Berlin, Lunen The former Berlin Tegel Airport is being transformed into a place of the future. A residential area with climate-friendly energy, heating and cooling supplies is being built in the north-west of the capital. The project has a model character for Germany. So-called district solutions are of great importance for the country and its climate goals. Germany should be CO2-neutral by 2045 – and without new ideas and initiatives this can hardly be achieved.
The idea of the Tegel project is to ensure the decentralized supply of green energy to several buildings at the same time. This brings considerable synergy effects, saves costs – and is urgently needed.
“The previous heat supply, essentially based on natural gas and heating oil, is falling away much faster than we previously thought,” said Christian Maass, head of the “Energy Policy – Heat and Efficiency” department in the Federal Ministry of Economics, with regard to the Ukraine war.
Maass explained: New technologies must now be brought directly from the laboratories to the market. It is important to bring innovations to the scale, “so that we can set up a safe, affordable and renewable heat supply much faster than we previously thought that we had time for it”.
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Energy companies and homeowners are working in many places in Germany to make new residential or business locations and existing residential areas more climate-friendly with innovative concepts. The challenges are just as varied and diverse as German residential areas.
Energy concept of the future at the old Berlin airport
The black Volvo takes you across the runway from Tegel to the E1 energy center, which, like the former terminal, the distinctive hexagon, must not be demolished. Massive lines, thick pipes, a massive control panel: “This old energy center with its old gas boilers is being retired and turned into a showroom,” says Andreas Ott, second managing director of Green Urban Energy.
Responsible for the energy concept of the future is Green Urban Energy, a consortium of Eon and the Berliner Stadtwerke, which won the EU-wide tender for the heating and cooling supply for the Tegel area in 2018.
Michael Behrmann, Managing Director of Green Urban Energy, speaks of a “piece of the future” that is being built in Berlin: “We are supporting the most innovative and largest infrastructure project in Germany.”
The project at Tegel Airport is designed for a period of 25 years. Two areas will be created on the site in several construction phases. First, the “Urban Tech Republic”, a research and industrial park with a special focus on sustainability in cities, resource conservation and the use of renewable energies, second, a residential area with around 6,000 apartments, the “Schumacher Quartier”.
The energy world of tomorrow will be less conspicuous than the old one with the energy center – and more sustainable. At its heart: a low-temperature network around twelve kilometers long, known as the “LowEx” network for short, which will be laid underground across the site. Water flows through it, which, like conventional district heating, supplies companies and apartments with heat, but also with cold.
>>> Read here: District heating as an alternative heating: It is so attractive for homeowners
In addition, the LowEx network is operated at a seasonally different temperature level between 20 and 40 degrees Celsius, i.e. with lower temperatures than with district heating. However, higher or lower temperatures are feasible. With the help of decentralized heat pumps and an individually configurable house station, water, heat and cold can be provided for the end user at almost any desired temperature.
Eon Manager Oliver Zernahle calls this an “intelligent and sustainable solution for local heating networks that only a few have on the radar so far”. The concept also includes the feeding in of energy by the companies, which receive remuneration for this. For example, companies can feed the waste heat from internal processes into the LowEx network via a heat exchanger before it is then reused. “We don’t need to generate the energy that we absorb elsewhere,” says Zernahle. “It saves money.”
Fossil energies are largely taboo, the goal is the use of green energies. In 2017, the state of Berlin made an 80 percent share of renewable energies a condition of the tender. In the meantime, Green Urban Energy has had another goal for a long time: 100 percent renewables. Whether electricity, heat or cold, everything should be produced on the site if possible, also to avoid traffic such as the transport of biomass for combustion.
One of the first milestones was a geothermal exploration well in July 2021, before the site was officially handed over for subsequent use. In the new sustainable energy world of tomorrow, geothermal energy is an important source for supplying the low-temperature grid – and thus all users – with heat or cold. Photovoltaics will also play a role, as will wind power and the use of waste water.
The brave new energy world is not uncomplicated. “It’s a kind of open-heart surgery,” says Zernahle. “We are breaking new ground, approaching the ideal world.” So it is not trivial to lay pipes today without knowing who will connect to the local heating line. “Who will that be in ten years?” asks Behrmann. “Do the future customers need a lot of heat, a lot of cold?” Despite all the planning, a lot of flexibility must be retained.
“It will be important that all the cogs mesh and that all investors identify with the concept,” says Leonardo Estrada, engineer and consultant at Drees & Sommer. At the end, the company will certify whether the necessary certifications can be issued.
