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Dishwasher vs hand washing: which is most energy efficient?

Posted by Ross Lammas on 6 March 2013 at 10:03 am

A simple internet search shows that the dishwasher versus washing up by hand debate can be the subject of much debate and heated argument. 

In the dishwasher’s favour, research carried out by Bonn University in 2003, found that, when used efficiently (ie run fully loaded) dishwashers canuse up to a third less water than hand washing the equivalent amount of crockery. The research was based on a 12 place setting or 140 items soiled with a interesting array of eggs, oatmeal and mince to reflect the average domestic washing up scenario.

Winning the argument on the energy-efficiency of dishwashers is a bit trickier, given 75 % of UK homes use gas to heat their water, which is more efficient and produces less CO2 than the electricity used to heat cold water in dishwashers. However, add solar PV panels into the equation, and use your dishwasher during the day and it’s a much more economical story.

Dishwashing habits, both by hand and using a machine can vary. The German research showed that nationalities differ in their habits too. I always twitch when I see cutlery being washed under a running hot tap, and we all know of the super quick ‘washer upper’ who fails to clean things properly!  And that’s another reason for choosing a dishwasher; hygiene – even the most diligent pot washer with asbestos hands and good pair of marigolds, can’t compete with the bacteria busting 60-65C dishwasher programme. 

Our tips on using your dishwasher most efficiently are:

1. run only full loads

2. scrape your plates first – but don’t be tempted rinse them under the tap

3. choose an eco-setting if available and doesn’t take hours to complete

4. if you’ve got solar panels use your dishwasher during the day, and

5. when it comes to buying a new dishwasher look for the most energy-efficient model available.

Dishwashers have improved in energy-efficiency in the last 15 years and dramatically reduced their water consumption too.

Photo Credit: Editor B via Compfight cc

About the author: Ross Lamas is founder of sust-it.

If you have a question about anything in the above blog, please ask it in the comments section below.

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Comments

3 comments - read them below or add one

richmc

richmcComment left on: 7 June 2015 at 7:29 am

If you have solar PV with a water heating diverter it makes no difference which method you use, as long as you use the dishwasher when the sun is shineing use it, if the day is dull but you have water heated for free and can't wait do a "manual" wash. for those with a less flexible lifestyle than I have watch the weather reports and get a dishwaher with a timed delay feature.

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pdf27

pdf27Comment left on: 7 March 2013 at 11:09 pm

Most dishwashers will accept hot water at up to 60 deg C (the same as the maximum you should be getting at a tap anyway). That minimises electricity consumption, and in my case anyway the dishwasher cleans a lot better.

If you've got solar hot water as well, it's clearly a no-brainer.

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utility-exchange

utility-exchangeComment left on: 6 March 2013 at 10:23 am

Interesting - never even considered it would be more economical to use your dishwasher during the day if you have solar panels...obvious when you think about it! Thanks.

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