Cooling Dock Load Calculation

So I'm doing an infiltration load calculation on a cooling dock and I was wondering if there was a different way to go about it than what ASHRAE states. ASHRAE's simplified equation is:

q = 3790*W*H^1.5 *(Qs/A)*(1/Rs)

where
q = sensible and latent refrigeration load
W = door width
H = door height
Qs/A = sensible heat load of infiltration air per square foot of doorway opening (taken from a figure in the book)
Rs = sensible heat ratio of the infiltration air heat gain (taken from a psychrometric chart)

I usually add a corollary that incorporates the exposure time, but we'll save that for another discussion.

The reason I am hesitant with using this equation is that this cooling dock has 25 overhead doors and a drive in door as well as other doors to various rooms. Anyone that can shed some light on this for me is a gentleman and a scholar.