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Consumer laundry practices in Germany

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Sustainability is a guiding principle for a responsible, future-oriented 21st century lifestyle and this already begins in private households with the daily household tasks. Approximately 25% of an average household's electricity consumption is required to do the laundry and dishwashing – 5% alone is for washing clothes with a corresponding energy consumption of 6 billion kilowatt hours. In addition, 600 000 tonnes of detergent and 330 million cubic metres of water are used for textile care in Germany. These figures provide the rationale for the scientific study of current practices of using washing machines and for a resulting estimate of the latent energy-saving potential in German households.In the context of the in-home study presented here, 236 private households throughout Germany were studied with respect to their washing practices and existing knowledge about topics on the sustainable, energy-saving use of their washing machines. Overall, across all households 2867 wash cycles were individually recorded and subsequently analysed over a 4-week period.The results of this study show that washing machines tend to be underloaded, and therefore maximum loading of the machines could lead to a reduction of wash cycles per household. With respect to detergent dosage, it was determined that the consumer does not adjust the dosage to the textile type, load size, soil level and/or water hardness, and this can lead to under- or overdosing depending on prevailing conditions. Finally, the selection of the wash temperature showed a 90°C/95°C programme was only chosen in 2.3% of all recorded wash cycles, however, every fourth cycle was completed at 60°C. Therefore, adjusting the load size and detergent dosage as well as selecting the right wash temperature are key themes to be taken into account in future consumer communication about energy-saving households.
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Consumer laundry practices in Germany
Anke Kruschwitz, Anja Karle, Angelika Schmitz and Rainer Stamminger
Household and Appliance Technology Section, Institute of Agricultural Engineering, Bonn University, Bonn, Germany
Keywords
Consumer behaviour, dosage factor,
household technology, laundry washing, load
factor, resource consumption.
Correspondence
Anke Kruschwitz, Rainer Stamminger,
Institute of Agricultural Engineering,
Household and Appliance Technology Section,
Bonn University, Nussallee 5, Bonn 53115,
Germany.
E-mail: haushaltstechnik@uni-bonn.de
doi: 10.1111/ijcs.12091
Abstract
Sustainability is a guiding principle for a responsible, future-oriented 21st century lifestyle
and this already begins in private households with the daily household tasks. Approxi-
mately 25% of an average household’s electricity consumption is required to do the
laundry and dishwashing – 5% alone is for washing clothes with a corresponding energy
consumption of 6 billion kilowatt hours. In addition, 600 000 tonnes of detergent and 330
million cubic metres of water are used for textile care in Germany. These figures provide
the rationale for the scientific study of current practices of using washing machines and for
a resulting estimate of the latent energy-saving potential in German households.
In the context of the in-home study presented here, 236 private households throughout
Germany were studied with respect to their washing practices and existing knowledge
about topics on the sustainable, energy-saving use of their washing machines. Overall,
across all households 2867 wash cycles were individually recorded and subsequently
analysed over a 4-week period.
The results of this study show that washing machines tend to be underloaded, and therefore
maximum loading of the machines could lead to a reduction of wash cycles per household.
With respect to detergent dosage, it was determined that the consumer does not adjust the
dosage to the textile type, load size, soil level and/or water hardness, and this can lead to
under- or overdosing depending on prevailing conditions. Finally, the selection of the wash
temperature showed a 90°C/95°C programme was only chosen in 2.3% of all recorded
wash cycles, however, every fourth cycle was completed at 60°C. Therefore, adjusting the
load size and detergent dosage as well as selecting the right wash temperature are key
themes to be taken into account in future consumer communication about energy-saving
households.
Introduction
In recent years, scarcely has a concept been so frequently used in
public discourse and political debates as the term ‘sustainability’.
‘The concept of sustainability combines economic power with
ecological responsibility and social justice (. . .) We are aware of
our responsibility not only for the present generation, but also for
those to come (. . .)’ (Merkel, 2008).
At the latest since the milestone of the global Earth Summit in
Rio de Janeiro in 1992 against the backdrop of climate change and
the scarcity of limited resources, the concept of ‘sustainable devel-
opment’ increasingly influenced people’s thinking and actions in
politics and the economy.
Consumers’ behaviour plays an essential role in practising sus-
tainability on a daily basis. In Germany, private households were
the direct cause of more than 20% of greenhouse gas emissions
(Presse und Informationsamt der Bundesregierung, 2008).
Pakula and Stamminger (2010) estimated resource use in
private households in practising a specific activity and they have
shown that worldwide every year around 100 TWh of electrical
energy as well as approximately 20 km3of water are solely used
for textile care with the aid of washing machines. Anastasiu and
Bertoldi (2007) estimated on behalf of the European Commission
that the rate of operating washing machines amounts to 6.4% of
the total overall energy consumption by private households in the
27 European Union member states. This corresponds to approxi-
mately 51.2 TWh per annum. Domestic laundry accounts for 21%
of American domestic water use and 12% of domestic water use in
the UK (Shove, 2003). In relation to Germany, a projected calcu-
lation dating from 2007 ascribes an overall energy consumption of
4.9 TWh and approximately 362 million m3of water per annum
to the operation of washing machines in private households
(Berkholz et al., 2007). To reduce the enormous input of resources
for washing laundry, it is necessary not only to optimize the
resource consumption of future washing machine models, but also
to change consumer behaviour when using washing machines
(Berkholz et al., 2007). Laundering of clothes is a process that is
initiated by the consumer and is heavily influenced by consumer
behaviour, because the choices consumer make when using appli-
ances can greatly influence, e.g. the energy conservation process
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International Journal of Consumer Studies ISSN 1470-6423
International Journal of Consumer Studies
© 2014 John Wiley & Sons Ltd
1
(Hustvedt, 2011). Based on his model for the activities of textile
care and dishwashing, Stamminger (2011) calculated the effects of
different patterns of behaviour on the use of resources. The calcu-
lation differentiates between six different consumer types for
which assumptions are made about the diverse behavioural pat-
terns and starting points, and thus the different consumption data.
