Most recent heat and light bill: $163. Last year at this time: $136.
Natural gas, forced air heat and this is a small house. Electric would be expensive even in this area with its cheap hydro power.
Doors, doors, doors ... even if they are blanket doors

! I close the heat registers when I do that 30 minutes of walking exercise in one-half of the house. Forgot to open the one in the bedroom last night. It was okay, pulling heat through 2 open doors.
Closed the doors this morning. Oops! Cold in there when I went back in to change out of my bathrobe!
However, that is exactly what I do if the outdoors drops below 10 degrees. Well, I don't close off the bedroom heat during the night but ... during the day, that room can be the same 60° it is overnight. Even colder, and that is true with half the house.
I'll even cover the passage between the living room and the kitchen during the coldest weather. The kitchen doesn't have to be 68° although it may be considerably warmer when we are cooking. That blanket (actually it is a pretty sheer piece of fabric) is more important to put up in the heat of summer. The AC is in a living room window. That little thing cannot cool the entire house. We can even take our meals into the living room.
Two freezers in the garage and a fridge in the carport - I doubt if they are working very hard lately. Oh, one is empty and off.
Steve