As German summers grow hotter and longer, the question of how to keep your home cool is becoming increasingly relevant — not just for comfort, but for health and productivity. Many homes across Germany have already been fitted with heat pumps as part of the country's shift away from gas heating. What many residents do not realise is that a modern heat pump can also work as a cooling system in summer. For expats living in Germany, understanding this can help you make better decisions about your home, whether you rent or own.
Heat pumps work by transferring heat from one place to another. In winter, they extract heat from the ground, air, or water outside and bring it into your home. In summer, the process can be reversed: the pump moves heat out of your home, effectively cooling it.
There are two main ways this works:
Passive cooling (natural cooling): This mode uses the naturally low temperature of the ground (in ground-source heat pumps) to cool the building without running the compressor. It is energy-efficient and quiet, but provides only mild cooling — enough to take the edge off the heat rather than create a cold room.
Active cooling: Here the heat pump works like a traditional air conditioning unit, running the compressor in reverse to actively cool the indoor air. This provides stronger cooling but uses more electricity. Not all heat pump models support this mode — it depends on the specific unit installed.
The cooling capability of a heat pump depends heavily on its type:
If you are a tenant in a flat or house with a heat pump, check with your landlord or building manager whether the system has a cooling function activated. In many cases, the hardware supports cooling but it has not been configured or switched on.
For tenants, the heat pump is part of the building infrastructure and is the landlord's responsibility. However, you can:
For homeowners or those planning to install a heat pump, it is worth asking the installer specifically about summer cooling options before purchase. Not all systems come with active cooling as standard — it may be an add-on that needs to be factored into the budget.
Passive cooling is very affordable to run, as the compressor is not active. Active cooling uses more energy, comparable to a mid-range portable air conditioner. Given current electricity prices in Germany, it is worth calculating the cost before running the system intensively. Energy comparison platforms and your heat pump installer can provide estimates based on your specific model and home size.
Also note that the Bundesförderung für effiziente Gebäude (BEG) subsidy programme, which supports energy-efficient heating upgrades, does not specifically subsidise cooling functions — though the base heat pump installation may still qualify for funding if you are in the process of upgrading.
Yes, you can ask. Whether the landlord is obliged to activate it depends on your rental contract and the specific system. There is no general legal requirement in Germany for landlords to provide active cooling. However, raising it as a request is entirely reasonable, especially during a heat wave. Frame it as a question about whether the existing system has unused functionality rather than a demand for a new installation.
Active cooling mode in a heat pump can be comparable to a traditional air conditioner in terms of cooling output, though performance varies by model. Passive cooling is gentler and works best in well-insulated homes. For very hot days above 35°C, some systems may struggle to cool efficiently. If you need guaranteed strong cooling, a dedicated split-unit air conditioner may still be more reliable — but for most German summer conditions, a heat pump in cooling mode is a practical and energy-efficient option.
If your home already has a heat pump, it may be quietly sitting on a cooling function you have never used. Whether you rent or own, it is worth investigating this before investing in a separate air conditioning unit. Talk to your landlord, building manager, or installer, and check the technical documentation for your specific model. As German summers continue to intensify, making the most of existing infrastructure is both practical and cost-effective.
Source: Tagesschau
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