Stamminger reached the conclusion that due to these different
behavioural patterns and prerequisites, the overall resource con-
sumption varies by a factor of five between the ‘sustainable con-
sumer’ (less than average laundry washing at lower temperatures,
good spin drying, use of efficient tumble dryer with heat-pump
technology, less than average ironing, efficient use of automatic
dishwasher) and the ‘wish-wash consumer’ (more than average
laundry washing at higher temperatures, line drying only, less than
average ironing, only manual washing up, uses old and inefficient
appliances).
Alongside the use of energy and water, of course, the use of
chemicals also has a decisive influence on the environment due to
the consumption of resources and an intrinsic substantial potential
for environmental pollutants (Wagner, 2010). The market launch
of super compact detergents in 1994 as opposed to the first gen-
eration of compact detergents meant that the recommended dosage
amount per wash cycle could be further significantly reduced.
However, this also could increase the risk of overdosing by the
consumer, based on the assumption that the consumer does not
notice the modified instructions on the packaging and adjusts his
or her previous dosage habits to the changed, recommended
dosage amount. Overall, in Germany in recent years, the consump-
tion of detergent of 12.2 kg per capita in 1984 has constantly
declined and in 2008 was 7.15 kg per capita and per annum.
A number of studies are already available that have gathered
data about consumer behaviour relating to textile care both domes-
tically as well as internationally. In the German context, Berkholz
et al. (2007) examined both behaviour-dependent as well as tech-
nical changes and their impact on the use of resources. They found
that there was a misunderstanding of the maximum use of a
washing machine’s wash capacity, and the underuse of the cotton
programme and overloading for other programmes, such as
delicates or the wool programme highlight this. They derived the
result that the average load size for all washing programmes was
2.9 kg per cycle. In 1996, the average load was still 2.75 kg per
cycle (Grießhammer et al., 1996). One possible reason for this
behaviour was recorded in a study dating from 2004 in the context
of a Germany-wide action day promoting ‘Sustainable Dish/
Washing’(Stamminger and Goerdeler, 2005). Atotal of 43% of the
interviewed consumers agreed with the statement that they delib-
erately refrain from filling the washing machine to maximum
capacity because this would give a better washing result. In con-
trast, the self-report provided by a further 23% of interviewees that
they ‘crammed’ the machine ‘full’ for every wash cycle merits
critical questioning in respect of the aforementioned measured
data. In Finland, we see another trend in laundry washing: from
1980 to the 1990s Finish people washed more laundry than before.
They washed smaller loads at a time but more frequently, even
daily (Heiskanen et al., 2005). The Finish researchers recommend
washing machines with reduced capacity ‘(. . .) for frequent
washing without wasting water and energy’.
In recent decades, with regard to the wash temperature, there
is an obvious trend for significantly lowered temperatures. In
particular, the cotton programme is largely avoided (Wagner,
2005). Hence, while in 1973 its share of overall laundry was still
40% in Germany this fell to approximately 8% in 2003 (Wagner,
2005). The reasons are on the one hand, the growing proportion of
coloured clothes, and on the other hand, greater eco awareness.
This trend was accompanied by different detergent recipes and
ingredients that could already release their full effective force at
lower temperatures (Rüdenauer and Grießhammer, 2004).
According to Berkholz et al. (2007), in Germany consumers did
not take the actual load sufficiently into account for the detergent
dosage, thus mainly dosing too much detergent. Furthermore,
users in Germany found it difficult accurately to evaluate the soil
level of the laundry and to take this into account for the detergent
dosage (Rüdenauer and Gensch, 2008). Additionally, Berkholz
et al. (2007) identified overdosage, in particular, of the super
compact and liquid detergents. Another point was, that throughout
history, the level of washing and acceptance of body odours had
varied greatly. Today, body odours were considered appalling and
daily washes and the use of artificial perfumes was almost a norm
(Ashenburg, 2007). These hygiene standards were culturally
depended with individual variations. In clothing, there were also
product-dependent variations: woollen garments could be washed
less often than cotton garments because of cultural standards and
inherent soil repellence, thus having potential to save energy. If
this difference in washing requirements between fibres is not com-
municated to users or if the users did not want to follow the
recommendation, the potential saving is lost (Laitala et al., 2011).
Despite earlier studies, it is important to gather detailed infor-
mation about consumer behaviour in order to identify and to be in
a position to evaluate the likely changes due to politically induced
measures, technological advances or social influences. The analy-
sis is decisive for revealing the potential energy-saving opportu-
nities and to develop mechanisms to fully exploit such
opportunities through technological advances, a change in con-
sumer behaviour or a combination of both aspects. Hustvedt
(2011) stated that two households with identical demographics and
identical appliances could still consume vastly different amounts
of energy based on their behaviour. Moreover, understanding con-
sumers’ reservations, attitudes and concrete behavioural patterns
for textile care is equally decisive for cleaning performance, the
time taken by the consumer and the consumption of resources as it
is for the wash temperature, load size, detergent consumption and
drying method (Laitala et al., 2011). Hence moving towards more
sustainable behaviour for textile care has substantial potential to
reduce the consumption of energy, water and detergent (Laitala
et al., 2012). Behaviour has a key role in the success of energy
conservation efforts and consumer scientists, whose focus is on the
needs and behaviours of households, have an important contribu-
tion to make to the development of more efficient households
(Hustvedt, 2011).
On the one hand, the purpose of this study is to record the
washing behaviour presently adopted in German private house-
holds, with emphasis on the use of the washing machine, the
choice of wash temperature and the use of detergent. This should
facilitate further information gathering about consumers’ state of
knowledge as regards sustainable practices in the use of resources
for textile care, and possibly also highlighting existing uncertain-
ties. This study tried to proof possible mistakes during the washing
process which were gathered within former. In addition to that, it
Consumer laundry practices in Germany A. Kruschwitz et al.
International Journal of Consumer Studies
© 2014 John Wiley & Sons Ltd
2
should discuss possible causes to provide an opportunity to make
recommendations pointedly. Within a next step these recommen-
dations could be adapt to this panel and its effectiveness could be
examined.
Material and methods
With the assistance of the market research company Toluna
Germany GmbH and based on a short screening questionnaire, a
total of 334 private households were recruited with access to their
own washing machine. Two hundred thirty-six of these private
households in turn agreed to participate in this study and pro-
vided feasible results. The important points for their selection
were, on the one hand, the household size and, on the other hand,
the age of the person managing the household (Table 1). The aim
for each of the three predefined subgroups – ‘singles over 50’,
‘couples without children aged between 30 and 50 years’ and
‘young families aged between 25 and 45 years’ – was to incor-
porate in each case one-third of the total population because these
subgroups were assumed to have a stable living situation over
time. Hence they seemed better suited for inclusion in a long-
term study.
