DThe heat pump is considered the environmentally friendly and future-proof alternative to oil and gas heating. In 2021, over 40 percent of new buildings were equipped with it.
This may also be due to the fact that heat pumps are generously subsidized by the state. But are they really the best solution for everyone? Owners should ask themselves these questions when planning.
Does the heat pump achieve the intended goal?
As of January 1, 2025, every newly installed heating system should be operated on the basis of 65 percent renewable energies. Experts are optimistic that this can be achieved with heat pump heating systems – provided they are correctly dimensioned and correctly installed.
“Heat pumps are without question sustainable and should play a key role in the energy transition,” says Stefan Materne from the energy advice team at the consumer advice center.
And Alexander Steinfeldt from the non-profit consulting company Co2online says about heat pumps compared to oil and gas heating: “In many cases, the heat pump is the better choice – especially if very efficient models are used, the building is well insulated and the heating system is combined with solar energy will.”
However, the flow temperature of the heating system is decisive for this question in individual cases. “The lower it is, the more efficiently the heat pump works and the less electricity is consumed,” explains Martin Sabel, Managing Director of the German Heat Pump Association. “However, it is definitely a suitable option for meeting the target of using more than 65 percent renewable energies.”
When does a heat pump work economically?
The important key figure is the highest possible annual performance factor of the heat pump. It provides information about the efficiency of the heating system. An annual performance factor of 4 means, for example, that 75 percent environmental heat is obtained from 25 percent electricity.
“The higher the annual performance factor, the lower the required flow temperature and the greater the use of additional renewable energies, the more economically the heat pump runs,” summarizes Alexander Steinfeldt from Co2online.
In concrete terms, this means for your house: “An optimally running heat pump achieves annual performance factors of 3 to 5,” says Stefan Materne. And the flow temperature is best below 50 degrees Celsius.
Is my house suitable for a heat pump?
The low flow temperature can be achieved in energy-efficient buildings that have panel heaters or other sufficiently dimensioned heaters and may be supported by solar thermal energy.
“These properties are already standard in new buildings, but in existing buildings they may first have to be achieved through refurbishment measures,” says Alexander Steinfeldt.
How extensive is such a renovation?
Of course, this depends on the energetic condition of the building. “Many things have to fit together,” says Steinfeldt. “The house must be well insulated and if possible have underfloor heating. It would also be nice if there was a buffer storage.”
In his opinion, it is difficult and expensive, but not impossible, to achieve reasonable flow temperatures in an old building. “If that doesn’t quite work, you can combine a gas heater with the heat pump. But that would only be the second choice,” says the expert Steinfeldt.
How can I prevent heat pump noise?
“Noise is definitely an issue that homeowners should think about right from the planning stage,” advises Martin Sabel. “Air-to-water heat pumps, for example, which draw their energy from the air, generate large volume flows that cause noise in the fan. It is therefore important to install the system professionally and to maintain the necessary distances to neighboring properties.”
The online sound calculator from the Federal Association of Heat Pumps helps to assess models and suitable locations for them. In addition, the noise immissions of air-water heat pumps in daytime operation can be determined at times of increased sensitivity and during the night.
With targeted measures, the noise can be significantly reduced: “If possible, installation on or in front of hard surfaces and walls should be avoided,” advises Alexander Steinfeldt.
“The sound is reflected on these surfaces and thus the volume of the operating noise is amplified.” If you set up the system in the room, you can reduce the noise pollution with rubber feet and a circumferential groove at the installation site as well as hose lines instead of pipes.
How are heat pumps funded?
The Federal Office of Economics and Export Control (Bafa) awards a subsidy of 35 percent of the eligible costs of a heat pump. If you replace an oil heating system with a heat pump in the existing building, it is even 45 percent of the eligible costs. There are also different regional pots. The Federal Heat Pump Association offers a subsidy calculator online, and Co2online also has a subsidy check.
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