## 3 Results and Discussion
### Analysis of the Total Environmental Impacts
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline
**Environmental Impact Indicators** & \multicolumn{3}{c}{**Manufacturing Building Materials**} & \multicolumn{3}{c}{**Transportation of Building Materials**} & \multicolumn{3}{c}{**Construction Machinery**} & \multicolumn{3}{c}{**Total**} \\ \cline{2-13}
**(Uni)** & **OSS** & **FPS** & **VDS** & **OSS** & **FPS** & **VDS** & **OSS** & **FPS** & **VDS** & **OSS** & **FPS** & **VDS** \\ \hline GWP (kg CO\({}_{2}\) & \(1.72\times\) & \(1.69\times\) & \(1.38\times\) & \(5.78\times\) & \(5.55\times\) & \(4.63\times\) & \(1.99\times\) & \(1.94\times\) & \(1.43\times\) & \(2.50\times\) & \(2.44\times\) & \(1.99\times\) \\ eq/m\({}^{2}\) & \(10^{2}\) & \(10^{2}\) & \(10^{2}\) & \(10^{2}\) & \(10^{1}\) & \(10^{1}\) & \(10^{1}\) & \(10^{1}\) & \(10^{1}\) & \(10^{1}\) & \(10^{1}\) & \(10^{2}\) & \(10^{2}\) \\ AP (kg SO\({}_{2}\) & \(4.83\times\) & \(4.75\times\) & \(4.15\times\) & \(1.19\times\) & \(1.14\times\) & \(9.51\times\) & \(4.09\times\) & \(3.98\times\) & \(2.94\times\) & \(6.43\times\) & \(6.29\times\) & \(5.39\times\) \\ eq/m\({}^{2}\) & \(10^{-1}\) & \(10^{-1}\) & \(10^{-1}\) & \(10^{-1}\) & \(10^{-1}\) & \(10^{-1}\) & \(10^{-1}\) & \(10^{-2}\) & \(10^{-2}\) & \(10^{-2}\) & \(10^{-1}\) & \(10^{-1}\) & \(10^{-1}\) & \(10^{-1}\) \\ EP (kg PO\({}_{4}\)-3.79\(\times\) & \(3.74\times\) & \(2.84\times\) & \(8.78\times\) & \(9.11\times\) & \(6.98\times\) & \(2.92\times\) & \(2.77\times\) & \(2.09\times\) & \(4.96\times\) & \(3.84\times\) & \(2.95\times\) \\ eq/m\({}^{2}\) & \(10^{-1}\) & \(10^{-1}\) & \(10^{-1}\) & \(10^{-1}\) & \(10^{-2}\) & \(10^{-2}\) & \(10^{-2}\) & \(10^{-2}\) & \(10^{-2}\) & \(10^{-1}\) & \(10^{-1}\) & \(10^{-1}\) \\ ODP (kg & \(6.28\times\) & \(6.16\times\) & \(5.10\times\) & \(1.76\times\) & \(1.69\times\) & \(1.35\times\) & \(5.18\times\) & \(4.83\times\) & \(3.88\times\) & \(8.55\times\) & \(6.16\times\) & \(5.10\times\) \\ CFC11 eq/m\({}^{2}\) & \(10^{-4}\) & \(10^{-4}\) & \(10^{-4}\) & \(10^{-4}\) & \(10^{-4}\) & \(10^{-4}\) & \(10^{-5}\) & \(10^{-5}\) & \(10^{-5}\) & \(10^{-4}\) & \(10^{-4}\) & \(10^{-4}\) \\ POCP (kg & \(3.54\times\) & \(2.91\times\) & \(2.87\times\) & \(9.53\times\) & \(6.99\times\) & \(6.60\times\) & \(2.83\times\) & \(2.31\times\) & \(2.24\times\) & \(4.78\times\) & \(3.04\times\) & \(2.97\times\) \\ C\({}_{2}\)H\({}_{4}\) eq/m\({}^{2}\) & \(10^{-1}\) & \(10^{-1}\) & \(10^{-1}\) & \(10^{-2}\) & \(10^{-2}\) & \(10^{-2}\) & \(10^{-2}\) & \(10^{-2}\) & \(10^{-2}\) & \(10^{-1}\) & \(10^{-1}\) & \(10^{-1}\) \\ ADP (kg Sb) & \(9.24 Table 5 summarises the reduction in environmental impacts by the application of alternative slab systems compared to the OSS. It was found that all the environmental impact indicators showed decreasing tendency as the selection of the slab system of the building changed from the OSS to the FPS to the VDS. In this research, the application of the FPS and the VDS would lower the environmental impacts from all the indicators, compared to the OSS. In particular, replacing the OSS by the VDS shows the highest reduction ratio of all the environmental impact indicators. In addition, the reduction ratio between the FPS and the VDS indicates the second largest value in all environmental impact indicators. While the change of slab system from the OSS to the FPS would lead to lower environmental impact, the reduction ratio of this variation is relatively smaller than for the other cases of this study (i.e., substituting the ordinary reinforced concrete slab by the flat plate slab or the voided slab system). Although the environmental impacts from the OSS to the FPS show a decreased tendency, the ratio is the smallest, as shown in column 3 in Table 5. Based on the results of the environmental impact reduction from the three slab systems, the VDS would incur the least environmental impacts in all indicators and is one of the effective replacements of slab systems to mitigate the environmental burdens. Figure 5: Reduction in environmental impacts.