The observation of washing behaviour was carried out during
the period May to November 2009. The participants were mainly
distributed in the German Länder with high population density –
in North Rhine-Westphalia, Rhineland Palatinate, Hesse and
Baden-Wuerttemberg.
Each household received a variety of test materials in order to
make a detailed record of the key parameters of washing behav-
iour. Equipped with a washing basket, personal scales and kitchen
scales (Table 2), each participant was asked over a 28-day period
to weigh the dry weight of dirty laundry for every wash cycle, as
well as the amount of detergent used and, if applicable, any addi-
tives and to record this information in a laundry diary. During the
first visit, a questionnaire was distributed to the participants that
they immediately filled in. Care was taken to ensure that the
project supervisor did not influence or aggravate the participants.
The participants were free to buy and use the detergents and
additives they normally use. If the consumers put the detergent
into the dispenser directly out of the package, they had to weigh
out the package before and after dosing. If they used a dosing aid
they were instructed to tare the weight of the dosing aid, fill the
dosing aid as usual and weigh it out.
Each wash cycle, which was completed during the period, was
to be recorded in the laundry diary. In addition to the results of the
weights, details were noted about which type and kinds of deter-
gents and additives were used, which washing programme and, if
applicable, which additional option was selected as well as the
wash temperature. Data were also gathered about the qualitative
composition of the load and the soil level of the laundry items. To
define the soil level, the same categories were adopted as used by
Stiftung Warentest (Stiftung Warentest, 2010) – ‘lightly soiled’
(defined as: ‘No visible dirt and stains. Some clothing items have
absorbed body odour’.), ‘normal soiled’ (defined as: ‘Visible dirt
and/or a few, slight stains visible’.) and ‘heavy soiled’ (defined as:
‘Dirt and/or stains clearly visible’.).
Finally, after the end of the wash cycle, a classification was
given of the satisfaction with the duration of the programme as
well as evaluating satisfaction with the washing results and pos-
sible corrective measures, such as, for example, repeat washing or
pretreatment of insufficient stain removal if the washing result did
not meet expectations.
Load factor
A load factor was calculated by the researcher to normalize the
actual amount of textiles loaded while having different washing
machine sizes and programme recommendations. The load factor
represents a measurable size, which combines information about
the available washing machine capacity in the household, the
recommended laundry amount depending on the selected wash
cycle and the actual laundry amount. The calculation is based on
the matrix of various recommended laundry amounts for the most
frequently used wash cycles, as stated by the manufacturers in
their instruction manuals. Because the relative loading recommen-
dations of the manufactures per programme and maximum capac-
ity are similar, this calculation is reasonable.
The load factor was calculated for each wash cycle by putting
the laundry volume, which was actually washed and recorded in
the laundry diary, in proportion to the recommendation for the
programme chosen for this wash cycle and the washing machine’s
maximum capacity.
Table 1 Distribution of participants per house-
hold size and age (n= 236 households) Households size (in
persons)
Total number
of households
Age (in years)
25–34 35–44 45–54 55–64 65+
1 77 2 331329
2 81 232828 20
3 43 2118310
4 29 1216100
5 4 31000
6 2 20000
Total 236 63 66 63 35 9
Table 2 Specifications of the equipment (Source: manufacturer
information)
Name Manufacturer Type Specification
Laundry basket Curver Maximum capacity: 35 l
Personal scale Korona Janina Maximum weight: 150 kg
Graduation: 100 g
Kitchen scale Soehnle Siena Maximum weight: 2 kg
Graduation: 1 g
Tare feature
A. Kruschwitz et al.Consumer laundry practices in Germany
International Journal of Consumer Studies
© 2014 John Wiley & Sons Ltd
3
load factor amount of load in kg
recommended maximum load in kg
=()
()
A load factor of 1.0 corresponds to the recommended guidelines
(Table 3), whereas a variation of >1.0 corresponds to overloading,
while a variation of <1.0 corresponds to underloading.
Dosage factor
Within the present study a dosage factor was calculated by the
researcher. The calculation of the dosage factor leads to a meas-
urable amount that can be used to make a comparison of individual
detergent dosage behaviour for each wash cycle in relation to the
quantity used and how it was dispensed, the subjective soil level of
the laundry items and the water hardness in the local area (Wasch-
und Reinigungsmittelgesetz, 2007). The calculation was based on
a matrix of the average dosage recommendations depending on the
type of detergent dispensed, the water hardness area and the soil
level (Table 4).
The assumption was that a minimum of 40% of the recom-
mended amount of detergent for a 4.5 kg load must be added to the
washing process even when almost no textiles are to be washed.As
a relevant volume of water will be in the tub even for a very small
load sizes, this guarantees a minimum detergent concentration.
recommendation recommend dosage
recommend dosage am
+× ×
04
06
.
(. oount of load kg/4 5.)
dosage factor detergent used in g
recommendation in g
=()
()
The dosage factor was interpreted in an analogous way to the
load factor.
Statistical analysis
The data were analysed using appropriate tests in the IBM SPSS 20
software programme (SPSS Inc., Chicago, IL, USA). Beside the
calculation of frequencies, arithmetic means and standard devia-
tions the Kruskal–Wallis and the Mann–Whitney U-test were used
to test non-parametric independent variables, while the Wilcoxon
test was used for non-parametric dependent variables (Field, 2005).
Results
Frequency of washing and satisfaction with
the washing result
During the 28-day test period, the 236 participating households
completed a total of 2867 wash cycles.
