@Nick618 Since Airbnb only has the cleaning fee slot open that is added on at the time of booking, you might consider raising your nightly rate to cover the heating costs. My winters are not like yours, but while some guests turn on the heat, others, who live in colder climates, do without, so if you add it as part of the nightly fee, you may come out ahead with some clients, not so with others. Trying to collect a fee at the end of the stay can be problematic, so it is in your best interest to try and figure out what could on average be used each day, so it will be prepaid.
You might be able to add an "overuse" fee for utilities in your rules section. You could say that upon occassion you have had guests that run up the heating bill excessively, because they leave it on when they are out, and that at the end of the stay, when you can read the meter, you may deduct an amount of ____pounds for anything above ____units (therms?, whatever is the average use per day) from their security deposit. I don't know if this will work on Airbnb or not. If not, you could add a flat amount to the cleaning charge and tell clients that you will refund all or part of that fee if they keep the utilities to average useage. That's all I've got.
