Our carbon footprint, which is responsible for global warming, is created by the volume of greenhouse gases (GHG) emitted by the products and services we consume. Achieving the objective of the Paris Agreements means finding ways to limit global warming to + 2 ° C, ideally minimising it to + 1.5 ° C, which will require a drastic reduction in our GHG emissions.
To determine the carbon footprint, we carry out a life cycle analysis (LCA) of an activity or product, by measuring the GHGs released into the atmosphere. We can thus measure the carbon footprint of a product, a service, an event, a company, a building, even a nation or even an individual.
When it comes to the LCA of a product, there are many factors that go into the carbon footprint calculation. The manufacturer submits to a third party all the data covering the impacts generated by raw materials extraction, components, transport, manufacture, use, maintenance and eventually the management of the product’s end of life. In this way, the manufacturer will work to reduce its impacts to mitigate global warming, or even reverse it.
Responsible for 39% of CO2 released into the atmosphere, the construction sector is one of the biggest sources of GHGs. To calculate the LCA of a building, in addition to the energy-related GHG emissions released during its use, called operational carbon, it will also be necessary to take into account the embodied carbon. The latter considers the emissions related to the materials used to build the building.
LCA is then used to create an Environmental Product Declaration (EPD) to help decision makers choose low impact materials. The process is strict and verified by an independent third-party. This declaration lists the components, energy consumption, water and various environmental impacts. The carbon impact is expressed as Global Warming Potential (GWP). GWP measures the amount of heat trapped by GHGs in the atmosphere up to a given point in time. The emission factor is the reference coefficient used to calculate the emissions of the six greenhouse gases recognised by the Kyoto Protocol and translated into CO2 equivalent.
GWP measurement is then broken down into several characteristic phases of a product’s life cycle. It includes the incorporated and operational carbon emitted from the extraction of raw materials (the cradle) until the end of life.
Products Life Cycle
The stages analysis from cradle to gate (stages A1 to A3), corresponds to the carbon emissions from raw material extraction (the cradle) to the point where the product is ready to leave the factory (the gate).
These are the stages best controlled by the manufacturer, because it has many levers for lowering its CO2 emissions. Unfortunately, manufacturers have limited control over the carbon emitted after they leave the factory. The stages of transport, installation, use and end of life vary according to the influence of the stakeholders. This is the reason why it is important to consider phases A1 to A3 when designing a project. It will make it possible to compare the efforts made by manufacturers to reduce their carbon emissions and therefore to choose virtuous products.
In several European countries, we are witnessing the emergence of new construction standards which impose a limit on incorporated carbon emissions into buildings, as in France with the E + C- and BBCA certifications or in the Nordic countries which are developing a set of legislation to limit incorporated carbon.