## 2 Methodology
### Properties of the Virtual Cubicle Model  
The space utilized as a calculation model in this study is based on a standard single ICU cubicle, with dimensions of 3.0 m in height, 3.5 m in width, and 3.25 m in depth. There is a single window, with a visible transmittance of 0.70 in the facade, matching its width and with a variable height, to achieve a window-to-wall ratio (WWR) of 15, 25, 35, and 45%. When choosing the range of WWR to analyze in the study, it was necessary to discard ratios that would not be feasible in a real ICU environment according to energy consumption performance. While a completely transparent facade would probably obtain the best results in terms of _DA_, _CSA_, and reduced lighting energy consumption, other kinds of consumption, such as heating or cooling, would drastically increase. The window position has two configurations: the first with its upper part at 1 m from the ceiling (defined as \"centered\", as depicted in Figure 1), and the second with its upper part flush with the ceiling (defined as \"upper\"). Table 1 provides the two reflectance values options (bright and dark) of the room surfaces, considered as diffuse reflectors, in accordance with the recommendations of EN 12464-1 [63]. These dimensions, totaling approximately 63.25 square meters, are representative of a standard single cubic within an intensive care unit (ICU). Patient beds and medical equipment were excluded in this study due to their minimal impact on light reflection compared to the ICU surfaces. As the location of the medical equipment is often temporary, its inclusion could reduce the reliability of results. Similarly, bed sheets, typically white, could lead to more favorable results by increasing reflected light. For the daylight autonomy (DA) calculations, a longitudinal array of points was utilized. Horizontal illuminance values were computed at intervals of 0.25 m (one-meter height, equivalent to the height of the bed). These calculation points were centered along an axis perpendicular to the facade plane, as illustrated in Figure 2a. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Cubic**} & \multirow{2}{*}{**Ceiling**} & \multirow{2}{*}{**Wall**} & \multirow{2}{*}{**Floor**} & \multicolumn{3}{c}{**Exterior Window**} \\  & & & & **Reflectance** & **Reflection** & **Transmittance** \\ \hline Bright & 0.9 & 0.8 & 0.4 & 0.3 & Specular & 0.7 \\ Dark & 0.7 & 0.5 & 0.2 & 0.3 & Specular & 0.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Reflectance values of the cubic surfaces. Figure 2: Location of calculation points (marked with crosses) and their viewing directions (marked with arrows) for the following: (**a**) energy efficiency calculations, _DA_; (**b**) _CSA_ trials with the headboard of the bed adjacent to the facade (_CSA_ 1); (**c**) _CSA_ trials with the headboard of the bed adjacent to one of the side walls (_CSA_ 2). Figure 1: Dimensions of the virtual cubicle model. The line A-A\({}^{\prime}\) on the floor plan marks the vertical plane where section A-A\({}^{\prime}\) is made. In the case of circadian stimulus autonomy (\(CSA\)), two different arrangements of calculation points were employed, as depicted in Figure 2. The first one (Figure 2b) is a line of vertical illuminance points which are placed 0.75 m from the facade, with a spacing of 0.25 m between the studied points. These points were positioned at a one-meter height and were oriented toward the back wall, replicating the view of a patient from a bed whose headboard is adjacent to the facade. The second one (Figure 2c) is a line of vertical illuminance points placed at 0.75 from one of the side walls, with the same spacing and height. This line replicates the view of a patient from a bed whose headboard is adjacent to the interior side partition. This last arrangement has been recommended by previous studies [62]. The reflectance of each surface within the cubicle's interior can play a critical role in determining the resulting spectral irradiance incident on the occupants' eyes.