As regulation and technical advances cut operational carbon, the construction industry must look at how it can reduce embodied carbon too. Marta Bouchard, AEC sustainability lead at Autodesk, explains
This is an excerpt from an article that originally appeared on Autodesk’s Redshift, a site dedicated to inspiring construction, manufacturing, engineering and design leaders. Read the full article here
More than 70 countries and 1,200 companies have committed to achieving net-zero emissions by 2050, according to the United Nations.
The goal of net zero is to cut carbon emissions to curb climate change to protect the planet and future generations.
Human-caused emissions of carbon dioxide and other greenhouse gases are a primary driver of climate change - which, if humanity wants to mitigate climate warming on the ecosystem - must be addressed from all perspectives, across all industries.
What is embodied carbon?
Embodied carbon in the context of the architecture, engineering and construction (AEC) industry refers to the greenhouse gas (GHG) emissions released into the atmosphere during the upfront activities necessary to construct or renovate buildings and infrastructure.
Reported as carbon-equivalent emissions (CO2e), the total accounting of GHGs emitted during the build phase is called embodied carbon because the environmental impacts associated with building activities are locked in place before building operation.
Embodied carbon includes all the upfront activities that are part of construction, as well as any kind of renovation - replacing a roof, fitting-out a tenant space or simply replacing carpet or repainting - activities that also generate GHG emissions.
Before the building systems are operating, a carbon footprint has been formed.
What is operational carbon?
Energy from fuel-burning activities during building operations can be converted to the metric of operational carbon.
Operational carbon, therefore, is the amount of GHG emissions released during the operational, or in-use, phase of a building; for example, it can be calculated from energy bills and reported annually.
Operational carbon is the carbon-equivalent emissions associated with the operation phase of the building, including heating, cooling, lighting and power.
Embodied carbon vs operational carbon
Many AEC professionals - everyone from designers and contractors to operators and owners - understand and focus on reducing operational energy costs due to fuel consumption such as oil, natural gas or electricity.
CO2e generated by the use, management and maintenance of annual building operations currently accounts for about 28 per cent of annual global GHG emissions.
Relative to operations, CO2e generated by construction activities are accumulated and considered ‘locked-in’ as embodied carbon before the operational phase. Annually, embodied carbon accounts for close to 11 per cent of global GHG emissions, attributed to the ongoing building activity and construction around the globe.
Year on year, this is a significant carbon footprint and a big opportunity for the AEC industry to address associated GHGs beyond operational energy.
Stricter building codes, more energy-efficient equipment and lighting and more renewable-energy sources will help reduce the operational carbon of buildings.
As buildings become more energy efficient, a larger relative percentage of a building’s total CO2e impact will be the upfront embodied carbon.
As part of the design and renovate process, AEC professionals can influence and reduce carbon impacts in the built environment.
Recognising the role that embodied carbon plays relative to the total CO2e is key to identifying how the AEC industry can help mitigate the climate crisis by reducing its carbon footprint.
How the AEC industry contributes to GHG emissions
The built world includes living, working and recreational spaces made up of buildings, roads, bridges and transportation and distribution systems (for example, utilities).
Everyday operations of these human-made systems affect the world’s ecosystem and contribute to climate change.
The AEC industry yields significant influence over the planning, design, construction and operations of the built environment.
Notably, the building sector is one of the biggest contributors to GHG emissions, which cause global warming.
Given this influence, the AEC industry is poised to adopt more sustainable practices and lead cross-industry decarbonisation efforts to reduce its impact on climate change.