Living in an old building with a boiler system so you have instant gratifying heat, oh yes the Having a live-in girlfriend raises a whole lot of questions, many of which cannot be answered.
You may want to stop and think a bit before you go and try to solve all those equations, the outcome may not be what you are looking for. Here I am comparing whether or not to have the heat on in your household when living with your significant other. Yes, your preference is most likely going to overrule the comparison in fact but lets give it a whirl. What if I told you that having the heat on could change your every night and make it more or less desirable for your or their needs. Say you want to have your partner close to you, cuddling and snuggling you looking for warmth. That would be an excellent example to turn the heat off. If you were to turn the heat off, then you would get much more “one on one” time whether you are getting down to watch a movie or just making dinner together. On the other hand you would be less likely to walk around on the cold floor. having your hands out in the cold air like, holding the refrigerator open or seldom typing with one hand to conserve your warmth in the other hand than switching back and fourth. When it is cold inside, your partner would be more inclined to wear more clothing like those blast sweatpants with funny characters on the sides of them that are definitely not sexually appealing. Or a really old oversized sweatshirt from college that your significant other just loves to wear because its “cozy.” This brings me to my next point. If you were to turn up the heat, way up, the amount of clothing would quickly dramatically decrease. Think about it, your partner walking around the house in slim tight fitted underwear, barely fitting into them as if they could not get less on.