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An Updated Life Cycle Study -

The Use of Disposable and

Reusable Nappies in the UK

Confidential Draft Final Report

March 2008

Delivering sustainable solutions in a more competitive world

CONTENTS
1
INTRODUCTION AND SCOPE OF THE STUDY
1
1.1
PRODUCT SYSTEMS AND SYSTEM BOUNDARIES
4
1.2
THE DISPOSABLE NAPPY SYSTEM
4
1.3
HOME LAUNDERED REUSABLE NAPPY SYSTEMS – SHAPED AND PREFOLD
7
1.4
INCLUSIONS/EXCLUSIONS 11
1.5
KEY ASSUMPTIONS AND LIMITATIONS 12
1.6
DATA REQUIREMENTS 12
1.7
INVENTORY ANALYSIS AND IMPACT ASSESSMENT 14
2
INVENTORY DATA FOR REUSABLE NAPPIES
15
2.1
SHAPED NAPPY NUMBER, WEIGHT AND MANUFACTURE 15
2.2
WRAPS 15
2.3
WASHING DATA 15
3
INVENTORY DATA FOR DISPOSABLE NAPPPIES
23
3.1
DISPOSABLE NAPPY NUMBER, WEIGHT AND MANUFACTURE 23
3.2
WASTE MANAGEMENT 23
4
RESULTS 25
4.1
SHAPED NAPPIES 25
4.2
DISPOSABLE NAPPIES 29
5
CONCLUSIONS 32

1
INTRODUCTION AND SCOPE OF THE STUDY
This study builds on a previous study for the Environment Agency, entitled
Life Cycle Assessment of Disposable and Reusable Nappies in the UK, ISBN:
1-84-432427-3, and is considered an addendum to the previous study.

Environmental Resources Management Limited (ERM) was asked by the
Department for Environment, Food and Rural Affairs (Defra), the
Environment Agency and the Waste Resources Action Programme (WRAP) to
update the previous life cycle assessment (LCA) study by assessing the
changes in the environmental profile of disposable and reusable nappies that
have resulted from developments in the manufacture and use of disposable
and reusable nappies systems in the UK since 2002/03.

Factors addressed in the study included: further weight reduction of
disposable nappies; the inclusion of shaped nappies; the changed energy
efficiency and different usage of washing machines and driers; and changes to
waste disposal options, including the use of reusable nappies for a second
child.

For this study ERM aimed to obtain:

•  updated energy generation data;
•  updated energy consumption data for washing machines and tumble
driers;
•  updated manufacturing data for disposables;
•  updated waste management data for disposables;
•  new manufacturing data for shaped nappies; and
•  new manufacturing data for prefold nappies (not obtained so were
excluded from the study).

The goal of the study was split into the following objectives:

•  to update the previous study (1) with changes in the market place
between 2002/03 and 2005/06, to include an assessment of the effects
of a range of behavioural assumptions on the life cycle environmental
impacts of the re-usable nappy types and to compare these with each
other and with modern disposable nappies;

to compile a detailed life cycle inventory of the environmental burdens
associated with the production, use and disposal of shaped and prefold
reusable (2) nappies and disposable nappies; and

(1) Life Cycle Assessment of Disposable and Reusable Nappies in the UK, Environment Agency, ISBN: 1-84-432427-3
(2) no data was forthcoming from prefold manufactures therefore they were excluded from this study.
ENVIRONMENTAL RESOURCES MANAGEMENT
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•  to use the life cycle inventory data to compare the environmental
impacts arising from reusable and disposable nappies under the various
scenarios considered.

The study aimed to inform, through simplification of parameters and clearly
defined scenarios, the audience about the significance and scale of the
environmental impact of nappies generally, as well as, and how, actions that
can be, and have been, undertaken by manufacturers and users of nappies
affect the environmental profiles.

The project was governed by a board comprising Defra, WRAP and the
Environment Agency. The board agreed that ERM would consider up to 10
scenarios; four for disposable nappies, and six for reusable nappies.    The
board also specified the scenarios to be assessed.

The scope of the study is consistent with the previous study with the
exception of the updated data above and the aim of the study to reflect
potential impacts in 2006.

The functional unit used is the same as that used in the previous study (1). It
is appropriate to the goals of the study, and is defined as “the use of nappies
during the first two and a half years of a child’s life”. This functional unit
results in a specific quantity of disposable and reusable nappies used within
the time period of two and a half years.

The reason for focusing on the first two and a half years is that by this point
nappy use is tailing off.    Beyond this point, nappy use varies considerably
because children are at different stages of toilet training.    Although they may
still use training pants, and/or overnight nappies, the use of these types of
products is outside the scope of this study.

1.1
NUMBER OF CHANGES
In support of the previous study the Environment Agency commissioned
surveys of both disposable and reusable nappy use.    These surveys
(Environment Agency, 2004) determined that the average child is out of
nappies at 2 years 2 months (same for both type of nappy) and that after 2.5
years 95 per cent of all children are out of nappies.    The study reflects the first
2.5 years of an average child’s life in the UK.    Therefore, the systems
modelled take account of those children who stop using nappies earlier than
2.5 years, see

Table 1.1.

(1) Life Cycle Assessment of Disposable and Reusable Nappies in the UK, Environment Agency, ISBN: 1-84-432427-3
ENVIRONMENTAL RESOURCES MANAGEMENT
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The time children spend in nappies is specific to the individual, but the
majority of children have undergone toilet training under the age of 2.5 years.
Although they may still use training pants or overnight nappies for a
significant period beyond this point, the use of these types of products is
outside the scope of this study.

Table 1.1
Children wearing nappies by child age (all types of nappy)
Age of child
Children wearing nappies    Children not wearing nappies
(%)
(%)
up to 6 months
                        100.0%
    0.0%
6 to 12 months
95.7%
    4.3%
12 to 18 months
82.8%
17.2%
18 to 24 months
45.6%
54.4%
24 to 30 months
17.6%
82.4%
30 to 36 months
    4.8%
95.2%
36 to 42 months
    1.8%
98.2%
42 to 48 months
    0.4%
99.6%
48 to 54 months
    0.1%
99.9%
54 to 60 months
    0.1%
99.9%
60 to 66 months
    0.1%
99.9%
Source: The Environment Agency surveys (Environment Agency, 2004)
Note: The surveys showed that there is no difference in age out of nappies between children
using reusable or disposable nappies. The figures in the table are for disposable nappies for
which there were more results but were applied to all children.
Note: The surveys showed that there is no difference in age out of nappies between children
using reusable or disposable nappies. This table is true for all children.

The UK sales figure for disposable nappies in 2001-2002 provided an average
daily use figure of 4.16 nappies a day, based on a market penetration of 96.4
per cent (Environment Agency, 2004).    The EA surveys found that number of
changes per day for children still using disposables starts at 7 and decreases to
5 by 2.5 years.    When the decreasing population is accounted for, the
Environment Agency surveys suggested a change frequency, for disposable
nappy users (both in and out of nappies), between 4.05 and 4.4 per day over
2.5 years.    Due to the clarity of the survey questions and responses, the
Agency statistician deemed a daily change of 4.16 to be appropriate and one
that is supported by the surveys.    An average daily change figure of 4.16 has
therefore been used in the assessment of the disposable nappy system.

