Hand wash vs dish washer

Daox · 03-25-09, 08:48 AM

According to "The Home Energy Diet" by Paul Scheckel, which I'm currently reading, there was a study done at a German university on this. They had volunteers wash 12 place settings and also had a dishwasher do the same. The results were:

.	Volunteer	Dishwasher
Water usage	27 gallons	4 gallons
Water Heating	2.5 kWh	1.5 kWh

I found this pretty interesting. I didn't think hand washing was THAT much less efficient. It also states that "about the dishes were were judged to be 'really dirty' or at least not acceptable to be placed on a dinner table, while the machine dishwashers offered consistently cleaner dishes".

Ryland · 03-25-09, 09:43 AM

I'll remember that next time I have 12 place settings sitting there, but to use 27 ga;;ons of water you would have to have the tap running nearly the whole time! I take the largest pan or bowl that needs to be washed, fill it with hot soapy water and wash, until I have a pile of clean soapy dishes, then I rinse those and keep washing, 27 gallons would be nearly 13 minutes of letting the faucet run at full blast (1992 Federal Energy Policy Act, 2.2gpm or less from all faucets), so I'm not sure who they had wash their dishes, but this study seems a bit skewed.

knowbodies · 03-25-09, 07:02 PM

That is quite ridiculous. Somebody needs to tell the designers of that study what a sink plug is and what it's used for.

Higgy · 03-25-09, 08:23 PM

What are you guys talking about? Are you telling me you're not suppose to flood your kitchen while you do dishes? How am I suppose to keep my floors clean if I don't? Huh?

pfff...and you guys call yourselves DIYers.

SVOboy · 03-26-09, 02:26 AM

I like to think of it as the opposite of the difference between a bath and a shower

TimJFowler · 03-26-09, 01:22 PM

Someone needs to teach those people how to wash dishes! I can only imagine that the tap was running completely open and they didn't plug the drain while washing or rinsing.

Those numbers are so skewed as to seem almost rigged. Can anyone find a link to that study?

Tim

Daox · 03-26-09, 08:21 PM

I'm guessing they just picked up random people to do them. Of course any energy concious person could use much less.

Ryland · 03-27-09, 12:54 AM

I have never seen someone wash dishes with the faucet on the whole time, but my room mate has said that her parents do wash the dishes that way and that they are not about to change their ways, I just know that i grew up in a house where we didn't waste water as we had to pump it by hand out of the ground, carry it in to the house, heat it on the stove and pour it in to the sink, you get to lazy to be wasteful, of course now that water comes out of that magical pipe in the basement in to a water heater and flows in to the kitchen you don't think about it until you get the bill then you are just baffled as to how it costs that much!
Anyway, the average sink is around 14x16x7 a large sink is that is 7.2 gallons of water, with what this study said is used you could fill the sink until it was full to the rim 3.75 times... I now understand why we have issues with water.

groar · 03-27-09, 01:09 PM

I saw a report on TV about some ecological people. The first one was leaving in city and was renting a room to a foreign student. When she was interviewed she immediately said that what is the more shocking is that she can get only one 5 minutes shower per day. She has the habit to stay at least a quarter of hour under the shower without stopping the water at any moment. Now she has to stop, and start, and stop, and start... the water. I had the feeling that each time she was saying "stop" or "start" it was costing her so much.

Other advices seams so silly to me, per examples to stop the water when you are brushing your teeth, to stop the light when you are leaving a room or when there is enough natural light...

People are people and they won't take care about what they don't know the cost.

Denis.

TimJFowler · 03-27-09, 01:13 PM

I just measured my kitchen sink (each side ~ 13.75" * 14.75" * 5") and did a rough calculation of volume (rounding down for rounded corners and sloping bottom) ~ 4 gallons. I can usually wash all the dishes from one to two meals in less water than will fill one bowl of the sink. So I can wash 4 settings of plates and/or bowls, cutlery, glasses, serving and cooking utensils, pots, pans, etc. in approximately 4 gallons of water.

I may just make a more rigorous study of this. It's geeky, but hey all in the name of efficiency!

