Heat pumps in older buildings — what really works in Bavaria

Updated: May 2026 — the short answer

Heat pumps work in most older buildings in Bavaria — provided the heat-emission surfaces are adequately dimensioned and the building envelope is not in completely poor condition. The annual coefficient of performance (JAZ) determines cost-effectiveness; with a well-engineered system, experience suggests JAZ values of 2.8 to 3.5 (air-water) and 3.5 to 4.5 (geothermal) are realistic in existing buildings. In the 5-Seen-Land and in water protection zones, special rules apply to ground-source and groundwater heat pumps — there, air-water is often the first choice.

Heat pumps and older buildings — the myth

"Heat pumps only work in new builds" — at enbe, we hear this sentence regularly. It dates back to a time when heat pumps were technically far less capable and heating systems were typically sized for flow temperatures of 70 to 80 °C.

In 2026, the reality is different. Studies by the Fraunhofer Institute ISE and real-world field measurements consistently show good performance figures in existing buildings — provided the flow temperature of the heating circuit can be lowered to around 55 °C or below. This is achievable in the majority of existing properties, without having to replace every radiator.

The decisive metric is the annual coefficient of performance — Jahresarbeitszahl (JAZ). It indicates how many units of heat the heat pump produces from one unit of electricity. A JAZ of 3 means: 1 kWh of electricity → 3 kWh of heat. The higher the JAZ, the more cost-effective the heat pump.

Prerequisites for a good JAZ in older buildings: - Heat-emission surfaces adequately dimensioned (primary factor) - Building envelope not in a state of complete renovation backlog (secondary) - Properly executed hydraulic balancing - Heat pump sized at a realistic design point — not oversized

Which types are suitable for older buildings?

Air-water heat pump. The most common variant in retrofit projects. Advantages: relatively simple installation, no excavation work, no water-law permit required. Disadvantages: an outdoor unit is needed — acoustically a challenge in gardens or on house walls, particularly in densely built-up areas such as Munich city; lower JAZ at very cold outdoor temperatures.

Ground-source heat pump (brine-water, geothermal). Higher JAZ than air-water, because the heat source (the ground at a depth of 50–100 m) maintains a stable temperature. Disadvantages: drilling costs — and a water-law permit. In the 5-Seen-Land (water protection zones around Starnberger See, Ammersee, Wörthsee), ground probes are restricted or excluded in several zones — we check eligibility for approval before every recommendation. In the Tölzer Land and Werdenfelser Land, geological conditions are often favourable.

Groundwater heat pump (water-water). The highest JAZ of the three variants. Condition: sufficiently productive, near-surface groundwater. Requires a water-law permit — frequently not possible in water protection zones. Also outside the protection zones in Bavaria, often subject to conditions.

Hybrid solution (heat pump + gas boiler). The heat pump covers the base load, while the existing gas boiler steps in at peak load (very cold days). A transitional technology that is often economically sensible in existing buildings — particularly when the existing gas heating is still young and not yet written down.

Prerequisites in existing buildings

Before any heat pump recommendation, at enbe we carry out a structured assessment in five steps:

1. Envelope assessment. What is the energy condition of the walls, roof, windows, basement? What U-value is present, how high is the heat demand? This is the basis for the heating load calculation.

2. Heat-emission surfaces check. Are the existing radiators large enough to deliver the required heat to the room even with a lowered flow temperature (e.g. 45 °C)? If not: which radiators must be enlarged or replaced? Underfloor heating is ideal — old panel radiators can often be replaced cost-effectively with larger Type-22 or Type-33 panel radiators.

3. Heating load calculation according to DIN EN 12831. Mandatory for a sound dimensioning of the heat pump. Anyone relying on rules of thumb or generic assumptions risks an over- or undersized system with poor JAZ.

4. Electrical connection. Is the electrical service capacity sufficient? Heat pump plus Wallbox (EV charging station) plus PV battery considered together — an integrated energy concept is almost always more cost-effective in existing buildings than an isolated single measure.

5. Noise and vibration assessment. Outdoor units generate noise. In densely built-up areas (Munich inner city, terraced-house neighbourhoods), the acoustic impact on neighbours must be legally assessed — TA Lärm sets the limit values. We factor this into every project.

Heat pumps in Munich & Upper Bavaria — local specifics

Munich city area. In the Munich city area, connection to the Munich district heating network is an attractive alternative to a heat pump in several districts — particularly in Sendling, Schwabing-West and parts of Bogenhausen. We recommend always checking the option of connecting to the heating network before deciding on a heat pump — the current situation is reflected in the city's municipal heat plan. Outside the heating network areas, an air-water heat pump is usually the standard solution.

5-Seen-Land. The water protection zones around Starnberger See and Ammersee significantly restrict ground-source and groundwater heat pumps. In large parts of the area, an air-water heat pump is the only practicable variant. Advantage: many existing properties are generously laid out, so the outdoor unit rarely poses an acoustic problem.