The Environment Agency surveys found that the average number of changes
per day for those children still using cloth nappies starts at 8 and decreases to
6 by 2.5 years. The average daily number for children still in reusable nappies
was calculated to be 6.1 changes (EA, 2004).      The average number of changes
per day, over the first 2.5 years, for all children (those in and out of nappies)
who used cloth nappies was established to be 4.3 – 4.7 changes (accounting for
both children in and out of nappies).

ENVIRONMENTAL RESOURCES MANAGEMENT
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The previous LCA study and this addendum takes account of the decreasing
population of children in nappies over the 2.5 years.    Therefore the results
reflect an average child and not a child in nappies for the full 2.5 years.

1.2
PRODUCT SYSTEMS AND SYSTEM BOUNDARIES
The nappy systems assessed included all life cycle stages.    All energy and
materials used was traced back to the extraction of resources.    Emissions from
each life cycle stage were quantified.    Waste management and waste water
treatment processes and their environmental releases were included (1) .

1.3
THE DISPOSABLE NAPPY SYSTEM
Disposable nappies typically consist of a plastic outer layer with integral
fastenings and a core of absorbent materials with a protective top layer.    The
nappy core is composed of fluff pulp (cellulose fibre) and a water-absorbent
polymer, sodium polyacrylate (SAP).    The function of the core is to absorb
liquid excreta.    The top layer is made up of a ‘non-woven’ polymer-based
material with a textile structure.    From the top layer, the fluids flow through a
pulp-based tissue layer down to the core.    Leakage is prevented by a plastic
bottom layer and by elastic barriers.    The nappy is prevented from falling off
by rubber waist elastics and is fastened around the child’s waist by velcro like
materials.    The different materials in the nappies are glued together with
polymer-based adhesives.    The packaging consists of polyethylene plastic
bags and corrugated board boxes.

The nappies are distributed from the manufacturers either directly to retailers,
or via distribution centres maintained by the manufacturers.    The retailers are
grocery chains, independent grocers or chemists.    Customers pick up their
nappies at the retailer and transport them home for use.    Used nappies,
containing excreta are discarded along with other municipal waste, and will
later on end up consigned either to landfill, mechanical-biological treatment
(MBT) or to incineration.

The main disposable nappies in the UK are very similar in terms of
composition and use.    ERM combined the composition and weight of nappies
sold in the UK in a particular year and calculated the ‘average nappy’.    This
average nappy takes account the fact that the size of the nappies used over the
baby’s first two and a half years will change depending on the baby’s age and
size.

Most of the disposable nappies that are sold in the UK are also manufactured
in the UK, although several raw materials are acquired from other European

(1) Waste management processes are treated in the same way as other processes within the life cycle.    The potential impact
contributions of the emissions that arise from each process are quantified.    The utilisation of a process in itself is not
considered an impact, therefore it is not reported as such.
ENVIRONMENTAL RESOURCES MANAGEMENT
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countries or from North America.    These considerations have been included
in the study.

Table 1.2 presents the average composition of a UK disposable nappy for 2006.
Table 1.2
Average UK Disposable Nappy Composition and Weight (2006)
Total
Fluff
SAP PP  LDPE
Adhesives
PET/polyester
Other
pulp
Units g
%  %  %  % %
%
%
Average
38.6 34.1 32.4 16.6 6.0 3.8
2.2
4.8
unit
weight

Using the average of 4.16 nappies used per day from the previous study and
an average nappy weight of 38.6g, an average child will use 146.5kg of
nappies over the two and a half year period.

The manufacturers of disposable nappies have provided manufacturing data
representative of 2006 conditions.    These data were used to characterise an
‘average’ manufacturing plant based on market share.

The study included all the significant processes, tracing material and energy
flows to the point where material and energy are extracted or emitted to the
natural environment.    Due to the complexity of the product system, it is
impractical to draw a full system diagram that includes all processes where
human influence occurs. Figure 1.1 details the main life cycle stages that are
included in the life cycle of disposable nappies.

1.3.1
Disposable Nappy Scenarios
For the disposable nappy systems, alternative scenarios are limited, as these
would require action from the manufacturers and or action from local
authorities for the provision of alternative waste management systems.

The manufacturers have reduced the environmental impact of disposable
nappies through product design and development.    Since 2001/02 the,
industry has reduced the weight by 11% through nappy design changes and
the development of materials.    It is expected by the industry that this scale of
reduction will continue in the short term.    We have assessed the potential
implication of future light-weighting in a sensitivity analysis.

Alternative waste management routes that used disposable nappies will
follow include separate collection for anaerobic digestion or recycling and
diversion with household waste through MBT.    Examples of recycling or
digestion schemes that have been offered include:

•  Almere (diaper biowaste household collection and biodigesting)
project in Holland; and
ENVIRONMENTAL RESOURCES MANAGEMENT
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•  Knowaste LLC who have reported diaper recycling programs in the
European Union, Asia and North America.

Due to a lack of detailed process data for nappies in these processes, ERM has
estimated, as a sensitivity analysis, the environmental impacts associated with
alternative waste management routes.

ENVIRONMENTAL RESOURCES MANAGEMENT
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Figure 1.1
System Boundary for the Disposable Nappy System

Env
n ir
i onme
o
nt: R
n
e
t: R sources

Tim
Ti b
m er
e
Pr
P od
r uct
od
i
uct on
o  of Feed
e stoc
t k
oc
Acry
Ac lilc A
i
c
c A id
NaOH
O
  E
pr
p oduc
od ti
t on
o
Poly
l mer
e s
Pr
P od
r uct
od
i
uct on
o
Pr
P oduct
od
i
uct on
E
o
T
  N
T
T
T
H
T
T
T
T
  E
E
  R
Produ
d cti
t on of
R
f
R
Pulp Produ
d ct
c io
i n
Plasti
s c
n
c
SAP
SA
Pack
c agi
g ng
  G
& B
& l
B each
e
i
ach ng
Compo
mp nen
e ts
ng
Produ
d ction
Pr
P oduc
od ti
t on
o
  Y
T
T
T
T

P

R

S
T
T
O
T
T

Wa
W st
s e Re
e R cyclin
i g
Dis
Di pos
p able
abl  Nappy P
Napp
r
y P oduc
odu tion
i
on
Land
n filil
l
U
D

P
U

P
T
P
C
  L
T

Ele
El ctr
c icit
i y
Y
Gen
Ge erati
e
on
T
on
Retail
Retai

Wa
W ste R
e e
R cyclin
i g
S

T
S
Y
  Y
S

Use

S
T
T
  T
E
  E
Inc
In in
i er
e ation
o
Land
n filil
l
M
  M
S

S

Envir
n
onme
o
nt: A
n
ir
i , Land
n  a
d nd Wa
n
ter

Nb. the main transport steps between processes and life cycle stages have been included in the assessment.    Waste
management activities associated with production and the supply chain have also been included in the assessment.

1.4
HOME LAUNDERED REUSABLE NAPPY SYSTEMS – SHAPED AND PREFOLD
In the previous study terry and prefold nappies were assessed, as these were
the most popular in 2002/03.    However, subsequent market analysis by
WRAP (pers. comm. Julian Parfitt, WRAP) indicates that shaped and prefold
ENVIRONMENTAL RESOURCES MANAGEMENT
DEFRA/EA/WRAP
7

nappies now have the greatest market share.    This study considered home
laundered shaped nappies.    It was intended that prefolds would also be
included.    However, no updated manufacturing data on prefolds was
forthcoming.

