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In manual dishwashing, many factors have an impact onto

Manual dishwashing

In manual dishwashing, many factors have an impact ontothe cleaning result: the amount, the composition and the adhesive forces of

the food residues; the pre-treatment of the dishes, especially whether and

how soaking or pre-rinsing is done; the realization of the actual dishwashing process, for

instance the water temperature, the used amount andt ti f di h hi li id th i t it f thconcentration of dishwashing liquid, the intensity of the

mechanical treatment, the number of water changes,the after-treatment of the dishes (especially whether andhow rinsing is done) as well as how the drying is done.

There are numerous habits and practices in manualdishwashing that differ in the amount of water, energy, timeand dishwashing liquid used. But cleaning results do notnecessarily depend on the resource utilization! Everybody

Comparison:

Washing up in a sink and under running water

necessarily depend on the resource utilization! Everybodycan try to optimize his/her manual dishwashing behaviour toa minimum use of water, heat energy and dishwashing liquid.

Studies about manual dishwashing

Numerous habits in manual dishwashing were found by astudy of the University of Bonn about European washing-up behaviour and practices. The average consumptionvalues per place setting of German test persons were:• Water: 6.06 L

E 0 15 kWhA comparison between doing the dishes in the sink or underrunning water has shown that washing up under runningwater uses more than twice as much water, twice as muchenergy and three times as much dishwashing liquid thanwashing up in the sink.

• Energy: 0.15 kWh• Dishwashing liquid: 2.81 g• Time: 8.05 min

(Source: Stamminger R., Elschenbroich, A., Rummler B. & Broil, G. (2007): Washing-up Behaviour and Techniques in Europe. In: Hauswirtschaft und Wissenschaft, 1, p. 31-40)

Depending on the household size and the eating habits,the daily amount of dirty dishes that need to be cleanedHygiene and skin compatibility the daily amount of dirty dishes that need to be cleanedvaries. Projected onto the whole of Germany manualdishwashing induces substantial resource consumptionand environmental pollution (see the Washing-up-calculatoron www.forum–waschen.de).

Therefore, manual dishwashing implicates financialexpenses for each household that can be considerablyminimized by optimizing the dishwashing habits for

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Air drying the dishes is more hygienic than wiping them dry. Ifwiping dry, the tea towel as well as all other dishwashingutensils (especially the dishcloth) shall be regularly washedat 60 °C using a powder heavy-duty detergent (containingbleach).

The use of rubber gloves helps to minimize possible skini it ti th h th di h hi li id

The 6 golden rules in manual dishwashing1. Put large food residues in the waste bin

2 Wash the dishes right after the meal or pre rinse them with a little cold water

minimized by optimizing the dishwashing habits, forinstance by following the 6 golden rules in manualdishwashing.

irritations through the dishwashing liquid.

2. Wash the dishes right after the meal or pre-rinse them with a little cold water

3. Soak dried-on or burnt-in food residues in water that should be as hot as possible and that contains little of dishwashing liquid

4. Wash the dishes in a sink that is filled with hot water and contains the recommended amount of dishwashing liquid. If you have sensitive skin use gloves

5. Do not rinse the dishes under running water

6 Change the dishcloth and the tea towel daily if necessary and wash them at 60 °C

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6. Change the dishcloth and the tea towel daily, if necessary, and wash them at 60 C

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An increasing number of households owna dishwasher (about 66 % in Germany in 2009). Through

Automatic dishwashing

How to load your dishwasher properly:recent years the consumption values of dishwasherscontinually decreased: the energy saving programme ofmodern dishwashers uses about 1.0 kWh of energy and10 L of water. Thereby, a dishwasher loaded to capacityundercuts most of the manual dishwashers when cleaningthe same quantity of dishes.(Source: Stamminger R., Elschenbroich, A., Rummler B. & Broil, G.(2007): Washing-up Behaviour and Techniques in Europe In:

1. Place jars (cups, glasses or pots) with the openingdownwards.

2. Place items with a deepening in a sloped position, so thatthe water is able to drain off.

3. Place heavy soiled items in the lower basket.4. Place dishes and cutlery in the provided places in the

baskets to prevent toppling or shifting.5 I d t th f ti lit f th(2007): Washing up Behaviour and Techniques in Europe. In:

Hauswirtschaft und Wissenschaft, 1, p. 31-40).5. In order to secure the functionality of the spray arms

manually check their unhindered rotation after loading.6. Empty the lower basket first so that no residual water can

drip from the upper basket onto the clean and dry dishesin the lower basket.

