Houses are used for decades; in terms of their maintenance and modernisation, one must therefore take a long-term view. Every owner who adopts a sustainable approach will invest in the building to maintain or increase its value. Some measures pay for themselves very quickly, others only after 10 or 20 years. In all cases, a properly executed energy retrofit contributes to reducing dependence on rising energy prices by reducing energy consumption for heating. And even if, in rented buildings, the savings in heating energy do not immediately compensate for any increase in rent, one must always take into consideration the fact that heating energy prices are constantly rising. In most cases, therefore, the measures pay off in the long term.
When calculating the cost of an energy modernisation, don't forget that many measures will have to be implemented sooner or later and that financial aid can be requested today.