In article a962g.908004$x96.138352@attbi_s72,
"Dave Lyon" wrote:

My shop is a 4000 square foot metal building with just a little insulation.
I've got 2 residential air conditioning units that keeps it bearable, but
....
It would sure be cheaper to operate than a 3rd AC unit.

Have you considered that more insulation would cost _nothing_ to run,
and enough of it could even get you down to running one A/C unit?

--
Cats, coffee, chocolate...vices to live by