I've done roofs, heating systems, monitored fire alarm systems, unit remodels, etc. 

So from my experience in Upstate NY with section 8 as long as it has an over head light, atleast one window that stays up on its own, electrical outlets, heating and smoke alarm and has a door that closes it off it is considered a room. 

Could the tenant reasonably claim they thought "all utilities" were just what they were paying (heat?)

A couple weights and yoga mats with a mirror, nothing crazy. 

The last few weeks the buying has been heating up for sure. 

Flooding, Fire , and loss of heat are the only real emergencies. 

I could just see somebody's dumb behind having a heart attack, heat stroke, or burn in that thing, then they or their family will hire an attorney to prove your sauna is 0.3 degrees hotter than the industry standard, doesn't have the correct signage, you didn't post the number to 911 inside the sauna....some sort of nonsense to make it your fault and expensive. 

How's he heating the home?

At that point have the heat restored.

Was the house vacant and the heat off or just bad luck?