Dear tal.hert,

if I test your example with your given formula, I get the following result for mean radiant temperature:

((45.4 + 273)^4 + ((1.1 * 10^8 * 0.13^0.6) / (0.95 * 0.15^0.4)) * (45.4 - 25.805))^0.25 - 273 = 55.9

How did you get your result of mean radiant temperature (67.7)

Regards
Marcel Gangwisch