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Key takeaways for policy and practice

Carolien van der Voorden (EPFL) reports on the 2026 Sustainable Buildings and Construction Summit.  This international event focused on practical implementation of the 2024 Déclaration de Chaillot and the Belem Call to Action. It will feed into the Intergovernmental Council on Buildings and Construction (ICBC) and the preparatory processes for COP 31 and 32.

The buildings and construction sector accounts for around 37% of global carbon emissions, and the challenge is only intensifying as construction accelerates. The IEA expects the addition of a further 159 billion m² of floor area between 2025 and 2050. Most of this growth will occur in Africa and South Asia. To avoid locking in decades of high emissions linked to the production and use of construction materials, as well as from building designs, construction methods, and operational requirements, urgent action is needed now.

This was the starting point of the Sustainable Buildings and Construction Summit co-organized by the EPFL Centre for Worldwide Sustainable Construction (CWSC) and the UNEP-hosted Global Alliance for Buildings and Construction (GlobalABC) in April 2026 in Lausanne, Switzerland.

A key summit conclusion was that implementation is the primary bottleneck, not innovation. The tools, frameworks, and technologies needed to decarbonise the sector largely exist. What is missing is the ability to deploy them consistently and at scale, with governance fragmentation, data infrastructure gaps, finance misalignment, and capacity deficits all slowing progress.

Four important strategies emerged:

1.        Optimise urban design/urban planning

Cities built in flood plains, uncontrolled urban sprawl and high congestion, divided cities, urban heat islands, inadequate access to safe, affordable housing and community services, and no resilience against extreme weather events are just some of the consequences of a lack of pro-active, urban planning discussed. These are made all the more pressing by the increasing impact of climate change.

A clear call emerged: urban planning must play a more prominent role in shaping sustainable and resilient cities, supported by the proactive use of mapping, geospatial data, and remote sensing tools to inform  analysis and decision-making. For example, satellite mapping of urban growth patterns, combined with publicly available data on building construction details can help better plan for material stocks and demand, low-carbon pathways, risk-sensitive upgrading, and investment targeting.

There is an obvious advantage to planning at an early stage for cities expecting rapid and/or substantial growth, but also for cities that may see more retrofitting. Beyond focusing on a low to mid-rise, high-density compact urban morphology and integration of rooftop solar PV,  Key strategies are: smartly designed green spaces for community wellbeing, resilience, and heat absorption and natural cooling; improved urban location for affordable housing; enforcement of development control regulations; and community participation and strengthening of local supply chains.

2.        Optimise building design, construction and materials

The following takeaways focussed on addressing access to basic affordable housing, rising urbanization and population growth rates, and an increasing need to focus on resilience:

Self-built construction represents the large majority of housing construction in Africa but is underrepresented in national policies, nationally determined contributions (NDCs), and funding priorities. Construction is often incremental, room-by-room as savings allow, and relies heavily on the informal services sector. Actions need to prioritize tenure security to de-risk household investment, along with enabling procedures and simplified permitting to enable access to technical support and financing. This can be combined with actions to decarbonize the (single) housing construction materials market, such as for low-carbon concrete blocks and precast items.

Resilience, sustainability, and affordability can go hand in hand, if designed that way. This requires a focus on low-carbon materials and construction practices, and stronger emphasis on community-centred, heritage-informed, and climate-driven design. For example, shading, ventilation and airflow, moderate use of glass wall facades and low-carbon hollow blocks can maximize passive cooling and reduce operational emissions and costs.

There’s a need to curb the over-design of buildings, through minimizing steel and cement intensity in structural systems and economizing building forms. Cities around the world have seen a steady increase in the number of high-rise buildings, with a drive to build ever-higher and in unconventional ways. This pushes up embodied emissions, particularly through the increased need for steel and concrete to provide structural support. These buildings also generally represent a western style of construction, drowning out local culture.

Decarbonizing cement is essential and achievable.   Industry actors are already taking a lead-role in scaling proven solutions, such as the production of low-carbon limestone calcined clay cement (LC3). An estimated 90% of global material use is for construction, cement-based materials make up three quarters of these by mass, accounting for about one-third of material-related CO2 emissions. Through adoption of existing technologies, low-carbon cement can be the lowest-carbon scalable option to meet global demand by 2050. In parallel, timber and other bio-based materials can be sustainably, steadily scaled to increase their share.

