There is growing interest in understanding ‘sustainable fashion’ and knowing how ‘eco-friendly’ our clothes are. However, measuring the sustainability of clothes is complex. Dr. Beverley Henry from Queensland University of Technology explains the basics on evaluating the environmental impact of textiles in these frequently asked questions.
FAQs on Environmental Impacts of Wool Textiles
How are the effects of wool products on the environment assessed?
The most widely accepted tool for evaluating the environmental impacts of a product is Life Cycle Assessment (LCA). This is a quantitative method described in standards published by the International Organization for Standardization (ISO 14040:2006 and 14044:2006). The LCA method aims to avoid a narrow approach by taking into account all the stages of a product’s life from cradle-to-grave and evaluating all important categories of environmental impact relating to resource use and emissions to air, water and land. LCA is a valuable tool for identifying ‘hotspots’, monitoring changes in impacts over time and reporting the effectiveness of actions taken to improve environmental outcomes.
For textiles, environmental impacts are assessed from fibre production or extraction and processing, through textile production, product manufacture (specified, for example, as an item of apparel or a square metre of carpet), distribution, use by consumers (including care, repair and re-use), recycling and final disposal. Impact categories generally important for textiles include climate change (i.e. greenhouse gas emissions), fossil energy use, water use (commonly weighted for regional scarcity), land use, eutrophication, eco-toxicity, and human-toxicity.
Wool LCA results can help wool growers, processors, spinners, weavers and all in the value chain to understand their impacts on the environment and to make changes to reduce those impacts and increase efficiency of resource use – changes which often have associated economic benefits. LCA also helps inform wool consumers about their supply chain and the potential to improve environmental performance.
What is allocation and why is it important in wool LCA?
In addition to wool, sheep farming commonly produces meat and sometimes other products such as milk and skins. Where multiple products share the same process, as for wool and meat from sheep, an allocation method is required to partition the environmental impacts between them wherever the system cannot be expanded to account for all products. The choice of allocation method can have a marked effect on LCA results and produce significant differences between LCAs for the same product. According to international standards (ISO 14044:2006) it is preferable to allocate impacts according to biophysical relationships, as opposed to methods such as the economic value of the products.
Results of wool LCA are particularly sensitive to choice of allocation method at the important fibre production stage. Recently published research1 compared alternative methods and demonstrated that allocation according to biophysical causality based on partitioning protein to wool and meat, provides for consistent and logical modelling of product environmental impacts. Consistent application of this method of biophysical allocation will reduce variability in results due to choice of method and/or fluctuating economic values of meat and wool. Biophysical allocation, in preference to economic value, has also been recommended in FAO Guidelines2.
1Wiedemann S, Ledgard S, Henry BK, Yan M, Mao N, Russell SJ (2015) Application of life cycle assessment to sheep production systems: Investigating co-production of wool and meat using case studies from major global producers. Int J LCA 20: 463-476.
2FAO (2015) Greenhouse Gas Emissions and Fossil Energy Demand from Small Ruminant Supply Chains: Guidelines for quantification, Version 1. Livestock Environmental Assessment and Performance Partnership. FAO, Rome, Italy.
Does LCA help identify which products have a lower environmental footprint?
When properly conducted using scientifically-sound methods and reliable, up-to-date data, LCA studies do enable comparisons between functionally similar products e.g. garments made from different fibres. However, there are a number of methodological issues that have limited the use of LCA to compare different products. A problem in a number of studies reporting comparisons for textiles or clothing is that they haven’t assessed all stages of the life cycle. Ranking based on partial life cycle impacts, e.g. for the fibre production stage alone, cannot be assumed to represent the full life cycle since products commonly differ in the dominant stage for any impact category. Similarly, results for a single impact category such as climate change (carbon footprint) should not be interpreted as a metric for more general environmental performance or sustainability. These two errors have often been the source of incorrect conclusions and misleading information.
LCA for products should also take into account the quality and representativeness of data. If regionally-relevant data are not available for natural fibres such as wool where sheep breeds, farming systems and climate are highly variable across production regions and countries, care is needed in interpreting results and especially in making comparisons. An important life cycle stage for which there are few statistics is the consumer use phase. Patterns of garment wear, frequency and type of cleaning and drying, period of use by the purchaser and whether the item is passed on for re-use, significantly affect evaluation of environmental impact. Surveys and research projects3,4 are starting to provide numbers supporting anecdotal evidence of wool’s natural advantages in the use, recycling and disposal phases. However, too few data still mean the environmental impact of these phases appears over-estimated in most comparisons and this is a high priority knowledge gap for wool LCA.
