The carbon footprint of your clothing has everything to do with how often you wash and dry them, said a Queensland University of Technology researcher.
Frequently washing and tumble drying a t-shirt consumes three-quarters of the energy used to make and use it, QUT Institute of Sustainable Resources researcher Francisco Javier Navarro said.
Mr Navarro has been commissioned by the Cotton Research and Development Corporation to undertake a "life cycle assessment" that compares the environmental impact of cotton and polyester t-shirts on their production, use and disposal stages, which is also known as the "cradle to grave" approach.
His investigation takes into account the entire life cycle of a t-shirt, and measures the environmental impact of growth and production of the materials, construction of the garments, transportation, retail, wear and disposal.
Mr Navarro said that throughout the life of a t-shirt made and sold in Australia, almost 75 per cent of its carbon footprint would be caused by machine washing and drying at home.
"Research shows that household washing cycles consume about 19 per cent of the total lifecycle energy consumption, whereas tumble drying consumes about 53 per cent," Mr Navarro said.
"As a way to compare, the production of raw cotton fibre uses 10 per cent of the energy and the different stages of cotton t-shirt manufacturing use up 12 per cent of the total energy. The manufacturing of polyester t-shirts consumes slightly higher amounts of energy.
"This means our decisions on washing our clothes have a big impact on the carbon footprint of our clothing.
"It makes a huge difference in energy consumption to hang clothes out on a washing line to dry instead of using a tumble dryer."
One of the goals of Mr Navarro's research is to analyse the effect of increasing the number of times t-shirts are worn before washing.
However, he admitted that in Western society, t-shirt rewearing was only realistic under certain circumstances, like when the shirt was worn for only a short time and while undertaking low intensity activity, for example, going out for afternoon tea after showering.
Mr Navarro said the use of "smell-friendly" fibres would also assist in increasing the number of times a shirt is worn between washes.
"Research shows that polyester is related to more intense sweat odour than cotton," he said.
"This means it is easier to wear a cotton t-shirt more than once before washing than a polyester t-shirt. Wearing a shirt for an extra half a day before washing would save high amounts of energy and water by washing the shirt slightly less."
A report on the research is expected at the end of the year.
Media contact: Rachael Wilson, QUT media officer, 07 3138 1150 or firstname.lastname@example.org
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