Making Natural Building Materials Work

This Commonwealth Association of Architects (CAA) CPD event examines the critical role of natural building materials in addressing the climate emergency and rapid urbanization across the Commonwealth. With projections showing an additional 2.5 billion urban dwellers by 2050 (95% in Asia and Africa) and buildings accounting for nearly 40% of global energy-related emissions, the session explores viable alternatives to high-carbon materials like cement and concrete. Expert presentations cover the properties, applications, barriers, and enablers for bamboo, earth construction, innovative bio-based materials like Sugarcrete, and practical implementation strategies drawn from projects across Africa, Asia, and beyond. The following short video provides further context of the issues discussed in this session.

Outline

• Global context for material sustainability addressing the triple planetary crisis of climate change, pollution, and biodiversity loss, with focus on the environmental and social impacts of conventional building materials throughout their lifecycle
• Bamboo as a structural material: properties, growth characteristics, carbon sequestration potential, engineered bamboo products, and applications from traditional housing to multi-storey construction
• Earth construction techniques including mass earth (cob), framed earth, light earth, compressed earth blocks, turf, earth mortars, rammed earth, and clay plasters, with discussion of codes of practice and vocational training frameworks
• Innovation in bio-based materials focusing on Sugarcrete (made from sugarcane bagasse waste), addressing global waste streams, performance characteristics, and open-source development strategies
• Case studies from Rwanda demonstrating market adoption, aesthetic development, supply chain localization, and reimagining architectural practice to support natural materials

Lessons Learnt

The following are among a list of lessons learnt during the course of the event:

• Understand the urgency and scale of the challenge: recognize that cement production alone contributes 8% of global emissions, making it the third largest emitter if it were a country, and that conventional building practices cannot sustainably accommodate projected urban growth
• Appreciate bamboo as a high-performance structural material with tensile strength 3-4 times that of timber, rapid growth (harvestable in 3-5 years), continuous carbon sequestration, and applications ranging from traditional construction to engineered products suitable for multi-storey buildings
• Learn about the diversity of earth construction techniques and their suitability for different contexts, from monolithic systems (rammed earth, cob) to framed systems and specialized applications including mortars, blocks, and high-performance plasters that improve indoor air quality
• Recognize the importance of codes, standards, and training frameworks in legitimizing natural materials, including the role of ISO processes, regional harmonization, vocational qualifications (NVQs), and training-for-trainers programs
  Understand how innovative bio-based materials can address multiple challenges simultaneously by utilizing agricultural waste streams (like sugarcane bagasse – 623 million tons annually), creating local economic opportunities, and achieving comparable or superior performance to conventional materials
• Appreciate that natural materials require different performance metrics and standards than those designed for concrete and steel, and that “appropriate performance” may be more valuable than maximum performance
• Recognize the economic and social benefits of natural materials including job creation, local skills development, reduced transportation costs, and empowerment of communities rather than dependence on global supply chains
• Learn strategies for overcoming barriers to adoption including consumer confidence building through demonstration projects, architectural celebration of material aesthetics, procurement process reform, and long-term policy commitments
• Understand the need to reimagine architectural practice including documentation methods (3D diagrams, step-by-step visual guides), fee structures, and the integration of material research into project delivery
• Appreciate the role of education and communication in accelerating adoption, including social media for knowledge sharing, changes to architectural curricula, and the impact of public buildings (especially schools) in shaping perceptions

Core Curriculum Themes

• Sustainable Architecture
  This is the primary focus of the session, extensively covering embodied carbon reduction, lifecycle thinking, material sourcing and supply chains, waste utilization, carbon sequestration, biodiversity protection, circular economy principles, and the integration of environmental and social sustainability objectives in material selection.
• Design, Construction & Technology
  The session provides comprehensive technical knowledge about alternative structural materials, their properties, performance characteristics, joinery systems, and appropriate applications. It addresses how architects must adapt documentation methods and construction detailing when working with natural materials that behave differently from conventional materials.
• Legal, Regulatory & Compliance
  The session emphasizes the architect’s role in advocating for systemic change, challenging conventional standards and practices, educating clients and stakeholders, contributing to policy development, sharing knowledge openly (including through social media and open-source approaches), and taking responsibility for the wider environmental and social impacts of material choices beyond individual projects.

SDG Learning Outcomes

• SDG 13: Climate Action
  Natural building materials directly address climate mitigation through dramatic reductions in embodied carbon (compared to cement and steel) and carbon sequestration (particularly bamboo and other rapidly renewable materials). The session addresses both reducing emissions from construction and increasing resilience to climate impacts.
• SDG 11: Sustainable Cities and Communities
  The session addresses the challenge of housing 2.5 billion additional urban dwellers sustainably, with particular focus on affordable, appropriate, and contextually-responsive solutions that don’t replicate the high-carbon development patterns of the Global North.
• SDG 8: Decent Work and Economic Growth
  Natural materials create significantly more local employment than industrialised materials, develop local skills and craft traditions, reduce dependence on imported materials, create opportunities for rural communities, and build resilient local economies throughout the supply chain.
• SDG 12: Responsible Consumption and Production
  The session addresses circular economy principles, waste utilisation (agricultural byproducts), design for disassembly and material reuse, appropriate use of resources, and challenging the assumption that higher performance is always better or necessary.

1. Climate Impact Assessment:
   What opportunities exist in your current projects to reduce embodied carbon by specifying natural materials instead of cement-based products?
   What percentage reduction might be achievable?
2. Local Resource Identification:
   What natural building materials (bamboo, earth, agricultural waste, or other bio-based resources) are available within your region?
   What would it take to develop viable supply chains for these materials?
3. Challenging Standards and Assumptions:
   How do current building codes and performance standards in your context favor conventional materials over natural alternatives?
   What assumptions about longevity, maintenance, and performance influence your material specifications?
4. Practice Transformation:
   How would incorporating natural materials require changes to your design process, construction documentation, contractor relationships, or fee structures?
   What skills development would your practice need?
5. Social and Environmental Responsibility:
   How do your material specification decisions impact local communities, workers, and economies?
   What opportunities exist to support decent work and environmental justice through material choices?
6. Long-term Strategy:
   What steps could you take over the next 1-3 years to introduce natural materials into your practice?
   How might you educate clients, demonstrate feasibility, and contribute to shifting market expectations toward bio-based construction?

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