I live with my sister, her partner and 2 children.?
You lay out very simple math. You are 4 people, I am 1, so I am actually 1/5 the electricity cost (unless you game or do something electric heavy). 1/4 if you want to generously combine the two kids. Shell either care or she wont. Bringing it up might hurt your relationship even if she acknowledges youre right because most people do not want to pay more than they are today. This is assuming youre on the same meter. If youre on different meters Id ask to just pay your own meter. Edit. I also agree with another answerer that looking at the bedrooms used is a way to look at this for fairness. Its hard to gauge who is using what electric unless you know someone like me, for example, who is a heavy gamer. I definitely use more electric than someone who collects rocks.