Due to the ownership exception I would recommend you contact GBCI to see if it would be acceptable to certify this as a separate building. They have the final word. I would hope they would factor in the European custom but you can't count on them to do that.
I don't think the heating should be an issue—buildings are often LEED-certified using district thermal energy systems. There is a LEED application guide for district energy situations you might want to review.