Green house effect is nothing but trapping of radiation by letting in radiation of short wavelength and shutting out radiation of long wavelength. a green house has a roof area of 100 m2 perpendicular to the solar inclination. the material has a transmissivity of 0.9 up to a wavelength of 4 µm and zero beyond. the solar flux has a value of 800 w/m2. the total wall area is 600 m2. it the inside is to be maintained at 22°c while the outside is at – 5°c, determine the maximum value of overall heat transfer coefficient for heat flow through the walls. the temperature of solar radiation may be taken as 5000 k.