Efficient land use in material production is critical to sustainable fashion which protects biodiversity.
How do wool, lyocell and cotton knitwear compare, when it comes to land impact?
Calculated by Emma Hakansson, verified by Jo Anderson at Faunalytics.
Building on our earlier calculations comparing Australian wool and cotton by the bale.
To produce 1 kg of Australian wool, 3,675 square metres of land must be cleared or kept cleared.
To produce 1 kg of Australian cotton, 14.87 square metres of land must be cleared or kept cleared.
To produce 1 kg of Tencel lyocell, 2.5 square metres of land must be cleared or kept cleared.
To produce 1 medium weight knit sweater made of Australian wool, 1837.5 square metres of land must be cleared or kept cleared.
To produce 1 medium weight knit sweater made of Australian cotton, 7.44 square metres of land must be cleared or kept cleared.
To produce 1 medium weight knit sweater made of lyocell, 1.25 square metres of land must be cleared or kept cleared.
Calculations
AUS WOOL
340,000 tonnes of greasy (unprocessed) wool produced on ‘more than’ 85 million hectares
AWEX, Learn About Wool: Australian Wool Innovation and The Woolmark Company (Summarised at CIRCUMFAUNA)
340,000 / 85,000,000 = 0.004
0.004 tonnes per hectare
= 4kg per hectare
= 4kg of Aus wool per 10,000 sq m of land
= 1kg per 2,500 sq m of land
According to the Australian Wool Exchange, only 68% of the weight of greasy wool is usable fibre for fashion use once it’s been cleaned.
Shear Destruction report
Greasy wool required to produce 1kg useable fibre:
1kg wool in bale / .68kg useable fibre = 1.47kg
2,500 x 1.47 = 3,675
1kg of Australian wool fibre = 3,675 sq m of land
(1 medium weight jumper (500g) = 1837.5 sq m land)
CIRCUMFAUNA (knit weight data)
AUS COTTON
0.12 hectares (1,200 sq m) per 227kg cotton bale CIRCUMFAUNA (revised with references here)
1200 / 227 =5.29
= 1kg of Aus cotton per 5.2 sq m of land
65% of weight of cotton bale is seed — used for oil and other products – and ‘cotton trash’ leaving 35% usable fibre
Cotton Australia
1kg cotton in bale / 0.35kg useable fibre = 2.86
5.2 x 2.86 = 14.87
1kg of Australian cotton fibre = 14.87 sq m of land
(1 medium weight jumper (500g) = 7.44 sq m land)
CIRCUMFAUNA (knit weight data)
TENCEL LYOCELL
In terms of land use, almost 1.1 ha is required for the manufacture of each tonne of cotton fibre, compared with 0.7 ha for viscose and only Just 0.25 hectares of land are used in the manufacture of Lyocell.
Fibre Fracture
(Note that this article also estimates that “almost 1.1 ha” is required to manufacture a tonne of cotton fibre, which is slightly less than our estimate above (as 14.87 per kg = almost 1.5 ha per tonne). We have chosen to use our higher estimate to be more conservative in the comparison against animal products.
0.25 hectares / 1000kg of lyocell
= 0.00025 hectares per kg of lyocell
= 1kg of lyocell per 2.5 sq m of land
(1 medium weight jumper (500g) = 1.25 sq m land)
CIRCUMFAUNA (knit weight data)