By enlarging its carbon accounting, a company can easily obtain the unit carbon weight of its products and its annual decarbonation result, i.e. the annual progress or decline in the company’s impact on the atmosphere.

1. Unit weight in carbons

Let’s take the example of a restaurant owner and see how, at the end of the year, he calculates the unit carbon weight of his product: the meal sold. He indicates in his unit carbon weight account that he sold 5,000 meals and that his purchases to produce them – food, energy, premises, etc. – “weighed” 6,000 kg of carbon (he finds their weights on the invoices of suppliers who have enlarged their accounts or, failing that, on a free calculator or on databases such as those of ADEME). Its carbon accounts divide the weight of purchases (6,000 kg) by the number of meals sold (5,000) to give the unit carbon weight of a meal sold: 1.2 kg of carbon, which it passes on to its customers on their invoices. (Other calculations would allow him to refine by menu or dish).

2. The result in carbons

From the second year onwards, its decarbonation account gives the company its carbon footprint: it measures the annual progress or decline in the company’s carbon impact on the atmosphere: positive if its direct or indirect activity has emitted less (or captured more) carbon, negative otherwise.

The calculation is made automatically by the carbon calculator. It measures the company’s carbon productivity gains (or losses) (for a constant quantity sold).

If sales increase to 6,000 meals and the weight of purchases remains stable at 6,000 kg, the carbon weight of the meal falls to 1 kg (6,000/6,000): a gain of 200 grams per meal. Let’s forget about the increase in sales for the moment and think about the 5,000 meals in the first year. The reduction of 200 grams per meal for 5,000 meals is a benefit to the atmosphere of one tonne less. Part of the gain is due to quantity savings on its purchases: less cooking, fewer meat products, less waste in the kitchen, etc. The carbon account gives this automatically, for example 600 kg (this is the sum of the variation in quantity of each purchase per meal sold, multiplied by the carbon weight of the purchase the previous year, multiplied by the 5,000 meals). The remaining 400kg are due to reductions in the unit weights of purchases and are included in suppliers’ results, which avoids counting the same result twice.

In the future, it will be possible to calculate two other components of the decarbonation result.

Productivity gains (or losses) in terms of carbon brought to customers and shared with them. They will appear if the restaurateur has signed a decarbonation sharing agreement (a type of agreement made possible in the future by enlarged accounting). For example, it will have agreed to share the carbon benefit of a new furnace with its supplier. Or his customer, whose canteen he supplies, will have agreed to share with him the carbon benefit of a reduction in the end-of-life carbon cost of the waste he is responsible for.

The gain (or loss) caused by the variation in the quantity of meals sold (at constant unit weight). It will appear if the company has access to the average weight of a meal, taken from a confidential statistical database listing the unit weights recorded (databases made necessary by the enlarged accounting system). The gain is equal to the variation in the quantity sold multiplied by the difference between the unit weight of the company’s meal and the statistical weight. If the statistical weight is 1.5 kg, and the restaurant owner’s weight is 1.2 kg, the additional gain for the company is 300 kg (the difference of 0.3 kg multiplied by the increase in meals sold of 1000 meals). Why this formula? If the number of meals sold remains the same, each additional meal for one company means one less meal for another, with a gain for the atmosphere (respectively a loss) to be shared between the two companies if a carbon-intensive meal is replaced by a lighter one (otherwise a loss).

(This example applies to the vast majority of companies. For some companies, it must be corrected by the weight of carbon captured (forests, industrial capture, etc.) or introduced by production processes (oil, cement, etc.). Few companies are affected, as supplier weights pre-count the carbon impact of burning carbon fuels. The accountant bases these adjustments on certificates from carbon experts).