Can we really measure embodied carbon in buildings?
The real estate sector, the largest greenhouse gas emmiter (accounting for 39% of Europe’s CO2 emissions), must reduce its environmental impact and achieve carbon neutrality by 2050, as stipulated by the Paris Agreement.
To cut our footprint, as most players in the industry are committed to doing, we first need to accurately measure carbon in building construction.
Marc Esposito, Director of Innovation at GSE, sheds light on calculation methods in a landscape marked by multiple standards and heterogeneous data.
The diversity of parameters and methodologies
Reducing a building’s carbon footprint – during both construction and operation – also means measuring it. Its calculation must be based on a proven scientific method that enables comparisons – both between buildings and over time. Lifecycle assessments (LCAs) are now a widely used method, governed by ISO and EU standards. However, each country, and even each organisation, can choose a higher or lower level of precision within the LCA. For example, France uses the RE 2020 regulation, involving a fairly comprehensive approach, while Germany applies a more limited framework. Similarly, the lifespan of buildings taken into account in the analysis varies from country to country, and some regulations require data to be updated over time – as carbon emitted today has a greater impact than carbon emitted in the future.
“There are as many different ways to measure carbon as there are local regulations and certifications,” says Marc Esposito. “You also have to combine several factors to obtain an LCA.”
In a building’s lifecycle analysis, two additional factors have a decisive impact on the result: the completeness of the documents assessed and the quality of the carbon database. Today, databases listing product data sheets for each construction material vary from country to country. Besides, they are incomplete: they should be populated by all suppliers and accredited by specialised engineering consultancies, which takes time in a market that has not yet reached maturity.
The challenge of standardisation
So, while we are now able to measure a building’s carbon footprint, the challenge lies in harmonising calculation methods between countries and ensuring their applicability. The Low Carbon Building Initiative (LCBI), launched by the association for the development of low-carbon buildings (BBCA) and bringing together many players in the construction industry (including GSE), aims to create a European low-carbon label. It is currently focusing on logistics buildings and aspires to standardise carbon measurements across Europe. “Standardisation is crucial to enable true and meaningful comparisons between projects,” emphasises Marc Esposito.
A science-based, universally approved method of calculation is needed. In the meantime, GSE has developed its own methodology – called “Quick Carbon” – to ensure a rapid, comprehensive and standardised assessment of its projects’ carbon emissions. While we initially designed it for France, we plan to roll it out in more countries. “Our goal is to have a single method for all the buildings we build, so that we can track our carbon footprint and the actions we take to reduce it between now and 2030 and 2050,” says Marc Esposito. “We are guided by our commitment to carbon neutrality, as defined by the Science-Based Targets initiative (SBTi), which requires us to reduce our carbon emissions by 90% by 2050.”
In short, while we know how to measure carbon in buildings, the data varies depending on the reference system used and local regulations. The indicators cannot be compared with each other, which limits visibility and transparency. The challenge is to standardise the calculation method and enrich databases in order to closely monitor actions taken to reduce buildings’ carbon footprint through the decarbonisation of materials and energy. Marc Esposito concludes: “The goal is to truly reduce our sector’s carbon footprint. It would be a shame not to be able to distinguish effective actions from greenwashing because of imprecise measurements.”
[1] https://www.batimentbascarbone.org/low-carbon-building-initiative-lcbi-label-bas-carbone-europeen/
