# Intelligent Office Lighting Control Using Natural Light and a GA-BP Neural Network-Based System
## 2 Overall Design  
### Model Development and Research Condition Analysis  
While designing lighting design, it is essential to adhere to established lighting standards. This study utilizes the GB-50034 \"Architectural Lighting Design Standard\" as a framework for all lighting designs [17]. According to this standard, when the work plane illuminance is set at 500 lx, the surrounding illuminance should be 300 lx. Therefore, in alignment with the objectives of this research, the illuminance of the occupied work plane are targeted at 500 lx, while unoccupied work planes are set at 300 lx.  
The illuminance uniformity denoted as \(U_{o}\) is defined as the ratio of the minimum illuminance of the work plane to the average illuminance, and it should be no less than 0.7. Additionally, the lighting power density (LPD) must remain below 6 \(\mathrm{W}/\mathrm{m}^{2}\). These indicators serve as target values for this study.  
Figure 1 illustrates the office space modeled using DIALux. The dimensions of the office are 8 m in length, 6 m in width, and 3.4 m in height. Located in Dalian, Liaoning Province, China (between 120\({}^{\circ}\)58\({}^{\prime}\) and 123\({}^{\circ}\)31\({}^{\prime}\) E and 38\({}^{\circ}\)43\({}^{\prime}\) and 40\({}^{\circ}\)10\({}^{\prime}\) N), this model serves as the prototype for analysis. Windows face towards the south, and the office includes six work planes and six LED lamps, with a total window area of 3 \(\times\) 3.24 m\({}^{2}\) fitted with adjustable blinds. The work plane is situated 0.75 m above the ground, while the lamps are installed at a height of 3.2 m, and the height of the windows is 0.75 m above the pavement. Additional parameters for the office are detailed in Table 1.  
China is categorized into five regions based on solar radiation intensity [18]. This study focuses on the office lighting environment in the third-grade region, where annual sunshine hours range from 2200 to 3000 h, and annual radiation varies between 1390 and 1630 kWh/m\({}^{2}\). Dalian, located in this third-grade region, was selected as the research site for this study. An experimental analysis of the office lighting environment has demonstrated that the most comfortable conditions occur when the color temperature is 5000 K and the illumination exceeds 300 lx [14; 19; 20]. Therefore, this paper utilizes San Xiong Aurora lamps with a color temperature of 5000 K and a luminous flux of 4000 lum  
Figure 1: Modeling of office space.  
\begin{table}
\begin{tabular}{c c c} \hline
**Parameter** & **Description** & **Value/Unit** \\ \hline \multirow{3}{*}{Office space} & Wall reflectivity & 50\% \\  & Floor reflectivity & 20\% \\  & Ceiling reflectivity & 70\% \\ \hline Windows & Glass transmittance & 90\% \\ \hline \multirow{3}{*}{Lamps} & \(P\) & 40 w \\  & \(\Phi\) (luminous flux) & 4000 lm \\ \cline{1-1}  & Tc & 5000 K \\ \cline{1-1}  & Number & 6 \\ \hline \end{tabular}
\end{table}
Table 1: Office area attributes.  
experiments. The parameters of the selected luminaires are provided in Table 1, and the light distribution curve is illustrated in Figure 2.