Berlin Household energy consumption in Germany is largely based on non-renewable energy sources. Heat and hot water are mainly generated with natural gas and fuel oil. Around half of all apartments are heated with natural gas, a quarter of all apartments with oil – directly and indirectly via district heating. In the event of a delivery stop or a shortage of Russian oil or gas, nobody would have to freeze. Households are particularly protected and would be given priority with heating energy. Nevertheless, there is a call to save energy.
For the civil engineer Lamia Messari-Becker, professor for building technology and building physics at the University of Siegen and former member of the environmental council, one thing is certain: “Appropriate energy saving is not an additional option, but elementary. In the private as well as in the public and industrial sector, everyone is required to raise savings reserves.”
In the building sector alone, the magnitude is not insignificant. Messari-Becker, who is also a member of the Federal Building Ministry’s “Future Construction” expert group, assumes that up to a quarter of the energy could be saved through short-term measures alone.
Julia Verlinden, deputy chairwoman of the Greens parliamentary group, also believes that energy consumption in buildings is “much higher than it should be”. Even more than in the case of electricity generation, the previous governments have done too little in the energy transition in the heating sector in recent years.
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According to figures from the Federal Association of Energy and Water Industries (BDEW), the share of renewable energies in heat supply is only around 15 percent, while it accounts for almost half in electricity generation. “From a purely technical point of view, you could halve the energy requirement in buildings if you wanted to,” Verlinden told the Handelsblatt. Three central measures in the building sector that reduce energy requirements in the short term:
Optimization of heating systems
Axel Gedaschko, President of the Central Association of the Housing Industry (GdW), advises building owners to have the operation of heating systems in buildings checked and improved.
In order to reduce energy consumption, the heating systems would also have to be optimized.
(Photo: dpa)
The alliance for a climate-neutral residential building stock explains that existing heating systems are often oversized. As a result, they often run inefficiently and waste energy.
If a heating system is replaced, the output of the new system is often based more on the old system than on the specific power requirements of the building. In day-to-day operation, the heating output and flow temperatures have often not been adequately adapted to the outside temperatures.
Messari-Becker also considers the optimization of heating systems to be a must. “This also includes an effective night-time temperature reduction in existing buildings. That is still the exception today.”
Reduce room temperature in private and public buildings
According to the International Energy Agency (IEA), the average temperature in heated buildings in the EU is 22 degrees Celsius. If people forgo just one degree of heat, this would result in immediate annual energy savings of around ten billion cubic meters of natural gas in Europe.
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For Germany, the Federal Environment Agency estimates that by reducing the room temperature by two degrees in all German residential and non-residential buildings and by using shower-saving heads, around ten percent of Russian natural gas can be saved.
Messari-Becker says: “The rule of thumb is: One degree less saves five to six percent of energy.” Although this is not arbitrarily scalable, two to three degrees are feasible. However, the temperature should not drop below 18 degrees. Otherwise, health risks and the risk of mold would be promoted.
The Bund für Umwelt und Naturschutz Deutschland (BUND) is also calling for the temperature in all public buildings to be reduced to 19 degrees as an immediate measure.
Proper ventilation
It reads banal, but it isn’t. Constant ventilation reduces the room temperature and the heating ramps up massively. For the GdW, user behavior is also a decisive lever for reducing energy consumption.
The right way to ventilate can reduce the energy demand.
(Photo: imago images/blickwinkel)
According to GdW boss Gedaschko, more energy-saving heating and ventilation should therefore be encouraged and clarified. The use of uniform, easy-to-use and inexpensive smart home devices in the apartments can support this.
Three key measures in the building sector that will reduce energy requirements in the medium term:
Replace heaters, speed up renovation
Environmental organizations such as BUND are calling for existing heating systems to be optimized or replaced with energy-saving alternatives such as heat pumps. The German Nature Conservation Union (Nabu) criticizes that there is a lack of clear will when it comes to the sanitation standards. Gas heaters should no longer be installed from now on and the promotion of wood heaters must finally be stopped – there are already too many.
Green politician Verlinden considers it crucial not only to replace the heating systems, but also to reduce energy consumption. “It’s not enough to run the heaters with green electricity,” she said. “There is currently not that much green electricity available.” In addition, the following applies: “The less energy we need, the faster we can achieve the goal of using 100 percent renewable energies in all sectors.”
According to Verlinden, the focus should be on the buildings with the worst energy ratings in order to progress. That would be a third of all residential buildings in Germany. “If we succeed in refurbishing these buildings to an efficiency house standard of level 55, then we would only consume about half the energy in the residential building sector,” Verlinden told the Handelsblatt.
An efficiency house is a building that meets a certain level of energy efficiency, which can be achieved through energy-related refurbishment. The following applies: the smaller the index of the efficiency house level, the less energy the property consumes. In new builds, a large part of the real estate already achieves the efficiency house standard 55, currently only the efficiency house level 40 is funded.
Support for renovation roadmaps
Verlinden, who was energy policy spokeswoman for her group for eight years, believes that financial support for homeowners to draw up renovation roadmaps is essential. “The free renovation schedules that we agreed in the coalition agreement must come this year,” said Verlinden. “This is the only way we can get the speed up in building renovation.”
>> Read More: “Unfulfillable dream” – climate neutrality of buildings by 2045 is hardly achievable
Especially if homeowners decide to renovate their property in stages for cost reasons, “all steps must be well coordinated to avoid unnecessary duplication of work”.
Municipal heat planning
District heating is considered a future-proof option, especially in cities. So far, this has mainly been generated by burning coal and natural gas – but it can also be produced using waste heat from power plants or industrial plants or with the help of geothermal energy, i.e. geothermal energy. “This potential must finally be checked and used before new power plants are built,” says Verlinden.
Some municipalities rely on geothermal heat for their heat supply
In addition, “the government has a funding program for the decarbonization of the heating networks in the pipeline, which the EU Commission still has to examine with a view to state aid law,” she said.
The challenges are complex. Civil engineer Messari-Becker says: “There is no ‘one’ solution that works well for everyone.” Both the supply infrastructure and the technical requirements in the buildings themselves are so different that one-size-fits-all solutions are simply impossible. “We need technically open solutions,” she said.
One thing is clear: the need for action is immense. “If Russian natural gas imports failed and there was no replacement, there would be devastating consequences with domino effects,” warns the scientist.
If basic industries such as glass, chemicals, steel and cement came to a standstill, all further efforts to achieve a heating transition would no longer be possible: no heating technology without steel, no solar modules or windows without glass, no wind turbines without cement for concrete foundations, no insulating boards without the chemical industry. The climate targets would also be a thing of the past.
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