Comment: Measuring the true carbon cost of buildings is critical to reaching UN 2030 goals

In a global climate emergency, the built environment is a critical battleground, says Nigel Tonks, director, WLC Transformation Lead, Arup UKIMEA.


Buildings account for a staggering 37 per cent of global energy related carbon emissions, yet we are falling dangerously behind in efforts to decarbonise this sector. If the built environment stands a chance of reaching its UN 2030 goals, we must act now to measure the carbon footprint of buildings to inform how we drive down emissions.

The 2023 Global Status Report for Buildings and Construction launched by the Global Alliance for Buildings and Construction, examines the progress towards the goal of halving emissions by 2030. The conclusion is alarming – buildings are not on track. And with emissions 15 percentage points behind, the gap is widening.

However, solutions to this problem already exist. We know how to insulate buildings, replace fossil fuel heating systems with electric alternatives, improve building performance, drive down embodied carbon, and decarbonise the grid. The challenge lies in accelerating action and implementing these solutions at scale and pace – all of which stems from effective carbon measurement systems.

A unified system of carbon measurement

To make any headway in the journey towards net-zero, we must first agree on what this means for buildings and establish a collective method to track our progress. Despite the rise in corporate net zero commitments, there is no globally consistent and robust definition of a net zero building, a set requirement to measure carbon emissions, or any national policy requiring buildings to be truly net zero now or in the future. This means less effective reporting, and insufficient data to set realistic industry targets. This is preventing the growing demand for net zero buildings from driving a desperately-needed market transformation.

At its simplest, a net zero building can be defined as one which is highly energy efficient, with low upfront and lifecycle embodied carbon, not connected to fossil fuel energy sources, supported by 100 per cent on-site or additional off-site clean energy, and where unavoidable residual emissions are offset by long term carbon removal. 

Each of these parameters is readily quantifiable despite the many complexities. However, the estimated proportion of new construction that is currently accounted for in this way is less than 1 per cent.  It is also estimated that each week, humanity adds to the built environment an area equivalent to a city the size of Paris.

An internationally agreed definition for net zero buildings is crucial for robust national and local government policies, underpinning measurement, and transparent reporting, and providing clarity to the market that will generate real value from climate-adapted assets.

This is where the Declaration of Chaillot, signed by the 72 countries at the Paris Building and Climate Forum, comes in. The Declaration commits to implementing roadmaps, regulatory frameworks, and mandatory building and energy codes. Currently, over 100 countries have no building energy regulations whatsoever, and less than 30 per cent have performance regulations for the entire sector. The declaration aims to close this gap, promoting ambitious policies, unlocking finance, and supporting research and development. This intergovernmental commitment is a crucial foundation for the change required in the built environment.

Proactive sector-led initiatives

But regulation alone will not be enough. The industry and supply chain must take action now, instead of waiting for policy changes that can take years to develop.

Arup’s dataset covering whole life carbon emissions across almost 1,000 projects across 30 nations and five continents, reveals the need for granular data on building function, size, location, materials and systems to inform and prioritise carbon reduction decisions. Openly sharing these data and insights across our industry is essential to ensure that we can work together towards net zero goals.

To scale these efforts, the building sector must collaborate on widespread adoption of standardised whole life carbon assessments and transparent data reporting, and train engineers across the sector to use them effectively – designing with carbon alongside cost.

Urgent, equitable action

The climate emergency will not be addressed by focusing only on net zero. It is vital that buildings are climate resilient, adaptable to increased risks of flooding, rainfall, and extreme temperatures. This transition must be performed in a just and equitable way, ensuring that policies do not leave behind poorer communities, or the one in eight people living in informal settlements worldwide, who are the most vulnerable to the impacts of climate change.

The time for action is now. By measuring the true carbon cost of our buildings, collaborating across the supply chain and with other sectors, and working together to drive down emissions, we can create a more sustainable and resilient built environment for all. We have the tools, the knowledge, and the mandate – let's use them to build a better future for generations to come.

Nigel Tonks, director, WLC Transformation Lead, Arup UKIMEA