【奥雅纳Arup】2024城市碳中和建筑手册_55页_7mb

Summary of City Handbook for Carbon Neutral Buildings

Core Content

This handbook, developed by the Carbon Neutral Cities Alliance (CNCA) in collaboration with Arup, provides a comprehensive guide for cities aiming to reduce embodied carbon in construction through the use of bio-based building materials. It outlines the challenges, benefits, and opportunities associated with the adoption of these materials, emphasizing the role of cities in shaping sustainable construction practices.

Main Viewpoints

• Urban Growth and Climate Impact: Rapid urbanization and increasing consumption are straining global resources and pushing the construction industry to adopt more sustainable practices.
• Biobased Materials as a Solution: The use of biobased materials offers a viable path to reducing carbon emissions and promoting healthier, more sustainable living environments.
• Role of Cities: Cities are uniquely positioned to integrate carbon performance into procurement and regulations, driving systemic change in the construction sector.
• Life Cycle Considerations: The environmental impact of construction materials is not only about production but also includes use, maintenance, and end-of-life scenarios.
• Need for Data and Collaboration: There is a critical need for more data, technical understanding, and collaboration across the construction supply chain to support the wider adoption of bio-based materials.

Key Information

Benefits of Bio-Based Construction

• Renewable: Sustainably sourced bio-based materials can be harvested and regenerated within years or decades.
• Low Embodied Carbon: These materials generally require less energy in production than traditional materials like concrete or steel. They also sequester carbon during growth, which is retained in the material upon harvesting.
• Low Toxicity: Bio-based materials typically emit fewer volatile organic compounds (VOCs) and endocrine-disrupting chemicals (EDCs), contributing to healthier indoor environments.
• Job Creation and Safety: The use of bio-based materials can create more jobs and improve safety conditions, especially in off-site construction.
• Local Social Value Generation: Local sourcing and manufacturing of bio-based materials can support regional economies and reduce transportation-related emissions.
• Resource Efficiency: Some bio-based materials, such as straw, hemp, and rice husks, are by-products of agricultural practices and can be repurposed to reduce waste and resource competition.

Misconceptions and Knowledge Gaps

• Data Availability: A lack of comprehensive data on technical performance, environmental impact, and supply chain transparency hinders the adoption of bio-based materials.
• Fire Performance: Bio-based materials are combustible, but fire safety can be improved through the use of natural additives like lime and through proper design and engineering.
• Moisture Regulation: Bio-based materials can help regulate indoor moisture and humidity when used correctly, creating more breathable and stable environments.
• Pest Attraction: While some bio-based materials may be more attractive to pests, proper storage and surface treatments can mitigate these risks.
• Durability and Scalability: There are concerns regarding the durability of bio-based materials and their scalability in large-scale construction projects.

Opportunities for Cities

• Knowledge and Collaboration: Cities should foster collaboration and knowledge-sharing across stakeholders to drive innovation and best practices in bio-based construction.
• Policy Development: Implementing policies that support the use of bio-based materials, such as building codes and procurement guidelines, is essential.
• Financial Incentives: Financial mechanisms, including subsidies and grants, can encourage the adoption of bio-based materials in construction.
• Regulatory Integration: Integrating carbon performance into building regulations and procurement processes will help cities meet climate goals and promote sustainable practices.

Key EU Regulations

The handbook references relevant EU regulations that support the use of bio-based materials in construction, although specific regulations are not detailed in the summary.

Materials Handbook

The handbook includes a range of bio-based materials, such as:

• Timber: Used for structures and cladding.
• Bamboo: Suitable for lightweight construction in regions where it is abundant.
• Hemp: Utilized as a plant-based aggregate and insulation material.
• Straw: Typically from wheat, used as insulation and a by-product of agriculture.
• Wood Fibre: Applied as sheathing and insulation.
• Cork: Used for insulation and internal finishes.
• Wool: Serves as an insulation material.
• Mycelium: Offers insulation and interior finishing options.

Case Studies and Examples

• Denmark: Introduced carbon regulations that promote the use of bio-based materials.
• Finland: Implemented a Wood Building Programme to increase the use of timber in construction.
• Tampere, Finland: Utilizes subsidy grants to support timber construction.
• Washington DC: Encourages the use of bio-based materials through building codes and procurement guidelines.
• Bigwood Interreg Project: Aims to overcome resistance to using timber in high-volume construction.
• InnoRenew CoE (Slovenia): Features the country’s largest wooden building.
• Barcelona and Rovereto (Italy): Examples of social housing projects that use recovered wood from natural disasters.

Glossary Highlights

• Embodied Carbon: The total GHG emissions associated with the production of a material or product.
• Bio-Based Materials: Derived from living organisms, may include natural or synthetic components.
• Mycelium: A fungal network that can be used in insulation and interior finishes.
• VOCs and EDCs: Substances that can negatively affect indoor air quality and human health.
• Hygroscopic Buffering: The ability of materials to regulate moisture and humidity, improving indoor environments.
• Life Cycle Assessment (LCA): A method to evaluate the environmental impact of a material or product throughout its life cycle.

Limitations

• The handbook does not provide an exhaustive list of bio-based materials or manufacturers.
• It does not include technical due diligence on the products mentioned.

Conclusion

The handbook serves as a valuable resource for city officials and planners seeking to reduce the carbon footprint of construction through the use of bio-based materials. It highlights the potential of these materials to support climate goals, improve health and safety, and promote sustainable economic development, while also addressing the challenges and knowledge gaps that must be overcome for wider adoption.