Heating is one thing we have tackle, but also transportation which uses up 27.1% of energy in German. Individual transportation should be a main target, we would all shift from cars to public transport or bicycles. About 40% of distances driven with cars are shorter than 5 kilometers, a distance that's perfect for a bicycle. On top of that, car owners tend to underestimate the cost of their cars[1]
[0] https://www.umweltbundesamt.de/daten/energie/energieverbrauc... [1] https://www.nature.com/articles/d41586-020-01118-w