The construction industry has an environmental impact that can no longer be ignored. Estimated at a third of the planet’s overall waste, the harsh reality is that 39% of global greenhouse gas emissions can be traced back to the building sector, with construction materials currently accounting for a staggering 11%. For jarring reference, the commonly vilified aviation industry is at the root of but 3% of global emissions while the manufacturing of cement alone is responsible for 8%.
With the support of the Danish philanthropic organization Realdania, our team set out to explore ways of designing a building that could capture more carbon than it emits. This means harnessing the natural carbon cycle to design a carbon-storing building; embedded with carbon that would otherwise be released into the atmosphere. In doing so, we chose to radically rethink our choice of materials; the literal building blocks with which we work.
This is something we are doing in many of our ongoing projects, including our urban development of Fælledby in Copenhagen, the forward-thinking World of Volvo experience center in Gothenburg, and the Quayside development of Toronto. But with Feldballe marking an exciting testing ground and an opportunity to push the matter several steps further, we turned to a seemingly unlikely choice of materials: wood, seagrass, and straw. Locally sourced, natural, and bio-based, they have proven themselves viable alternatives to conventional materials like concrete, bricks, and steel
In selecting materials that naturally absorb and store CO2 in the carbon cycle, not only did we generate immense carbon savings, but we successfully designed a structure that is composed of carbon sequestering elements. These elements are completely free of toxic chemicals, fire-safe, and once assembled, offer efficient insulation as well as an exceptional indoor climate. The latter is achieved by means of natural and passive ventilation systems that eliminate energy consumption on a daily operational level. But it does not stop there - with circularity and waste management in mind, the entire structure is designed for easy disassembly and reuse, offering flexibility, ease of repair, and making it possible to reinstall or recycle its parts in the future.
Historically, bio-based materials have been used in construction for thousands of years. Adapted to meet today’s needs and requirements, they mark viable alternatives to conventional practice and a means of prioritizing both people and planet.
Partnering with EcoCocon, a small business headquartered in Slovakia, we were able to integrate their pioneering panel system of compressed straw in wooden cassettes, as the primary element within our design. Produced with the utmost precision, these elements form a construction system that is adaptable and applicable in a vast range of building typologies. With the surface of the straw panels covered in clay, the structure’s roof made solely of timber, and a ventilation system filter made of seagrass, the school extension is built almost entirely of locally sourced, natural, and bio-based materials.
Going beyond the project’s innovative design itself was our team’s formulation of a forward-thinking and transparent framework for sustainable design that does not exceed planetary boundaries. Comprising of five ambitious principles, the framework opens possibilities for redefining industry benchmarks by examining the entire life cycle of a project, cradle to cradle.
1. Incorporate sustainably sourced, renewable, bio-based materials to sequester rather than emit carbon.
2. Use already produced local materials to save resources and energy during manufacturing and transportation.
3. Employ materials that are free of toxic chemicals, minimizing off-gassing and ensuring clean production and processing procedures.
4. Lower operational energy consumption by ensuring a healthy indoor climate, fostering an environment that balances daylight with passive ventilation.
5. Design for disassembly, enabling the reuse of building components in the future.
Operationalizing our five principles for sustainable design with the construction of the Feldballe School extension, the school has a footprint of 339 kg of CO2e per m2, which includes emissions from embodied carbon in materials and technical installations and also building operations. The life cycle impacts are calculated over a theoretical 50 year building lifetime and include production phases, replacements and end-of-life impacts.