The five- to seven-storey New Courts building on Gerichtstraße in Berlin-Wedding (Germany) redefines the previously lacking spatial boundaries with its meandering form: welter+welter architekten placed the five-part structure on the open space (previously used as a car park) like a horizontal “S”. The building parts respond to the surrounding development in both height and depth and create a variety of intermediate spaces. Three new courtyards have been created, among other things, some of which are used for deliveries to the building behind. The thoroughfares required for this have resulted in a light, floating structure that has clear edges while remaining permeable. This motif is replicated in the glass facade that, depending on the weather, reflects and appears to merge with the adjacent city park.

Functional metal insert for visual protection

Flexibility was one of the greatest challenges in this project. The almost 20,000-square-metre office space was originally intended for variable use, accommodating both large and small office units as well as co-working spaces and other modern office concepts. The facade therefore needed to be correspondingly versatile and equipped for all conceivable layout variations. This later turned out to be unnecessary when a government authority moved in and requested that the majority of the building be comprised of traditional cubicle offices and communal meeting spaces.

Instead of the usual office grid of 1.35 metres, the owner and developers agreed on a generous facade division and double the usual grid dimensions. This means there is only ever one opening in the now 2.70-metre-wide glass elements. For the railing elements, an extended aluminium mesh was set into the space between the panes of insulating glass that reflects the thermal radiation at floor level and offers semi-transparent visual protection. The view and perspective change depending on the angle. The vertical positioning of the extended metal honeycombs is a combination of functional and design goals: the interplay of views depending on where you are standing was absolutely necessary, as was the play of light conjured on the facade by the interior and exterior lighting.

Sun shading fabric with synergy effect

“In our office, we always try to combine function and design as much as possible, or to harness synergies”, explains Philipp Welter. This also goes for sun shading. It quickly became clear that exterior sun shading was needed that doesn’t just offer the glare protection required by law, but can also reduce solar thermal radiation by harnessing building physics. Warema SecuTex A2 fabric came into play due to the need for a staircase facade suitable for fire protection in which all components had to fulfil fire protection class A2. The fabric, certified non-flammable in accordance with DIN 4102-A2, is made up of a silicone-coated glass-fibre fabric with no poisonous or dangerous chemicals added. This means that in the event of a fire, no poisonous gases are emitted and smoke development is minimal. Unlike other textile sun shading products, this fabric does not act as an additional fire accelerant, preventing life-threatening smoke inhalation.

Warema SecuTex fabric can be used flexibly both inside for roller blinds and outside for window awnings. The fabric is aluminium vapour coated on one side and has a reflective surface. “We opted for a neutral, light grey tone on the room side and placed the aluminium side on the outside. This allows us to maximise heat reduction while also protecting against fire and enhancing the visual effect: when the sun shading is closed, the entire building is enveloped in a silvery shimmer” Philipp Welter enthuses.

Testing window awnings in a wind tunnel

After considering the structure’s susceptibility to wind, the architects decided not to use the awning variant originally planned. A thorough simulation was carried out beforehand by placing a building model in a wind tunnel. The evaluation returned a reduced wind threshold value for the tilted awnings, meaning they were retracted at relatively low wind strengths. Together with the facade planner, the architects therefore chose sun shading fitted tight against the building with front-mounted awnings and lateral easyZIP guidance from Warema, which is extremely wind-stable. The complex building geometry also required the variously oriented facade parts to undergo a shading test. The window awnings on the purely north-facing facades were therefore replaced with interior anti-glare blinds in the same silver-coloured fabric, a welcome reduction in cost. The ceiling connection of every window is fitted with a device to manually operate blinds, allowing easy retrofitting where necessary. This flexibility – including sun shading – was an important criterion when the building received Gold certification from the German Sustainable Building Council (DGNB).

For design reasons, window awnings were also used on the street side, even though it faces north. “The main facade should present a uniform appearance and shimmer in the sunshine, even on the street”, says Welter, explaining his decision.

Window-specific sun shading control system

Automatic sun shading control was part of the plan from the early stages. “Automated control is particularly important in office buildings because in the summer, the solar gain places too much strain on the indoor climate in the early morning and on the weekend when nobody is working, making the rooms much hotter”, explains Philipp Welter. The facade planners, architects, developers, control system planners and experts from Warema worked together to come up with the most functional and economic concept that meets all requirements. This allowed all project participants to find the most flexible control solution for optimal user comfort. The sun shading ensures thermal comfort for users all year round; it helps stop the sunlight from heating the building in the summer and keeps the warmth inside in the winter.

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