Heat pump in an existing building: what applies in 2026
Updated:
Short answer
In an existing building you may install a heat pump, and you do not have to replace a working heating system. KfW funds the installation in existing homes through product 458.
RECOMMENDED PROVIDERS
What the law requires in existing buildings
The Gebäudemodernisierungsgesetz has applied since 29 July 2026, and there is no duty to replace a working heating system. A heat pump is one permitted option under that law, not the only one.
What funding existing buildings receive
KfW funds the purchase and installation of a climate-friendly heating system in existing buildings. You file the application before you award the contract, and current rates sit in the heat-pump funding tip.
The overview is on the Heat pump topic page, and selected providers sit in the provider list.
PROVIDERS
Official sources
Open KfW heating funding 458 →
More information
Open selected heat-pump providers →
Open Heat pump →