• Reduce ongoing operating costs and therefore also ancillary costs
• CO2 Emissionen durch den Stromverbrauch sinken mit steigendem Anteil regenerativer Energien am Strommix
• Klimafreundliche Wärmepumpen erfüllen alle Vorgaben des GEG
• Der Wert einer sanierten Immobilie steigt
• Verminderte oder gar keine CO2-Kosten im Gegensatz zum Heizen mit Gas und Öl
• Umlagemöglichkeit der Investitionskosten für die Wärmepumpe auf die Kaltmiete (wenn bauliche Maßnahme)
• Klimafreundliche und energieeffiziente Wärme steht bei Mieterinnen und Mietern hoch im Kurs
• Staatliche Förderung für die Wärmepumpe

Rising energy costs and the amended Building Energy Act (GEG), which has been in force in Germany since January 1, 2024, make solutions for climate-friendly heating an ongoing issue for owners of multi-family houses. This is because from mid-2028 at the latest, all new heating systems are to be operated with 65% renewable energy.
According to the "dena practical guide for heat pumps in multi-family houses" from March 2024, one in three heating systems in multi-family houses is already over 20 years old. With a total of 3.3 million multi-family homes in Germany alone, a huge wave of refurbishment is rolling towards owners and heating companies.

Sounds like a clear case for the heat pump, doesn't it? It uses around three quarters of the free ambient energy from air, earth, water or waste heat. It works much more efficiently than a heating system powered by oil or gas and, as the proportion of renewable energies in the electricity mix increases, the operating costs for the residents of the apartments will also fall in the medium term. However, there is no one-size-fits-all solution for either new or existing buildings. Logically, because no two apartment buildings are the same in terms of building fabric, insulation standard, building density, apartment sizes, required heating load and heat demand. The available heat sources and the space available, for example for the probes of a geothermal heat pump, a large buffer cylinder or outdoor installation, are also always different. Therefore, our tip: Make sure you rely on the experience of a specialized installer if you want to make sure that the heat pump is perfectly designed for the required heat load in your multi-family home.

An individual renovation roadmap is also important here: If you want to install the heat pump first and then renovate your apartment building step by step, a bivalent system is an option, for example, in which you combine the heat pump with a gas boiler to cover the higher heating requirements. In addition, undersized radiators are identified and models recommended for replacement in order to further reduce the heating load and flow temperature.

Multi-family houses are diverse. Although this increases the complexity, it also opens up more technical possibilities than single-family homes. For example, several heat sources such as geothermal energy, waste water, waste heat or outside air, as well as heat pumps and heating systems, can be combined in multi-family buildings. As part of the IEA HPT Annex 50 Heat Pumps in Multi-Family Buildings working group, solutions that have already been implemented in several countries were divided into five "families".

Family 1 describes central heat pump systems for the entire building, family 2 the combination of central and decentralized solutions, family 3 the use of heat pumps for specific residential units, family 4 the installation of heat pumps in individual apartments and family 5 the single-room heat pump.

According to the dena guideline mentioned above, "More than half of existing buildings are operated with central boilers and fossil fuels; 18.2% are supplied with heat via decentralized, apartment-based heating systems such as gas floor heating or individual stoves. More than a third of centrally heated buildings have an additional decentralized DHW heating system." Accordingly, solution family 1 with monoenergetic, monovalent and bivalent heating systems and solution family 2 are currently predominant in Germany. The latter describes, for example, the combination of central heat supply and decentralized provision of hot water with domestic hot water heat pumps in the individual apartments. This solution also prevents the formation of legionella bacteria. If your building has a large storage tank and large-volume pipes for hot water, you will certainly be familiar with this topic.

If there is enough space on the property, you can install the air/water heat pump outside. In this case, you should of course ensure sufficient sound insulation and an attractive design. A little self-promotion is allowed at this point: Our Hybrox air/water heat pump has a noise level of 45 dB(A) measured directly at the sound source and is therefore officially considered quiet. In cascade, it achieves a heating output of up to 52 kW and is operated with the natural refrigerant propane.

If the load-bearing capacity is sufficient, an air/water heat pump or a heat pump cascade can also be installed on the roof. Up there, the air usually circulates undisturbed and the heat pump does not take up any valuable space on the property. However, the installation is usually more complex.

In many cases, the basement is also a suitable installation location for an air/water heat pump. Here, it must be clarified in advance whether the air duct to the pump or, in the case of a split unit, the supply of the cooling circuit pipe is feasible without major conversions and openings. In the case of a brine/water heat pump, which draws its thermal energy from the ground, it almost goes without saying that the indoor unit should be installed in the basement, as long pipes always result in a loss of heat.

More and more studies and reference reports are showing that heat pumps can also be used efficiently for heating, cooling and hot water in multistorey buildings. In new buildings in particular, the heating system, a large-scale heat distribution system such as underfloor heating or wall heating and the thermal insulation can be optimally coordinated. But it is also becoming more and more common in existing buildings. However, regardless of whether it is a new or existing building, the lowest possible flow temperatures and the lowest possible heat losses are always a decisive factor for the energy efficiency of a heating system and especially of the heat pump, which can work with lower heating circuit temperatures than a modern condensing boiler due to its design.

To heat as efficiently as possible, your heat pump should be able to adapt the heating output to the actual demand. Fluctuating temperatures of the energy source and outside temperatures change the heat requirement, and a clever system can react to this. There are several technical options for this in multi-family houses:

• The heat pump with inverter technology: These speed-controlled units are permanently in operation and can regulate their output continuously to the desired temperature for heating and hot water.
• The heat pump with cascade connection: In a cascaded system, the heating output of the individual heat pumps is added together. It can therefore supply large properties with heat on the one hand, and on the other hand it can provide this flexibly and in line with demand by switching individual appliances on and off. Ideally, you should consider an inverter heat pump cascade, which enables even more precise and faster modulation of the heating output.
• Multi-stage heat pumps: Here, several circuit processes can be switched in succession. The temperature level reached in each case is the starting point for the next stage.