Carbon Footprint Of Buildings: Challenges

by Irene Domínguez Pérez

To achieve climate neutrality by 2050, we need to decarbonise every sector of the economy. The building sector, often overlooked, amounts to 36% of emissions in the EU and 39% of global emissions [1,2].

Most of these emissions come from the energy used during the operation of the building, such as lighting or heating, and they are known as operational carbon. However, as energy efficiency measures start to be implemented, the share of operational carbon decreases, highlighting the importance of the emissions derived from materials and construction, or embodied carbon.

Relative impact of embodied and operational carbon of a new building from 2020-2050. Source: Carbon Leadership Forum (2020) [3].

What is embodied carbon, and why do we need to tackle it?

Embodied carbon is the greenhouse gases emitted from the manufacturing, transportation, installation, renovation, and end-of-life treatments of building materials [3]. Put simply, it is all the emissions that happen during the lifetime of a building or an infrastructure project, with the exception of those related to the operation. 

Embodied carbon (yellow) and operational carbon (blue) across the key life cycle stages of a building. Source: Carbon Leadership Forum (2020) [3].

The biggest share of embodied carbon happens right before the building is put to use: during the extraction of raw materials, manufacturing of construction products, and construction of the building, together with all the transport activities happening in between. This is known as upfront carbon. It is estimated that it amounts to at least 11% of global emissions [2]. 

The biggest emitter among construction materials is concrete. This is not surprising, considering that it is the most widely-consumed man-made material in the world [4]. Together with steel, they represent two of the largest sources of industrial emissions due to their production processes, which on the one hand involve chemical reactions that emit carbon dioxide directly and on the other hand are very energy-intensive, requiring high temperatures which often involve fossil fuel combustion.

What are the main challenges of decarbonising construction?

Reducing embodied carbon in buildings is a multifaceted challenge, as it involves emissions throughout the entire lifetime of a building. The two stages with the largest share of embodied carbon emissions are the manufacturing of raw materials, and the construction of the infrastructure [5].

When it comes to the manufacturing of raw materials, the main challenges are: carbon intensive and high-energy demanding production processes; insufficient development of decarbonisation technologies, such as carbon capture and storage (CCS); potential increases in costs in the switch to low-carbon technologies; and the need for coordination of multiple stakeholders in a complex and fragmented supply chain [6].

On the other hand, when it comes to the construction phase, emissions are mostly derived from the use of fossil fuel-powered machinery, which pollutes urban areas with greenhouse gases and noise. 

Fortunately, there are solutions in the short-, mid-, and long-term, that we will explore in the next article of the series.

References:

[1] European Parliament (2023). Energy performance of buildings: climate neutrality by 2050. https://www.europarl.europa.eu/news/en/press-room/20230206IPR72112/energy-performance-of-buildings-climate-neutrality-by-2050 accessed on 6th June 2023.
[2] World Green Building Council (2019). Bringing embodied carbon upfront. WorldGBC_Bringing_Embodied_Carbon_Upfront.pdf
[3] Carbon Leadership Forum (CLF) (2023). Embodied Carbon 101. https://carbonleadershipforum.org/embodied-carbon-101/ accessed on 6th June 2023
[4] Rodgers, L. (2018). Climate change: The massive CO2 emitter you may not know about.https://www.bbc.com/news/science-environment-46455844 accessed on 6th June 2023
[5] McKinsey (2021). Call for action: Seizing the decarbonization opportunity in construction. https://www.mckinsey.com/industries/engineering-construction-and-building-materials/our-insights/call-for-action-seizing-the-decarbonization-opportunity-in-construction accessed on 6th June 2023
[6] Eunomia (2022). Is Net Zero Enough for the Material Production Sector? https://www.eunomia.co.uk/reports-tools/is-net-zero-enough-for-the-materials-production-sector/ accessed on 6th June 2023