## 3 Results and Discussion
### Circadian Characteristics
Figure 5: Photopic illuminance (lux) values measured depending on the season (from December 2018 to November 2019); orientation of north (**top**), east (**right**), south (**down**), and west (**left**); and elevation from the horizontal level of 15\({}^{\circ}\) (black), 30\({}^{\circ}\) (striped), and 45\({}^{\circ}\) (grey). Both the photopic illuminances and EMLs reach higher illuminances in the east and south orientations and in the summer months, as is the case with the EDIs that can be calculated according to the relation EML = 1.104 EDI. The minimum illuminances, both photopic and melanopic, were taken in December at a west orientation with an angle of 15\({}^{\circ}\). The maximum illuminances, both photopic and melanopic, were taken in August at an east orientation with an angle of 45\({}^{\circ}\), as has been previously described for EDI due to their proportionality relationship. [PERSON] et al. [17] modelled the nonvisual potential of daylight in terms of the melanopic/photopic ratio calculated from the SPD, finding values very close to 1 and similar to those calculated by using the D\({}_{40}\) to D\({}_{120}\) illuminances. Although this definition differs from our MAF, both indicate practically the same melanopic contribution as the photopic for daylight, and the spectra could be considered to be covering similar ranges to our CCTs. Figure 6: EDIs calculated depending on the season (from December 2018 to November 2019); orientation of north (**top**), east (**right**), south (**bottom**), and west (**left**); and elevation from the horizontal level of 15\({}^{\circ}\) (black), 30\({}^{\circ}\) (striped), and 45\({}^{\circ}\) (grey). Other authors have developed circadian theories. One of the most widespread is [PERSON] et al. who defined the circadian stimulus (CS) and the CL\({}_{\text{A}}\), parameters directly proportional to the levels of night-time light-induced melatonin suppression [29]. This method is not based on any standard but has been adopted by most researchers to define the circadian effect of light [18]. The highest CS, 0.699, is found in the south and east orientations than in the north and east orientations, especially in the winter months (Figure 7). The lowest CS found is in the month of December facing the west at 15\({}^{\circ}\) with a value of 0.685. Given the outdoor SPDs with higher short wavelength contributions than longer ones, the corresponding CSs are always very close to the 0.7 saturation value in the studied period during the evaluated hours. Our calculation shows a CS (mean \(\pm\) standard deviation) of 0.695 \(\pm\) 0.004 throughout the evaluated year for all orientations and elevations with a variation of <1%. There are higher CL\({}_{\text{A}}\) values in the east followed by the south orientation, and the lowest values are in the west followed by the north orientation (Figure 8). The measurements taken at 45\({}^{\circ}\) are generally the highest values compared to those measured at 30\({}^{\circ}\) and those measured at 15\({}^{\circ}\), which have the lowest values. The highest values measured in the east occur in spring and summer (from March to August) at the three elevations, and the lowest occur in the west in winter (from December to March). Our calculations show a CL\({}_{\text{A}}\) (mean \(\pm\) standard deviation) of 77,935 \(\pm\) 62,347 circadian lux (range 11,665-215,042 circadian lux). It should be noted that our obtained values of CL\({}_{\text{A}}\) for daylight are proportional to the EDIs, as shown by the analysed data, with CL\({}_{\text{A}}\) = (2.3 \(\pm\) 0.1) EDI. Therefore, based on this relationship and for cool daylight, CL\({}_{\text{A}}\), EDI and EML are parameters proportional to each other. According to the mathematical model based on spectral sensitivity data proposed by [PERSON] et al.