# Building Energy Savings by Developing Complex Smart Windows and Their Controllers
## 3 Results
### Comparison of Cooling and Lighting Energy Consumptions  
To reduce the cooling load and lighting energy in summer effectively, an experiment was conducted using a complex smart window combined with a dimming LED to maintain indoor illumination levels. For this purpose, we simulated the reduction of cooling and lighting loads through actual monitored SPD transmittance and dimming control. This window combines SPD glass, which actively responds to changes in indoor and outdoor environments and can control light transmittance, with LGG, which can actively control solar reflectance. The results of a comparative analysis of the energy consumption of the test and reference groups in the experiment using a complex smart window are shown in the following graph. In Figures 10 and 11, the data for days 1 to 15 refer to the period from 1-15 August, which is when the cooling load is the highest during the summer season. Also, in Figures 12 and 13, the monthly data include all days of the respective month.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{2}{c}{**Skin Type**} & \multicolumn{2}{c}{**Glass**} & \multicolumn{2}{c}{**Size (mm)**} & \multicolumn{2}{c}{**Thickness (mm)**} & \multicolumn{1}{c}{**EA (Each)**} \\ \hline \multirow{3}{*}{Test room} & LGG & 5 CL + 22 Ar (blind) + 5 PLA ONE & 1140 \(\times\) 540 & 32 & 2 \\  & inside & 5 CL + 16 Ar (SWS) + 5 PLA ONE & 1140 \(\times\) 800 & 26 & 4 \\  & outside & 9.75 SPD + 16 Ar (SWS) + 5 PLA ONE & 30.75 & 4 \\  & top & 5 CL + 16 Ar (SWS) + 5 PLA UN & 1140 \(\times\) 540 & 26 & 2 \\  & bottom & 5 CL + 16 Ar (SWS) + 5 PLA UN & 1140 \(\times\) 800 & 26 & 4 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Glass compositions in the conducted experiment.  
Figure 11: Experimental results of daily cooling energy consumption.  
Figure 10: Experimental results of daily lighting energy consumption.  
Figure 9 displays the lighting energy consumption from 1-15 August, revealing that the Test group equipped with SPD and LGG generally exhibits lower consumption (<1.5 kWh). Figure 11 presents cooling energy consumption, indicating larger daily variations due to external temperature influences rather than lighting, yet similarly, the Test group demonstrates lower cooling energy consumption, consistent with the lighting energy results. Figures 12 and 13 depict lighting and cooling energy consumption from June to September. Overall, the Test group consistently exhibits lower energy consumption, and the highest reduction rate is observed in August, a period of heavy load.  
Figure 12: Experimental results of monthly lighting energy consumption.  
Figure 13: Experimental results of monthly cooling energy consumption.  
The experiment yielded energy consumption under the same external and internal conditions, as shown in Table 3. The cooling and lighting energy consumptions of the test room were 138.6 kWh and 124.1 kWh, respectively, whereas the cooling and lighting energy consumptions of the reference room were 219.8 kWh and 272.7 kWh, respectively. By applying smart skin, energy-efficient use was achieved in parallel with dimming control. By combining LGG and the dimer, the lighting load was reduced by 54.5% and the cooling energy consumption was reduced by approximately 36.9% compared with the reference room.