The target was to stop natural gas consumption. This was initiated by balcony solar both solar thermal and PV, exchange of single glazing by double glazing on inner box windows, so there are now three sheets of glass. The gas furnace was retired and heating air conditioners installed. In one room, 5cm inner CaSi insulation was attached to the outer wall.
It is important to remove paragraphs in legislation hindering such doing, since we are in a climate emergency.
https://NoGasChallenge.html