I have a sigma 2016 dual extruder model with no enclosure, although there are walls on three sides and an open top. When I print ABS, which has been quite a bit recently, I place a piece of cardboard over the front opening. There's always a gap, but I have no real external airflow generators (fans, a/c ducts) that are a factor.

I'm using 100°C for the bed temperature, although the FLIR device for my iPhone shows about 10° colder. I've been running 245° on MatterHackers economy filament. If I run too cool, I get delamination.

It's a tough call to address the warping, though. I've been using Wolfbite on the bare glass bed and it's been incredible. Not a warped part if I do everything else correctly. Early batches of Wolfbite had some chemistry problems, which garnered it a shaky reputation right at the start, but the new batch is great. It's marked for 30 day expiration after opening, but I've been using a food-sealer vacuum and sealing it after every use. It's been three months and the handful of prints I've done today are holding great. I re-apply every five or six print jobs, but it barely makes a dent in the bottle.

I had been using brims of 2mm, single layer, but lately dropped to no brim, no raft, unless it's a tiny footprint.

I've never heard of a too-hot bed causing warping, but it's not out of the question either.