I can see where you're both coming from to be honest, but that bill - YIKES!
I heat whatever room my parrots are in, they have no choice but to be here with me and come from sunnier climes so spend daytime in the conservatory which is 'their' playroom. In the evenings we room together, in a better insulated part of the house, and overnight they have a heat mat at the moment, but as it gets colder I'll move their cage into the other room and they'll have a heater on overnight.
I dress warm, and still feel the cold, and find it miserable. I love the thought of being able to come in to a warm house. I hate the Winter when I'm at my desk and freezing, wrapping blankets round my legs and even occasionally 'splurging' with a heater and closed door. My Mum andbrother are always telling me to put the heating on, but I cannot afford to, so I manage without it until I really can't. Because of this, I'm currently rearranging my house so that when the cold really hits, the parrots and I can be in the better insulated room together as soon as darkness hits. I'll probably be in there without heat in daylight hours as it's warmer than my current 'office', but as usual the parrots will have heating. It's cheaper than a vet bill.
When I moved here I foolishly (or so it seemed at the time) got talked into an electric boiler, and having done one Winter in the same way as described above, I tried another leaving the heating on a timer and loved having a warm house, was still careful re closing doors and containing it etc. My quarterly bill at that point was circa £650 - not affordable for me. I have not used the boiler since. I have solar panels for hot water and an immersion heater that I put on when I need hot or additional hot water. If I had some solar panels for electricity I would definitely have the heating on right around the house, but that is a luxury that I cannot afford.
I also have a window open at night, pretty much all year round, otherwise I feel dreadful and have a very pudgy face upon waking. I'm snug under my duvet.
I think the issue for you is the temperature he wants to be in. I have a thermometer that shows the temperature and suitable ranges, i.e. Cool - Good room temperature and Warm - turn down heating. Maybe if you could get something like that, he'd realise that he's the one that needs to adapt.
I have friends who have an annual argument re the heating, and rarely argue other than that. Just a reminder that we are all different.