Average sustainability index

We have chosen to work with an overall sustainability index for all garments, as opposed to a more specific, item-by-item approach. There is no reason to buy T-shirts differently to trousers

We decided to work with 2 sets of data: the average number of times a garment is worn, taken from a recent ADEME study (to be published in June) and also the number of garments actually purchased per year. Cross-referenced with the number of times in the year that the garment can be worn and the number of 'active' garments in the wardrobe, we obtain a real number of wears.

For each garment, we calculated an average durability index according to the formula: 'durability index = actual number of wears / average number of wears', bearing in mind that the value of this index is restricted to between 0.67 and 1.45. This gives an average figure of 0.95 for average purchases.