Why the switch to climate-friendly heating systems is so difficult

SPD, Greens and FDP want to change that and drive the heat transition forward, after all, they want to Germany be carbon neutral by 2045. Newly installed heating systems should therefore be operated on the basis of at least 65 percent renewable energies from 2025, according to the coalition agreement of the traffic light government.

Around half of the approximately 21 million heating systems installed in Germany are considered outdated and technically inefficient. According to the German Energy Agency (Dena), a good 75 percent of residential buildings are equipped with oil or gas heating.

For reasons of climate protection, the government’s plan is correct, but there will be problems when it comes to implementation. “A sudden three-year period is simply not realistic for the development and implementation of comprehensive solutions that should also be marketable and affordable,” says Axel Gedaschko, President of the Central Association of the Housing Industry GdW.

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One-size-fits-all solutions impossible

Gedaschko warns that the 65 percent requirement from the coalition agreement would affect all systems across the board without being able to take into account the different local energy supply situations and the given conditions. The supply networks, especially for electricity but also district heating, are not ready yet.


The challenges are complex: “There is no ‘one’ solution that works well for everyone,” says Lamia Messari-Becker, civil engineer and former member of the Advisory Council on the Environment, describing the problem.

Different ways are needed to achieve climate protection in the building stock. Both the supply infrastructure and the technical requirements in the buildings themselves are so different that general solutions are simply impossible.

With natural gas and solar thermal energy, the 65 percent cannot currently be reached, and wood pellet solutions are becoming scarce, Messari-Becker points out. “What remains is the electricity-based heat pump.” But with the current electricity prices, that would be very expensive for many people, especially in existing buildings, and could lead to social upheaval. With the current green electricity supply and demand in all sectors, the project was not thought through to the end “and more of a blind flight”.

>>Read more: “Unfulfillable dream” – climate neutrality of buildings by 2045 is hardly achievable

Simon Müller, Germany director of the Agora Energiewende think tank, is also skeptical. “In new construction, it is not a problem to achieve a share of 65 percent renewables,” says Müller. The technical and financial effort is significantly higher in the existing building, and a clever mix of instruments is needed.

Even within the new traffic light government, people know how ambitious the project is. In the building sector, however, not enough has happened in recent years, says Daniel Föst, spokesman for construction and housing policy FDP-Bundestag faction. If the climate goals are to be achieved, “we need ambitious goals”.

Demands for a rehabilitation roadmap

The climate-friendly alternatives to old oil and gas heating systems include heat pumps, which use electricity to extract heat from the outside area and emit it into the house. Their sales are increasing, but above all for one- and two-family houses, less for the apartment buildings in the big cities.

new housing estate

In new construction, it is not a problem to achieve a 65 percent share of renewables.

(Photo: dpa)

“Heat pumps often have to be considered together with other measures on the building technology and shell,” explains Stefan Schönberger, climate expert at the Boston Consulting Group (BCG). “Compared to fossil boilers, this also results in a higher capital requirement.” In addition, there is currently a huge lack of information among homeowners as to which solution makes sense and which alternatives exist.

BCG sees the government as having a duty to provide more clarity. “It would make sense to draw up a renovation schedule for each building that describes a solution that is optimal in terms of costs and technology,” says Schönberger. “Anyone who will have to replace the heating system from 2025 should be able to decide what to invest in, what funding options they have and how they can finance it. Otherwise you are completely at the mercy of the market.”

>> Read here: In 2021, Germans will install more gas heaters than they have in 25 years

District heating is also considered a future-proof option for cities. So far, however, according to BCG, only up to 30 percent of households in large cities such as Berlin and Hamburg are supplied with district heating, while this proportion is over 80 percent in Scandinavian cities such as Stockholm or Copenhagen.


In addition, district heating has so far mainly been generated by burning coal and natural gas. But it can also come from waste heat from power plants or industrial plants or be produced with the help of geothermal energy, i.e. geothermal energy, which is increasingly happening in Munich. Today, the share of renewable energies in district heating is just 17.5 percent, according to the industry association BDEW.

Demands for municipal heat planning

The Federal Ministry of Economics relies on heat suppliers developing new areas and consolidating existing district heating networks by connecting additional buildings in an existing district heating area. A new federal subsidy for efficient heating networks (BEW) is to start before the end of this year. This should make it easier for suppliers to convert existing heating networks to renewable energies and otherwise unused waste heat at economical conditions.


Experts are therefore calling for municipal heating planning as soon as possible in order to offer investors long-term orientation. What are the general conditions? What renewable heat sources are locally available? What does the current network look like? What is the building stock like on site? Does it make sense for individual cities to connect to district heating networks, or are neighborhood solutions needed?

Replacing the heater is not enough

Buildings must also be able to absorb the heat, and this also requires investment. Large district heating networks are currently bringing the heating water to the house transfer station at a temperature of 90 degrees Celsius and higher, from where the heat is then distributed to the heating systems. In the long term, heating networks can and should be converted to lower temperatures.

“We have to use the resources for energy-efficient renovation efficiently,” warns Agora thinker Simon Müller. Replacing the heating system, which is already complicated enough, is not enough. “You need to work together when renovating buildings.” That means thinking about how the most emissions can be saved in the long term: by insulating the building shell, replacing the windows, replacing the heating.

The question of how well hydrogen is suited to promoting the heat transition is controversial. In the future, green hydrogen could be fed into the existing gas network and mixed with natural gas, but it is likely to be in short supply in the next few years and better used in other sectors, such as industry or shipping.

More: Gas heating, heat pump, wood pellets? This is the best way for consumers to heat in the future

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