In terms of sustainability, what are the key advantages of bio-based construction techniques over traditional methods?
Conventional building methods have a great impact on the environment. The embodied energy we will need to spend in the next decade will be huge if we don’t change radically our way of building.
Carbon emissions in our built environment also have to be reduced drastically. What we call regenerative materials at ETHZ (earth, bio-based, and reused materials) are efficient in reducing our impacts and improving air quality, health, and global resilience of ecosystems. Using less and better concrete is as important as developing alternative materials.
What are your thoughts on mycelium-based materials in the construction industry?
Mycelium-based materials are fascinating. Their potential in the building industry is not yet fully understood. Their main advantages would be in their production process and for waste management. They definitely have a place to take in the paradigm shift that already started.
However, no material will be a solution for itself and mycelium-based materials will have to be combined with a better use of concrete and other regenerative materials (earth, bio-based, and reused). The market is not yet ready for large-scale use of mycelium-based materials but I see no reason for this not to change in the next decades.
How does the use of sustainable materials in retrofitting existing buildings contribute to overall environmental goals?
Retrofitting existing buildings is by itself already a powerful way to reduce the global carbon emissions and the amount of embodied energy spent to fulfill our need for buildings (especially in Europe).
Using earth-based materials relocates material flow at the regional level, with almost no embodied energy and provides an excellent healthy indoor air quality. They also introduce thermal mass and hygroscopic capacity in the buildings helping to temper temperature and moisture variation in summer and winter. Using bio-based materials helps to better use agricultural and forestry waste, sequestrate carbon, and help to build energy-efficient buildings. They also favor high indoor air quality and are perfectly compatible with traditional (vernacular) building techniques.
Using reused materials, within the building project or sourced in other projects, is an excellent way to reduce the impact of the structure and other carbon-intensive elements (such as windows and doors).
What’s the most interesting development you’ve witnessed in terms of regenerative materials in the construction industry?
I think incredible developments are happening at the moment:
- Optimised concrete structure, using less (recycled) concrete and less steel
- Large-scale earth techniques such as poured earth and prefabricated rammed earth elements
- Multistorey building insulated with straw using timber-based materials for the structure
- Time-efficient spaying techniques with lime-hemp or earth-hemp mixture for insulation
- Network and tools to allocate reused materials
- Strong political sign to support regenerative materials in architectural competitions and public buildings
- New models to help the early design of low-carbon buildings
- New strategies to support “sustainable finance”
Do you think the construction industry is ripe for a paradigm shift in terms of the environmental impact of its material choice?
I think the inevitable paradigm shift has already started. However, there is still a lot to do and strong lobbies are not always helping to go in the right direction. In addition, the very large amount of practitioners and stakeholders in the building industry make all changes rather slow. New collaborative organisations are needed. There is still a lack of information on the side of decision-makers and a lack of competence on the side of practitioners.
At the Chair of Sustainable Construction of the ETH Zurich, we organise continuing education programs on Regenerative Materials to tackle this problem.