Reusable cotton nappies come in a number of types.    Nearly all are fitted and
fastened with poppers and or velcro straps instead of pins.    The different
nappy systems can be divided into the following categories:

•  all-in-ones - shaped, fitted nappies with velcro or popper fastenings,
which include a waterproof cover.    No folding or pinning is required;

•  shaped nappies - similar to all-in-ones, but wraps or pants have to be
purchased separately to provide the waterproof cover. These do not
require folding.    They are fastened by velcro or poppers; and

•  prefolds - requires folding and a separate waterproof wrap/pant, with
fasteners used in some cases.

All-in-ones and shaped nappies are generally considered easier to use than
flat/prefold nappies, in that no folding is required.    Shaped nappies either
have velcro or popper fastenings, or rely solely on the wrap/pant to hold
them in place.

Prefold nappies are made from woven cotton and consist of a large rectangle
of fabric that has been folded and stitched into three panels; the centre panel
being thicker than the two outer panels.    Prefolds are considered to be easier
to dry than all-in-ones and shaped nappies.

Wraps/pants are used to hold up nappies and to prevent leakage.    They are
made from different materials and combinations of materials, such as: nylon;
polyester; cotton; wool; PVC; EVA; hemp; and polyurethanes.    Wraps/pants
are not considered as durable as nappies to washing, drying and wear, and
hence they may need to be replaced.    For any given size, the frequency of
replacement is dependent on the care they receive. Following manufacturers’
care guidance is essential for maximising the lifetime of the wrap/pant.
Some wraps/pants are adjustable and are designed for use from birth to potty;
others are replaced when necessary to fit a growing baby.    Generally, three
different sizes will be needed over the two and a half year period.

In combination with the nappies and wraps/pants, parents can use liners and
booster pads to improve performance and ease of cleaning.    Liners are used
to provide a drier layer between the baby and the absorbent nappy and to
assist in containment of faecal matter for ease of cleaning.    Liners come in
reusable or disposable forms.    Materials used include: paper; polypropylene;
fleece; and silk.    It is sometimes necessary to boost the performance of a
nappy by using booster pads.    The study has not included booster pads in the
assessment.
ENVIRONMENTAL RESOURCES MANAGEMENT
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The major retail routes for reusables appear to be through high street shops,
mail order and via the internet.

Figure 1.2 details the main life cycle stages that have been included in the life
cycle of home laundered shaped (sized) nappies.    All key material, energy
and waste streams are traced to the point at which environmental flows cross
the system boundary.

Reusable nappies are sold in birth to potty packs and ERM used samples of
these packs, together with data provided by suppliers, to specify reusable
nappy consumption.    Table 1.3 the contents of a shaped nappy birth to potty
pack.

Manufacturers of each type of reusable nappies were contacted for
manufacturing data through the Nappy Alliance.
Figure 1.2
System Boundary For Home Laundered Reusable Nappy System`

Environm
Envi
e
ronm n
e t:
n  Resources
t:

Cotton
tton
O

Cult
Cul iva
v tion a
a
nd
tion a
Cotton Gi
Cotton G nn
n ing
Cotton
E
Harvesting
T

Harvesting
Spinning
N
H
  E
T
E
E

Fab
Fa ric
R
c
R
Produc
r
tion a
oduc
nd
tion a
R

Fe
F rti
e lise
l r
ise and
a
Wet
We  Processing
Pestic
Pe
id
stic e
id
G
e
G

Produc
r
tion
oduc
Y

Other Napp
her
y
y
P

Packaging
Nappy
y
Construction
Construc

tion
Produc
r
tion
T
oduction
Construct
Construc iton
T
on
R

Mater
e i
r als
S
O
  U
T
U
D

Wr
W ap
a  and L
a
i
nd L ner
ne
r
De
D te
e r
te g
r en
e t
Reta
e il
ta  a
il nd
P
a
P
Manufa
a
c
nufa t
c ure
T
ur
T
U
Manuf
Ma
a
nuf c
a t
c ure
ur
Distribution
Distributi
  P
T
P
C
  L
T
L
T
  Y

Consume
um r
e  Us
r
e
Sew
Se a
w g
a e
e
e
S
Treatment
Treat
  S
Y
T
  Y
Water
e
S

Packaging Wa
W s
a te
Treatme
m n
e t and
S
T
Disposal
Disposa
Supply
  T
E
  E
M
  M
S
  S

Environment: Air, L
Environm
and and Water

Nb. the main transport steps between processes and life cycle stages have been included in the assessment.
Waste disposal activities associated with production and the supply chain have also been included in the
assessment.
ENVIRONMENTAL RESOURCES MANAGEMENT
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Table 1.3
Shaped Birth to Potty Pack
Weight per item
Total

(grams)  No of items  Material
(grams)
Nappy size 1
132
15
95.5% cotton 4.5% velcro
1980
Nappy size 2
164
15
96.7% cotton 3.7% velcro
2460
Packaging size 1
42
1
LDPE (15 nappies/bag)
42
Packaging size 2
38
1
LDPE (15 nappies/bag)
38
Same composition assumed as
Wrap size S
54
4
for size L, see below
216
Packaging wrap size S
8
1
LDPE (4 wraps per package)
8
Same composition assumed as
Wraps size M
58
4
for size L, see below
232
Packaging wraps size M
8
1
LDPE (4 wraps per package)
8
Analysed: 6g velcro; 4g
lining (unidentified plastic
material); 30g unidentified
plastic laminated fabric
material; 18g cotton (all per
Wraps size L
58
4
wrap) 232
Packaging wraps size L
8
1
LDPE (4 wraps per package)
8
Paper; 14g/10 liners = 100
Liners 138
20
liners per roll
2760
Packaging liners
42
1
LDPE (20 rolls/bag)
42
Total

68
8026

1.4.1
Home Laundered Scenarios to be Assessed
ERM has approached this study in a different way from the previous study,
which used the results of a survey commissioned by the Environment Agency.
For the baseline scenario ERM assumed that nappies are used on one child
only, dry-pailed (not soaked in sanitising solution) and washed in a washing
machine with an average energy efficiency rating for appliances owned in
2006 (1).    ERM also used average use of average tumble driers and washer-
driers from the same source. ERM assumed that three-quarters of nappies are
line dried outside and the remainder are tumble dried.    Nappies are assumed
to be washed with wraps at 60°C, the minimum temperature recommended
by the Department of Health.    Each wrap is assumed to be used twice
between washes.

With the agreement of the Project Board, ERM developed scenarios to
demonstrate the environmental benefits of separate user choices, such as:
reduced temperature washing; using more energy efficient appliances; and
high/low utilisation of tumble driers.    With the exception of the baseline and
reuse on a second child, the scenarios are considered to be extremes, rather
than general practice.    For example, it is not possible for everyone to line dry
outside, and it is not practicable for anyone to line dry all the time, nor is it
likely that mny people will always tumble dry.

(1) From Market Transformation Programme
ENVIRONMENTAL RESOURCES MANAGEMENT
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The objective of showing the effect of these scenarios separately is to indicate
the environmental costs of different actions, so that people understand how
environmental advantageous is any action they may choose.    The scenarios
are presented in Table 1.4.

In addition to these scenarios the study has considered, in a sensitivity
analysis, the scale of the benefit that can be achieved by combining some of
these choices, viz; reuse on a second child; high load efficiency; and 100% line
drying.    The study has also considered, in a sensitivity analysis, the scale of
environmental harm that can be done through a high energy consumption
scenario, of 100% tumble drying and washing at a high temperature.

