CO2 can be a bit of an enigma. It's an essential component of our planet's life cycle, yet in excess, it's a potent greenhouse gas (GHG) that contributes to global warming and climate change. While the need to reduce our carbon footprint is clear if we are to remain within the 1.5° threshold, talking about CO2 can be difficult at times. Since at standard temperatures and pressures CO2 is an invisible gas, numbers are the only way for us to put it into perspective. It makes up around 0.04% of the air we breathe in and around 4% of the one we breathe out. CO2 is all around us, and yet its intangible nature makes it difficult to truly grasp its significance. Unlike plastics or fossil fuels, consumers usually don’t come in contact with it on a daily basis. And yet, CO2 is one of the main culprits of the current climate change crisis, representing almost 80% of the greenhouse gases in our atmosphere.
But how is CO2 related to the construction industry?
There are two main types of GHG emissions connected to the construction industry: operational and embodied.
Operational carbon emissions refer to the CO2 released during the use of a building, mainly through energy consumption for heating, cooling, lighting, and other electrical needs. These emissions can be substantial, especially with older buildings that are not as energy efficient, and operational carbon still represents the majority of the emissions of the sector.
Embodied carbon emissions, also known as embedded or 'hidden' carbon, refer to the CO2 emissions associated with the entire lifecycle of a building. This includes the extraction, processing, and transportation of raw materials, construction, maintenance, and eventually, demolition and disposal. Embodied carbon is a major component of the total carbon footprint of a building. In fact, as operational efficiencies improve, embodied carbon becomes a more significant proportion of a building's overall carbon impact.
Most worldwide regulations focus on operational carbon, as it’s easier to tackle with policies favouring renovations and upgrades to cooling and heating systems. Embodied carbon on the other hand remains largely unresolved. The strategies to mitigate embodied carbon quantities are not so straightforward, and require an industry-wide sensibilization to low-carbon building materials.