Table 3 Recommended amount of load in kg
depending on maximum capacity of available
washing machine and chosen programme
(Source: own calculation from various instruc-
tion manuals)
Capacity of washing
machine (in kg)
Maximum load (in kg) per washing programme
Cotton Mix Synthetic Easy care Silk Wool Delicates
3 3 2 2 2 1 1 1.5
5 5 3.5 3 3 2 2 3
66444223
77544223
Table 4 Recommended amount of detergent
in g for a 4.5 kg load (Source: own calculation
based on market survey of common deter-
gents and own density measurements)
Powder detergent
Water hardness in °dH
Recommended amount in g/4.5 kg load
Lightly soiled Medium soiled Heavy soiled
<7.3 47 65 112
7.3–14 47 88 136
>14 65 112 156
Compact/pearls/tabs detergent
Water hardness in °dH
Recommended amount in g/4.5 kg load
Lightly soiled Medium soiled Heavy soiled
<7.3 41 61 98
7.3–14 41 81 118
>14 41 98 138
Liquid detergent
Water hardness in °dH
Recommended amount in g/4.5 kg load
Lightly soiled Medium soiled Heavy soiled
<7.3–14 52 76 128
>14 76 99 156
Consumer laundry practices in Germany A. Kruschwitz et al.
International Journal of Consumer Studies
© 2014 John Wiley & Sons Ltd
4
In relation to the cycles washed per week in a household, the
results for a single person household were on average 2.2 cycles
and 6.8 cycles for a household with at least five persons. Across
the total cycles of all households, the results were on average 4.0
cycles per household and week. Washed cycles per week in rela-
tion to the number of persons living in the household reduced as
the household size increased. The average number of wash cycles
per person and household irrespective of the household size was
1.7 wash cycles (Fig. 1).
The average load size was 2.8 kg per wash cycle for single-
person households, and as the household size increased this rose to
4.5 kg per wash cycle for households with at least five persons. On
average across the wash cycles of all households this meant a load
of 3.3 ±0.8 kg per wash cycle. The average laundry amount per
person washed per week reduced as the household size increased.
Thus, on average 5.9 kg of clothes per week were washed in a
single-person household, whereas in a household with at least five
persons only 4.5 kg of clothes are washed per week and person.
Across all households, the result was an average amount of
laundry of 5.0 ±2.0 kg per week and person (Fig. 2).
Consumers were satisfied with the washing result in 93% of all
completed wash cycles. If the consumer was less satisfied to dis-
satisfied with the result of washing the clothes, the reasons were
primarily related to insufficiently removed stains, the bad smell of
the clothes, notably much wrinkling or detergent leftovers on the
laundry (Fig. 3).
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
Average number of wash cycles
1234>5
(n = 535
wash cycles)
(n = 947
wash cycles)
(n = 703
wash cycles)
(n = 542
wash cycles)
(n = 140
wash cycles)
Household size (in persons)
Arithmetic average number of wash cycles per
week with standard deviation
Arithmetic average number of wash cycles per
week and person with standard deviation
2.2 2.2
3.4
1. 7
4.8
1. 6
5.3
1. 3 1. 3
6.8
Figure 1 Arithmetic average of wash cycles
per week and per week per person with
standard deviation (n= 2867 wash cycles).
10.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
Average amount of clothes (in kg)
1234>5
(n = 535
wash cycles)
(n = 947
wash cycles)
(n = 703
wash cycles)
(n = 542
wash cycles)
(n = 140
wash cycles)
Household size (in persons)
Arithmetic average amount of washed clothes per week and person with standard deviation
Arithmetic average amount of washed clothes per wash cycle with standard deviation
5.9
2.8
4.9
3.0
5.1
3.3
4.7
3.6
4.5
3.7
Figure 2 Arithmetic average amount of
clothes per week and person and per wash
cycle with standard deviation (n= 2867 wash
cycles).
A. Kruschwitz et al.Consumer laundry practices in Germany
International Journal of Consumer Studies
© 2014 John Wiley & Sons Ltd
5
Use of washing programmes and
additional options
Of a total of 2867 wash cycles, information about the washing
programme used were recorded for 96.4% of the cycles. The
cotton programme was the washing programme used by far the
most frequently with 68.6%. This was followed by the easy care
programme (17.2%) and the programme for delicates with 5.3%.
All other and in some cases special programmes were only used
rarely or not at all.
A look at the use of additional programme options showed that
these were used in 43.6% of the total wash cycles. Of all the
chosen programme options, the majority related to the short wash
option (45.8%) followed by the energy-saving option (20.4%).
The trend in recent years for less frequent use of the pre-wash
cycle was confirmed by the gathered data, as this additional option
was only chosen in 4.7% of all wash cycles.
Loading the washing machine
A total of 94.5% of the participants owned a washing machine
with a capacity of 5 kg during the period of the test. Whereas 2.9%
of households owned a washing machine with a capacity of 6 to
7 kg. Only a single household stated having access to a machine
with a capacity of 3 kg.
A look at the average laundry amounts in relation to the washing
programme used in each case shows hardly any differentiation was
made between the available washing programmes and their char-
acteristics. Thus, for example, the washing machine for a cotton
programme with an average 3.4 kg of laundry per wash cycle was
loaded in a similar way to an easy care programme with an average
2.8 kg of laundry per wash cycle (Table 5).
This was even clearer from the analysis of the load factor. The
average, absolute load sizes of approximately 3 kg were com-
parable for the cotton, synthetic and easy care programmes.
However, as the manufacturers’ recommendations varied for
how much the load size should be according to the respective
programme, different load factor results were achieved per
programme. Thus, an average absolute load amount of 2.8 kg
in an easy care programme corresponded to the recommended
laundry amount for this programme, whereas the load amount
of 3.4 kg for the cotton programme only covered 68% of the
recommended load and therefore represents underloading
(Fig. 4).
100.0%
90.0%
80.0%
70.0%
60.0%
50.0%
40.0%
30.0%
20.0%
10.0%
0.0%
Percentage of wash cycles (in %)
52.3%
10.1 %
1.5%
6.5%
22.6%
4.5% 2.5%
No stain
removing
(n = 104
wash
cycles)
Laundry is
crumpled
(n = 20
wash
cycles)
Laundry is
damaged
(n = 3
wash
cycles)
Detergent
leftovers
(n = 13
wash
cycles)
Bad smell
(n = 45
wash
cycles)
Foam still
visible
(n = 9
wash
cycles)
Discoloration
(n = 5
wash
cycles)
Figure 3 Reasons for dissatisfaction with the washing performance (n= 199 wash cycles with at least less satisfying washing result).