Table 1.4
Cloth Nappy Behaviour Scenarios to be Assessed
Dry
Pailing
Pre-wash
Nappy Wash  Tumble
Load Energy
Wrap
Wrap
Temp
Drying
Efficiency
Washing
Washing at
with
40° with
Nappies
other
clothes
Scenario 1
Yes Yes 60°C MTP Calculated MTP
average
Yes
No
Baseline
average??
High efficiency  Yes
Yes
60°C
MTP average  Calculated
A+ rated
Yes
No
High load
Yes
Yes
60°C
MTP average  3 day wash
MTP average  Yes
No
efficiency2:
High
Yes
Yes
90°C
MTP average  Calculated
MTP average  No
Yes
temperature
100% tumble
Yes Yes 60°C 100%
Calculated
MTP
average
Yes
No
Drying
100% line
Yes Yes 60°C No  Calculated
MTP
average
Yes
No
Drying
100% use on
Yes
Yes
60°C
MTP average  Calculated
MTP average  Yes
No
second child
Notes:
1) Unlike the previous study where 9.5% of users were found to iron nappies, ERM has
assumed for this assessment that no ironing occurs.
2) For the high load efficiency scenarios, ERM has assumed a 33% increase in the number of
nappies and wraps owned and washing every 3 days compared with every 2 days for the other
scenarios.

1.5
INCLUSIONS/EXCLUSIONS
As in the previous study, and in line with accepted LCA practice, ERM has
excluded capital equipment and workforce burdens from both the reusable
and disposable nappy systems.

1.5.1
Excreta
Excreta is considered within the system boundaries when comparing
disposable and reusable nappy systems.    The main reason for this is that both
nappies and excreta will undergo a different type of waste treatment in each
case, due to the different characteristics of the systems.

ENVIRONMENTAL RESOURCES MANAGEMENT
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For disposable nappies, ERM believes that it is reasonable to assume that all
excreta will be disposed together with the nappies. Consequently, excreta
will follow the household waste stream from the nappy waste bin in the home
to landfill, MBT and incineration facilities in the UK.

For users of home laundered reusable nappies, a proportion of the excreta will
be flushed down the toilet, together with soiled disposable liners, before the
nappies are washed. This effluent will enter the sewerage system.    The
remaining excreta will also enter the sewerage system through the washing
machine outflow.    Sewage treatment has been modelled on the basis of
typical sewage treatment processes in the UK.

1.6
KEY ASSUMPTIONS AND LIMITATIONS
Changes to the assumptions in the previous study have been recorded and are
presented in this report.

1.7
DATA REQUIREMENTS
In addition to collecting data describing the manufacture of the nappy types
assessed, the following are identified as key elements for which new inventory
data were required:

•  UK electricity generation (2005/06) by type (eg coal, gas, nuclear,
hydro, wind etc.);
•  washing machine performance;
•  tumble drier performance; and
•  waste management.

1.7.1
Disposable Nappy Systems
The manufacturers of disposable nappies supplied data describing both the
average composition and weight of a disposable nappy in 2006, and the
average manufacture of disposable nappies.

Material life cycle inventories associated with the manufacture of disposables
were the same as those provided previously by EDANA.

The WRATE software and supporting literature was used to model the
disposal of disposable nappies, replacing the WISARD software previously
used.

1.7.2
Home Laundered Reusable Nappy System
The type of nappies to be assessed and the use scenarios considered were
agreed with the Project Board.    For the nappy types specified, shaped and
prefold, ERM purchased a birth to potty pack for each.    These were used,
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along with manufacturing data, to specify a typical composition and weight of
each nappy type and their associated wraps.

To assist ERM in defining the manufacturing process for the reusable nappy
system, a survey of nappy manufacturers was undertaken.    ERM provided
questionnaires to manufacturers, WRAP and reusable nappy industry
representatives.

ERM sourced data from the Market Transformation Programme (MTP) UK
data for UK washing machine and tumble drier performance.

The data collection for reusable nappies for this study has been limited to:

•  manufacturing data for nappies, wraps and liners; and
•  updated energy and water consumption data for washing machines
and tumble driers.

ERM amended the behavioural data that the Environment Agency found from
the surveys it commissioned for the previous study to reflect the scenarios as
described.

All other data used to model the scenarios described above was extracted
from the previous study.

1.7.3
Data Quality Requirements
The key requirements regarding data quality are that data are as accurate and
representative as possible of nappies used in the UK in 2006.

Data have been collected from the following sources:

•  questionnaires and interviews with experts regarding the foreground
system;
•  validated life cycle inventory databases for the background system;
•  literature for the background system;
•  Time to Change?: A Study of How Parents and Carers Use Disposable
and Reusable Nappies (Environment Agency Science Report), ISBN:
978-1844324521; and
•  Life Cycle Assessment of Disposable and Reusable Nappies in the UK,
Environment Agency, ISBN: 1-84-432427-3.

The data collected for, and used in this study were documented and assessed
with regard to their quality.    The data used were selected on the basis of
availability and on how representative they are of nappy systems in the UK in
2006.

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1.8
INVENTORY ANALYSIS AND IMPACT ASSESSMENT
Similar inventory analysis and impact assessment methods as in the previous
study were used for this study.    ERM has reported significant inventory items
such as energy and water use separately.    All new data and assumptions
have been documented.

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2
INVENTORY DATA FOR REUSABLE NAPPIES
2.1
SHAPED NAPPY NUMBER, WEIGHT AND MANUFACTURE
Based on two complete sets of manufacturing data for shaped nappies, and
the specifications of further popular shaped nappies, an average weight of
139.3g per nappy has been assumed.    The nappies are 100% cotton.    ERM
has assumed, based on the birth to potty pack and guidance from other
suppliers that a minimum of thirty nappies are required over the two and a
half year period that a child is in nappies.

2.2
WRAPS
Based on the birth to potty pack for shaped nappies, and a survey of two other
wrap types, ERM assumed an average wrap weight of 47.6g, and that a
minimum of 12 wraps are required for the two and a half year period.

Only one complete set of manufacturing data for wraps was obtained, and this
has been used in the assessment.    The composition of these wraps was: 21%
cotton; 39% polyester; and 40% polyurethane.

2.3
WASHING DATA
ERM used data relating to domestic washing and drying that represent 2005
and 2006 in the UK.    These data were sourced primarily from Defra’s Market
Transformation Programme (MTP), from the online ‘What if? Tool’.    The tool
provides forecast data from 1999 up to 2020 for the consumption of electricity
and water for washing machines (WMs), washer/driers (WDs) and tumble
driers (TDs).

Based on these data, ERM calculated domestic washing and drying
performance in the UK for the following:

•  UK stock average performance for:
-  water use; and
-  electricity use.

•  UK ‘most efficient’ performance for:
-  water use; and
-  electricity use.

