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A private residence in Karuizawa, Nagano, has become one of Japan’s first CO2 concrete architecture projects. With the concept developed over 3 years, this architectural work showcases different ways carbon can be visualised, educating a wider audience about the potential and need for Carbon Capture and Utilisation (CCU). This project demonstrates the versatility of how carbon can be used as a creative solution to secure privacy from passing traffic and pedestrians whilst acting as a foil for basking in the natural surroundings. In the design, approximately 2,050 CO2 concrete blocks are staggered in parallel rows to create five 3m-high walls arranged in a gradient-like pattern.

The concrete blocks are produced from CO2-SUICOM (CO2-Storage and Utilisation for Infrastructure by Concrete Materials), a CO2-cured concrete developed by Kajima, Chugoku Electric, Denka Company Limited Denka and Landes Co. This material is made by replacing a portion of the cement with an industrial byproduct and adding a carbon dioxide-absorbing material, resulting in net zero CO2 emissions during the production. By using CO2-SUICOM, more than half the cement is replaced with a more sustainable substitute. The residence was designed by nendo, a design firm known for creating the recent Tokyo Olympic torch, the Issey Miyake chair, Daniel Arsham furniture and more.

CO2 mineralisation is a set of technologies transforming CO2 molecules into valuable products for the construction industry, in a real application of the circular economy, and without requiring any significant external energy input.

Mineralisation is a natural phenomenon, where minerals containing calcium or magnesium react with carbon dioxide (CO2) to produce calcium or magnesium carbonate, also known as limestone or dolomite, one of the most abundant rock types formed throughout the 4000 million-year history of our earth.

This natural carbonation reaction, which happens in nature over thousands of years, can be accelerated and take only a few minutes in man-made manufacturing processes (accelerated carbonation) by using high CO2 concentrations and optimised reaction conditions. The reaction is called exothermic, meaning that it releases energy as heat and leads to the creation of stable products in which CO2 is permanently captured.

Find out more about the architectural project here.