Table 5 Arithmetic average amount of load per
washing programme (n= 2762 wash cycles,
with standard deviation)
Washing programme
Number of
wash cycles
Arithmetic average amount
of load with standard
deviation (in kg per wash
cycle)
Cotton 1967 3.4 ±1.2
Synthetics 47 3.0 ±1.0
Easy care 492 2.8 ±1.3
Mix 74 3.7 ±1.4
Wool 31 2.1 ±1.1
Delicates 151 2.3 ±1.2
Consumer laundry practices in Germany A. Kruschwitz et al.
International Journal of Consumer Studies
© 2014 John Wiley & Sons Ltd
6
Overall across all washes, the average load factor was
0.74 ±0.32 which equated to general underloading. In this case,
89% of the values of all average load factors calculated per house-
hold were spread at values below 1.0, whereas 66.5% of all
average load factors per household were less than 0.8, and thus on
average not even utilizing 80% of the given recommendation for
each respective selected programme.
For each recorded wash cycle, on the basis of the laundry diary,
the question asked was why the consumer was washing his or her
laundry at this precise moment. An analysis of the wash cycles
only in the cotton programme for a machine capacity of 5 kg
(n=2031 wash cycles) showed that for 20.3% of wash cycles at
least one item of laundry was needed soon. In 13.3% of cotton
wash cycles, the reason given was the regular washing day, and in
6.7% of wash cycles the reason was that no more items of laundry
were owned in the household. However, for the majority of wash
cycles (59.7%), the response recorded was that the stated load size
corresponded to a maximum, recommended load size. If these
answers were used to establish the average load factor in each
case, it was clear that for the majority of consumers a load factor
of 0.73 ±0.22 was regarded as a maximum load size. Furthermore,
the average load factor for the laundry washed on the regular
washing day was only 0.67 ±0.23 (Fig. 5).
Wash temperature
For all 2832 valid wash cycles, for which a wash temperature was
reported, it emerged that the wash temperature of 40°C was most
frequently selected for 45.2% of all washed cycles. For a share of
about one-fourth of all washed cycles, the temperatures 30 and
60°C were used comparatively often (Fig. 6).
An analysis of all wash cycles gave an average wash tempera-
ture of 44.5°C. A look at the average wash temperatures per
household clearly showed that about one-third of all observed
households used an average wash temperature of between 40 and
45°C. However, the average wash temperature was over 50°C for
15.2% of households with a maximum average temperature of up
to 75°C. On the other hand, 25.8% achieved an average wash
temperature of under 40°C (Fig. 7).
When the wash cycles were interpreted on the basis of the used
washing programmes and the respective average wash tempera-
ture, it can be seen that the participants selected a higher wash
temperature for the cotton programme than, for example, when
using an easy care programme. Looked at statistically, the selected
temperatures for the cotton, easy care and delicates programmes
differed significantly from each other (Wilcoxon test, P=0.000).
Lower temperatures tended to be chosen for the programmes
designed for more delicate textiles (Fig. 8).
Use of detergents
Overall 2773 valid wash cycles confirmed that heavy duty deter-
gent with and without bleach were used most frequently.
‘Vollwaschmittel’ was used in 50.0% of all valid wash cycles
and ‘Colorwaschmittel’ in 43.1%. The special detergents
were underrepresented with 5.0% (‘Feinwaschmittel’) or 1.6%
(‘Wollwaschmittel’). The most frequently used type was compact
detergent (42.6%) followed by liquid detergent for 37.1% of all
valid wash cycles. Tabs were only used in 3.6% of all valid wash
cycles.
For heavy duty detergents, the most commonly used types were
powdered ‘Vollwaschmittel’ (56.7%) and liquid ‘Colorwas-
chmittel’ (48.5%). Liquid dispensing types were mainly used for
special detergents, according to the recommended guidelines.
The soil level was recorded based on a subjective evaluation in
the laundry diary and per wash cycle for 2662 cycles. According to
this data, 63.5% were for lightly soiled, 27.2% for medium soiled
and 9.2% for heavy soiled bundles.
2.00
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
Average load factor
0.68
0.99 0.93
0.41
1.06 1.07
0.77
0.49
Cotton
(n = 1967
wash
cycles)
Synthetics
(n = 47
wash
cycles)
Easy care
(n = 492
wash
cycles)
Silk
(n = 1
wash
cycles)
Mix
(n = 74
wash
cycles)
Wool
(n = 31
wash
cycles)
Delicates
(n = 151
wash
cycles)
Not specied
(n = 104
wash
cycles)
Figure 4 Arithmetic average of load factors per washing programme. Black line: arithmetic average amount of load equates to recommendations
depending on washing programme and maximum capacity (n= 2867 wash cycles, with standard deviation).
A. Kruschwitz et al.Consumer laundry practices in Germany
International Journal of Consumer Studies
© 2014 John Wiley & Sons Ltd
7
During visits to the households, samples of tap water were
taken for each household in order to determine the water hard-
ness in each location. Based on the questionnaire, it was clear
that only 124 households could give an estimate of the prevailing
water hardness area, whereas the remaining 112 households did
not know their water hardness area at the time of the interview.
A look at consumers’ estimated about their water hardness area
and a comparison with the measured data highlights that only
approximately 65.3% accurately estimated their water hardness
area. A total of 17.3% stated their area had higher water hardness
than determined by the measurements, whereas 17.4% believed
they live in an area with less water hardness than was actually
found.
Although according to the detergent manufacturers the dosage
amount should be about 20% more for 21°dH, respectively, 3.80
mmol/l water hardness than for an average hard water area, the
measured, average dosage amount was significantly lower
(Table 6). The average detergent amount, which was used for
laundry in areas with extra hard water, differed significantly from
the average detergent amounts for other areas (Kruskal–Wallis test
for independent random samples, P=0.003; Mann–Whitney test
for independent random samples, soft – extra hard: P=0.001,
medium – extra hard: P=0.004, hard – extra hard: P=0.003)
(Table 6).
A look only at the households that – according to the diary
differentiated during the predefined 4-week observation period
I don’t own more items that suit together.
(n = 136 answers)
This amount of laundry corresponds
to a full machine load.
(n = 1213 answers)
Today is my ‘washing day’.
(n = 270 answers)
At least one item is needed soon.