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2.3.1
Summary of Washing and Drying Performance
Table 2.1 shows the electricity and water use figures for washing used by ERM
in the study.    These figures were calculated from the more detailed data
shown in Section 2.3.2.    The stock average figures represent the market
average performance for washing machines and washer/driers, based on
electricity and water consumption by energy label class.      The numbers in
Table 2.1 exclude electricity and water consumption for a pre-wash cycle.
ERM estimated an average pre-wash cycle, based on an Öko-Institut (2005)
LCA study of washing machines in Germany.    No data were available
describing temperature or frequency of pre-washing in the UK.    ERM
assumed that a pre-wash is run as cold wash and consumes a minimum
quantity of electricity and water, as shown in Table 2.2.    It was assumed that a
pre-wash is used before every washing cycle for nappies.
Table 2.1
Summary of UK Washing Performance
Washing
Electricity Use:
Water Use:  Electricity Use: A+
Water Use:
Temperature
Stock Average  Stock Average
Rated Washing  A+ Rated Washing
Machine
Machine
oC
kWh per load
litres per load
kWh per load
litres per load
40 0.74
70
0.60
46
60 1.04
70
1.00 46
90 1.85
70
1.66 46

Table 2.2
Pre-Washing Performance
Washing Temperature
Electricity Use:
Water Use:
Average
Average
oC
kWh per load
litres per load
20 0.25
35
Source: (Öko-Institut, 2005)
Note: Data provided in the Öko-Institut report provides an estimate for a minimum electricity and water
consumption per load.    ERM assumed this to be equivalent to a pre-rinse cycle.

Table 2.3 shows the electricity and water use figures for drying.    These figures
were calculated from the more detailed data shown in Section2.3.3. The stock
average figures represent the market average performance for washer/driers
and tumble driers based on electricity and water consumption by energy label
class.
Table 2.3
Summary of UK Drying Performance
Electricity Use:
Water Use:
Electricity Use:
Electricity Use:
Stock Average
Stock Average
A-Rated Tumble
Stock Average
Drier
A-Rated Drier
kWh per load
litres per load
kWh per load
kWh per load
2.99 19
1.71
1.88

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2.3.2
UK Washing Data and Assumptions
The data used to calculate UK washing performance (combination of washing
machines and washer driers) are presented below, including data for the
following:

•  washer stocks;
•  washer energy consumption;
•  washer water consumption; and
•  washer load size.

Washer Stocks
Table 2.4 shows a breakdown of the stocks of washing machines and
washer/driers for the UK in 2005/06, according to energy class.
Table 2.4
UK Washer Stocks 2006
Type Model
Stock
2006
Washing machines  A+ rated
720 011

A rated
7 724 644

B rated
4 018 681

C rated
3 135 109

D rated
663 254

E rated
234 888

F rated
110 332

Other
3 734 567

Total
20 341 485
Washer/driers A+
rated
-

A rated
32 962

B rated
541 715

C rated
1 086 161

D rated
1 103 089

E rated
150 972

F rated
826 237

G rated
239 938

Total
3 981 075
Source: (MTP, 2007)

Washer Water and Energy Consumption
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Table 2.5 shows the consumption of electricity for washing machines per load,
according to energy class in 2006.    Table 2.6 shows the water consumption of
washing machines by energy class.    UK stock average consumption figures
were calculated from these data.

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Table 2.5
Washing Machine Energy Consumption per Load by Energy Class
Energy Class
A+
A
B
C
D
E
F

kWh kWh kWh kWh kWh kWh kWh
90°C
1.66 1.77 1.77 1.86 2.32  2.5 2.69
60°C
1.00 1.06 1.06 1.12 1.39 1.50 1.61
40°C
0.60 0.64 0.64 0.67 0.83 0.90 0.97
Source: (MTP, 2007a)
Table 2.6
Washing Machine Water Consumption per Load by Energy Class
Energy class
A+
A
B
C
D
E
F
G
litres
litres
litres
litres
litres
litres
litres
litres
60°
- 53 61 75 86 94 109 163
Adjusted for reduced
- 46 53 65 75 82 95 142
load
Source: (MTP, 2007a)

From testing conducted by MTP, a typical consumer wash is usually less than
a full load, using 13% less water.    Table 2.6 accounts for this reduced water
use which has been assumed to be average behaviour in the UK.

Washer/Driers
Table 2.7 and Table 2.8 show the consumption of electricity and water for
washer driers per load according to energy class, in 2005/06.    Data were not
available for washing energy consumption.    ERM assumed that an average
washer/drier has the same electricity consumption as a B-rated washing
machine per load.    Additionally, water consumption data only cover energy
ratings B to D.    When calculating stock average water consumption we have
only considered these energy ratings.    Other ratings were excluded.    This
assumption covers approximately 70% of washer/driers on the market.
Table 2.7
Washer/Drier Energy Consumption for Washing per Load by Energy Class
Stock
Average
kWh
90°C 1.77
60°C 1.06
40°C 0.64
Note: ERM assumed that an average washer/drier has the same electricity consumption as a B-rated
washing machine per load.

Table 2.8
Washer/Drier Water Consumption for Washing per Load by Energy Class
Energy class
A+
A
B
C
D
E
F
G
litres
litres
litres
litres
litres
litres
litres
litres
60°
- -
51
61
61 - - -
Source: (MTP, 2007a)

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Washing Load
In terms of washing load, according to MTP (2007a), the UK average washing
machine capacity is 5.6kg.    Additionally, Table 2.9 shows the load capacity
data available from MTP.    Data were only available for class A+ and class C.
For the study we have assumed an average load of 2.8kg for a wash load.
Table 2.9
Washing Machine Load Capacity by Energy Class
Energy class
A+
A
B
C
D
E
F
G
kg
kg
kg
kg
kg
kg
kg
kg
Washing
capacity
5.86 - -
4.86 - - - -
Source: (MTP, 2007a)

2.3.3
UK Drying Data and Assumptions
The data used to calculate the drying performance are presented below,
including data for the following:

•  drier stocks;
•  drier energy consumption;
•  drier water consumption;
•  drier load; and
•  frequency of drying.

Drier Stocks
Table 2.11 shows a breakdown of the stocks of driers for the UK in 2005/06,
according to energy class.    Table 2.4 shows a breakdown of stocks of
washer/driers.

The Office for National Statistics (ONS) publish data relating to tumble drier
household ownership in the UK.    From 1994 to 2002/03 tumble drier
ownership by household has increased from 50% to 56% (ONS, Table 9.3, Ref
D7611).    The ONS also publishes data relating to ownership by household
type, which suggests that tumble drier ownership is higher in households
with children. In households with two or more children ownership ranges
between 61 and 76%.
Table 2.10
Tumble Drier Ownership Amongst Households with Children
Composition of Households with children
Percentage of households with a tumble drier

One adult, one child
46
One adult, two or more children
61
One man and one woman, one child
73
One man and one woman, two or more
children
76
All other households with children
62
Source: Office for National Statistics, Table 9.4, Percentage of households with durable goods by income
group & household composition based on weighted data and including children's expenditure 2002-03
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Table 2.11
UK Drier Stocks 2006
Type Model

Stock
2006

Condenser
A+ rated
-
A
rated

B
rated
-

C rated
2 202 156

D rated
543 447
E
rated
-

F
rated
-

Other
-

Total
2 745 605
Vented A+
rated

-

A rated
58 763
B
rated

-

C rated
2 295 130

D rated
2 912 330

E rated
654 654
F
rated

-
Other

-

Total
5 920 878
Vented compact
A+ rated
-
A
rated

-
B
rated

-
C
rated

-

D rated
236 685
E
rated

-

F rated
337 092
Other

136
841

Total
710
618

Grand Total
9 377 101
Source: (MTP, 2007)

