How this architect is building stunning office spaces while reducing carbon footprints

The smaller building, the Solitaire, has a more traditional rectangular shape.

Inside the atrium, one can find four graduated trees or mushroom-like structures of different heights that support common platforms used for recreation. They are connected to each other and office floors by bridges and filigree staircases. On the fifth floor is a sky lounge with panoramic windows.

The designers have made wood visible in the interiors of the building, and the facades are constructed with sustainable and weather-resistant glass-fiber concrete panels that absorb CO2.

The foundation slab is made of concrete but is around 30 percent thinner than in conventional buildings. This is possible because the building is also around 30 percent lighter than conventional buildings, thanks to the extensive use of wood. Using a combination of wood and concrete can lead to a reduction of up to 80 percent CO2 per square meter of floor area, the firm claims.

Interesting Engineering (IE) spoke to architect Sergei Tchoban to learn more about Suedkruez Berlin and about sustainable construction.

German architect and artist Sergei Tchoban is active in many European locations. He founded the Tchoban Foundation, which is housed in the Museum for Architectural Drawing in Berlin, and he serves as managing director of the architectural firm TCHOBAN VOSS Architekten.

The following conversation has been edited for clarity and flow.

Interesting Engineering: What lessons from this project could be applied to future projects? 

Sergei Tchoban: The choice of the timber-concrete hybrid system is unique in Germany for a project of the size of the EDGE Suedkreuz Berlin and sets an impulse for modular construction with timber-hybrid on a large scale in the future.

IE: Why is sustainable architecture important now?

Sustainable, resource-saving construction is one of the most important topics within architecture. Globally and socially, it is no longer appropriate not to build sustainably. In all our projects, we consider aspects of sustainability from the very beginning of the planning process, including, for example, design sustainability! And this applies to new construction projects as well as to revitalization projects.

IE: What factors played a role in determining the sustainable methods to be used for the construction of these buildings?

In the construction of the buildings, the focus was on reducing the carbon footprint as much as possible, especially the weight of the complex, and on using sustainable materials that can be recycled according to the cradle-to-cradle principle. The project is registered in the Madaster database (an online registry for materials and products used in a real estate or infrastructure project). It has a material passport that enables the materials utilized to be reused and recycled. 

Due to an approximately 50 percent saving of reinforced concrete compared to conventional in-situ concrete construction, the construction-related CO₂ footprint of the ensemble is significantly lower. Industrial pre-production (also of the lightweight façades) and the use of wood were essential building blocks.

IE: In terms of the cost of construction, were there any savings from using this method?

Yes. The prefabricated timber hybrid ceiling and wall modules were delivered from Germany with a precise fit and without long transport routes. They were assembled directly on-site, which ensured not only precise construction scheduling but also a particularly time-efficient and economical construction process.

IE: The four tree-like supports for the staircases in the atrium. What was the inspiration for the design?

From supports, beams, windows, and doors to cladding and handrails: Wood is visible in all interior areas of the building, enriching the clear architecture with a living element and thus bringing the aspect of nature into the individual rooms of the office complex, which is conceived as an open ecosystem. The forest, as the origin of the defining material wood is thus also symbolically unmistakably at the center of the architecture with the trees.

IE: What measures have been taken to fireproof the construction?

Due to a demanding overall concept, the requirements for fire protection products in the publicly accessible area had to be reconciled with the high demands on functionality and appearance as well as sustainability.

For example, as part of the fire protection concept, an overpressure smoke extraction system was installed, in which smoke extraction takes place via outflow shafts. The openings of these shafts are closed with specially developed smoke extraction flaps as part of the smoke protection pressure systems. The goal is to keep safety stairwells smoke-free.

IE: Could you tell us more about the CO2-absorbing front panel facades on the building?

The façades are clad with weather-resistant glass-fiber concrete panels from the company Rieder, with a weight of only 30 kg/sqm. They have a glass fiber content of only approx. Four percent, are thus up to 96 percent recyclable and have a decarbonizing effect due to their unique, rough surface structure of the cement ground into small particles.

The façades are constructed in a uniform grid, which is structured by horizontal bands and by colored vertical panels. Pylons structure the façades vertically. Pilasters made of fiber concrete visually strengthen the plinth area. The rhythmic façades have a restrained color scheme individually chosen for each volume. They clearly reflect the load-bearing timber system of the interior to the outside.

IE: Attention has also been given to the e-mobility of people who use the building.

The building was specially designed for the tenant Vattenfall to accommodate their electric mobility car fleet. The parking spaces can be used hybrid, i.e., all are electromobility compatible.

IE: What hurdles did you face during the design and construction phase of the building?

Smooth planning and realization of the complex building project were achieved through a high level of professionalism, good communication in the coordination processes, as well as the high flexibility and solution-oriented teamwork of all those involved. Open Building Information Modeling (BIM) planning made an essential contribution to this.

The planning implementation of the timber hybrid building and the lightweight façades as special components required very close cooperation between structural planning, fire protection, acoustics, building physics, and the architects up to the executing trades under the leadership of the general contractor Zechbau.

For the atrium, too, optimized, innovative solutions for fire monitoring, smoke extraction, and air-conditioning were developed by an interdisciplinary team. The three-dimensional, particularly light roof construction (only 45 kg/sqm) was a project within the project, and also the trees and bridges in the atrium.

IE: What are the benefits of innovative constructions such as these for architects and builders?

EDGE Suedkreuz Berlin is a pilot project in many respects. All those involved in the project had to face a lot of new challenges and find innovative solutions that had never been seen before. There are challenges in all construction projects and in all processes. But you always learn from them for the next tasks. Only in this way can new projects be optimized. Without challenges, there would be no learning process, and everything would be too pragmatic and, therefore very boring.

IE: If we are to use such construction methods for all buildings in the future, what are the hurdles along the way? 

The current logistics of procuring non-price driving and ecologically sensible wood as a renewable material can be a significant challenge in this regard.