Heat pumps in flats and multi-party buildings

If you live in a detached house, you decide on your heating system yourself. In a flat, it is different: the building belongs to many, the facade, roof and cellar are shared parts, and the heating is often either central for everyone or installed as a gas boiler in each individual flat. Nevertheless, there are also ways to get a heat pump in a multi-party building. According to klimaaktiv, there are generally suitable heat pump solutions for all types of residential buildings.

This guide provides you with an overview. It is not a substitute for legal advice: if you have specific questions about your building, please contact your property management, a tenant or owner advisory service, or a lawyer.

What you as a flat owner are allowed to decide on your own

The Wohnungseigentumsgesetz 2002 (Condominium Act 2002) regulates in Section 16 what you are allowed to change in your flat. The basic principle: you are entitled to make changes to your condominium property at your own expense. However, according to the law, the change must neither damage the building nor impair the protectable interests of the other owners, in particular not the external appearance of the building, and must not pose a danger to persons or property.

If common parts of the building are used for the modification, such as the facade for an outdoor unit or the attic for pipes, Section 16 states that it must additionally either correspond to common practice or serve an important interest of the flat owner. For certain installations, the law explicitly mentions cases in which consent must not be withheld. These include, among others, electricity, gas and water pipes as well as heating systems, but only if a connection to an existing facility in the building is not possible or not reasonable. Under the statutory conditions, consent that has not been granted can be replaced by a court ruling.

What this means in practice:

An outdoor unit on the facade or balcony almost always affects common parts and the external appearance of the building. Speak to your property management and co-owners at an early stage.
Noise is a concern for neighbours. A loud unit outside another owner's bedroom window can impair their protectable interests.
Simplified consent through silence is only provided for by Section 16 in certain cases, such as charging stations, balcony photovoltaics or shading. Heat pumps are not explicitly mentioned there.

In addition, there are building regulations of your federal state and your municipality. You can find general information on this under Approval.

Centralised solution: one heat pump for the whole building

It is often more sensible to convert the building together, rather than everyone looking for a solution on their own. In this case, a centralised system replaces the previous central heating or the individual gas boilers.

The City of Vienna shows what this looks like in practice with its initiative "100+ Projekte Raus aus Gas" (100+ Projects Out of Gas). The focus is on multi-storey residential buildings that cannot be connected to district heating. The examples range from centralised and decentralised air-source heat pumps to geothermal probes and groundwater utilisation.

One example is a building from 1966 in Vienna's Miesbachgasse with 21 flats, each of which previously had its own gas boiler. According to the City of Vienna, a centralised air-source heat pump was installed in the attic there. The pipes to the flats run through the chimneys that are no longer in use, and the connection can be made within a single day in each case. This allows flats to be converted step by step.

Checklist for the owners' meeting:

Are there unused chimneys, shafts or risers through which new pipes can run?
Where can a centralised system be located: attic, roof, cellar, inner courtyard?
Is there space in the courtyard or garden for geothermal probes?
Can flats be connected step by step, for example if a gas boiler needs to be replaced anyway?
Who will take care of the planning and coordination? The property management, a planning office?

Decentralised solution: one heat pump per flat

If a joint solution cannot be reached, the only option left is a heat pump for the individual flat. Here, the hurdles are higher: an outdoor unit usually requires space on a balcony, terrace or on the facade. This touches upon the questions of consent and noise mentioned above.

Checklist:

Is there a location for the outdoor unit that does not disturb anyone and does not alter the appearance of the building?
How is hot water prepared, and is there space in the flat for a storage tank?
How does the unit behave at night? With our noise calculator, you can roughly estimate what reaches your neighbour.

District heating as an alternative

If your building is located in the supply area of a district or local heating network, you should seriously consider this option. According to klimaaktiv, such networks deliver high flow temperatures and also large amounts of energy, and no fuel storage is required. This is particularly suitable for older multi-party buildings with radiators.

The federal public subsidy logic also applies here: for Kesseltausch, according to the info sheet, priority is given to subsidising connection to climate-friendly or highly efficient local or district heating. A heat pump receives a public subsidy there if this connection is technically impossible or economically unreasonable. However, the 2026 relaunch (eligible from 7 October, registration from 2 November) applies only to detached/semi-detached houses and terraced houses, not to flats in multi-unit residential buildings. The dedicated federal scheme for buildings with three or more residential units has ended and was not relaunched in 2026. You can find current conditions in the Förderübersicht and in the Förder-Manager.

Your next step

In a multi-party building, the journey usually begins with the property management and at the owners' meeting. If you want to know what is technically possible, you can use our request for quotes to obtain quotes from a maximum of three checked installers. Please state how many flats the building has and how it is currently heated.