Drier Water and Energy Consumption
Table 2.12 and Table 2.13 show the consumption of electricity for tumble driers
and washer/driers per load, according to energy class, in 2006.    Table 2.14
shows the water consumption of washer/driers for the drying cycle.
Washer/driers consume water to aid the condensing process when drying.
UK stock average consumption figures were calculated from these data.
Table 2.12
Tumble Drier Energy Consumption per Load by Energy Class
Energy Class
A
B
C
D
E
F
G

kWh kWh kWh kWh kWh kWh kWh
Vented
1.71
1.98
2.24 2.51 2.78 3.05 3.35
Condenser 1.84
2.14
2.45 2.75 3.05 3.35 3.69
Source: (MTP, 2007a)

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Table 2.13
Washer/Drier Energy Consumption for Drying per Load by Energy Class
Energy class
A+
A
B
C
D
E
F
G
kWh
kWh
kWh
kWh
kWh
kWh
kWh
kWh
Drying
- 2.18 2.92 3.52 4.12 4.72 5.32 5.88
Source: (MTP, 2007a)

Table 2.14
Washer/Drier Water Consumption for Drying per Load by Energy Class
Energy class
A+
A
B
C
D
E
F
G
litres
litres
litres
litres
litres
litres
litres
litres
Drying
- -
29
65
79 - - -
Source: (MTP, 2007a)

Drier Load
Based on data from MTP (2007b), ERM estimated the stock average drier
capacity to be 3.5kg.    This data reference was used to determine the average
energy consumption for drying 1kg of nappy.

Frequency of Drying
The total number of washing machines in the UK is 21 341 485 and 3 981 075
washer/driers.    The total number of washing cycles per year per machine is
predicted to be 274 by MTP.    Additionally, the total number of tumble driers
in the UK is 9 377 101.    The total number of drying cycles per year per
machine is predicted by MTP to be 148 for tumble driers and 97 for
washer/driers.

Based on these data, ERM estimated that, on average, 26.6% of all washing
cycles are followed by a drying cycle.

The use of tumble driers is dictated by ownership, convenience and the
availability of other drying methods. Other drying methods include
radiators, line drying indoors and line drying out of doors. Indoor drying
consumes energy for part of the year as a result of an increased demand on
central heating systems that are generally thermostatically controlled, whilst
outdoor drying uses solar energy (wind and temperature).    Outdoor line
drying relies on climatic conditions.    In the UK, precipitation is expected
between 150 and 200 days per year (Met Office UK Summary).

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3
INVENTORY DATA FOR DISPOSABLE NAPPPIES
3.1
DISPOSABLE NAPPY NUMBER, WEIGHT AND MANUFACTURE
Updated manufacturing, nappy composition and nappy weight data were
obtained from AHPMA members.    From the previous study, the number of
nappies used over the average two and a half year period that a child is in
nappies is 3796.
Table 3.1
Average UK Disposable Nappy Composition and Weight (2006)
Total
Fluff
SAP
PP
LDPE  Adhesives PET/polyester Other
pulp
Units
g  % % % % %  %
%
Average  38.6 34.1 32.4 16.6 6.0 3.8
2.2
4.8
unit
weight


3.2
WASTE MANAGEMENT
Based on data from Defra on waste management routes in 2005/06, ERM
assumed 86% landfill and 14% energy from waste for residual waste
management.

3.2.1
Excreta
In the previous study, it was assumed that 365kg of excreta was disposed with
nappies as municipal solid waste.      A small survey and analysis of bins by
WRAP estimated the weight of excreta as 727kg.    ERM modelled the WRAP
estimate in a sensitivity analysis.    The composition of excreta was assumed to
be the same, 18% faeces and 82% urine.

3.2.2
Modelling of Waste Management
Regarding landfill and energy from waste, the recent peer-reviewed software
tool WRATE (http://www.environment-agency.gov.uk) was used to model
waste management activities. The research and documentation associated
with WRATE suggests gas generation is complete within 100 years, and
leachate release to groundwater is approaching levels of contaminant
detection within 20 000 years.    WRATE assumes that the emissions of gas and
leachate over these time periods are instantaneous, ie they are allocated, with
no discounting for time, to the material as it is landfilled.

WRATE takes into account all the stages in the management and processing of
waste, from the point where it is discarded to the controlled disposal or
recovery of the waste.

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The tool also takes into account operational inputs and outputs of the waste
management facilities according to the municipal solid waste fractions
handled.    It calculates avoided burdens due to materials and energy
displacement.

The upstream limit of the system is the production of municipal solid waste.
The model does not account for the energy and material costs of producing
the products that make up the waste.    The model covers municipal solid
waste, which is comprised of household collected waste and the main civic
amenity/bring system wastes.

The tool takes account of waste collection and processing stages and their
associated sub stages.

To model the 100% anaerobic digestion sensitivity scenario, the MBT - Hydro-
Mechanical Separation and Anaerobic Digestion (with energy recovery) technology
in WRATE was manipulated by ERM to accept and to process disposable
nappies.

Table 3.2
Disposable Nappy Composition
Scenario Urine
Faeces
Plastics Pulp
Miscellaneous
Kg
Kg
kg
kg
kg
Original
299 66 84 50
13
WRAP
Estimate*
596 131 84 50
13
*The same urine to faeces split is assumed

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4
RESULTS
The results presented reflect the assumptions made and the scenarios
assessed, and should be read in this context.

4.1
SHAPED NAPPIES
Table 4.1 and Table 4.2 summarise a selection of the life cycle inventory
environmental consumptions and flows for the manufacture and use of
shaped nappies for each scenario.
Table 4.1
Electricity and Water Consumption


Electricity consumption
Water consumption

Washing  Drying Washing Flushing  Drying

kWh
kWh
l
l
L
1
Baseline
402.1
141.0
36 126
12 853
1576
2 High
energy
389.7
80.6
27 869
12 853
1576
efficiency
3
High load efficiency
268.1
141.0
25 216
12 853
1576
4
High temp
686.6
141.0
36 126
12 853
1576
5
100% tumble drying
402.1
529.9
36 126
12 853
5923
6
100% line drying
402.1
0.0
36 126
12 853
0
7
100% use on second
402.1
141.0
36 126
12 853
1576
child
8 Reuse,
high
load
268.1
0.0
25 216
12 853
0
efficiency and 100%
line-drying

These results indicate that the high temperature and 100% tumble drying
scenarios, overall, have the largest inventory flows.    This is due primarily to
increased electricity consumption for washing or drying in consumer use.
The extreme sensitivity scenario (100% reuse, high load efficiency and 100% line
drying) generates the lowest profile in terms of inventory flows.    With the
exception of the baseline, which reflects what could be expected of the
population as a whole, the scenarios reflect the differences that could be
achieved by an individual’s actions.    Some, such as 100% line drying outside
are unlikely or even impossible.

Table 4.3 and Table 4.4 show the whole life impact profile for each of the
shaped nappy scenarios.    A similar pattern to the inventory results is
followed.    The main driver for the impacts is the electricity consumption in
washing and drying the nappies.    The high temperature and 100% tumble
drying scenarios show the least beneficial environmental profile across the
impact category indicators, compared to the baseline.    The global warming
potential has increased by 31% for the high temperature scenario and by 43% for
100% tumble drying scenario.

