At Greenly, by continuously trying to improve our product and our services, a Greenhouse Gas (GHG) inventory may evolve over time.
There are two main reasons for this:
Implementation of new regulations and methodological guidelines
Substitution of old emission factors by new, more relevant ones: e.g. publication of a new scientific study, a supplier carried out a life cycle assessment, etc.
Regulatory and methodological changes
New regulations and directives are regularly published to support the rapid spread of carbon accounting.
🌐 The GHG Protocol often publishes new recommendations and guidelines to specify new calculation rules and share methodological updates:
Corporate Standards (2004)
Scope 3 Standards (2011)
Scope 2 Standards (2015)
PCAF (2020)
Etc.
❗ Following a public consultation in 2023, the GHG Protocol plans to update its guidelines in the coming years.
When these changes occur, your GHG inventory may evolve. For example:
New GHG emission categories may need to be included or excluded
The scope of emissions to be taken into account may change
Further details may be required
Changes in emission factors
Emission factors also change frequently. Current emission factor databases are incomplete and new, more accurate calculations are often carried out. Methods used to compute these emission factors are constantly being improved and updated, and the latest scientific and technical advances are taken into account.
When emission factors change, so does your GHG inventory.
💡 When several emission factors are available, we select the most relevant one: use of reliable and recent data, transparent methodology, well-known and trustworthy source and database, consistency with other emission factors used.
Nevertheless, in some cases, several similar emission factors may coexist, but have different values. For example, the emission factors for copper or steel are different depending on whether they are provided by the French Environment Agency (ADEME), Ecoinvent or a supplier. In general, differences stem from:
The region is different: World, Europe, North America, USA, UK, etc., with each region having its own specific characteristics (e.g. a more or less carbon-intensive energy mix).
The scope of the study is different: including or not transport, use, end-of-life, etc.
The industrial process is different: the same good can be produced in several ways (different physical or chemical manufacturing and transformation techniques, process optimisation and automation, process electrification, etc.).
The supply chain is different: mode of transport, transport distance, etc.
The raw data and inputs that are used are different: more or less recent and accurate data.
When this occurs, all the emission factors are accurate and well-accepted, and it can be difficult to understand the differences between their values. Thus, we try to select the emission factor that best suits the reporting company's needs and specificities.
Updating your previous GHG inventories
These changes do not call into question the accuracy of your previous GHG inventories and the computations that were carried out.
Nevertheless, when a significant change occurs, it is necessary to retrospectively recalculate your previous GHG inventory taking into account new data and guidelines (rebaselining). These updated GHG inventories are necessary to accurately monitor your GHG emission trajectory and to assess the efficiency and relevance of your action plans.
❗ For example, when certain emissions factors increase, your GHG inventory may also increase even though your overall performance has improved.
Further details are provided by the GHG Protocol (Corporate Standards - Chapter 5)
🛠️ Examples
Meta updated its baseline in its 2023 sustainability report. Some emission factors were updated, the methodology evolved (moving from monetary to activity-based studies for some categories) and organizational boundary changed.
"Going forward, we will focus on increasing accuracy and granularity of our data. For example, we rebaselined our 2020 data based on updated LCA data for key data center hardware and our AR/VR-related consumer hardware. We will use activity data for more emissions categories as methods to do so become available. We will continue reporting and updating our emissions boundaries as our business grows on our path to net-zero emissions."
Swiss RE updated its baseline in its 2021 sustainability report. Some emissions factors were updated, and a new methodology more aligned to existing regulatory frameworks was used.
"We undertook a full rebaselining exercise to update the greenhouse gas emission factors and improve our calculation methodologies, aligning them with the latest climate science and relevant frameworks."