Tölzer Land, Werdenfelser Land. Geology is often well suited to geothermal energy. Here, the brine-water heat pump is often the economically most attractive variant — higher initial investment, but better JAZ over the system lifetime.

Augsburg and western Upper Bavaria. Here there are municipal funding programmes for connection to district heating or for the installation of efficient heat pumps. We review the combination options as part of the [funding strategy](/foerderberatung).

Funding 2026

The federal funding programme for efficient buildings — individual measures (BEG EM) currently provides substantial support for heating system replacement, with an additional efficiency bonus for heat pumps with a high JAZ and a heat source of ground or groundwater. Concrete rates are subject to the programme logic and may change — we recalculate for every project.

iSFP bonus. Anyone who has had a [renovation roadmap](/sanierungsfahrplan) drawn up before the heating replacement receives, in practice, an additional bonus on BEG EM measures. The iSFP is itself eligible for funding and is often the economically smartest first step.

Combination with municipal programmes. For Munich properties, BEG EM can experience suggests be combined with the Munich city Climate Protection Funding Programme (FKG). Our [funding strategy](/foerderberatung) reviews the combinations for each project.

Tax leverage. As an alternative to direct funding, energy-related renovation measures can be deducted under § 35c EStG — tax advantages may be possible. Which option is more favourable depends on the individual tax situation — we run the numbers.

Cost-effectiveness — how much electricity does a heat pump use?

The cost-effectiveness of a heat pump stands and falls with the JAZ. A rough orientation for older buildings:

• Air-water in older buildings: JAZ typically 2.8 to 3.5 — depending on envelope condition and heat-emission surface design.
• Brine-water (geothermal) in older buildings: JAZ typically 3.5 to 4.5.
• Water-water (groundwater) in older buildings: JAZ typically above 4.5, in favourable constellations up to 5.5.

These figures are rough orientation values, not guarantees — actual cost-effectiveness depends on the electricity supply contract (heat pump tariff, PV self-consumption), real-world user behaviour and meteorological conditions. We model the case for each project individually.

Anyone combining a PV system with a battery can significantly increase the self-consumption share of the heat pump electricity. In many cases, this makes the heat pump the most cost-effective heating option — provided the system is properly engineered.

Common mistakes during installation

In practice, we at enbe see the same problems again and again:

1. Undersized heat-emission surfaces. The heat pump is sized for the old, high flow temperature — the resulting JAZ is poor. The heat-emission surfaces must be checked and, if necessary, adjusted in advance.

2. Heat pump as a 1:1 replacement without an overall concept. The old heating system is simply replaced by a heat pump, without optimising hydraulics, buffer storage and control system. This rarely works economically.

3. Missing heating load calculation. Rules of thumb frequently lead to oversizing — and therefore to cycling of the heat pump, poor JAZ and premature wear.

4. Incorrect hydraulics. Buffer storage too small, volumetric flow too low, wrong control strategy. Classic pitfalls with non-specialist installers.

5. No hydraulic balancing. Hydraulic balancing according to method B is mandatory for funding — and indispensable for a reasonable JAZ. Cutting corners here means paying more on the electricity bill for years.

FAQ in brief

Heat pump without insulation — does it make sense? A completely uninsulated envelope is a problem, because the heat load remains high and the flow temperature has to be raised accordingly. A moderately renovated envelope (e.g. windows replaced, top floor ceiling insulated) is sufficient in many cases.

What does a heat pump cost? The investment varies strongly by type, heat load, radiator layout and local conditions. For a typical existing single-family home, total costs (heat pump + installation + adjustments) experience suggests range in the mid- to high five-figure bracket — funding covers a relevant share. We work out the concrete figures in the initial consultation.

Is an air-water heat pump sufficient at -15 °C? Modern air-water heat pumps reliably deliver heat even at -15 °C — but the COP drops significantly. The system design must ensure that the heat load is covered even in the coldest design case. In very cold locations (Alpine foothills), a hybrid solution with gas or pellet peak load is sometimes more sensible.

How loud are outdoor units? Modern units often operate with sound pressure levels of 35 to 50 dB(A) at 5 m distance. For the neighbourhood, TA Lärm applies — in residential areas a maximum of 35 dB(A) at the immission point at night. In dense developments, we examine sound propagation before making a recommendation, and consider neighbour rights.

Does a heat pump make sense in a listed building? For listed buildings, a heat pump is often possible, but requires special consideration. The outdoor unit and cabling must be placed in a way that is compatible with heritage protection. Ground probes often need additional permits. A well-founded on-site assessment is essential here.

Next step

Are you considering switching to a heat pump in an older building in the Munich area or Upper Bavaria? In a complimentary 20-minute initial consultation, we will clarify the realistic variant and the funding effect. The [BAFA energy consultation](/bafa-energieberatung) is also available for advisory funding. [Book an appointment](/kontakt) or by phone 089 / 215 484 720.