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The most beneficial scenarios, in terms of reduced global warming potential,
relate to the full load and 100% line drying scenarios, which show a decrease in
global warming potential of 16%.    If an A+ rated washer and an A-rated drier
are used, as shown by the high efficiency scenario, then the global warming
potential is reduced by 9%, compared to the baseline.

If we consider the global warming impact potential for the baseline scenario,
569kg CO2 equivalents per child over two and a half years, this would equate
to an estimated total global warming potential of approximately 0.4mt CO2
equivalents per year (based on 1.7 million children in nappies at any one
time). The impact profile calculated is similar to that calculated in the
previous nappies study (559kg) (1).    However, care should be taken when
comparing the numbers, as it has not been possible to determine average use
across the population, and there are significant differences in the nappy
systems assessed and the assumptions made this time.

This estimate can be considered in the context of total greenhouse gas
emissions for the UK of approximately 700mt of CO2 equivalents per year.

Based on the scenarios assessed, individual users of shaped nappies have the
potential to improve the impact profile of nappy use per child by some 200kg
over the two and a half years.    Similarly, if users tumble dry every load, wash
at 90°C and adopt other similar behaviours the impact could increase by
between 175kg and 425kg of additional CO2 equivalents.

The water use related to shaped nappies over the two and a half year period
amounts to 41 m3 of irrigation water for cotton growing, 53 cubic metres of
direct water demand and a total water requirement, including water used
indirectly as a result of using shaped nappies, eg due to production of
detergents and water used in the generation of electricity, of 1221 cubic
metres..    If all children in nappies were to use shaped nappies, this would
equate to approximately 40 million cubic metres of direct water demand per
year. Putting this in the context of total water usage: in 1997/98 3.2 billion
cubic metres of water, was used by households through the public water
supply network(2) , so if all children used reusable nappies this would add one
percent to direct household water consumption.

(1) Life Cycle Assessment of Disposable and Reusable Nappies in the UK, Environment Agency, ISBN: 1-84-432427-3
(2) Environmental Accounts Autumn 2004, Office for National Statistics
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Table 4.2
Inventory Analysis for Each Shaped Nappy Scenario (Manufacture and Use Excluding Disposal)
Inventory Flow
Coal (hard)
Oil  Natural gas  Carbon dioxide
Methane SOx NOx
N2O Total Water
Water
(fossil)
water*
(direct)
Cotton
Irrigation
Scenario
kg kg
m3
kg kg kg kg kg m3
m3 m
1 – Baseline
156
28  76
515 1.7 1.1 1.0 0.03
1221  53  41
2 - High efficiency
139
27
69
469
1.6
1.1
1.0
0.03
1136
42
41
3 - High load efficiency
127
25
65
431
1.4
1.0
0.9
0.03
1277
40
55
4 - High temperature
216
29
100
678
2.1
1.3
1.2
0.04
1482
51
41
5 - 100% tumble dry
239
30
109
740
2.4
1.3
1.2
0.04
1588
55
41
6 - 100% Line dry
126
27
64
432
1.4
1.1
0.9
0.03
1082
49
41
7 - 100% re-use on 2nd
child
148
26  70
484 1.6 1.0 0.9 0.03 913  51  21
Combined sensitivity

8 – Combined (re-use, load, line dry)-
environmentally aware scenario
87
22  45
308 1.0 0.8 0.7 0.02 735  38  27
9 – Combined (high temp,100% tumble
dry) – high energy scenario
299
31 133
904 2.8 1.4 1.4 0.05
1854  55  41
*includes hydro power requirements and power station cooling

Table 4.3
Impact Profile for Each Shaped Nappy Scenario (Whole Life – Includes Disposal)
Impact category
Abiotic depletion  Acidification  Eutrophication  Fresh water aquatic
Global warming
Human toxicity
Photochemical
ecotoxicity
potential
oxidation

kg Sb eq
kg SO2 eq
kg PO3- eq
kg 1,4-DB eq
kg CO2 eq
kg 1,4-DB eq
kg C2H4
1 – Baseline
4.2 1.9  0.3
4.3
568.9
73.3
0.1
2 - High efficiency
3.8 1.9  0.3
4.0
519.7
68.4
0.1
3 - High load efficiency
3.5 1.7  0.3
3.5
475.4
62.1
0.1
4 - High temperature
5.5 2.1  0.4
5.6
745.7
90.8
0.1
5 - 100% tumble dry
6.0
2.2 0.4
6.1  815.1  97.5  0.1
6 - 100% Line dry
3.5
1.8 0.3
3.6  478.3  64.4  0.1
7 - 100% re-use on 2nd child
3.9
1.7
0.3
4.1
535.4
70.3
0.1
Combined sensitivity

8 – Combined (re-use, load, line dry)
2.5 1.3  0.2
2.6
342.3
49.5
0.1
9 – Combined (high temp,100%
tumble dry)
7.3 2.4  0.4
7.5
992.8  115.0
0.1
Note: The human and aquatic toxicity impact methods should be treated with caution due to the limitations associated with the methods.

Table 4.4
Impact Change (%) for Each Shaped Nappy Scenario Compared with Baseline
Impact category
Abiotic depletion  Acidification  Eutrophication  Fresh water aquatic
Global warming
Human toxicity
Photochemical
ecotoxicity
potential
oxidation

kg Sb eq
kg SO2 eq
kg PO3- eq
kg 1,4-DB eq
kg CO2 eq
kg 1,4-DB eq
kg C2H4
1 – Baseline
4.2 1.9  0.3
4.3
568.9
73.3
0.1
2 - High efficiency
-9%
-3%
-2%
-8%
-9%
-7%
-3%
3 - High load efficiency
-16%
-11%
-13%
-19%
-16%
-15%
-9%
4 - High temperature
31%
11%
7%
31%
31%
24%
10%
5 - 100% tumble dry
43%
16%
14%
42%
43%
33%
15%
6 - 100% Line dry
-16%
-6%
-5%
-16%
-16%
-12%
-5%
7 - 100% re-use on 2nd
child
-6%
-10%
-9%
-5%
-6% -4% -6%
Combined sensitivity

8 – Combined (re-use, load, line dry)
-40%
-30%
-30%
-41%
-40% -33% -23%
9 – Combined (high temp,100%
tumble dry)
74%
27%
21%
73%
75% 57% 25%
Note: bold and italic indicates where impacts have increased compared to baseline.
Note: The human and aquatic toxicity impact methods should be treated with caution due to the limitations associated with the methods.

To place the scale of baseline shaped nappy scenario impact contributions in a
more manageable context, Table 4.6 compares the impacts with the average
impact profile of an average European person, this step is referred to as
normalisation.    As can be seen the contribution

Table 4.5
Normalised Baseline Results (Europe 1995 (EU15+NO&CH))
Shaped Nappy
Impact category
Unit
Baseline
Abiotic depletion
person year equivalents
0.043
Acidification
person year equivalents
0.011
Eutrophication
person year equivalents
0.004
Fresh water aquatic ecotoxicity
person year equivalents
0.001
Global warming potential
person year equivalents
0.018
Human toxicity
person year equivalents
0.001
Photochemical oxidation
person year equivalents
0.002

4.2
DISPOSABLE NAPPIES
Table 4.7 summarises a selection of the life cycle inventory flows for the
manufacture and use of disposable nappies for the baseline scenarios
examined in the sensitivity analysis.    These results compare the baseline with
the 10% lightweighting sensitivity scenario.    Unlike nappy care changes which
can be made by users of reusable nappies, lightweighting is not a change that
can be achieved immediately and the results should be considered in this
context.    For all inventory flows, the results directly relate to the reduction in
manufacturing material inputs, where a 10% reduction in weight gives a
comparable reduction in the inventory flow.

