How COP31 can help to house the world, without costing the earth

Shelter is a basic human need. The world must deliver more than a billion new or improved homes by 2050, while dramatically reducing the environmental impact of construction. It is therefore no surprise that housing is becoming a central climate issue. One year after the launch of the Principles for Responsible Timber Construction at COP30, the question for COP31 is: can we show that housing delivery and urgent climate action can go hand in hand? 

One challenge, not two 

Housing and climate are often presented as competing priorities. In reality, they are increasingly interrelated. The world will need billions of homes in the decades ahead, at the same time as governments work to reduce emissions and strengthen resilience in the face of a visibly changing climate. The built environment sits at the centre of both. 

How we renovate existing buildings, choose and use construction materials to deliver new homes will shape not only whether we can meet those growing housing needs, but whether we can do so within planetary boundaries. 

There is no single pathway. Different countries and cities will require a different mix of tactics and tools to navigate the challenge. But from retrofitting and adaptation to timber and biobased construction, a growing range of approaches are showing that it is possible to deliver the decent and climate resilient homes people need while reducing the environmental impact of construction. The challenge now is not identifying solutions, but how we can rapidly scale the right mix of solutions in the right places. 

From principles to practice 

One year ago at COP30, we presented the Principles for Responsible Timber Construction. Today, nearly 400 governments, businesses and civil society organisations have endorsed them, creating the first shared global framework for scaling timber construction responsibly.  

Importantly, implementation has begun. National  governments including Brazil, Costa Rica, France, Japan, Kenya and the UK are embedding the Principles in regulations and their commitments to accelerating timber construction; at the sub-national level, cities are acting too. Inspired by the leadership shown by Amsterdam, which has seen timber housing grow from 0.5% to 17% in 5 years, Built by Nature is working with  the Carbon Neutral Cities Alliance (CNCA) on a Cities Challenge that has already engaged 20 cities to focus on how they can help enable this biobased transition.  

The lesson so far is simple: ambition is growing fast, but impact depends on practical action. Policies, procurement, investment and project pipelines will determine whether principles translate into meaningful progress. 

Building a global coalition for low-carbon housing 

The transformation of the built environment, and the delivery of millions of low-carbon homes, will not be achieved by any single organisation, government or industry. Success depends on connecting the actors who shape housing, climate policy, finance, construction, forestry and supply chains around a shared objective: delivering many more homes with a much lower environmental impact. 

Progress is often slowed not by a lack of solutions, but by fragmentation and friction in the value chain. Governments need practical policy pathways. Cities need procurement tools and project pipelines. Industry needs demand signals. Investors need confidence and evidence. Together, these are the elements needed not simply to deliver individual projects, but to scale low-carbon housing solutions to the level required by a rapidly urbanising world. 

That is why, ahead of COP31, Built by Nature is partnering with the Climate Champions team to help accelerate the sustainable buildings transformation globally. Through the Global Climate Action Agenda, we have an opportunity to work alongside national governments, cities,  industry and civil society leaders to strengthen collaboration, align action and turn ambition into implementation. At a time when housing, climate and economic priorities are becoming increasingly intertwined, success will depend not only on individual projects, but on our collective ability to scale proven solutions. All around the world we need homes that are affordable for people, and the planet.  

Climate High-Level Champions

Join us in Barcelona and Antalya 

This October, on World Architecture Day, our Annual Summit takes place in Barcelona, the designated UNESCO-UIA World Capital of Architecture for 2026. It will provide an opportunity to take stock of progress. Bringing together leaders from national governments, cities, industry and finance, it will focus on a practical question: what evidence do we have that housing and climate policy are beginning to move in the same direction? 

The Summit will also be an opportunity to consider what comes next. Five years ago, Built by Nature was founded. Now we have seven national and regional networks, more than 200 Frontrunners, nearly 400 endorsers of the Principles for Responsible Timber Construction and have succeeded in attracting more that €7m to research and innovation in the biobased building sector. How can we build on these foundations to accelerate the responsible use of timber and biobased materials for the benefit of climate, nature, and people? 

That answer could be housing. The world will need billions of homes in the decades ahead. If the  examples of timber and biobased homes that are affordable, safe, fast to build, low carbon and create healthy living conditions emerging today can be scaled, how many of those homes could be delivered in ways that support climate goals, strengthen nature and create healthier places to live? Tens of millions? Hundreds of millions? Perhaps even a billion? 

These are the questions that should guide us on the road to COP31. 

Annual Summit 2026