The Current Column

Sustainable Buildings and Construction Summit 2026

Urban transitions need bio-based materials—here’s why

Never, Babette / Alexander Stoecker
The Current Column (2026)

Bonn: German Institute of Development and Sustainability (IDOS), The Current Column of 20 April 2026

Bonn, 20 April 2026. Urban transitions need more than low-carbon cement. Bio-based materials can cut emissions while creating jobs and boosting local economies—yet remain largely overlooked.

This week, representatives from academia, government and industry seek to find solutions to decarbonise the built environment at the Sustainable Buildings and Construction Summit in Lausanne. The heat is on: the buildings sector emits more than a third of global CO₂ annually and urbanisation in many low- and middle-income countries is soaring, especially in Sub-Saharan Africa (SSA). The key question is whether solutions will be fast, feasible and deliver economic co-benefits. Much of the international debate highlights low-carbon concrete such as LC3 as a quick fix requiring minimal adjustments to business as usual. Yet its development potential is limited, which might be different when adding bio-based materials to the construction mix.

Many countries in SSA face a triple challenge: First, providing adequate housing for a growing urban population, many with low incomes. Africa already faces a deficit of about 50 million housing units, expected to reach 130 million by 2030. Second, creating jobs and increasing firm productivity are key priorities for policymakers. In Kenya, for example, 1 million youth enter the job market every year. Third, pursuing economic development along a greener pathway than the carbon-intensive trajectories of today’s advanced economies. Infrastructure and buildings make this choice especially consequential, as carbon-intensive construction locks in emissions, raises urban heat and limits re-use of materials. As much of SSA’s built environment is yet to be built, there is a chance to avoid costly retrofits, which needs to go hand in hand with needed shifts in the construction sector in the Global North.

The switch to low-carbon concrete may meet only two of the three challenges in a fast and feasible way: providing housing and decarbonising construction LC3 requires minimal changes in cement factories and is applied the same by masons. Modelling shows it is particularly suitable for multi-storey buildings, where its carbon footprint is lower than for a mix of bio-based materials and fired clay bricks. For these buildings, LC3 makes sense. Yet, many homes in SSA are and will remain single-storey, where emissions depend heavily on material composition and transport distances.

Bio-based materials as a solution to SSA’s triple challenge have so far been largely neglected. This is significant, as improved adobe blocks, timber or bamboo offer not only lower-cost but also more labour-intensive alternatives to LC3, generating stronger local economic benefits and supporting firm development. Improved adobe or interlocking soil blocks can often be produced at or near the construction sites, reducing transportation needs and enabling local SMEs to participate. Both are well suited for affordable housing: research in Rwanda shows wall costs can fall by 60% or more, while improved production standards ensure comparable strength and durability. Our research also finds that bio-based materials can create greener, better-quality jobs in Kigali. However, wider adoption faces supply- and demand-side barriers, including limited awareness and perceptions of low quality that restrict financing. 

This points to a hybrid approach that must be clearly defined: LC3 for multi-storey buildings and structural uses, and bio-based materials for single-storey housing and non-load-bearing interior walls, where they are often more affordable and locally appropriate. In Rwanda, clear government direction is needed for business adoption. Across Sub-Saharan Africa, similar hybrid approaches are promising, but scaling bio-based materials requires locally grounded research. Suitable materials depend on a) type of soil and materials locally available, b) import dependence on cement, steel, etc. c) transport and other lifecycle costs. Sustainable timber and mycelium may suit Europe and bamboo Asia, while in SSA stabilised adobe blocks, soil-cement mixes and plants such as typha offer strong potential.

German development cooperation should bring the economic co-benefits and development potential for local firms working with bio-based more strongly to the international table. In its own development cooperation projects, greening the construction sector including bio-based material options for green job creation and firm upgrading should become an explicit goal. The exact type of bio-based material and its value chain to be supported needs to be analysed ex ante in the country regarding: Soil (availability and quality), import-export structure and tariffs of construction materials, market conditions and bottlenecks on supply and demand side. At the same time, scaling bio-based materials requires local political willingness to confront entrenched interests in the construction sector, alongside clear government regulations that set direction and create a level playing field for sustainable alternatives. This may be somewhat slower than other solutions, but just as feasible and it likely increases economic co-benefits for partner countries.