From their iconic skylines to beautiful and historic architecture, buildings and infrastructure define our cities. They protect, connect and create  spaces for  people to live, work, study, visit and play. However, our built environment is also one of the largest sources of greenhouse gas (GHG) emissions, and drives a significant  amount of air pollution in our cities, threatening our public health and the well-being of our communities. Specifically, building materials, construction, maintenance, and demolition are responsible for a growing share of buildings’ carbon footprint, and they make up the largest share of the infrastructure we rely upon daily.

The construction sector alone is responsible for more than 23% of global GHG emissions and consumes more than 30% of global resources. Continuing business- as-usual in this sector, which relies on carbon-intensive machinery and materials, threatens to put the world on a fast track towards a global temperature rise of 3°C or more. 

By 2050, an additional 2.5 billion people are projected to live in the world’s cities. As urban populations grow, the need for new buildings and infrastructure around the world will intensify, and refusing to make our urban infrastructure more sustainable will have devastating consequences for the environment.

The global COVID-19 crisis has highlighted the need for our built environment to support public health and improve resilience, adaptability, and equity. A number of cities have already committed to ensure their buildings and infrastructure support a green agenda and promote healthy, sustainable, and energy efficient communities via C40’s Net Zero Carbon Buildings Declaration. But, this is not enough. Our efforts to improve energy efficiency must now be complemented with a whole life-cycle approach to our built environment. 

As mayors, we commit to working together to shift the global construction industry towards a more sustainable future. We will lead the way towards clean construction to achieve thriving, resilient and healthy communities in our cities, especially for the most vulnerable. Clean construction values our existing stock, prioritizing building retrofits, and ensures that new buildings and infrastructure embed circular economy principles in their design, material and construction choices. Supporting clean construction will allow us to  deliver a green and just recovery from the COVID-19 crisis by improving social equity and reducing air pollution that disproportionately impacts the most vulnerable communities. Clean construction also has the power to create good, green jobs by investing in local sustainable businesses and educating and reskilling workers. 

We acknowledge that achieving clean construction can only be done in collaboration with our partners in the construction sector, as acknowledged in the World Green Building Council’s Bringing Embodied Carbon Upfront report. We cannot transform built environment systems alone, and we remain committed to bringing together the necessary and relevant stakeholders to deliver results quickly and urgently.

To ensure that our cities develop the net zero emission buildings and infrastructure of the future, we pledge to bring together and inspire stakeholders to take action, and enact policies and regulations where we have the powers to:

  • Reduce embodied emissions by at least 50% for all new buildings and major retrofits by 2030, striving for at least 30% by 2025
  • Reduce embodied emissions by at least 50% of all infrastructure projects by 2030, striving for at least 30% by 2025
  • Procure and, when possible, use only zero emission construction machinery from 2025 and require zero emission construction sites city-wide by 2030

To meet these commitments, we, as mayors, will take the following actions:

  • Prioritise the better use, repurposing, and retrofit of existing building stock and infrastructure across the city to ensure their optimal use before new construction projects are considered.
  • Lead by example with municipal procurement by requiring life cycle assessments (LCAs) and the diversion of construction and demolition waste from disposal for all municipal projects. Use municipal purchasing power to procure or demand zero emission construction machinery in municipal projects. Reward resource efficient and circular design, use of low carbon materials, and low to zero waste construction sites for all new projects and major retrofit.
  • Demand transparency and accountability, starting with requiring LCAs in planning permissions and embedding them into planning policies, processes and building codes within a year of endorsing this declaration or in the next revision of planning policies and codes. Require the public disclosure of this data to facilitate greater transparency and foster accountability to develop robust baselines, standards, certifications and policies.
  • Work with businesses, industry, public institutions, citizens and other organizations to establish a joint roadmap adhering to circular economy principles within two years of endorsing this declaration and incorporate it into our Climate Action Plan. The roadmap will provide an implementation pathway to the Clean Construction Declaration commitments and to reaching its targets inclusively and equitably.
  • Approve at least one net zero emission (operational and embodied) flagship project by 2025.
  • Assess the impact our choice of materials and construction design will have on our cities’ overall resilience to climate impacts (i.e., increasing urban heat island, impermeable surface increasing the risk of flooding, etc.)
  • Work with and advocate for regional, national and supranational government to take action on sources outside the boundaries of our control.
  • Publicly report every year on the progress our cities are making towards these goals.


Read the full text of the declaration.