The analysis for the optical properties of the effective layer can be performed by modeling the blind as the closed enclosure.
The blind closed enclosure can be formed from the two adjacent slats as a cell bounded by a total of six segments, denoted by s1 to s6 as shown in Fig. 5.
The view factor of specific surface can be determined from the Hottel’s crossed string method (Siegel and Howell, 1972) which can be written as