A DATA-DRIVEN COLORIMETRIC ANALYSIS OF THE CIE STANDARD GENERAL SKIES

This paper studies the colorimetric characteristics of daylight within the framework of the CIE Standard General Skies. The correlated colour temperatures (CCTs) were studied based on long-term measurements. The colorimetric analysis employed in this study comprises: (i) the CCT occurrence; (ii) the CCT ranges; (iii) the CCT variation depending on the solar altitude; in function of season, time of day, and orientation, all corresponding to the fifteen CIE Standard Skies. The last part of the analysis illustrates the practical application of the results in the urban structure, represented in spectral daylight potential diagrams. The findings show significant colorimetric discrepancies both between and within the sky types and support the key argument against a fixed CCT for all sky types. The paper helps to understand the spatio-temporal variability of the CCT and indicates what possible effect that variation might have on the colorimetric daylight characteristics on façades, and therefore on the potential of a building regarding the ipRGC influenced responses to light.