Housemate keeps leaving the heating on...

then turn it off yourself

I wish I could give useful advice but all I would've told you to do is try and talk to her and establish that you're serious

My housemate keeps leaving the heating on constantly all the time. She turns the heating on to max, then goes out from about 10 am and gets back after midnight most nights. She gets annoyed that I turn it off when I go out because when she gets back, it's not warm (I generally don't have it on that much as I don't get cold, I wear appropriate clothing like thermals and have a blanket). Still, she also walks around the house wearing a vest top that exposes her belly and the thinnest leggings I've ever seen.

I don't mind her having the heating on, of course, but I fear the heating bill is going to be huge because on the days I don't get back from classes early, the heating would have been on an entire day keeping nobody warm, it's wasteful and costly. I have moments where I wake up in the middle of the night sweating because it's that hot. She has to have it on max all the time, and lower settings aren't good enough for her. I've tried talking to her, but she doesn't listen. It seems like she was probably spoilt back at her parents because she doesn't seem to know how to clean correctly and do other stuff around the house. And to top it all off, she is not even a student. She failed her first year but still applied to move into student accommodation even though the university would not accept her for another year. She did not apply for extensions or even finish her work.

Who else is living there, can you check they're onside and then call a house meeting.

Might help if you get some meter readings to show the evidence that you energy usage is excessive and you're headed for a whopper of a bill if you don't start using the heating sensibly.

You should try to set a timer for the heater so it comes on at certain times.

Have you got one of those portable thermostats?
If so, hide it.
My sister is the same, she wants to walk around in leggings and a t shirt, like put on a jumper!

Nope, we don't even have a thermostat at all. We just have the boiler where you turn it on and set the temperature etc.
I feel you haha, that is why they are cold because they aren't wearing much.

Right, so you know your boiler will have two heat settings. One for heating and the other for water, you can reduce that. So when she turns the heating on to say 20 degrees, it will actually be lower in the mains. Therefore resulting in less waste.

I have to go to extreme measures because of my sister but I’m naturally very warm, I walk around in a t shirt too but I’m fine.

My housemate keeps leaving the heating on constantly all the time. She turns the heating on to max, then goes out from about 10 am and gets back after midnight most nights. She gets annoyed that I turn it off when I go out because when she gets back, it's not warm (I generally don't have it on that much as I don't get cold, I wear appropriate clothing like thermals and have a blanket). Still, she also walks around the house wearing a vest top that exposes her belly and the thinnest leggings I've ever seen.

I don't mind her having the heating on, of course, but I fear the heating bill is going to be huge because on the days I don't get back from classes early, the heating would have been on an entire day keeping nobody warm, it's wasteful and costly. I have moments where I wake up in the middle of the night sweating because it's that hot. She has to have it on max all the time, and lower settings aren't good enough for her. I've tried talking to her, but she doesn't listen. It seems like she was probably spoilt back at her parents because she doesn't seem to know how to clean correctly and do other stuff around the house. And to top it all off, she is not even a student. She failed her first year but still applied to move into student accommodation even though the university would not accept her for another year. She did not apply for extensions or even finish her work.

make her pay extra for the bill if she keeps doing it

I do that, but a short while after I start feeling hot, and lo and behold she has turned it up to max again. She just does not listen to me.

I'm naturally warm too so I don't need it on that high, but it sounds like your sister and my housemate are the same, just layer up a bit more haha.

It doesn't have a timer that allows for that unfortunately, just a timer that you start so that once the timer has finished it just turns the heating off. And since my housemate turns the heating on after I have already left for class or whatever I am doing there isn't anything that I can do about that.

Are you living in Halls or privately. If you are not paying the bills, then ignore and move on.

It's private. Obviously I would ignore if I wasn't paying the bills, but I am paying them sooooo...