Just look out of the window, at the house next door: Will it still look like it will in ten years? Will the smoke of the old oil heater still rise from the chimney? If so, it is time to think about your own home. Because if the Hamburg climate plan works out, it will be like this in the future: for every building, be it public or private, that will still be there in ten years' time and be heated like these days, you have to think of a second building that reaches its limits the technically feasible is modernized. As early as 2030, this eco-house may no longer consume fossil heat. If this succeeds, both buildings have halved the CO₂ emissions of their heating systems. That would not be enough to achieve the Hamburg climate plan's savings target, but it would be a start.