The potential of a heat pump in older buildings depends on the insulation and existing systems. Studies show that it can operate efficiently in existing buildings:
https://www.ise.fraunhofer.de/de/presse-und-medien/presseinformationen/2020/warmepumpen-funktionieren-auch-in-bestandsgebaeuden-zuverlaessig.html

Points to consider:

  • Insulation: The better a building is insulated, the more cost-effective an investment in a heat pump is
    . Insulating the ceiling and floor is the most effective. Replacing
    windows or insulating the exterior walls are more expensive measures.
  • Heating surfaces: Larger surfaces allow for low-temperature operation, increasing
    efficiency. Underfloor or wall heating is ideal but expensive to install. In
    many cases, replacing a few radiators with larger models is sufficient.
  • Condition of the existing generator: If the current system is still working properly, a hybrid solution may be considered.
    Otherwise, the heat pump can operate on its own.
  • Available space: Check the space required for the heat pump. Monobloc air-to-water models require
    little space, while ground-to-water or groundwater heat pumps require
    outdoor work.

For a quick overview, the heat pump compatibility tool can help:
https://www.energiewechsel.de

If you are interested and are seriously considering installing a heat pump, we recommend that you contact the Klima-Agence for a free, personalized in-home consultation before reaching out to contractors or manufacturers:
https://www.klima-agence.lu/de/mein-beitrag-zum-klimaschutz/heizen-mit-erneuerbaren-energien