Operational or embodied: changing perceptions about carbon Today it is impossible to talk about decarbonizing the construction sector without making the distinction between two types of CO2 emissions: operational carbon and embodied carbon. In the past few years, there has been a great deal of effort to reduce operational carbon emissions related to building use: such as heating, cooling systems, and lighting. With the introduction of new technologies and increasingly stringent legislation, new constructions emphasize their low-energy consumption attributes, asserting themselves as ‘passive’ or even ‘positive’ because they produce their own energy. But much remains to be done to reach zero-carbon. Reducing operational carbon is an important first step, but it’s not enough to create zero-carbon buildings. The focus should not only be on the use of the building, it should also include all the CO2 emissions the building has generated. From the extraction of raw materials and the production of building materials to the recovery of building site waste and the demolition of the building. This is the principle underlying the concept of embodied carbon which represents nearly 50% of a building’s CO2 emissions. This intrinsic carbon takes into account the entire life cycle of a construction. That ranges from the origin of the raw materials – which sometimes require long journeys – to the production of the materials, all the way to the end of the building’s life. Unlike operational carbon – which can be addressed throughout the life of the building, especially through energy retrofitting – embodied carbon emissions are an indelible part of the building’s envelope (especially insulation) and its equipment. This leads to a need to envision each step of a construction from the ’net zero emissions’ viewpoint, assessing emission inputs and outputs. That is the challenge currently facing the industry. It is a global challenge that requires construction stakeholders to start thinking in a circular, rather than linear manner, including being proactive in the sourcing of raw materials with a low carbon footprint. In this Copernican revolution towards a construction world that is finally fully decarbonized, the sector will have to improve building design and production processes to make them more efficient, with fewer CO2 emissions. 27 CONSTRUCTING A SUSTAINABLE FUTURE
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