The decision for a heating system depends on many factors. We provide an overview of the various technologies and their respective advantages and disadvantages.
Energy transition, gas embargo, price explosion, shortage of tradesmen, funding chaos: these days, homeowners feel like a pawn in the game of authorities, geopolitics and energy markets. Anyone who needs to renew their heating system is faced with a bill with numerous unknowns. And quite a few are considering replacement in view of rising energy prices, even though the system is far from having reached its technical end of life. But the decision is complex, and uncertainty has never been as great as it is today.
This is particularly true for owners of residential and commercial buildings. Not only is the investment usually considerably larger than for a single-family home, they also have to take into account the respective requirements of the different types of use and tenants.
One thing is clear: There is no one optimal solution for all buildings. It depends on the type, condition and location of the property. It also depends on assumptions about the future development of the energy markets. But a heating system is an expensive and long-term investment. If regulation and markets develop differently than expected, this can throw the profitability calculation out of kilter.
But there are trends that can help with the decision. One thing is clear: systems that burn fossil fuels will be phased out in the medium term. This has already been ensured by installation bans and CO2 taxation. The current geopolitical upheavals, which are leading to a price explosion for oil and gas, are likely to accelerate the process. In the following, we provide an overview of the technical heating alternatives with their respective advantages and disadvantages:
The majority of heating systems in German buildings are still so-called condensing boilers that burn natural gas or fuel oil. Gas heating systems generally require a connection to the gas network. If there is none, it is possible to operate the heating system with liquefied petroleum gas (LPG). This requires a tank that must meet high safety standards because LPG is highly explosive.
Condensing boilers generate CO2 and particulate matter and are therefore only to be allowed to be newly installed in exceptional cases from 2024 onwards, according to the political will. Existing systems may continue to be used, however, provided they were built after 1992.
Heat pump heating is still not very widespread, but it is on the rise. It draws thermal energy from the environment, usually the outside air. However, it is also possible to use heat from the ground or groundwater. The actual heat generation is CO2-free, but the system needs electricity to operate. The heat pump works most efficiently when high flow temperatures are not required. This is most likely to be the case in modern new buildings that are well insulated and have underfloor heating. In old buildings with poor insulation, the system works less efficiently because it then consumes more electricity.
Solar thermal uses solar radiation to generate heat for heating and hot water. The technology is not to be confused with photovoltaics, which generates electricity from sunlight. Solar thermal energy heats water that is passed through collectors usually installed on the roof. It is thus one of the emission-free types of heat generation. Whether a solar thermal system can be used effectively depends to a large extent on whether sufficient unshaded outdoor space is available for the installation of collectors, as well as on their orientation and inclination. Even if the conditions are met, the energy yield varies greatly depending on the weather and season. Therefore, the technology is usually not suitable as a stand-alone heating system, but it is suitable as part of a hybrid system together with another technology.
In pellet heating systems, pellets are burned from wood residues or other plant material. This produces CO2, and fine dust is also released. However, the technology meets the requirements of the Renewable Energy Sources Act because the fuel is a renewable raw material.
Fuel cell heating is a relatively new technology that converts a fuel directly into electricity. This can be used for heating as well as for other power supply of the house, surplus energy is fed into the power grid. The fuel used is usually natural gas, but operation with liquefied petroleum gas is also possible. The technology is considered environmentally friendly because it is highly efficient. CO2 emissions are lower than with conventional condensing boilers, and particulate matter is not produced.
Combined heat and power plants generate electricity and heat simultaneously from one fuel according to the principle of cogeneration. They have better energy efficiency than electricity and heat supply because the waste heat from electricity generation is used. In the residential sector, cogeneration units are mostly used for apartment complexes or housing estates, but there are also small units for single-family houses. The amount of CO2 or particulate emissions depends on which fuel is used. In addition to fossil fuels, biogas can also be used, and operation with a fuel cell is also possible.
District heating systems draw heat from a district heating network. For this purpose, water is heated in a combined heat and power plant and distributed to the individual buildings via a network of pipes. The installation effort in the building is relatively low: A connection to the district heating network is required, as well as a transfer station that transfers the heat to the building's own heating circuit.
The prerequisite for use is that a district heating network exists at the location. If this is the case, some cities and municipalities impose a connection and use obligation; homeowners are then forced to use district heating and cannot resort to other types of heating instead.
How environmentally friendly district heating is is determined by the power plant supplying it. District heating plants can run on fossil fuels or renewable fuels, which means CO2 and possibly other emissions. Geothermal or solar thermal as renewable heat sources are also possible, but are not yet widespread.
In some cases, it can make sense to use several heating technologies in parallel. Solar thermal, for example, cannot usually provide sufficient heating energy throughout the year. However, it can complement existing condensing boilers and improve the energy and cost efficiency of the overall system. Heat pump heating systems often reach their limits, especially in older, poorly insulated houses. In high-load periods, they either do not supply enough heating energy, or this becomes uneconomical due to the high electricity consumption. Depending on the conditions, however, it can make sense to use a heat pump as the main heating system, and to additionally use an existing condensing boiler during high-load periods.
The costs of installing the various heating systems depend, among other things, on the dimensioning and the individual conditions on site. Recently, costs have been subject to strong fluctuations, but with a clear upward trend. On the one hand, this has to do with the growing demand for more efficient systems, driven by increasing energy efficiency requirements and rising energy prices. However, an important cost driver is also the short supply of certain parts as a result of the pandemic and the Ukraine war, as well as the acute shortage of skilled workers at specialist companies. Cost figures can therefore only ever be a snapshot. Future-oriented systems such as heat pumps and fuel cells are currently still more expensive than conventional condensing boilers.
However, the operating costs over the following service life, which depend heavily on the fossil fuels used or saved, must be offset. These also fluctuate extremely at present due to geopolitical events; driven by climate policy, however, the trend is likely to point strongly upward in the long term.
The cost of renewable fuels also fluctuates wildly at present and is expected to rise in the longer term due to increasing demand. Pellets are currently mostly made from wood processing waste and are relatively inexpensive; however, if the technology becomes more widespread, they could become more expensive in the future. The cost of district heating can fluctuate widely and depends on the cost structure of the power plant supplying it.
An important factor in the economic calculation and at the same time an indicator for the political future of the individual systems is the state subsidy. The website of the KfW development bank provides an overview.
There are already no subsidies for oil heating systems, and only particularly energy-efficient gas heating systems are currently eligible. Those who replace an oil heating system with an eligible new system can receive additional subsidies.
In principle, the federal government supports the installation of systems that rely wholly or partially on renewable energy sources with varying amounts of funding. Additional funds are possible if an old oil heating system is replaced in the process.
One thing is clear: the decision to renovate a heating system cannot be made by a layperson alone; it is strongly recommended that a knowledgeable energy consultant be engaged. The costs are money well spent, and if you buy a heating system that is eligible for funding, the state will also pay part of the fee.
Opening hours:
Mon - Fri from 9 am to 6 pm