How cities can achieve net zero by targeting building emissions from design to demolition

Cities are at the epicentre of environmental impact and play a critical role in combating the climate crisis. They currently account for 70% of global CO2 emissions, primarily stemming from fossil fuels used in industrial processes, motorized transportation systems, and infrastructure constructed with carbon-intensive materials. Despite some positive effects observed during the COVID-19 pandemic, the gap between the trajectory and decarbonization target for the buildings and construction sector is widening, and it appears unlikely to achieve net zero by 2050.

Reversing the adverse effects of the climate crisis on society, biodiversity and the economy is imperative. This urgency was evident at COP28, where global leaders called for collaborative climate action, emphasizing shared responsibilities and accelerated efforts to limit global warming to below 1.5°C. As part of this effort, COP28 launched the Building Breakthrough initiative with 28 countries committed to making near-zero emissions and climate-resilient buildings the new normal by 2030.

Measuring and reducing operational emissions from the use and maintenance of buildings has so far made up the majority of decarbonization efforts. But this provides only a partial view of a built asset’s carbon footprint. It is essential to also evaluate the embodied carbon of built assets. Embodied carbon refers to greenhouse gas emissions produced in a building or infrastructure’s life cycle, including for manufacturing, maintenance and decommissioning.

While the buildings and construction sector can determine carbon emissions from day-to-day operations, embodied carbon factors are often not measured and reported. Measuring both embodied and operating carbon completes the picture of a building’s Whole Life Carbon Assessment (WLCA).

A WLCA is a summation of the entire amount of carbon produced by any particular built asset throughout its life cycle, comprised of both operational and embodied carbon emissions. The emissions associated with building materials life cycle, from extraction and manufacturing to transportation, maintenance and eventual disposal, can be complex to measure without reliable guidance.

The G20 Global Smart Cities Alliance and the Net-Zero Carbon Cities initiatives at the World Economic Forum, in collaboration with Infosys and C40 Cities, are leading a multistakeholder taskforce. It aims to collate and evaluate best practices and actions taken by local governments worldwide concerning embodied carbon and facilitate discussions to promote the adoption of proven best practice.

Drawing from best practices seen worldwide, the taskforce has released a model policy on Whole Life Carbon Assessment Mandates, an Adoption Playbook for city officials, and a Practitioner’s Guide. Together, these resources collectively serve as a template to assist cities and relevant stakeholders in crafting policies that mandate whole life-cycle assessments for significant developments within the built environment.

The policy will help governments initiate the monitoring and reduction of emissions from their building and construction sector assets. With the help of the taskforce, the model policy and accompanying guides are being promoted for adoption by cities around the world.

The policy was developed by examining practical and implemented policies by cities like London, Toronto, Vancouver and supporting tools by other organizations. These governments are taking a crucial step toward reducing emissions and advancing their net-zero goals by measuring the carbon emissions produced through the whole life cycle of a building, from design to demolition in the construction value chain.

The following existing policies helped guide the creation of the global model policy:

In the urgent battle against climate crisis, cities stand at the forefront of driving environmental impact. To address CO2 emissions comprehensively, evaluating the embodied carbon of built assets – covering their entire life cycle – is essential. WLCA can pinpoint sources of carbon emissions and facilitate a more representative long-term carbon impact reporting and planning.

Operational carbon as the sole indicator of emissions is no longer enough to address the climate crisis and to accelerate the transition to net zero, especially considering the growing global risks impacting people’s quality of life and biodiversity. For instance, extreme weather patterns such as wildfires alone have a magnitude of impact – from safety and health risks, housing supply reduction, employment challenges, to population shifts. The 2020 wildfire in California USA resulted in insured losses estimated at $5 to $9 billion, while the 2017 wildfire in Sonoma Country increased the asking rent by 40%.

The WLCA model policy serves as a foundational guide, building upon existing best practices, to support the standardization of WLCA practices. This policy will help governments monitor decarbonization progress and help the private sector develop shareable data and tools for supply chain coordination and low-carbon project benchmarking.

To enable world leaders to make informed strategic, investment and policy decisions in addressing the climate crisis, reliable and accurate information is essential. A shift toward an embodied carbon approach can allow capturing emissions data from built assets that better reflects reality and foster best practices.

A comprehensive understanding of the carbon footprint associated with the built environment represents a crucial step in reducing global emissions. Cities like London, Toronto and Amsterdam are at the forefront, championing sustainable practices through whole-life carbon assessment approaches. However, greater international collective action is essential now to expand best practice policies that safeguard both people and the planet while promoting economic prosperity.