<aside> ℹ️ Here you will read about:
Defining ‘low-carbon’ - the why
What are the greenhouse gas reductions?
What is the use intensity of the resource and the effect on decarbonisation pathways?
What is the deployment potential at scale in the near-, mid-, and long-term?
In the absence of science-based thresholds in line with the Paris Agreement, whole-life emissions from a particular product or process need to be reduced to the minimum. When it is a product integrating several intermediate products (e.g. a building made up of different materials) it can only be called low-carbon when all its components and the processes related to the final product during its whole lifecycle are also low-carbon. If only part of the final product is made up of low-carbon products or processes, then it should be indicated which parts. Emissions should be accounted for properly, following a robust methodology that includes all relevant emissions, both direct and indirect, caused by a product including its production, use and disposal.
There should not be trade-offs in terms of emissions (no switching of emissions to another value chain: no carbon leakage), and the decisions for using low-carbon products should always be justified in terms of emitting less at a system level. When there is an impact, it needs to be taken into account. For example, when building a structure, if a low-carbon material is chosen, it is necessary to make sure that the overall quantity of material going into the building is going to emit less overall than the alternative. If a material has less embodied carbon per mass unit, but more material is needed to achieve the required structural properties and this results in more CO2 emissions overall, efforts to decarbonise could be futile (18). Lower emissions should also not be traded for a shorter lifespan of the building, and a ‘minimum waste first’ strategy should be in place when using by-products from other industries (like SCMs or blast-furnace slags).
When strategic decisions need to be taken regarding the timing of the reduction, ‘the sooner, the better’ principle shall apply. In particular in the case of buildings, where the biggest share of embodied carbon is emitted before the building is put to use (upfront carbon), there is a risk of “locking in” emissions for the lifespan of the building. Once it is constructed, there is limited potential for reductions of embodied carbon. Therefore, measures that aim to tackle upfront carbon should be prioritised and incentivised with proper financing and regulation. However, this principle should enable the minimising of emissions from a holistic perspective, over the whole lifespan of the building, also considering the potential variations of operational carbon emissions (for example: waiting longer to install a heat pump than instantly setting up a hydrogen-ready gas boiler).
As addressed, subjectivity is rife when it comes to these definitions, with them differing across stakeholders. Here, this study therefore looks at some other stakeholders’ and evaluates these vis-a-vis the 3 criteria used to analyse the technologies [64].