Tim

03-26-09, 01:22 PM	#6
TimJFowler Apprentice EcoRenovator Join Date: Dec 2008 Location: Santa Fe, NM Posts: 184 Thanks: 9 Thanked 12 Times in 11 Posts	Someone needs to teach those people how to wash dishes! I can only imagine that the tap was running completely open and they didn't plug the drain while washing or rinsing. Those numbers are so skewed as to seem almost rigged. Can anyone find a link to that study? Tim __________________ - DIY Adventures in Applied Sustainability - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

03-27-09, 01:09 PM	#9
groar X-Frenchy: very Join Date: Sep 2008 Location: Toulouse, France Posts: 153 Thanks: 0 Thanked 2 Times in 2 Posts	I saw a report on TV about some ecological people. The first one was leaving in city and was renting a room to a foreign student. When she was interviewed she immediately said that what is the more shocking is that she can get only one 5 minutes shower per day. She has the habit to stay at least a quarter of hour under the shower without stopping the water at any moment. Now she has to stop, and start, and stop, and start... the water. I had the feeling that each time she was saying "stop" or "start" it was costing her so much. Other advices seams so silly to me, per examples to stop the water when you are brushing your teeth, to stop the light when you are leaving a room or when there is enough natural light... People are people and they won't take care about what they don't know the cost. Denis. __________________ Earth absorbs 1.8 t CO2/head/yr, while a French generates 6.2 t CO2/yr To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. kg saved 06/08-08/09: 1816.9+382.9 (ecodriving / 1420mi not driven) = 2199.8 To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. (2.66 kg/l diesel) kg saved by 3kWc photo-voltaic solar panels : 187 kg/yr To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. (59.1 g/kWh) Radioactive wastes saved by 3kWc photo-voltaic solar panels : Long life (>100,000 years) : 2.85 g/yr (0.9 mg/kWh) Short life (<300 years) : 31.7 g/yr (10.0 mg/kWh) Based upon "official" French figures...

03-27-09, 01:13 PM	#10
TimJFowler Apprentice EcoRenovator Join Date: Dec 2008 Location: Santa Fe, NM Posts: 184 Thanks: 9 Thanked 12 Times in 11 Posts	I just measured my kitchen sink (each side ~ 13.75" * 14.75" * 5") and did a rough calculation of volume (rounding down for rounded corners and sloping bottom) ~ 4 gallons. I can usually wash all the dishes from one to two meals in less water than will fill one bowl of the sink. So I can wash 4 settings of plates and/or bowls, cutlery, glasses, serving and cooking utensils, pots, pans, etc. in approximately 4 gallons of water. I may just make a more rigorous study of this. It's geeky, but hey all in the name of efficiency! Tim __________________ - DIY Adventures in Applied Sustainability - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

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03-25-09, 09:43 AM	#2
Ryland Master EcoRenovator Join Date: Mar 2009 Location: Western Wisconsin. Posts: 913 Thanks: 127 Thanked 82 Times in 71 Posts	I'll remember that next time I have 12 place settings sitting there, but to use 27 ga;;ons of water you would have to have the tap running nearly the whole time! I take the largest pan or bowl that needs to be washed, fill it with hot soapy water and wash, until I have a pile of clean soapy dishes, then I rinse those and keep washing, 27 gallons would be nearly 13 minutes of letting the faucet run at full blast (1992 Federal Energy Policy Act, 2.2gpm or less from all faucets), so I'm not sure who they had wash their dishes, but this study seems a bit skewed.

03-25-09, 07:02 PM	#3
knowbodies Home Improvement Goon Join Date: Oct 2008 Location: Moose Jaw, SK, CA Posts: 96 Thanks: 0 Thanked 2 Times in 2 Posts	That is quite ridiculous. Somebody needs to tell the designers of that study what a sink plug is and what it's used for.

03-25-09, 08:23 PM	#4
Higgy The Gardener Join Date: Oct 2008 Location: Manitoba - Canada Posts: 492 Thanks: 17 Thanked 8 Times in 7 Posts	What are you guys talking about? Are you telling me you're not suppose to flood your kitchen while you do dishes? How am I suppose to keep my floors clean if I don't? Huh? pfff...and you guys call yourselves DIYers.

03-26-09, 02:26 AM	#5
SVOboy Administrator Join Date: Aug 2008 Posts: 291 Thanks: 3 Thanked 4 Times in 4 Posts	I like to think of it as the opposite of the difference between a bath and a shower

03-26-09, 08:21 PM	#7
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	I'm guessing they just picked up random people to do them. Of course any energy concious person could use much less.

03-27-09, 12:54 AM	#8
Ryland Master EcoRenovator Join Date: Mar 2009 Location: Western Wisconsin. Posts: 913 Thanks: 127 Thanked 82 Times in 71 Posts	I have never seen someone wash dishes with the faucet on the whole time, but my room mate has said that her parents do wash the dishes that way and that they are not about to change their ways, I just know that i grew up in a house where we didn't waste water as we had to pump it by hand out of the ground, carry it in to the house, heat it on the stove and pour it in to the sink, you get to lazy to be wasteful, of course now that water comes out of that magical pipe in the basement in to a water heater and flows in to the kitchen you don't think about it until you get the bill then you are just baffled as to how it costs that much! Anyway, the average sink is around 14x16x7 a large sink is that is 7.2 gallons of water, with what this study said is used you could fill the sink until it was full to the rim 3.75 times... I now understand why we have issues with water.