A clean manufacturing space in an industrial area with dimensions 400x400x60ft3

, need to be directly illuminated by day light using 400(4x4ft2)

sky lights where each flat dome has a transmissivity of 60%.

Consider the date is 2.00 PM on September 21st

, sky is clear, and using the following assumptions:

Depth of each well is 24 inches, the site is located 42o

north latitude, walls reflectance is 30%, the well is painted with the same color and has the same reflectance of the ceiling of 80%, Rg=0.95

, no louvers at the base of the well, floor reflectance is 20% and finally the cleaning is done every 9 months

Tnd

approximated

Select one:

a. 0.66

b. 0.77

c. 0.44

d. 0.55