Residential area redevelopment in the Ruhr area
Many a resident has lived in the buildings of the Bauverein zu Lünen cooperative for decades, as its board member Carsten Unterberg explains. Not much changed in the district near Dortmund during that time. But now the upheaval is coming: The construction association wants to supply its houses with completely CO2-neutral energy by 2045 – and is turning entire neighborhoods inside out.
Unterberg speaks of a “strategic change”. From now on, the cooperative wants to modernize around four percent of its housing stock every year, equipping it with new heating systems or replacing it. The buildings around Espelweg in the Lünen district of Brambauer are currently being renovated. 18 houses with a total of 126 apartments are here in several rows, with sidewalks, trees and meadows in between.
One innovation immediately catches the eye: there is a metal balcony in front of each apartment, which clearly differs from the rest of the house in terms of color and style. The reason: The balconies do not hang directly on the house wall as they used to, but stand in front of it as scaffolding. This means that the heat from the interior of the apartments cannot escape to the outside via the floor panels of the balconies.
From now on, the Bauverein zu Lünen wants to modernize around four percent of the housing stock every year, equip it with new heating systems or replace it.
(Photo: Stiebel Eltron [M])
In addition to an energetic refurbishment of the balconies, windows and walls, the Lünen construction association has already fitted all the houses with heat pumps and thus replaced the old gas heating systems. Three heat pumps each supply a row of houses with heating energy. A spokesman for the heat pump manufacturer Stiebel Eltron, who made the devices in Lünen, says that works without any problems even when the temperature is below zero.
>> Read here: Is a heat pump worth it now?
The green areas around the houses are watered with the water that condenses on the heat pumps. The same applies to rainwater that runs off the roofs and would normally disappear into the sewage system: it runs into trough-shaped depressions in the lawn and seeps away there to keep the surrounding soil moist. The heat pumps obtain their electricity at times from photovoltaic systems on the roofs of the houses.
The Bauverein Lünen receives the remaining electricity as green electricity from the public utility company. As a major electricity consumer in Lünen, the construction association gets the green electricity from the public utility company at the same price that it would pay for the normal tariff, according to Unterberg. The tenants do not have much say in all the measures.
The Bauverein modernizes where necessary and then raises the basic rent. In the Espelweg, it increases from an average of 5.25 euros to 6.75 euros – an increase of almost 30 percent. At the same time, says Unterberg, the rent including heating has fallen by 30 cents per square meter due to lower heating costs. But an increase in the rent including heating of 1.20 euros per square meter remains. Unterberg says: “We cannot manage the energy transition for free.”
Solar hydrogen energy plant in Schulzendorf
“Your green home in Ritterschlag 3” is how the Swedish-German project developer Bonava advertises its new quarter in Schulzendorf near Berlin. In the case of the houses that have already been completed, “green” primarily refers to the many small private gardens, meadows and trees in and around the district. So far, the owners of the houses have obtained their heat from a gas boiler.
But the next houses could be equipped with a CO2-free solar-hydrogen energy system called “Picea” – if the customer is willing to pay the effective acquisition costs of 45,000 to 79,000 euros. “If the pilot project is successful, we can definitely imagine installing more systems,” says Bonava project manager Alexander Malwig. “The technology has the potential.”
For the time being, Bonava has installed the system from the Berlin company HPS Home Power Solutions in a model house on Ernst-Thälmann-Straße in Schulzendorf, in the utility room with a space requirement of around 1.5 square meters. Bonava wants to clarify the question here: “Does this type of energy supply fit in with Bonava’s standardized design?”
The system serves as an electricity storage device, heating backup and living space ventilation at the same time – in a compact device that is powered by the sun via photovoltaic modules on the roof. The unused solar energy is stored in a battery. When this is full, the excess electricity is converted into hydrogen in an electrolyser and stored in a hydrogen storage facility outside the house for the winter. This can be flexibly expanded.
In the winter months with little sunshine, electricity can then be generated again with a fuel cell from the stored hydrogen. District heating or an additional heat pump to be installed supplies the house with heat. The heat generated by operating the “Picea” is also made available to the household.
The advantage is obvious: With a one-off investment, customers can protect themselves against rising energy prices and maximize their security of supply. The warranty period is ten years if annual maintenance is used for 420 euros per year. According to HPS, the system has so far been sold around 250 times throughout Germany.
How independent a household is depends on the amount of electricity required. “Sensitivity is required for complete self-sufficiency,” says HPS sales consultant Markus Rösler. “If I have a duck in the oven, charge the electric car, have the washing machine and dishwasher running and heat the apartment to 25 degrees, you will need additional electricity.” And that has to be drawn from the public power grid.
More: Infographic: This is how districts become climate-neutral