Table
1
| Effect
of changing energy use assumptions on home washed reusable system |
| Composite
kWh per wash |
Assumption
|
Washing
behaviour |
Reduction
in global warming (mainly CO2) and fossil resource use |
Reduction
in kWh rel. to 1.38 |
Total
global warming (kg CO2 equivs) |
1.38
|
EA
baseline 1997 UK machines Table 5.7
|
EA
terry users distribution, Table 2.27
|
nil
(baseline)
|
nil
|
559
(Table 8.13) |
1.20
|
ERM
sensitivity 2000 UK machines Fig 9.5
|
EA
terry users distribution, table 2.27
|
6% |
13% |
525 |
1.25
|
No
washes above 60o, 1997 machines
|
WEN
calculation using terry distribution, modified (see calc) |
4% |
10% |
534 |
0.95
|
A-rated
machines
|
Terry
distribution of washing temps |
14%
|
31%
|
481 |
| 0.86 |
A-rated |
No
washes above 60°C |
17% |
38% |
464 |
KWh use derived
from National Energy Foundation information www.natenergy.org.uk/washing.htm
using the distribution of washing temperatures from the Environment Agency
Life Cycle Assessment of reusable and disposable nappies 2005 www.environment-agency.gov.uk.
Energy use, with its global warming potential, is a major impact of all
nappy systems. Use of washing machines from 1997 was assumed for the reusable
system. The effect of using machines as bought in 2000 was tested, and
gave a reduction in CO2 of 6%. The report finds that “electricity
use for nappy care is the most significant single contributor to the impacts
assessed”, yet the effect of further improvements in washing machines,
and of following nappy companies’ instructions and washing at 60oC
or below was not tested. The LCA assumed a 1.38 kWh wash, but a 0.86 kWh
wash will soon be the average. (DEFRA Market Transformation Programme:
UK Energy Consumption of Domestic Washing Machines 22/01/2005 www.mtprog.com)
Table 2
| Effect
of changing type of wash and energy rating |
| |
|
|
|
No
70°C or 50°C (1) |
1997,
not above 60°C (2) |
B-rated |
A-rated |
A-rated,
not above 60°C |
| EA
washing temp (3) |
%
of washes |
kWh
(ERM) Table 5.7 |
weighted
kWh |
%
of washes |
weighted
kWh |
%
of washes |
weighted
kWh |
kWh
per wash |
weighted
kWh |
kWh
per wash |
weighted
kWh |
%
of washes |
weighted
kWh |
90°C
|
32.1%
|
1.77
|
0.57
|
33.2%
|
0.59 |
|
|
1.46
|
0.48
|
1.22
|
0.41
|
|
|
80°C
|
0.0%
|
1.63
|
0.00
|
|
|
|
|
|
|
|
|
|
|
70°C
|
7.1%
|
1.50
|
0.11
|
|
|
|
|
|
|
|
|
|
|
60°C
|
35.7%
|
1.36
|
0.49
|
45.9%
|
0.62 |
79.1%
|
1.08
|
1.12
|
0.51
|
0.94
|
0.43
|
79.1%
|
0.74 |
50°C
|
7.1%
|
1.09
|
0.08
|
|
|
|
|
|
|
|
|
|
|
| 40°C |
17.9% |
0.82 |
0.15 |
20.9% |
0.17 |
20.9% |
0.17 |
0.67 |
0.14 |
0.56 |
0.12 |
20.9% |
0.12 |
| |
|
|
|
|
|
|
|
|
|
|
|
|
|
| Total
kWh per wash |
1.38
|
|
1.38
|
|
1.25
|
|
1.14
|
|
0.95
|
|
0.86 |
| Percent
reduction in kWh relative to 1.38 |
|
9.9% |
|
17.7% |
|
31.1%
|
|
37.8% |
Notes
1. The Environment Agency Survey found that people washed with the distribution
in column 2. (Table 5.7 of LCA) Public information on washing machine
energy use uses three temperatures only: 90°C, 60°C & 40°C.
To make comparisons with lower energy machines easier, the percentages
were redistributed as fairly as possible so that some of those washing
at 70°C were moved up to 90°C, and others down to 60°C; and
similarly with those washing at 50°C. This gave a modified distribution
with the same energy use as the EA: 1.38 kWh. This distribution was used
to obtain all the other washing energies.
2.
Table 2 tests the effect of no-one washing above 60°C
3.
Table 1 calculates the approximate effect on the global warming potential
in kg of CO2 equivalent. Using the results of the sensitivity analysis
in the LCA where a change in machines from those bought in 1997 to machines
bought in 2000 gives a 6% drop in CO2 (Fig. 9.5) the approximate drops
for other changes in washing machine energy and use are calculated in
the final column using Table 8.13.
By
using an A rated machine and following manufacturers instructions to wash
at 60o parents can reduce energy use and global warming impact by 17%.
Many
parents use 20-24 nappies. By using half the 47.5 nappies suggested in
the Environment Agency report parents can half the 13.8% global warming
impacts associated with their production, storage and transport home making
an additional saving of 6.9%.
Therefore
by using 24 nappies (saving 6.9%) and laundering them in an A rated machine
at 60 o parents can reduce energy use and global warming impact by 23.9%
rounded to 24%.
|
