That is why we put in geothermal. I love it. We were on heating oil and with a baby in the house - 70 degrees was as low as we dared leave it that winter. almost 2k a month in heating bills justifies a 15k geothermal system pretty quick. lol I love it - flip a switch and it runs backwards for a free bonus of central air!
My mom has that! When we moved to this property there was an existing house that she moved into and it had ground source heating. We built on the other side of the property and did look into that option while building but we had limited funds to build and decided we would rather have a roof! It is really nice and her winter bills are a fraction of mine and that includes electric to her barn and her little guest cabin.
Again to go that way now I would have to duct the house and that would require work equivalent to tearing the house apart and rebuilding.