Within the sustainability discourse today the term “carbon” is frequently used to represent the impacts that we are having on our climate. Carbon, however, seems to have gotten a bad reputation. It is an essential chemical element that makes up a great deal of our world and even us, as it is the second most abundant element in the human body.
Only when bonded with oxygen does carbon take on a gaseous form carbon dioxide (CO2) that is considered a greenhouse gas (GHG) and can be dangerous to our environment. The word “can” is not to be glanced over as CO2 is crucial to the survival of plants via photosynthesis. The process in which plants create food, photosynthesis relies on carbon dioxide…so much of our planet’s biomes wouldn’t be here without CO2.
It's also important to clarify the term “carbon” in embodied and operational carbon. Although CO2 is the prevalent GHG emitted through human activity, GHGs are a collection of harmful gases that are commonly expressed as CO2, CO2e (carbon dioxide equivalent), or simply carbon.
So, why all the shade thrown at carbon during sustainability discussions? It’s sort of a misnomer… let’s dig in.
When you hear the term “embodied carbon”, it is referring to the GHG emissions that are emitted from the manufacturing, transportation, installation, maintenance, and disposal of all man-made materials. When the term “operational carbon” is used, it is referring to the GHG emissions that are emitted when energy is consumed when operating buildings, infrastructure, and vehicles.
What is the difference, then?
Operational Carbon is turning off and on the light switch in your home or office. It’s heating and cooling that same area or driving to work in a combustion engine vehicle. Embodied Carbon is the running of factories to make products, mining of raw minerals, and the shipment of supply chain goods to an end user. If you think about the two terms at a building scale, the below graphic (thanks to New Building Institute) visualizes the lifespan of a building from construction material extraction to destruction or reuse.
The green arrows represent all the areas where there are embodied carbon impacts that should be calculated, while the red box represents the operational impact of running the building. There are a variety of caveats to this visualization and the resulting impacts at each phase. For example, what if the manufacturing facility producing a product for the building’s construction is powered by a fully renewable grid? The embodied carbon during A3 would be far less than a coal-powered power grid.
With numerous embodied carbon green arrows, you would expect production and end-of-life impacts to be a far greater consideration in our struggle against climate change. However, we have primarily focused on operational carbon for the past decades. This is due to a few logical factors: the first is that operational carbon has a direct impact on our wallets when paying energy and water bills; two is that it is something we can control (turning heating off and on, walking more/driving less); and three, we can measure it much easier than embodied carbon. Recently evidence has shown that embodied carbon is as big of an environmental problem as operational carbon, so luckily the industry is quickly moving toward measuring embodied carbon easier and explaining how and why to reduce it.
As this graphic shows it is almost equal in terms of total carbon emissions in terms of new construction thru 2050. And this could be wrong if our electric grids continue to become more renewably focused, therefore forcing more burden on the embodied carbon (thanks to 2030, Inc for the graphic).
Since carbon is all around us and in fact…is us, we need to focus on minimizing the excess creation of its volatile forms into the atmosphere. Whether it is coming from operational energy usage or from developing the materials and product around us, we must control our release of ‘carbon’ no matter what we call it.