Table 4.8 and Table 4.9 show the whole life impact profile for the disposable
nappy baseline and scenarios considered in the sensitivity analysis.    As with
the inventory results, all impact category indicators reduce for the 10%
lightweighting sensitivity scenario, compared to the baseline. The main driver
for the impacts is the production of the materials used to construct the
disposable nappies. Across all impact categories, should the manufacturers
deliver continued lightweighting there is a beneficial reduction in impacts,
which ranges from 5% to 9%.    For global warming potential the 10%
lightweighting sensitivity scenario shows a 8% reduction in impact.

The sensitivity analysis scenarios considering additional excreta from the
WRAP excreta estimate sensitivity scenario results in a 3% increase in the
global warming impact category.    The greatest influence this scenario has is
on the water pollution impact categories.

The anaerobic digestion sensitivity analysis scenario shows that diversion of
disposable nappies away from current residual waste management routes can
benefit greenhouse gas profiles through digestion and energy recovery from
the biogas produced.
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If we consider the global warming impact potential for the baseline scenario,
551kg CO2 equivalents per child over the two and a half year period, this
would equate to an estimated total global warming potential of approximately
0.4mt CO2 equivalents per year.    This assumes that all children wear
disposables (based on 1.7 million children in nappies at any one time).

This estimate can be considered in the context of total greenhouse gas
emissions for UK of approximately 700mt of CO2 equivalents.

Between 2001/02 and 2006 the disposable nappy industry has reduced the
weight of the average disposable nappy by some 11 per cent. This has reduced
the global warming impact resulting from nappy use across all children by
around 10 per cent.

To place the scale of baseline disposable impact contributions in a more
manageable context, Table 4.6 compares the impacts with the average impact
profile of an average European person, this step is referred to as
normalisation.
Table 4.6
Normalised Baseline Results (Europe 1995 (EU15+NO&CH))
Disposable Nappy
Impact category
Unit
Baseline
Abiotic depletion
person year equivalents
0.048
Acidification
person year equivalents
0.018
Eutrophication
person year equivalents
0.004
Fresh water aquatic ecotoxicity
person year equivalents
0.000
Global warming potential
person year equivalents
0.016
Human toxicity
person year equivalents
0.001
Photochemical oxidation
person year equivalents
0.003

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Table 4.7
Inventory Analysis for Baseline Disposable and Lightweighting Sensitivity Scenario (Manufacture and Use Excluding Disposal)
Inventory Flow
Coal (hard)
Oil  Natural gas
Carbon
Methane SOx NOx
N2O Total Water
dioxide
water*
(direct)
(fossil)

kg kg m3 kg kg kg kg kg m3
m3
0 – baseline
43
107
86
474
1.1
1.8
2.2
0.02
141
0.048
Sensitivity

00 - 10% Lightweighting
39  98  77 436 1.0 1.6 2.0 0.02 130
0.043
*includes hydro power requirements and power station cooling

Table 4.8
Impact for Disposable Nappy Baseline and Sensitivity Scenarios (Whole Life – Includes Disposal)
Impact category
Abiotic depletion
Acidification Eutrophication
Fresh
water
Global warming
Human toxicity
Photochemical
aquatic
potential
oxidation
ecotoxicity

kg Sb eq
kg SO2 eq
kg PO-- eq
kg 1,4-DB eq
kg CO2 eq
kg 1,4-DB eq
kg C2H4
0 – baseline
4.5
3.4
0.40
1.9
551
58
0.20
Sensitivity

00 - 10% lightweighting
4.1 3.1 0.37 1.9 509  56 0.19
000 – with WRAP excreta estimate
4.4 3.4 0.46 2.5 570  61 0.21
0000 – with 100% anaerobic
digestion
4.4 3.3 0.39 2.8 512  68 0.20
Note: The human and aquatic toxicity impact methods should be treated with caution due to the limitations associated with the methods.
Table 4.9
Impact for Disposable Nappy Baseline and Sensitivity Scenarios (Whole Life – Includes Disposal)
Impact category
Abiotic depletion
Acidification Eutrophication
Fresh
water
Global warming
Human toxicity
Photochemical
aquatic
potential
oxidation
ecotoxicity

kg Sb eq
kg SO2 eq
kg PO3- eq
kg 1,4-DB eq
kg CO2 eq
kg 1,4-DB eq
kg C2H4
0 – baseline
4.5
3.4
0.40
1.9
551
58
0.20
Sensitivity

00 - 10% lightweighting
-9%
-9%
-7%
-5%
-8%
-5%
-5%
000 – with WRAP excreta estimate
-1%
2%
14%
26%
3%
4%
3%
0000 – with 100% anaerobic
digestion
-1%
-2%
-2%
46%
-7%
16%
-1%
Note: The human and aquatic toxicity impact methods should be treated with caution due to the limitations associated with the methods.

5
CONCLUSIONS
The study has estimated, using a 2006 reference point, the impact contribution
profiles for a child using disposable nappies for the first 2.5 years of its life
and a child using shaped cloth nappies for the same period.

The study demonstrates the environmental effects of:
•  disposable nappy design and manufacturing;
•  disposable nappy disposal choices; and
•  laundry choices for shaped nappy use.

The average 2006 disposable nappy would result in a global warming impact
of approximately 550kg CO2 equivalent if used over the 2.5 years a child is
typically in nappies. The global warming impact from disposable nappies use
has decreased since the earlier study due to changes in production operations
and an 11% reduction in the weight of nappies.

The report highlights that the manufacture of disposable nappies has greater
environmental impact in the UK than their waste management by landfill.

For reusable nappies, the baseline scenario based on average washer and drier
use produced a global warming impact of approximately 570kg CO2
equivalent.

However, the study showed that the impacts for reusable nappies are highly
subject to the way they are laundered.

Washing the nappies in fuller loads or line-drying them outdoors all the time
(ie ignoring UK climatic conditions for the purposes of illustration) was found
to reduce this figure by 16 per cent.    Combining three of the beneficial
scenarios (washing nappies in a fuller load, out door line drying them all of
the time, and using them on a second child) would lower the global warming
impact by 40 per cent from the baseline scenario, or some 200kg CO2
equivalent over the two and a half years, this is equivalent to the emissions
associated with 0.016 person years .

In contrast, the study indicated that if a consumer tumble dried all their
reusable nappies it would produce a global warming impact 43 per cent
higher than the baseline scenario.    Similarly, washing nappies at 90°C instead
of at 60°C would produce 31 per cent more CO2 equivalent than the baseline.
Combining these two energy intensive scenarios would increase the global
warming impact by 75 per cent over the baseline scenario, or some 420 kg CO2
equivalent over the two and a half years, this is equivalent to the emissions
associated with 0.033 average person years.

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The environmental impacts of using shaped reusable nappies can be higher or
lower than using disposables, depending on how they are laundered..

Cloth nappy users will reduce their impacts by :
•  line drying outside whenever possible;
•  tumble drying as little as possible;
•  when replacing appliances if possible choose more energy efficient
appliances (A+ rated machines are preferred)
•  not washing above 60°C
•  washing fuller loads; and
•  re-using nappies on other children.

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