Environmental Performance of Washing Machines Varies Substantially Electricity Consumption Could Differ by 70%

15 June 2017
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Environmental Performance of Washing Machines Varies Substantially  Electricity Consumption Could Differ by 70%

The Consumer Council joined with the Electrical and Mechanical Services Department (EMSD) in conducting tests on 12 models of washing machines.  Variance among the tested models in both rinsing and water-extraction efficacy were found.  Among models of the same category, energy and water consumption could vary as much as 70% and 50% respectively.  Although 4 models failed to fully comply with the safety standard requirements, they were considered safe to use under normal circumstances.

Of the 12 tested models of washers, 8 were front-loading types (so-called "Big Eyes"), priced from $4,690 to $7,990.  Manufacturers claimed maximum washing capacity ranging from 7kg to 10kg and spin speed from 1,000 rpm to 1,400 rpm.  The 4 impeller types (so-called "Japanese types") were priced between $1,888 and $3,080, with a claimed maximum washing capacity of 5kg or 6kg, and spin speed of 700 rpm or 740 rpm.

Commissioned by the Council, the independent laboratory tested models' washing and environmental performance, ease of use, noise level, reduction of vibration, door design and anti-water leakage design with reference to international standard.  Separately, the EMSD commissioned another independent laboratory for safety performance of all models.  On a 5-point scale, the overall performance of the respective impeller type models was quite comparable that all scored 4 points, while the front-loader models scored 3.5 or 4 points.

Safety test

8 models passed all safety tests specified under the international standard IEC 60335-2-7.  Deficiencies were found in the manual instruction of 2 other models, e.g. warning statement was not included.  1 model's earthing terminal wire was not clamped according to the method specified in the standard, which might affect earthing reliability.  In another model, the test finger was able to be inserted through the gap between the drum and the enclosure of the washer, and touched the internal wire with only basic insulation.  In case the insulation fails, it could pose a potential hazard of electric shock to the user.  However, users are not likely to touch that internal wiring during normal usage.

In view of previous media coverage of accidents involving children falling into washing machines in Hong Kong and overseas, the Council conducted tests specifically on the safety design of the washers' doors, in addition to the international safety standard's testing requirement.  Results showed that the front-loader models had their doors firmly locked during the entire wash process, even when the child lock was not activated and thus all scored 5 points.  The impeller types however allowed users to open the lids to add detergent or softener during a wash-cycle.  Although this feature was convenient to users, it provided a relatively low level of protection for children, so these models scored from 2.5 to 3.5 points.

All models of the test were equipped with child lock functions.  Once activated, the wash programme would stop automatically and the alarm would set off when the lid of some impeller type washers were opened during a wash-cycle.  2 models would drained automatically to reduce the risk of children drowning should an accident occur.  Parents are advised to make good use of this function in safeguarding their children's safety.

Washing performance

All models were tested on their ability to tackle stains.  The level of cleanliness was determined by the washer's ability in removing stains on clothes in different fabric types from cotton to synthetics fibres.  The front-loader models scored between 3.5 and 4.5 points, while the impeller type obtained 3.5 to 4 points.  Both types performed similarly in overall cleaning efficacy.

However, the rinsing performance varied significantly among the tested models.  The rinsing index reflects the amount of detergents remaining on clothes after washing.  The index of front-loader models ranged from 0.97 to 2.14, a difference of around 54% on cotton pieces.  The index on synthetics ranged from 0.87 to 1.39, a difference of around 37%.  The difference in the best and the worst rinsing performance among impeller type models is relatively small. The difference on cotton pieces was about 32% and the difference on synthetics was about 27%.

Water extraction performance was tested on the basis of the default spin speed of the corresponding wash programme.  The spin speed of the front-loader types was faster than the impeller types, hence the extraction performance was better.  1 model of the front-loader type has the lowest spin speed in its category was, in fact, not the poorest performer in the water extraction.  This could be due to the longer time taken for spinning.

The duration of wash cycles of each model was also evaluated based on the average time taken in washing every kilogram of clothes.  It was found that the front-loader models took around 14 to 43 minutes to complete a wash cycle for a kilogram of cotton pieces and 19 to 46 minutes for a kilogram of synthetics pieces.  For impeller types, the time needed ranged between 10 and 14 minutes for cotton pieces and 14 and 18 minutes for synthetics pieces.

Environmental performance

Washing machines that consume less energy to wash a kilogram of clothes represents higher energy efficiency.  Since the front-loading types are equipped with heating functions, energy consumption is inevitably higher.  Energy consumed by front-loading models for washing every kilogram of clothes in cotton varied up to 69%, while energy consumed for washing synthetics pieces varied by nearly 60%.

Calculating the electricity cost at $1.2/kWh, the estimated cost of every wash cycle is $0.4 to $1.2 for the front-loading types, and $0.1 to $0.2 for the impeller types.  Assuming that consumers use their washing machine 260 times a year with reference to the Voluntary Energy Efficiency Labelling Scheme for washing machines, based on the models' energy consumption for washing clothes in cotton, the annual electricity cost is estimated at $110 to $314 for front-loading types, a difference as much as 65%, and from $27 to $43 for impeller types.  But the actual electricity cost is determined by various factors, for example load size of the laundry, wash programme and the number of washings per year.

As far as water consumption is concerned, the front-loader types use less in average, thus, all scored 4.5 points.  It is noteworthy that water consumed for washing a kilogram of cotton pieces could vary by 53% among the tested models.  The impeller types are less water efficient, hence scored 3 or 3.5 points.  Water consumption for washing a kilogram of synthetics pieces ranged between 25L and 49.8L, about half difference.

The Council also surveyed the after-sales service of the tested models.  All new washers have a 1-year to 39-month "whole machine warranty" schemes, and the cost of warranty extension ranges from $320 to $780 a year.  These schemes provide free on-site basic inspection for consumers in city areas, while 3 models even waive the on-site inspection fees for consumers reside in remote areas.  Moreover, labour charges are also waived during the warranty period.

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