We are lucky here in Canada where i am in british columbia, we have large reserves of natural gas which is in turn is even sold to the united states (california, washington state) our gas rates increases are not that bad yearly. but even so have to plan for the future.
When i built my house i sealed the plywood sheet seams and covered those with a membrane material and then entire house with tyveck wrap then on top of that another layer of paper/mesh then a skim coat over that then the stucco. insulated all exterior walls. gasket lining foam on all framing uppers and lowers and then flex air barrier sheeting. attic stuffed full of insulation and all exterior venting all wrapped with insulation. Then insulated all interior walls and floor joists. Window ledges and surrounds all insulated double and membrane material, backer foam rod and spray foam around all window seams when in framing stage, same for all exterior doors. basement floor before being poured was insulated not a single gap. the heat isn't going on in this house gas bill for september was 32 dollars Canadian = 26 pounds which would be attributed to the gas appliances and boiler producing hot water for sinks showers etc. the exterior concrete foundation of the house was covered with a waterproof membrane i have 2 gas fireplaces but don't use them so turned off the pilot lights for those. the basement heat has never been turned on in the house. just looked at the thermostats and the house is at 21.5 degrees at the moment and the weather today is heavy rain around 10 degrees.