Just chiming in to make some of y'all feel better. We are four adults in a 2600 Sf single-story home. Common areas of home have 14' ceilings, rest are 9'. House is only 10 years old, so fairly energy efficient. Scores of can lights, all LED's.
We live in this house to care for my MIL, who has Alzheimer's. This winter, DH decided it might be cheaper to leave the heat at a constant 68 degrees 24/7, as there is almost always someone home. Last month's gas & electric bill was $432.00. To add insult to injury, I often find MIL wandering around with a coat and knit hat on. We have to laugh and be happy that we're FI, or it just might be too hard to take.
Did you notice that we live in California? We also receive expanded baseline hours because DH uses a C-Pap. Off the top of my head, I'd say we average somewhere around $175/mo, but this month was a doozy, and there's not much to be done about it. Someday, when MIL is gone, we'll downsize and eventually make up for this exploding volcano of wastefulness, we hope.