3.        Regenerate, extend, recycle and reuse

The most effective way to reduce embodied carbon emissions of built environments is to stop building. Since that’s not always an option, the next best thing is to build less, and build smarter.

In existing built-up environments like London as well as rural heritage-sites like in Niger, building could be adapted and extended rather than demolished and rebuilt. Value added can be achieved in many ways, be it by adding floor area, redesigning for repurposing, or improving energy efficiency.

Where buildings do get taken down, there is an ever-growing range of opportunities to recycle building waste, including concrete, glass, and plastics, into new building materials. Contextual factors, such as distance to processing sites, waste collection practices, and preparation requirements do influence cost-effectiveness of these solutions. Overall, recycled materials’ scale is increasing and costs are coming down.

Lastly, cost-effectiveness of adaptation, recycling, and reuse can be greatly helped by designing and constructing new buildings with adaptivity and disassembly in mind. This includes modularity and use of reusable precast and prefab components.

4.        Integrate infrastructure

That the Summit’s infrastructure workshop was over-subscribed was telling. Infrastructure is a key part of designing, planning, and constructing new and growing cities, but is not part of the institutional, collaborative sector set-up around sustainable built environments. Well-designed infrastructure systems, from transport and energy networks to water and waste services, are critical enablers of sustainable, resilient, and inclusive cities. When infrastructure is planned in an integrated manner, it can reduce emissions, improve resource efficiency, enhance connectivity, and support compact urban development.There was as strong call for more pro-active integration of infrastructure from the GlobalABC members and construction sector broadly. Doing socould acceleratethe scaling of low-carbon cement, concrete, and steel, including through the more standardized application of Green Public Procurement processes across both public buildings and infrastructure. Given that three-quarters of the infrastructure that will exist in 2050 still has to be constructed, optimization of low-carbon infrastructure designs and construction processes combined with the use of low-carbon materials can drive construction sector decarbonization overall and reduce embodied emissions contained in this construction wave.

Concerted action is required

The sector needs an enabling environment aligned towards effective implementation. This includes more appropriate financial instruments and institutional arrangements that support investment, and shared, harmonized data infrastructure that can compare different approaches on a common basis, such as through the Coalition for Life Cycle Emissions Alignment and Reporting (CLEAR) launched at the Summit.

Specific key actions for three groups of stakeholders include:

UNFCCC and the upcoming COPs

• Position the Déclaration de Chaillot and the ICBC Belém Call to Action as key opportunities to simultaneously tackle the housing and climate crises.
• Position construction sector decarbonization as an opportunity rather than a constraint, focusing on lock-in avoidance.
• Stimulate member states to sign up to the ICBC Call for Action on Blended Lower Carbon Cements and SCMs to reduce Clinker Content and GHG emissions.

Individual member states

• Update standards to allow performance-based, lower-carbon products onto the market.
• Engage in ICBC country dialogues and/or use roadmaps (e.g., those driven by GlobalABC, GCCA, and WorldGBC) as a powerful tool to map out decarbonization pathways and address policy enablers, e.g.,
• Strengthen inter-ministerial policies and collaboration across fragmented silos.
• Use public green procurement processes and harmonized reporting standards for high-impact materials to create demand for low-carbon materials.
• Urge, enable, or de-risk private sector/industry investments in low-carbon production and construction processes.
• Increase policy, investment, and capacity development focus on self-construction and sustainable affordable housing; ensuring contextualization and involvement of local actors and end-users.

NGOs and professional institutions

• Raise awareness of the ways the built environment interacts with the planetary boundaries.
• Avoid dogmatism at the cost of pragmatism
• Educate and empower people to make the best construction decisions in their context, at their price point, for their aspirations. This includes pro-active focus on training actors along the building value chain on low-carbon construction, for example through the Certificate of Advanced Studies in Sustainability in the Built Environment.
• Acknowledge that buildings require a mix of materials and address barriers to scaling low-carbon construction materials and solutions.

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