This is a City West Water Project

Life Cycle Analysis of Clothes Washing Options

Project Date: 31 December 2010
Project Status: Complete
Research Organisation: ARUP
Project Number: CWW + EPA Project

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The Challenge

The project provides quantified information on environmental impacts of clothes washing by providing a life cycle analysis of the process at upstream, use and downstream phases. This can inform decisions around the value of future machine technologies and behaviour change initiatives to reduce environmental impacts of domestic clothes washing. Environmental impact categories assessed include: water use, energy consumption, greenhouse gases, eutrophication, resource depletion and land use.

The Project

The LCA separated the clothes washing process into three phases; upstream, use and downstream and examined each separately.

The upstream phase involves those processes relating to the production and delivery of key products involved in the washing process.

The use phase, as defined in this study involves the regular use of products and equipment by households to wash and dry their clothes, it involves all the resources consumed during the process including amongst others, water, detergent and energy.

The downstream phase relates to the disposal and treatment of all the materials and chemicals produced during the process including the machines, detergents and waste water.

Within each phase are a series of individual unit processes (the smallest element considered in the life cycle inventory analysis for which input and output data are quantified). Process flows were produced for washing machine manufacture, detergent manufacture, wastewater treatment and water supply.

The Outcome

The LCA determined that the use phase of the washing process has the largest proportion of environmental impacts due to the frequency of operation of the machines and utilisation of the detergents. The use phase contributes to impacts across:

  • water use (92% of the life cycle impact);
  • energy use (60% of the life cycle impact);
  • global warming potential (73% of the life cycle impact); and
  • fossil fuel depletion (62% of the life cycle impact).

Of the 92 per cent life cycle impact, 91 per cent is attributable to the washing machine water consumption, which represents a significant opportunity in forming a behaviour change program. In regards to global warming, 30 per cent of impacts are associated with the mechanical energy of the washing machine and 25 per cent with standby power. There is potential to reduce the contribution to global warming by influencing household behaviour regarding standby power. It is also noted that for energy use, 32 per cent of impacts are
associated with the upstream manufacture of detergent.

The LCA determined that the addition of a dryer, either electric or condenser, to the base case scenario lead to increases in the environmental impact categories of energy use, global warming potential and fossil fuel depletion land use. Rationalising the use of dryers presents an opportunity to reduce a number of environmental impacts.

The investigation of future washing machine technologies highlighted that they can reduce the environmental impacts of the washing process, particularly in respect to eutrophication, land use and water use, although in some circumstances, impacts can also be higher than current market leading technologies.

The scenario analysis assessed changes to the base case environmental impacts through alteration of individual unit processes. In relation to washing machines the LCA indicated that the water consumption impacts for front loading and top loading machines are consistent with the star rating. For energy use, impacts are more closely linked to machine size than energy rating.

The LCA indicates that the lowest impacts are associated with cold washing and that an increase of a relatively minor 10oC can lead to a disproportional increase in environmental impacts. If a household determines there is a need to wash at elevated temperatures than the off peak electric and 3 star gas storage perform worse across all impact categories, with solar gas split system having the lowest environmental impacts across a range of
categories.

With regard to loading, the LCA determined that environmental impacts increase exponentially as washing machine loading decreases, such that very small loads have a disproportionately high impact on the environment.

The LCA model found that use of a normal household grey water system can have positive environmental impacts through the reduction in water use and the decreased potential for eutrophication. However it did not address other negative environmental impacts which may be associated with the use of grey water.




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