So the last few years we've really put an effort to help with warehouse temps. We put in a big exhaust system that pulls the spillout heat from each end of the oven. This has done more than probably anything we've done honestly.
Just last week we had the roof coated in white silicone. It's not cheap, but the roof was in need of it, we had some leaks and the old elastomeric coating was cracking and wearing out. For a 7500 square foot building it ran about $19,000. But holy cow does it reflect the heat. Back in the day the roof was black(the silver coating washed off). In the summer I measured the temp at 185 on the roof. The next day with similar conditions after we had 2 coats of elastomeric coating on the roof it came in at 125. I measured it yesterday, full sun at 90 outside and the roof measured 100.3 with a donut probe, not a non-contact since this stuff is so reflective it probably wouldn't have worked.
I was amazed. We'll see what a difference that makes this week. It's supposed to hit high 90's soon. This also takes a lot of pressure off the HVAC systems in the office. It also comes with a 10 year manufacturer's warranty, so GACO was out inspecting the roof to certify the mil thickness meets or exceed spec. I know this doesn't apply to a lot of folks here since they have no say in building maintenance and repairs, but those that do should really look into coating the roof in silicone.