Discovery Guides Areas


Hidden Histories:
the Story of Sustainable Design

(Released June 2009)

podcast link 
  by Alison Knight  


Key Citations




Return to Nature


Lifecycle approach

Life Cycle Assessment (LCA) started in the 1960s, with the earliest documented example attributed to Coca Cola comparing the impacts of a glass bottle and a can. "LCA is technically defined as an investigation and valuation of the environmental impacts of a product or service that is caused or necessitated by its existence."30

We will now return to the example of the T-shirt mentioned at the beginning of this Guide and the discovery that economist Pietra Rivoli made about the cotton T-shirt. We will examine both the environmental impacts of cotton and the human costs. The USA is a large cotton producer but not a cotton manufacturer; it exports most of its cotton because it does not have a cheap labor force available to turn it into cloth economically. That is why the cotton for the T-shirt bought by Rivoli went to China to be processed and was then imported back into the USA. The USA is able to grow and sell cotton competitively because the government pays its farmers huge subsidies to do so. This in turn keeps the world price of cotton down so that farmers in developing countries are only able to get a low price for their cotton even though they depend on the crop for survival. To put this in perspective: "The annual US cotton subsidy is roughly three times greater than the amount the US Agency for International Development gave Africa in aid in 2004."31 The Environmental Justice Foundation has noted other social effects of global cotton production including the use of child labor in Uzbekistan and the toxic effects on humans due to the use of pesticides. Uzbekistan is the world's second biggest exporter of cotton and it is here that children of seven years old have been reported harvesting the cotton crop. Workers have also been affected by toxic chemicals used in growing cotton resulting in an estimated 1 million to 5 million cases of pesticide poisoning each year.32

6 stages of cradle to grave
Life Cycle Assessment examines the total environmental impact of a product

A life cycle analysis comparing cotton and polyester cloth is interesting as it shows that cotton is not as environmentally friendly a fabric as retailers would have us believe. A case study of the two fibers over a lifetime of two years shows the following results for one kilogram of fabric.33 The amount of energy use to produce the polyester fabric was 171.5 mega Joules compared to 140.1 mega Joules for cotton. Oil and gas usage for polyester fabric production was 1.5kg compared to zero for cotton as it grows naturally. However, cotton uses 457g of fertilizers and 16g of pesticides to facilitate growth (unless it is organic cotton which uses neither of these) compared to zero for polyester. Emissions produced in polyester production account for 3.8kg of carbon dioxide and 0.2g of sulfur dioxide compared to 5.3kg carbon dioxide and 4g sulfur for cotton. Finally, polyester fabric production uses 1,900 liters of water compared to 26,700 liters for cotton production, most of which is for irrigation.

It is difficult making true comparisons between different materials and products; however, the results above show that organic cotton which does not use fertilizers or pesticides should produce less greenhouse gases than non-organic cotton. One study shows that an organic T-shirt produced 2.4kg of greenhouse gases over its product life cycle. Continental Clothing Co. Ltd, a pilot partner with the Carbon Trust's product footprinting and labeling initiative, has released the results of a study into the life cycle greenhouse emissions of their organic cotton T-shirts, sweatshirts and tote bags. The results indicated that use of renewable energy and low-impact techniques of manufacture could reduce emissions significantly. Other factors affecting the carbon footprint included the number of colors added to the print design, ocean and land transport, packaging, and finally washing, drying and ironing by consumers.34

In producing this case study the Continental Clothing Co. Ltd used a methodology from BSI PAS 2050:2008 the Specification for the assessment of the life cycle greenhouse gas emissions of goods and services standard. Another tool available to designers and product manufacturers is the Cradle to Cradle protocol.

Go To Cradle to Cradle protocol

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