Figure 1: Development of the average consumption values of dish-washers through recent years(Basis: Stiftung Warentest; Calculation of the University of Bonn, Household and Appliance Technology Section)

Belonging into the upper basket:Cups, saucers, small plates, l d l it (l dl

Belonging into the lower basket:Pots, pans, large plates,

glasses and long items (ladles etc.)

p g pcutlery basketFigure 2: Costs per year of a dishwasher depending on its age and

the number of cycles per week(Basis: Average values of dishwashers tested by Stiftung Warentest and prices for electricity (0,21€/kWh) and water (4,15 €/m³). Interpolation and calculation of the University of Bonn, Household and Appliance Technology Section)

Items that are not dishwasher proof:

(Partly) wooden itemsWood leaches out, gets unsightly and deformed. Alsoadhesive joints may not be temperature resistant.

Delicate glasses with decor handcrafts vases orDelicate glasses with decor, handcrafts, vases orantique dishes

Especially on glaze decorations bleach out or getremoved.

Heat-sensitive plasticsHeat-sensitive plastics may get deformed.

Copper, tin and aluminiumThe surface gets tarnished through oxidation processes.

The 6 golden rules in automatic dishwashing1. Put large food residues in the waste bin

2. Do not pre-rinse the dishes by hand

3. When loading the dishwasher, make sure that all parts of the dishes are accessible to the water jets

4. Load the dishwasher to capacity if possible, but avoid that parts of the dishes are in contact with each other

5. Use dishwashing agents, rinse agents and regenerating salt either individually or within a multicomponent product, as instructed by the manufacturer

6. Select dishwashing programmes and temperatures according to the type of dishes and the degree of

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g p g p g yp gsoiling, observing information by the manufacturer

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Comparison of the running costs

Comparison of manual or automatic dishwashing

The average running costs (supply and equipment) forwashing up 12 place settings (comprising of 12 soupplates, dinner plates, dessert plates, cups, saucers,glasses, knifes, forks, tablespoons, cake forks andteaspoons) by hand are twice as high than whenwashing up the same quantity of dishes in a dishwasher.

p g

Comparison of costs (in €, Basis: 2010)Washing up 12 place settings

Resource average costsin a

dishwasher by hand

water 4.15 €/m³ 0.04 0.30energy 0.21 €/kWh 0.21 0.39detergent 2.20 €/kg 0.07rinse aid 2.29 €/L 0.07regenerating salt 0.63 €/kg 0.01dishwashing liquid 1.33 €/L 0.01 0.04

washing up

Depending on the individual manual dishwashing habits,the age of a dishwasher, the frequency of use, the wayof hot water treatment and its supply, the running costsshow substantial differences.

Comparison of the operating costs over the past 40 years

g qsum 0.35 0.73

Source: TAK Maschinelles Geschirrspülen, University of Bonn, Household and Appliance Technology Section

Utensils for Manual dishwashing(dishcloth, gloves, hand creme, tea towel including washing cycles) 0.28Amortization costs dishwasher

0.25Source: Estimation by Uni Bonn, Sektion Haushaltstechnik

total sum 0.60 1.01

(500 € purchase costs; 2000 cycles in 10 years)

The comparison of operating costs is based on the averageprices for water, electricity, equipment and supply(detergent, rinse aid, salt, dishwashing liquid) in therespective year in Germany. Source of data was, inter alia,Stiftung Warentest. The constancy of manual dishwashinghabits over the years and the use of a dishwasher alwaysl d d t it d

Comparison of the operating costs over the past 40 years

loaded to capacity were assumed.

The figure shows: until 25 years ago, manual dishwashingwas more cost-efficient than automatic dishwashing. Sincethen the reduced consumption values of dishwasherscompensated the considerably increased prices for water,waste water and electricity.

Of course the investment costs of a dishwasher need to bet k i t t A i iti t f 500 € d

Comparison of the investment costs

Cleaning tools and frequency of changefrequency of costs in € costs in €

taken into account. Average acquisition costs of 500 € anda frequency of 2000 cycles (which corresponds to alifetime of 10 years) result in amortization costs of 0.25 €per cycle.

But also the equipment needed for manual dishwashingcosts money: dishcloth, tea towel, gloves, hand cream andthe expenses for the regular washing of the utensils (forh i i )

cleaning tool change per item per year1 dishcloth all 2 month 1.20 7.201 pair of gloves per month 1.00 12.001 hand cream all 2 month 2.00 12.001 tea towel per year 3.00 3.001 brush per half year 2.00 4.001 scrubbing sponge per month 0.70 8.401 washing cycle (dishcloth, tea towel, etc) per quarter year 1.00 4.00

sum per year 50.60

hygienic reasons).

The comparisons of costs show that automaticdishwashing is not only more convenient but can also bemore cost-effective than manual dishwashing. Prerequisitefor that is the compliance with the 6 golden rules ofautomatic dishwashing.

Comparison of investmentsfor cleaning of 12 place settings in €

Manual dishwashingaverage household: 0.283 place settings per day, 2 persons

automatic dishwashing

0.25Depreciation of automatic dishwasher(500 € purchase costs; 2000 cycles in 10 years)

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Source: Estimation by Uni Bonn, Sektion Haushaltstechnik