(n = 412 answers)
0.57
0.73
0.67
0.58
0.00 0.20 0.40 0.60 0.80 1.00 1.20
Average load factor
Figure 5 ‘Why do you wash at that moment?’ and the arithmetic average load factor. Black line: arithmetic average amount of load equates to
recommendations depending on washing programme and maximum capacity (multiple answers allowed, n= 2031 wash cycles, only cotton cycles,
with standard deviation).
50.0%
45.0%
40.0%
35.0%
30.0%
25.0%
20.0%
15.0%
10.0%
5.0%
0.0%
Percentage of wash cycles (in %)
Cold/20 °C 30 °C 40 °C 50 °C 60 °C 70 °C 80 °C ≥90 °C Others
Wash temperature (in °C)
0.5%
22.0%
45.2%
24.7%
4.6%
0.2% 0.2%
2.3%
0.2% Figure 6 Distribution of wash temperature
(n= 2798 wash cycles, with standard
deviation).
Consumer laundry practices in Germany A. Kruschwitz et al.
International Journal of Consumer Studies
© 2014 John Wiley & Sons Ltd
8
between lightly soiled, medium soiled and heavy soiled laundry –
showed that the amount of detergent used here fluctuates depend-
ing on the soil level and water hardness area between
58.2 g ±25.0 g (medium soiled, very hard water) and 81.4
g±36.6 g (heavy soiled, soft water). Even if a difference was
noted in the soil level of the laundry, this did not lead to adjusting
the detergent dosage (Fig. 9).
The calculation of the dosage factor showed that, taking into
consideration the soil level and water hardness as well as the
absolute load size and type of detergent, a dosage of approxi-
mately 50% more was used for lightly soiled laundry than
necessary, and approximately 50% too little detergent for heavy
soiled laundry (Fig. 10).
A look at the absolute, average detergent dosage amounts clas-
sified according to the detergent types gave comparable results for
the use of powdered and liquid detergents. Super compact and tab
detergents were used slightly more sparingly on average across all
wash cycles. However, this general analysis meant that no account
was taken of the dosage recommendations, which depended on the
prevailing water hardness area, the stated soil level of the clothes,
the laundry amount actually washed and the type of detergent. Yet
the calculated dosage factor did integrate these aspects. Here, the
50.0
45.0
40.0
35.0
30.0
25.0
20.0
15.0
10.0
5.0
0.0
Percentage of all wash cycles
<30.0
30.1–35.0
35.1–40.0
40.1–45.0
45.1–50.0
50.1–55.0
55.1–60.0
60.1–65.0
65.1–70.0
>70.1
Classied average wash temperature (in °C)
1.3
4.2
20.3
31.8
27.1
8.5
2.5 2.1
0.4 1.7
Figure 7 Classified average wash tempera-
ture per household (n= 236 households).
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
Average wash temperature (in °C)
Cotton
(n = 1967
wash
cycles)
Synthetics
(n = 47
wash
cycles)
Easy care
(n = 492
wash
cycles)
Silk
(n = 1
wash
cycles)
Mix
(n = 74
wash
cycles)
Wool
(n = 31
wash
cycles)
Delicates
(n = 151
wash
cycles)
Not specied
(n = 104
wash
cycles)
47.1 44.1 38.8 20.0 43.7 30.3 34.6 40.6
Figure 8 Arithmetic average wash temperature per washing programme (n= 2763 wash cycles, with standard deviation).
A. Kruschwitz et al.Consumer laundry practices in Germany
International Journal of Consumer Studies
© 2014 John Wiley & Sons Ltd
9
average values for all types of detergent – for tabs as well – were
above the target amount of 1.0 (Table 7).
The description of pairs of values for the ‘load factor’ and
‘dosage factor per wash cycle’ in a scatter plot clearly revealed the
diversity of washing behaviour for the random sample. When the
average of all dosage factors and load factors was calculated for
every household, and if these were described in pairs per house-
hold, the overview is obtained as presented in Fig. 11. The major-
ity of households were in an area of between 0.5 and 1.0 in relation
to the load factor, and only a few households consistently
Table 6 Arithmetic average amount of detergent per wash cycle and water hardness area (n= 2867 wash cycles, with standard deviation)
Water hardness area
(in °dH)
Water hardness
area (in mmol/l)
Number of
wash cycles
Arithmetic average
amount of detergent
with standard deviation
(in g per wash cycle)
Soft; <7.3 <1.30 583 74.2 ±32.2
Medium; 7.3–14 1.30–2.50 1136 72.9 ±35.5
Hard; 14–21.3 2.50–3.80 712 73.1 ±33.3
Extra hard; >21.3 >3.80 436 69.5 ±42.0
140.0
120.0
100.0
80.0
60.0
40.0
20.0
0.0
Average amount of detergent (in g)
Lightly soiled
(n = 685 wc)
Medium soiled
(n = 399 wc)
Heavy soiled
(n = 211 wc)
70.3 71.8
66.2
58.8
67.7
73.4 69.4
68.2
81.4 78.5
72.1
59.3
Soft; <7.3 °dH Medium; 7.3–14 °dH Hard; 14–21.3 °dH Extra hard; >21.3 °dH
Estimated soil level
Figure 9 Arithmetic average amount of
detergent per soil level and water hardness
area only of those households who chose
every soil level at least once (n= 1295 wash
cycles, with standard deviation).
3.00
2.50
2.00
1.50
1.00
0.50
0.0
Average dosage factor
Lightly soiled
(n = 685 wc)
Medium soiled
(n = 399 wc)
Heavy soiled
(n = 211 wc)
Soft; <7.3 °dH Medium; 7.3–14 °dH Hard; 14–21.3 °dH Extra hard; >21.3 °dH
Estimated soil level
1.72
1.83
1.28
1. 17
1.07 1.05
0.79 0.70
0.88
0.75
0.57 0.52
Figure 10 Arithmetic average of dosage
factors per soil level and measured water
hardness area only of those households who
chose every soil level at least once (n= 1295
wash cycles, with standard deviation).
Consumer laundry practices in Germany A. Kruschwitz et al.
International Journal of Consumer Studies
© 2014 John Wiley & Sons Ltd
10
exceeded the load recommendations. A different picture was
obtained with regard to dosage factors because here the majority
of households were between 0.7 and 2.0. The range of the dosage
factor extended from 0.22 to 4.60 and the range of the load factor
from 0.23 to 2.17.
