We had closed cell spray foam insulation installed and painted in our shop. We did 3″ on the ceiling and south facing wall, and 2″ on the rear and side walls. The difference is HUGE! The ACs can now keep up no problem, keeping it a nice 75F inside even in the 105F Texas heat! It’s pretty expensive, very messy to install, and takes a LOT of work, but I’m pleased with the outcome.