Hello,  I’ve been away from this forum for quite a few years.  I used to lurk a lot back when I was still a home builder.  I built numerous ICF homes, including my own.  But I hung up my hammer a dozen years ago and started a food manufacturing business.  It has gone well and we are breaking ground on a new larger facility.  

I just signed the contract today on a new 100′ x 200′ steel building with 20′ eaves and a 2/12 pitch roof.  My question is regarding the color of the roof metal.  I am paying quite a bit extra for R-38 Simple Saver insulation package in the roof.  Standard roof metal is Galvalume.  On my other buildings I have paid for a white coating on the roof metal.  For this size building, the white coating adds around $6,700 over the galvalume.

There is also a PVDF Cool Coating option in white that would be about a $12,000 upgrade cost.

All of the options have Initial Solar Reflectance, Initial Thermal Emittance and Solar Reflectance Index numbers.  They are as follows:
Galvalume = IR/.77  IT/0.08  SRI/72
White = IR/.67  IT/0.83  SRI/81
PVDF White = IR/.72  IT/0.85  SRI/88

With the extra insulation in the roof system, will the white roof coatings make a measurable difference in the indoor temperature?  Is it worth the upgrade cost?

I’m in central GA.  Part of the building will be conditioned but 75% will just be warehouse space.  Regardless, I want the interior to be as cool as possible in the hot summer months.