SAWA: 90% wood and balconies in slender concrete
The SAWA residential building in the Lloydkwartier of Rotterdam (NL) is fully committed to CO2 reduction, energy neutrality, circularity, biodiversity and inclusiveness. It is not surprising that the Sawa building also called 'the healthiest building in the Netherlands' has already won several architectural awards, before construction has even started (Q1, 2022). The use of steel and concrete is minimised. Nevertheless, the balcony slabs are made of concrete. Or better: slender ultra high performance concrete (UHPC) from Hi-Con. A novelty!
The sustainability ambitions for the 50-meter high SAWA building have resulted in a modular main structure in CLT (cross-laminated timber), which has been made visible as much as possible. Compared to concrete, CLT is very light. Too light to anchor balconies in traditional concrete to it. Because balconies in wood were not a solution, the choice was made for UHPC. This saves 50-60% weight compared to regular concrete.
SAWA is the first large-scale project with UHPC balconies in combination with a CLT structure. In total, Hi-Con Netherlands produces 238 balconies and a spectacular walkway between the two parts of the building.
The design of the balconies was made in close consultation with Mei architects and planners, Pieters Bouwtechniek (also the main structural engineer of SAWA) and Era Contour. The biggest challenge was to limit the weight of the balcony slabs, because of the relatively low carrying capacity of the wooden consoles that support them. The concrete also has a wooden look, in colour and with a relief structure.
Soon we will tell you more about the ambitious CO2 savings that you can achieve with UHPC balconies from Hi-Con in combination with CLT structures.