Berlin The transition to climate-friendly living is one of the major challenges for German politics. After all, real estate accounts for around a third of energy consumption in this country. The climate protection targets for 2020 have already been missed, and things are not looking much better for 2021 either. Without a higher renovation rate, without more renewable energies in the buildings, the goal of climate neutrality in 2045 can hardly be achieved.
Georg Friedrichs, head of the Berlin power supply company Gasag, already sees a climate-neutral building stock in just over 20 years as an “unfulfillable dream”. The refurbishment rate in Germany is around one percent, and in Berlin it is even lower at 0.6 percent, said Friedrichs on Wednesday at the three-day Handelsblatt energy summit.
“Even if we triple or quadruple that, we’ll achieve a refurbishment rate of a maximum of 2.5 percent per year.” That’s not enough to make the buildings climate neutral by 2045. His prognosis: “Half of the German building stock will not have been renovated in a sustainable manner by 2045.”
Florian Bieberbach, head of Stadtwerke München, is also skeptical. “We assume that the refurbishment rates will slowly increase to around 2.5 percent, we think more is illusory,” he said at the energy summit.
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As a result, the building sector will also need more electricity in the coming years in order to be able to at least heat poorly renovated properties with green energy.
Gasag boss: “The battle will be won in stock”
The problem is not so much in new buildings, where green solutions are often used today. “The battle will be won in the inventory,” said Friedrichs. In Berlin, for example, 90 percent of the residential units are apartment buildings, some with complex ownership structures, “that’s not easy to renovate”.
Friedrichs dispelled the hope that individual houses or neighborhoods could supply themselves with their own electricity. “A capital like Berlin cannot supply itself with energy independently,” he said. This dream should be buried. It always makes sense that every city, every house, tries to produce as much direct green energy as possible, for example through photovoltaics. The neighborhood approach is also correct, especially in the new building. Nevertheless, this is only one building block so far. “I don’t know of a single neighborhood project where it has been possible to combine several existing buildings into a uniform energy supply.”
Many individual solutions are required for a heat transition in Germany. “We have to specifically address individual locations,” said Uwe Lauber, head of engine manufacturer MAN Energy Solutions, at the Handelsblatt energy summit. Verena Graichen, deputy chairwoman of the German Federation for the Environment and Nature Conservation (BUND), made it clear: “We need tailor-made solutions everywhere in the heating sector.”
The heat transition is a little-noticed but important aspect for a successful energy transition. Gas is still the most used energy source in Germany when it comes to heating. According to an evaluation by the industry association BDEW, around half of all apartments in Germany are still heated with gas. Another quarter is heated with oil. According to the Federal Environment Agency, only 15.6 percent of the energy in the heating sector comes from renewable energies.
Little has happened in recent years. Unlike the energy transition in electricity production, which is already much more advanced, the heat transition also depends heavily on the local level: millions of private households have to contribute.
District heating as the dominant technology in Munich
More funding than before will therefore be essential. Verena Graichen from BUND warned that when it comes to refurbishment, one must also focus on tenants and less affluent homeowners who cannot financially carry out the refurbishment themselves.
In addition to renovations, old oil and gas heating systems also have to be exchanged for more climate-friendly alternatives. These alternatives include heat pumps, which use electricity to extract heat from the outside area and emit it into the house. Sales of heat pumps are increasing, but primarily in the area of detached and semi-detached houses, less so in apartment buildings.
Meanwhile, MAN manager Lauber reported: “The topic of large heat pumps is on our minds.” Heat pumps are also important because they can serve as a control element for network stabilization. For example, heat pumps can be switched off temporarily when there is little renewable electricity from wind and sun in the grid.
An alternative to the heat pump is supply via district heating. According to BDEW, more than every fourth new apartment is equipped with this in new housing construction. Waste heat from a nearby power plant, for example, is routed directly to households.
District heating will be the dominant technology in Munich in the future, said Stadtwerke boss Bieberbach. However, district heating can not only come from conventional power plants, but can also be produced with the help of geothermal energy, i.e. geothermal energy. It is extracted from the ground via geothermal heat exchangers. Stadtwerke München has been using this technology since 2004 and has now built six geothermal systems.
Set priorities when using hydrogen
Even if tailor-made solutions are needed for the heat transition, according to Bieberbach, it is too often assumed that geothermal energy is a specific solution. In Germany there is geothermal energy in many places. “It’s the second major source of energy next to solar energy, only it’s always available,” he said.
One thing is clear: craftsmen are needed to implement all the necessary renovations – and they are increasingly scarce in Germany, which also became clear once again at the energy summit. Industry representatives are therefore campaigning for young people to be trained as quickly as possible.
“We have to ensure that the people who are now entering the workforce develop the appropriate skills,” said Karl Gruber, Managing Director of the Austrian energy supplier Wien Energie. MAN manager Lauber also emphasized that there are hardly any resources available, especially in the area of smaller workshops. Environmental expert Graichen added that it is also important to reduce the time that craftsmen spend on a construction site, for example by cutting insulation boards beforehand.
However, 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 to cause fewer emissions. However, BUND expert Graichen said: “Hydrogen admixtures in the natural gas network are not sustainable.” This causes problems for industrial companies that use pure natural gas as a raw material.
MAN manager Lauber warned to think carefully about the areas in which the scarce, green hydrogen is actually necessary and where there are more sensible alternatives. “There are sectors such as shipping on the world’s oceans, where hydrogen is essential,” says Lauber. “Using hydrogen for heat generation is not the top priority.”
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