Whilst out in the sunshine reading The Guardian this weekend, I got incredibly excited by a tiny article on page 8 entitled “Washing dishes by hand wastes millions of litres” (http://www.guardian.co.uk/uk_news/story/0,,1821067,00.html). According to the article, the UK pressure group Waterwise has found that modern dishwashers could save the average UK household 11,000 litres of water a year compared with hand washing the dishes.
Apparently we all need to change our perceptions of these shiny cleaning beasts. The old rumour that dishwashers are a waste of water and energy is based on now obsolete models that used an astounding 50 litres of water to complete a cycle. Today’s innovations now can use as little as nine! Add to that the advances we’ve seen in energy efficiency and it starts to make sense.
Good news all round then and further proof that it doesn’t have to be a hardship to live more sustainably. Of course, nothing is ever that simple and I can hear the perpetual sceptics already whispering about energy use, embodied energy, end-of-life disposal and of course the loss of the social ritual of doing the washing up.
Energy Efficiency
Let’s take energy use first. According to The Energy Saving Trust, (www.est.org.uk), using an energy efficient dishwasher will cost you just 8p per wash. Of course, if your electricity comes from a renewable source, your dishwasher’s carbon footprint can be even further reduced. The Green Consumer Guide (http://www.greenconsumerguide.com/dishwashers.php) has a handy list of the top rated dishwashers with 28 models rated A for energy efficiency, wash efficiency and dry efficiency.
Going back to our comparison with washing up by hand, the question is, do we use more energy heating water for hand washing than our energy efficient dishwasher uses in a normal cycle? Rainer Stamminger from the University of Bonn says yes we do. In his comparative study, the hand washers used on average 2.5kWh of electricity to heat the water they required, whereas the dishwasher achieved just 1kWh. Another victory for our mechanised friend.
Of course, you could add a million other factors into this mix, including the efficiency of your boiler, the fuel you use to heat your water and how good you are at washing up! Taking the average from Stamminger’s study though and the dishwasher appears to be the clear winner in the majority of cases.
Embodied Energy
Embodied energy (the energy used in the manufacture of the dishwasher including raw materials, production and distribution) is always a tough one to measure. Through researching energy efficiency labelling, I couldn’t find any reference to embodied energy, nor any evidence that energy efficiency labelling takes it into consideration. Even Stamminger doesn’t mention it in his study.
Lacking any quantitative data then, I decided to turn to the environmental policies of the dishwasher manufacturers. This is not an easy task either. Although I couldn’t find any specific references to embodied energy, nearly all the manufacturers were keen to tell you something about their environmental credentials. This article seems to have gone on long enough already so I won’t analyse each one but the best as far as I could see was Bosch. Not only do they have more A rated dishwashers than any other manufacturer, they also have a whole site devoted to their environmental good deeds – www.bosch-environment.com.
End of Life
Ever since the EU started talking about the Waste Electrical and Electronic Equipment Directive (WEEE), manufacturers have really had to start thinking more carefully about how their equipment can be dismantled, recycled, refurbished and ultimately disposed of.
The Directive puts the responsibility for disposing of electrical appliances firmly back with the manufacturer, meaning that they will need to remove your old appliances free of charge. Suddenly they are faced with an image of warehouses stacked full of old dishwashers and recyclability seems to come further up the agenda.
The Directive came into force in 2003 and since that time, manufacturers have supposedly been developing new materials and methods of production to aid recycling and disposal at the end of an appliance’s life. Again, it is difficult to obtain concrete evidence of this in easy to digest format but like the embodied energy research, I found it helpful to have a look through some company websites to see what was going on. There are certainly many written promises but nothing short of a thesis could really get to the bottom of the matter. For now, we will have to rely on the manufacturers and the hopeful impact of the WEEE Directive over the next few years.
Down to you
With all this in mind, also remember that you can hugely alter the impact of your dishwasher by using it efficiently. Always make sure that you only put it on when it’s full, use the economy or lowest heat setting and for real savings, cut out the dry cycle, which is by far the most energy intensive, and open the door to let the dishes air dry.
Remember also, the detergent you use can also have an environmental impact. I’m a great lover of Ecover’s products (www.ecover.com) and their ecological dishwasher tablets and rinse aid get my crockery and glasses sparkly clean without dumping any harsh chemicals into our sewage systems.
In the end, despite the stories and evidence, I just can’t promise that using a dishwasher is better for the environment. It certainly seems to save a lot of water unless you have the time to hone your washing up skills to a miraculous level. By the same token, they seem to save energy in water heating. Manufacture and disposal are just such huge fields that far more research is needed.
In the end, I have chosen to stand by the dishwasher and use it in the best way I can. Here’s a quick summary:
- Get yourself an A-rated dishwasher
- Only switch it on when it’s fully loaded
- Use an ecological detergent
- Open the door to air dry the dishes
If you have any more information about the sustainability of using a dishwasher or you think I’ve made a mistake in this report, please do leave me a comment and let me know.