Discussion
With respect to all the factors concerning textile care, which the
individual consumer can influence through his or her individual
behaviour, there are clearly identifiable sustainability deficits. In
approximately 70% of all wash cycles recorded, the cotton pro-
gramme was used and the recommended load size corresponds
to the washing machine’s maximum load volume – however,
this was only practised in up to 68% of cycles. This observation
corroborates both the results obtained from Norwegian consum-
ers (Laitala et al., 2012) as well as the insights gained from the
preceding study of German consumers (Berkholz et al., 2007).
In the majority of cases for the cotton programme underloading
was clearly in evidence, so that savings could be made for wash
cycles for an optimal load and by paying attention to the sorting
criteria, and thus resource consumption could be reduced. This
was also observed by Berkholz et al., as for the cotton pro-
gramme here, on average 3.18 kg of laundry per cycle could
be measured with comparatively low use of the drum volume.
Jack (2013) recommended alternative ways to achieve cleanli-
ness, like airing or spot-cleaning. But she alluded that people
perform cleanliness rituals and follow social standards of clean-
liness so people tend to go above and beyond basic sanitation
requirements, wasting significant quantities of water, energy and
chemicals in pursuit of these undefinable and ever-increasing
cultural conducts of cleanliness (Jack, 2013).
Evidently, the consumers were unaware of the actual laundry
amount, which can be put in the washing machine with the right
load, and were uncertain about when the drum volume is opti-
mally used. In the study by Berkholz et al. (2007), reasons were
identified for the loading behaviour, so that 31% of the 100 inter-
viewed households stated they deliberately did not fully load the
washing machine to maximum capacity in order to achieve a
better washing result, while a further 34% stated that only the
laundry amount is washed that was dirty at a particular time.
However, in this analysis, there was a missing link to the real data
measured for the laundry amount. The present data showed that
the feeling about a full washing machine load in practice was
approximately 70% of the maximum recommended load for the
cotton programme.
The 1.8% share of 90° or 95°C-wash cycles for all washed
laundry is very low and compared with experiences of Berkholz
Table 7 Arithmetic average amount of detergent in g per wash cycle and average dosage factor per type of detergent indicating misbehaviour in
detergent dosage (n= 2773 wash cycles, with standard deviation)
Type of detergent
Number of
wash cycles
Arithmetic average
amount of detergent
with standard deviation
(in g per wash cycle)
Arithmetic average
dosage factor with
standard deviation
Powder 1183 74.6 ±37.9 1.41 ±0.91
Compact/pearls 460 64.4 ±29.5 1.55 ±0.87
Tabs 100 55.5 ±25.2 1.38 ±0.77
Liquid 1030 75.5 ±34.7 1.38 ±0.73
2.5
2.0
1.5
1.0
0.5
0.0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
Average load factor per household
Average dosage factor per household
Figure 11 Scatter plot of average load factor
and dosage factor per household (n= 236
households).
A. Kruschwitz et al.Consumer laundry practices in Germany
International Journal of Consumer Studies
© 2014 John Wiley & Sons Ltd
11
et al. (2007) reduced. Wash cycles at lower temperatures of a
maximum 40°C seemed to be increasingly frequent. However, the
average wash temperature calculated as 47.1°C for the cotton
programmes is to be classified as too high for a sustainable
washing behaviour. Lichtenberg et al. (2005) recommend to do the
washing a maximum of once to twice per month at 60°C, and to
use 30°C for all other wash cycles because this is usually sufficient
for machine good washing results and textile hygiene. Compared
with the data obtained by the group of Norwegian researchers
(Laitala et al., 2012), the wash temperatures of below 40°C is even
less popular to wash at 90°C or 60°C in more common, resulting
in an average wash temperature at 48.4°C. Hence the authors
conclude, too, that there is quite a potential for improving the
sustainable use of resources by reducing the wash temperature. In
recent years, information campaigns have communicated the
message of reducing washing temperatures to 30°C in Europe. In
the UK, a change was reported in consumer behaviour as in 2002
only 3% of survey respondents washed at 30°C or below, whereas
by 2007 this percentage had increased to 17%. During these 5
years, the average washing temperature in the UK had decreased
from 43.5 to 40.2°C (The World Business Council of Sustainable
Development, 2008).
Another large saving potential was identified for the use of
detergent. A total of 44.5% of all households under analysis only
had one detergent for textile care, however, in most cases they own
textiles made from cotton, synthetic and mixed fibres, as well as
light and also coloured textiles that each require separate treat-
ment. The wrong treatment of the textiles is therefore predestined.
Furthermore, it is clear that no adjustment was either made of the
dosage amount for the volume of textiles to be washed, the type of
detergent and water hardness or for the soil level of the clothes.
This was clearly shown by the group of Norwegian researchers
(Laitala et al., 2012), as only a few of those interviewed stated that
they included the water hardness, the machine capacity or water
status of a specific programme when selecting the dosage amount.
In this study, too, more than half of those interviewed could not
describe the water hardness for their region.
Independently of these criteria, on average approximately
70–75 g of detergent was added per cycle. This means the
optimum dosage amount for medium soil level, medium water
hardness and a 4.5 kg load. However, 63.6% of the recorded
laundry items were classified as lightly soiled. The average dosage
chosen was much too high for these laundry items. If the regional
prevailing water hardness is included in this analysis, the picture
becomes even clearer. For lightly soiled wash cycles in soft water
areas, approximately 70% more detergent was used per cycle than
recommended, whereas for wash cycles classified as heavy soiled
in hard water areas, only approximately 50% of the recommended
detergent amount was added.
Given that for the duration of the study the participants were
invited deliberately to record their behaviour, it can be assumed
that they already slightly oriented their behaviour along the lines
of socially desirable practices. Therefore, it is to be expected that
in reality the washing behaviour differs more acutely from optimal
washing behaviour than has been described here. Considerable
uncertainty emerges, in particular, in relation to the optimal load
size of a wash cycle as well as the choice of a suitable detergent
and the dosage amount adjusted for the soil level and water
hardness.
Conclusion
This study, although based on a non-representative sample of the
German population, describes people’s behaviours and attitudes in
doing laundry in Germany. It reveals details about variations in
washing habits, gives consideration of selected washing tempera-
tures, as well as the selection of washing programme and the
detergent consumption. In addition to that, it discloses user’s
knowledge with regard to the use of resources in private house-
holds and identifies a possible of knowledge in washing behaviour.
