I've got a new lodger and she's been putting on the heating in her room (can control individual bedroom heating) but she will leave the bathroom window open all the time.
I don't think it's a bad thing to leave the bathroom window open, however it's a bit contradictory - she's always cold and the bathroom window needs to be open all year round. The shower doesn't have a door and it can be cold, so it's not the best in winter generally as despite an extractor fan it's best if the window is also opened (or at least after you've showered).
I hate confrontation but I can see her being "cold" in winter and using up lots of gas and as well as keeping the upstairs bathroom window open.
AIBU to expect it to be shut the majority of the day?