building.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Number of Storesy** & **Type of** & **Concrete** & **Rebars Tensile** & **Coherent** & **Load** & **Servicing** \\
**Ground/Basement** & **Structure** & **Type of Footings** & **Strength (MPa)** & **Strength (MPa)** & **Strength (MPa)** & **Strength (MPa)** & **Strength (m/m\({}^{2}\))** & **Strength (m/m\({}^{2}\))** \\ \hline
10/4 & Rigid frame & \begin{tabular}{c} Bearing capacity of \\ soil (Mat footing) \\ \end{tabular} & \
\begin{tabular}{c} \(f_{x}=24\) \\ (All storeys) \\ \end{tabular} &
\begin{tabular}{c} \(f_{y}=400\) \\ \(f_{y}=500\) \\ \end{tabular} & 7.52 & 3.00 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Profile of the studied building.  
methods for the ordinary reinforced concrete slab. When the value analysis was carried out in this project, the cost-effectiveness and the serviceability for future occupants were the most significant factors. The voided slab system is a newly developed voided slab system that combines lightweight void formers and bottom steel decking for anchoring void formers inside the slab. For the voided slab system, anchoring the void formers firmly in the slab is one of the significant compositional elements. Various methods have been suggested to overcome such difficulties during the construction of the voided slab. In this study, the voided slab system proposed a new method to fix the void formers, as shown in Figure 3: