I've got a 10 x 12 ft garden shed that I hang tobacco to air-cure. Shed has two small windows (open), ridge and roof vents, so it get some fresh air. Temp inside the shed goes about 10 degrees hotter than ambient on sunny days, which is most days. It's been hitting 105 to 115 inside this summer, 70's at night. RH goes to as high as 80+, but down to 20-30-40 in the daytime as an average. I've got 2 small oscillating fans on low speed running 24/7.
Everyting has been curing very nicely, only a very few leaves got some dried green segments. Last of my leaf was primed yesterday, 160+ plants. The total area is covered with hanging leaf on the top tier (rafters), two more tiers suspended below these, covering about 2/3rd of the area - can barely get in my shed now. Strings of leaf are on 8-inch spacing, touch when first hung, but ample air/ventilation space when leaf curls or limps up as it starts to cure.
Thin leaf burleys and virginias get hung straight from priming when ripe, and start changing color within a couple days. Thick leaf strains like the mature-primed Havana 142, or the ripe Marylands, need to the piled/stacked (coffinnails sweat method) for 3-4 days or longer until they start to turn before I will hang them to finish air-curing.
I have been lucky so far this year, no signs of mold, and very little dried green - very lucky, given the extreme weather we've been having. As hot as it's been, I'm surprised that the leaf hasn't gone straight to brown, i.e. cooked.
Being the dumbass that I am sometimes, I started hanging leaf in the back of the shed about 5-6 weeks ago, and it's fully cured and dry now. But I can't get to it because all the new leaf in front of it. Got to wait another month for the last primings to cure/dry before I can start processing this.