3Russell SJ, Swan P, Trebowicz M, Ireland A (2015) Review of wool recycling and reuse. Proceedings of 2nd International Conference on Natural Fibres. Portugal 2015.
4Consumers’ wool wash habits – and opportunities to improve them
What life cycle stages dominate the total environmental impact of clothing?
The life cycle stage making the dominant contribution to the total cradle-to-grave environmental effects varies for different fibre types and different impact categories. There are relatively few comprehensive textile LCA studies but examples can be taken from results that are available for the climate change impact (carbon footprint).
5WRAP (2012). A carbon footprint for UK clothing and opportunities for Savings.
- For wool garments, greasy wool production on sheep farms contributes most to greenhouse gas emissions (climate change impact) producing in the order of 50% of the total emissions. The dominant greenhouse gas is methane which is emitted as a by-product of the natural digestive process that enables sheep and other ruminant animals to thrive on grasses that provide insufficient nutrition for most animals. The use phase is also a significant source of greenhouse gas emissions in the supply chain mainly as a result of energy use for laundry.
- For garments from other fibres, UK data5 indicate that the greatest source of greenhouse gas is the fabric production stage (weaving, knitting, treatment etc), comprising a third of total life cycle emissions in carbon dioxide-equivalent units.
- For cotton garments, on-farm irrigation of cotton plants is the major contribution to water consumption. The use phase dominates water consumption for most other fibres, but lack of defensible regionally-relevant data mean impact assessments currently have a high uncertainty.
Why does wool get a poor score for land use?
Land use (‘land occupation’) is estimated in some LCA studies and some tools used to rank fibres or textiles. It is often reported simply as the area of land used to produce a product. For wool from sheep farms, particularly those in pastoral regions, the area, expressed as hectares per kg wool fibre is large relative to other fibres. Although some arable land may be used for feed crops or supporting wider farm management most land for wool production is non-arable.
Occupation of pastoral land in arid or semi-arid regions or on slopes cannot be compared with use of highly fertile cropping land or land in strategically important locations as a metric for environmental impact. In fact, an outcome of a simple land area approach is that lower stocking rates produce a worse rating for land use impact. This is inconsistent with established ecological science which accepts that low intensity grazing is less likely to cause environmental damage through degradation and erosion or biodiversity loss. It is quite incorrect to suggest that less land equates to better environmental outcomes generally for fibres and textiles and promotion of this as a sustainability measure for all wool products would likely result in perverse environmental outcomes. Case studies have shown that light grazing can improve biodiversity values6 and pastoralists often provide valuable stewardship of large areas of semi-natural landscapes where extensive grazing is the only practical and economically viable productive use.
Some LCA studies have used more defensible approaches in which land is disaggregated according to its productivity7. At a minimum, reporting separately arable land and non-arable land occupation enables more meaningful comparisons. Dividing arable land further into cultivated and non-cultivated permanent grassland leads to more accurate assessment of production impact. Development of agreed methods for assessment of land occupation in LCA is an area of work that is underway to improve consistency, fairness and support improved management.
6FAO (2016) Principles for the assessment of livestock impacts on biodiversity.
7Wiedemann SG, Yan M-J, Henry BK, Murphy CM (2016) Resource use and greenhouse gas emissions from three wool production regions in Australia. Journal of Cleaner Production 122: 121-132.
How accurate are assessments of wool’s environmental performance?
A major source of uncertainty in assessments of the environmental impacts across the wool supply chain is data quality. Collecting comprehensive or representative data for diverse wool production and processing systems is a major challenge due to its scope and, in some instances, its commercial sensitivity. For other stages of the life cycle of wool products, the challenge is in collecting and analysing data for the wide range of human practices relating to purchase, care and disposal of clothing which can be highly personal and reflect social, economic and cultural factors.
In many cases, there has simply not been an incentive to invest time and money in building and managing datasets for environmental performance assessment. Where research has been published, it often relates to local or application-specific situations and lack of updates mean that available data are not representative of current practice. For example, a recent UK study8 cited data used for waste from yarn and fabric production published in 1980 and 1993, respectively. In particular, knowledge and innovation relating to chemicals and their toxicity have developed enormously over recent decades and major changes have occurred, challenging confidence in studies assessing toxicology impacts based on older data. The wool industry continues to invest in contemporary data collection along the supply chain to support more accurate environmental assessment and sustainability choices by the consumers and NGOs such as the Sustainable Apparel Coalition and Made-By.
8WRAP (2012) A Carbon Footprint for UK Clothing and Opportunities for Savings.
Author: Dr. Beverley Henry (2016)