I regularly get asked for utility costs for my listings from other realtors and the general public and I find it somewhat frustrating and I want to explain why. First of all the costs mean almost nothing unless they are put in context.
My elderly in-laws keep their thermostat set at a balmy 85 degrees F (29.4 degrees C) 24 hours a day. My kid sister keeps her home at 64 degrees F (17.8 degrees C) and has a programmable thermostat that turns the heat down further at night and also weekdays when she's at work. Needless to say my In-laws' utility bills are drastically higher than my little sister's bills despite the fact that their home is smaller, well-built and has new windows.
I'll give you another example. Take a family with three teenagers in high-school (lets say they all play sports at school and also outside of school sports like hockey, soccer etc.), both parents working (and lets imagine the parents as very physically active as well). We now have 5 adults showering at least once a day and often twice, loads and loads of laundry and lots of lights and tvs on when everyone's home. Then we'll compare this family with a childless professional couple who both workout at the Y and shower there every day. They both send out most of their clothing to the drycleaners and do one or two loads of laundry a week. They dine out a lot and are seldom home except to sleep. They live in identical houses but their utility bills are a universe apart.
I could go on with other examples that I've experienced over my career but I think these 2 examples provide enough of an example of how important context is. So the next time you ask a Realtor about utility costs just think of the amount of information you really need for it to have any meaning. If you're worried about insulation and heating costs have the home inspected by a qualified professional. It will give you so much more information and assurance than asking what the current owners spend unless you also find out a great deal of information on how they live.