Definition and scope

To begin with, let's clearly define the scope of our purchasing carbon footprint.

In the sense of the "Bilan Carbone®", the reference method developed by ADEME in the early 2000s, calculating the carbon footprint of an organization's purchases (company, local authority, association, etc.) involves measuring the GHG emissions generated by the manufacturing phase of the products (or services) purchased for consumption during the year. Examples include reams of paper for office printing, or the copper used in a metal pipe manufacturer's production process.

The carbon footprint of purchasing as defined by the Bilan Carbone® method is therefore limited to :

• The carbon footprint of the "upstream" or manufacturing phase - excluding the other phases of the product life cycle (distribution, use and end-of-life),
• The carbon footprint of items that will be consumed during the year - excluding fixed assets (fixed assets provide lasting economic benefits, beyond one year, to the company).

In addition, the carbon footprint of waste from purchased goods is also an issue (for example, what happens to fabric scraps that are not used by a textile manufacturer?)

Steps in the manufacturing phase

By breaking down the manufacturing phase of a tangible good, the regulatory methodology for calculating the GHG balance distinguishes between the following stages[2 ] :

• Raw materials extraction
• Energy consumption for the following intermediate stages:
• Transformation of purchased materials/products
• Assembly
• For agricultural activities: change of land use (e.g. conversion of forests to cropland or built infrastructure - housing, industry, transport, etc.).
• Product transport between all processing stages

Manufacturing, just one stage in the product life cycle

Beyond the manufacturing stage detailed above, the total carbon footprint of a physical good is measured in terms of its life cycle, from the extraction of raw materials to end-of-life.

There are generally 5 main stages in a product's life cycle: extraction of raw materials, manufacturing, distribution (transport to the customer/user), use and end-of-life.

Lifecycle analysis consists precisely in assessing all the different environmental impacts of a product or service (impact on climate, impact on natural resources, impact on water, etc.).

Product life cycle stages

Here's an example of the breakdown of greenhouse gas emissions generated over the entire lifecycle of a smartphone (iPhone 14 Pro), according to data provided by Apple. It can be seen that production accounts for 80% of the product's carbon footprint, compared with 15% for the use phase.

Purchases account for a significant proportion of greenhouse gas emissions for individuals and companies alike.

The weight of purchasing in people's carbon footprint

In France, Carbone4, the leading consultancy on energy and climate issues, has broken down the average carbon footprint of a French person, highlighting the proportion linked to purchases: 1.6 tonnes of CO2e out of a total footprint of 9.9 tonnes CO2e, i.e. 16% of the footprint comes from purchases (household goods, electronics, clothing, etc.). This figure (1.6 tonnes CO2e) does not include purchases linked to food or spending on public services (administration, education, culture, etc.).

The weight of purchasing in a company's carbon footprint

As far as companies are concerned, as shown by a study by the Carbon Disclosure Project (CDP)[3], scope 3 (which includes GHG emissions from the upstream/supplier and downstream/customer chain) can account for over 90% of the carbon footprint of companies in certain sectors (financial services, construction, transport).

Within scope 3, greenhouse gas emissions generated by purchasing account for an average of 20% of a company's carbon footprint, but this figure can climb much higher for certain activities (44% for chemicals, 63% for agriculture, 67% for food, beverages and tobacco).

Example of the chemicals sector (breakdown of Scope 3 GHG emissions)

In addition to measuring the carbon footprint of their purchases, companies have a number of levers at their disposal to control or even reduce their GHG emissions.

1) Limit purchases

Avoid or reduce purchases whenever possible

Clearly, the first way to limit the carbon footprint of your purchases is simply to...reduce your purchases by avoiding unnecessary orders. While this option may seem radical at first glance, it nevertheless has the merit of questioning purchasing decisions and ensuring that they are essential to the smooth running of operations. Each organization is then free to set the cursor at the level that suits it best, to differentiate the indispensable from the superfluous.

The key is to be aware that every purchase has a carbon footprint.

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Favoring the purchase of less carbon-intensive products

Another option is to purchase goods whose production has emitted fewer greenhouse gases than similar products. However, the absence of carbon data for certain products makes it difficult to integrate this decision criterion into buyers' specifications. The general trend should, however, lead to a greater emphasis on less carbon-intensive products in the years to come.

As shown in the table below detailing the carbon footprint of several smartphones, the storage capacity of an iPhone, for example, has a significant influence on the greenhouse gas emissions generated by its manufacture (from 128 GB of storage to 1TB).

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Supplier analysis criteria incorporating the "carbon footprint" dimension

Focus on refurbished products

Another solution is to choose reconditioned ("second-hand") goods.

The logic is as follows: when we look at the carbon footprint of an object over its entire lifespan(cradle-to-grave), a significant proportion of GHG emissions come from the manufacturing phase (extraction of raw materials, transformation & assembly). So, by delaying the purchase of new products, we avoid the manufacture of these new products and therefore the greenhouse gas emissions generated by this manufacturing phase.

Minimize the impact of transporting your purchases

The product distribution phase, between supplier and customer, is also a lever to be studied in order to reduce the product's carbon footprint measured over its entire life cycle.

The most obvious options are :

• selecting a less carbon-intensive mode of transport: for the same distance covered, delivery by sea (boat, often container ship) will have a lower carbon footprint than delivery by air. This option is subject to customer constraints. Indeed, while sea freight emits fewer GHGs than air freight for the same distance and weight transported, delivery times are generally significantly longer by sea.

• selecting a supplier closer to the customer, in order to reduce the distance travelled and thus the GHG emissions associated with the transport service. This option is, however, subject to the presence of suppliers meeting the customer's needs in the region.

Extend the life of purchased goods (repair)

Beyond the possible - and sometimes difficult - reduction of purchases, we can reduce our carbon footprint by extending the life of the objects we use, always with the idea of delaying the purchase of new equipment (same logic as for the purchase of reconditioned equipment).

If we take the example of a smartphone, we can see that by extending the useful life of a terminal by 2 years instead of buying a new one, we avoid the emission of 16 kg CO2e (according to a study by ADEME[4]). This life extension is generally made possible by repairing or reconditioning existing objects.

Longer use of smartphones and associated climate impact

Enhancing product value at end of life

When a product is no longer in use, there are several options for limiting the carbon footprint of its end-of-life phase, such as recycling, reuse or energy recovery[5].

• Recycling refers to the direct reintroduction of a waste product into the production cycle from which it came, as a total or partial replacement for a new raw material (e.g.: a bottle is melted down and used to make a new bottle).
• Reuse consists in using a waste product for a purpose other than its original use, or using a waste product to make a product other than the one that gave rise to it (e.g. used car tires are used to protect the hull of a boat).
• Energy recovery involves using the calories contained in waste, by burning it and recovering the energy thus produced to heat buildings or generate electricity, for example.

The purchase of tangible goods is a significant source of greenhouse gas emissions, particularly during the manufacturing stage, which consumes raw materials and energy to transform materials and assemble products.

Taking this carbon footprint into account in corporate strategy and reporting is gradually becoming standard practice, and is becoming an issue of differentiation and competitiveness, in the context of regulations that increasingly favor low-carbon products (obligations to display a reparability index or even a carbon score on products, etc.).

Carbon accounting is gaining ground and can no longer be ignored by decision-makers.