Decarbonization of the Construction Process

Decarbonization of the
Construction Process

The focus on decarbonization gained momentum after the 26th UN Climate Change conference (COP26) in November 2021, where governments outlined necessary steps to limit the pace of global warming in support of the Paris Agreement. Hundreds of cities and companies have pledged to reach “Net-zero by 2050,” yet most of these commitments have yet to be backed up by detailed plans and execution. A transition to net-zero would be a fundamental step to ensure that the Paris climate targets are met. In response to this, the global construction industry needs to become a climate leader by moving towards net-zero construction.

Research suggests that the construction industry is responsible for approximately 39% of all carbon emissions in the world; 28% from “operational carbon” and 11% from “embodied carbon.”

Figure 1. Carbon Emissions in the Construction Industry

Operational carbon is the amount of carbon emitted during the operational or in-use phase of a built asset, which includes the use, management, and maintenance of the asset – think about lighting power, heating, etc. Embodied carbon is the amount of carbon emitted during the actual construction process, including the extraction of raw materials, manufacturing and refinement of materials and equipment, transportation of the materials and equipment to site, the building of the asset itself, and the deconstruction and disposal of materials as the end of the construction process. The figure below clarifies the various Life Cycle Assessment (LCA) stages of a building in accordance with European Standard EN 15978, including both embodied and operational impacts. Our research focused mainly on the [A1] to [A5] blocks, highlighted below.

Figure 2. Building life cycle, adapted from EN 15978:2011

Throughout this intensive research period, we have also identified top construction activities with the highest carbon emissions – concrete manufacturing, steel manufacturing, asphalt manufacturing, heavy transportation, and construction machinery or equipment. By focusing on these activities we are able to evaluate which areas of opportunity for innovative solutions the industry can focus on in order to achieve the net-zero goal.

Figure 3. Highest Carbon-Emitting Construction Activities

From our study, we have determined that the majority of the research and development (R&D) focus involving construction decarbonization has been focused on “operational carbon” mitigation and reduction. As operational carbon constitutes the larger contribution percentage, this focus is clearly justified and warranted. However, we feel that it is essential to evaluate and measure the carbon that is emitted during the construction process, also known as “embodied carbon.”

As part of our industry research effort, we have identified over 20 entities around the world; from companies, universities and organizations working towards the decarbonization movement. Skanska, AECOM, WSP, Lendlease, Perkins+Will, Autodesk, IES, ICF, and McKinsey are some of the companies that are leading this development. Academic institutions such as, University of Washington, University College London, and State University of New York System (SUNY) are also diving into this great challenge. And finally, organizations like the Carbon Leadership Forum, RICS, London Energy Transformation Initiative (LETI), and Green Building Councils (GBCs) around the world have conducted most of the embodied carbon research that has been commonly adapted into the AEC industry.

Our research involves three areas of study. The first assesses the carbon emissions associated with the manufacturing, extraction and processing of the materials and equipment that are designed as part of the scope of the project. The second assesses the carbon emissions associated with the transportation of the materials and equipment from the fabrication/manufacturing source to the construction site. And lastly, the third assesses the carbon emissions during the on-site construction processes by the vehicles (e.g., cranes, trucks, pick-ups, etc.) used during the construction phase. In order to support the goals of the Paris Agreement, the total amount of embodied carbon emission from these three areas should not exceed 500 kg CO2 /m2 , according to the LETI standard which has been globally recognized.

In order to effectively reduce the carbon emissions from the construction sector, we have to start measuring the individual emissions from each phase based on reliable data. This heavily relies upon the EPDs (Environmental Product Declarations) released by manufacturers and proper documentation maintained by contractors regarding the sources of their materials and usage of equipment on site. Moreover, through this research we are seeing future developments in material recycling and waste management sectors. There is clearly a trend of ongoing research and investment opportunities towards construction decarbonization due to the increasing commitment of governments and private companies. And, as more data becomes available, greater steps can be achieved to monitor and reduce carbon emissions from construction projects.