Germany's first large commercial building made of infralight concrete is located in Berlin

Structurally a lightweight, for the neighborhood a heavyweight: In Berlin-Friedrichshain, Germany's first REWE store made of the high-performance building material infralight concrete has opened. Thanks to the air trapped in the concrete, the material is lighter than water and also provides thermal insulation. "For us it's a test run, the building material has potential. It has a lower carbon footprint than conventional concrete due in part to its lower cement content. We don't need any additional insulation; it's a bit of a return to simple construction," explains Dirk Heimann, head of construction at REWE Ost. The company has invested around 14 million euros in the new building. The supermarket is located between the RAW site and Ostkreuz, at Revaler Straße 33.

"Infra-light concrete is positive for the CO2 balance"
REWE owns the land between the RAW site and Ostkreuz. "The advantage for us is that we have a free hand in the planning within the framework of the legal requirements. We can select the building materials according to our convictions, design the interior of the building and specify sustainable criteria," Heimann emphasizes. "In Berlin-Friedrichshain, we are now testing infralight concrete for the first time; it will be used for the exterior walls and the firewall."

The Technical University of Berlin (TU) has been researching the material since 2006, and it was presented at a trade fair in 2019. At 800 kilograms per cubic meter, infralight concrete has a very low bulk density. It is created by adding very light aggregates such as expanded clay to concrete. In the process, air is trapped in the material. "Projects in residential construction and single-story public buildings have already been implemented with infralight concrete, and the REWE store is now Germany's first commercial building," says Prof. Mike Schlaich of the Institute of Civil Engineering at TU. "The concrete variant is lighter than water and thermally insulating. Since the exterior walls require neither extra insulation nor soundproofing, infralight concrete is positive for the CO2 balance and the subsequent separation of building materials by type."

"Return to the roots of construction"
The Baumgardt Franke architectural office from Leipzig planned the experimental building. A particular challenge for the specialist firms involved in the project was the construction in the existing building; the entire object was made up of three connected building blocks.

The previous supermarket, with its main store and beverage market, was divided into two building blocks. Both were demolished and rebuilt in connection with the third building block. The walls of the new building are nine meters high and 40 to 50 centimeters thick.

Infra-light concrete:
Architect Dagmar Baumgardt says, "Constructive lightweight concrete combines the load-bearing and heat-insulating functions of a single-layer building envelope in a monolithic material. Working with infralight concrete represents a return to the roots of construction." The building material was mixed at Heidelberg Materials' plants. "A project with this special building material in these dimensions was new territory for everyone. With infralight concrete, probably the biggest challenge was to design the firewall, which is more than nine meters high, in terms of both building materials and design technology, while still being practicable to implement," says Robert Bachmann, Head of Technical Sales at Heidelberg Materials. The engineering firm schlaich bergermann partner and Prof. Mike Schlaich helped design the project and provided intensive support.

Away from the building envelope, other construction materials were used.
The roof of the market building consists of a lightweight, insulated trapezoidal steel construction, while the supporting structure is formed by glulam beams with spans of up to 27 meters. The interior walls are made of sand-lime brick and gypsum plasterboard stud walls. The glass facades, windows and doors are framed in aluminum structures. The Revaler Strasse site also houses an ALDI store, a gym and office space.

Energy consumption almost halved
In addition to the use of infralight concrete as a building material, other factors at the REWE store in Friedrichshain ensure a significantly better energy and CO2 balance compared to a standard building: The new building is a REWE Green Building with state-of-the-art heating, ventilation and lighting technology as well as economical refrigeration systems. There are around 250 of these energy-saving stores nationwide, 14 of which are in Berlin. "Such a resource-conserving energy-saving store saves up to 40 percent energy. 80 percent of the heating energy is covered by waste heat recovery from the central commercial refrigeration system and 20 percent by the use of heat pumps," explains REWE construction manager Heimann. The heating, ventilation, lighting, air-conditioning and refrigeration systems do not pollute the environment with CO2 emissions, which means that the store is operated on a CO2-neutral basis. The modern building services also include fully glazed refrigerated shelves with LED lighting, in which only natural refrigerants are used. Since 2010, all REWE stores have been powered by 100 per cent green electricity. After completion, REWE Green Buildings are inspected and officially certified by the German Sustainable Building Council (DGNB).

For further information about the growth industries, economic development, business and technology support for companies, investors and scientific institutions in the Airport Region Berlin Brandenburg please contact:

Sandra Koletzki ​​​​​​ | sandra.koletzki(at)airport-region.de

(Source: REWE GROUP, 05|12|2023 | "Rewe baut in Berlin ersten Supermarkt aus Infraleichtbeton")