The analysis of the recorded data of 236 German households
shows that there are uncertainties while handling the machine, the
textiles and the different washing agents. More consumer educa-
tion is needed on how to use detergents, additives, water and
energy in terms of laundry washing being more sustainably. It is
necessary to teach the consumers about the consequences of their
behaviour. A plausible approach could be to revise the communi-
cation for dosage recommendations as well as to reinforce the
support and information provided for consumers via consumer
information centres and independent consumer organizations (e.g.
Forum Waschen). Furthermore, it is advisable to examine the
effectiveness of existing communication channels (e.g. informa-
tion brochures) as well as the technical solutions (e.g. automatic
detergent dosage) in terms of the sustainability of user behaviour.
Acknowledgements
The authors would like to thank the companies Henkel, Reckitt
Benckiser Ltd. and Miele & Cie. KG for supporting this research.
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Circular economy is gaining attention in business and society to advance sustainability. This paradigm is particularly relevant for energy-consuming products such as washing machines, where alternatives to linear economy such as pay-per-use and refurbishment are gaining ground. To succeed, these business models should achieve consensus and acceptance among users. However, little attention has been paid to customers’ interest for circular economy business models so far. This paper aims to compare the economic and environmental impacts of pay-per wash and refurbishment business models, while investigating the degree of users’ acceptance and factors influencing it. A survey has been designed to collect users’ data regarding washing machine consumption patterns and acceptance rates of the circular business models. An evaluation model was developed to assess the economic and environmental impacts of pay-per-wash and refurbishment against a traditional linear model, fed with data from 279 Italian households collected through the survey. Finally, logistic regressions were carried out to investigate the influence of different customer, product, and usage factors on the acceptance rates of the two circular business models. Results show that, on average, pay-per-wash business models and washing machine refurbishment can guarantee environmental savings. However, only refurbishment generates economic savings for users. Moreover, only around half of the users’ sample shows a positive degree of acceptance of such alternatives. Respondent age has been found as a significant factor influencing the interest towards a refurbishment model, while the washing machine failures experienced by users and the relevance of the environmental gains achievable influence the acceptance rate of pay-per-wash models. Thus, when offering pay-per-wash schemes, suppliers should emphasize the information on the environmental benefits of this alternative, and that with such models they take over the responsibility and costs for maintenance and repair. On the other hand, providers of refurbished products should target younger consumers, who are less affected by a bias against second-hand goods.
... LCA studies of clothing, detergents and washing machines show that the use phase is generally the most energy consuming phase in the life cycle of clothing, ahead of the production and transport phases [4]. Consumer washing habits vary [5,6], but in the last 20 years the preferred washing temperatures worldwide have been between 30 • C and 60 • C [4][5][6][7][8]. However, these washing methods cannot guarantee the sufficient cleanliness of the laundry and especially the sufficient disinfection of the laundry [9]. ...
... It has been found that hygienic textiles can only be achieved at a washing temperature above 60 • C [15]. Accordingly, it is realistic to assume that potentially pathogenic microorganisms are not eliminated when infected laundry is washed at temperatures of 30-40 • C, especially since these temperatures are ideal for their development and multiplication [7,11,16]. ...
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In the Water, Energy and Waste Directive, the European Commission provides for the use of household washing programmes with lower temperatures (30–40 °C) and lower water consumption. However, low washing temperatures and the absence of oxidising agents in the liquid detergents, and their reduced content in powder detergents, allow biofilm formation in washing machines and the development of an unpleasant odour, while the washed laundry can become a carrier of pathogenic bacteria, posing a risk to human health. The aim of the study was to determine whether the addition of hydrogen peroxide (HP) to liquid detergents in low-temperature household washing allows disinfection of the laundry without affecting the properties of the washed textiles even after several consecutive washes. Fabrics of different colours and of different raw material compositions were repeatedly washed in a household washing machine using a liquid detergent with the addition of 3% stabilised HP solution in the main wash, prewash or rinse. The results of the antimicrobial activity, soil removal activity, colour change and tensile strength confirmed the excellent disinfection activity of the 3% HP, but only if added in the main wash. Its presence did not discolour nor affect the tensile strength of the laundry, thus maintaining its overall appearance.
... Unilever is one of the major laundry detergent manufacturers in Europe with sales of powders, liquids and capsules with varying market share depending upon consumer preferences. The consumer habit in actual dosing of powder, liquid and tablet laundry detergents was based on a comprehensive study performed in Germany (Kruschwitz et al., 2014). In the absence of comparable data for all countries we assumed that the variability in product dosing measured in Germany was representative for all countries. ...
... Inter-country and intra-country variability in consumer behaviour in relation to GHG footprinting studies, have been partially addressed in a number of previous studies (Pakula and Stamminger 2010;Schmitz and Stamminger 2014;Stamminger et al. 2007;Kruschwitz et al. 2014;Laitala et al. 2012;Wang et al. 2014;Ableitner et al. 2016b;Binks et al. 2016). The inter-country variabilities in chapters 2-4 of this thesis showed the significant importance of supply-side solutions such as Synthesis 111 electricity decarbonisation. ...
... Scenario 2-washing method. A washing machine with an average load of 2.1 kg at 30 °C (Laitala et al. 2012) was selected as the best practice washing method (S2B) as it is similar to the recommended maximum load for many woolspecific washing cycles (Kruschwitz et al. 2014;Gooijer and Stamminger 2016). This is slightly lower than the typical washing machine load for other fibres (2.3-3.7 kg) (Laitala and Vereide 2010) and realistic, because many washing machines have a general 30 °C wash cycle with a recommended maximum load of 3.5-4.0 ...
... kg . A study of washing loads in German households showed that wool programs are selected at a similar rate to their overall share of the garment market (Kruschwitz et al. 2014). The specifications of a contemporary A +++ electricity efficiencyrated washing machine (Bosch 2020a) were used to define the water and electricity consumption of S2B. ...
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... 58 Furthermore, the proposed laundry rate of 5.0 kg per week per person estimated based on an avg. 3.3 kg per wash for Germany, 67 is comparable to that estimated for Europe (3.7 kg per wash); 69 so that the estimation can be applied to many other European countries. ...
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