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2 Dehumidifiers Failed to Meet Grade 1 Energy Efficiency Claims with HEPA Filters Installed Promotions Utilising Results Under Manufacturers’ Test Environment Potentially Misleading Prompt Improvement Urged

  • 2023.02.15

In the transitional season between winter and spring which promises damp weather, a dehumidifier is certainly a “gift against clamminess”. In addition to conventional models, 2-in-1 air purifying dehumidifiers equipped with High Efficiency Particulate Air (HEPA) filters have emerged on the market in recent years. The Consumer Council tested 14 dehumidifier models under both a standard test environment (STE) of 26.7°C and 60% relative humidity (RH), and manufacturers’ own test environment of 30°C and 80% RH. Results showed that after HEPA filters were installed, the measured daily dehumidifying capacity of 2 models were 13.2% and 23.1% lower than its claim respectively under the STE, and 14.7% and 41% lower than its claim under the manufacturers’ own test environment. Both models were marked with Grade 1 rating on the energy label, but dropped to only Grade 2 and 4 respectively based on its energy factor after installation of HEPA filters. The Council has forwarded the test results to the Electrical and Mechanical Services Department (EMSD) and the Customs and Excise Department (C&ED) for follow-up. Moreover, over the years the claimed daily dehumidifying capacity of some dehumidifier manufacturers were measured under their own test environment, but it might not reflect actual indoor use and were possibly misleading to consumers. The Council urges manufacturers to use the dehumidifying capacity measured under the STE for consumer reference, while consumers are advised to study the dehumidifying capacity on the energy label rather than relying solely on the manufacturer’s claimed values measured in a non-standard test environment when making purchase decisions.

The 14 dehumidifier models tested by the Consumer Council included 4 models of 2-in-1 air purifying dehumidifiers and 10 models of conventional dehumidifiers. All were compressor-type models with filters, but the thickness, quantity, and claimed functions of the filters varied. The price of the 2-in-1 air purifying dehumidifier models ranged from $3,990 to $6,180 with HEPA filters included, while that of conventional dehumidifier models ranged from $2,099 to $6,080, 1 of which was furnished with a HEPA filter as a gift. The rated daily dehumidifying capacity of 14 models under the STE was 8.5L to 18L, and 14L to 30L under the manufacturers’ own test environment. The test items included dehumidifying performance, accuracy of dehumidifying capacity claims, noise level and ease of use, while the air purifying performance of the 4 models of 2-in-1 air purifying dehumidifiers was also measured.

Dehumidifying Performance of 2 Models Dropped Significantly After Installing HEPA Filters

Whether for conventional dehumidifiers or 2-in-1 air purifying dehumidifiers, the dehumidifying performance is certainly consumers’ main concern for purchase. The Council measured the weight of condensate collected by each model under constant temperature and relative humidity for 6 hours to extrapolate the daily dehumidifying capacity, and then compared against the manufacturer’s claims to assess the accuracy. With reference to the Mandatory Energy Efficiency Labelling Scheme (MEELS) of the EMSD and US national standards, the measured daily dehumidifying capacity of test models ranged from 8.5L to 17.8L under the STE with filter installed, of which the measured value of 1 model was 23.8% higher than its claim, while that for 6 models were lower than claimed by 0.6% to 5.3%. 2 models were equipped with HEPA filters and the measured dehumidifying capacity were close to its claim without installing the filter. However, under the test which simulated consumers installing the HEPA filter for daily use, the measured dehumidifying capacity were around 13.2% and 23.1% lower than its claim under the STE, and about 14.7% and 41.0% lower than its claim under the manufacturers’ own test environment, representing a huge discrepancy. The Council has forwarded relevant test results to the EMSD and the C&ED for follow-up.

2 Models Did Not Comply with MEELS’s Requirement

As dehumidifiers are used for longer periods on damp days, power consumption is also a major consumer concern. Assuming the test models are used for 90 days per year and 5 hours each time at $2 per electricity unit, the annual electricity cost for the 14 models ranged from $146 to $260. The energy factor can be derived by calculating the litres of water extracted per unit of electricity. The electricity cost would naturally be higher for a larger living area or more humid living environment as the frequency of usage is higher. With filter installed, the energy factor among the models ranged from 1.61L to 3.06L under the STE, and from 1.92L to 4.65L under the manufacturers’ own test environment. For the calculated energy efficiency grading, 10 models reached Grade 1, 3 models reached Grade 2, and 1 model reached Grade 4 only. The calculated energy efficiency grading of 12 models were the same as declared on the energy label on the product. However, for 2 models marked with Grade 1 rating on the energy label, including a 2-in-1 air purifying dehumidifier and a conventional dehumidifier, the calculated energy efficiency grading achieved Grade 1 only when operating without installing a HEPA filter; if a HEPA filter was installed, the energy efficiency grading slipped to Grade 2 and Grade 4 respectively, and the energy factor measured under the STE dropped by 20.2% and 33.2% respectively. Upon receipt of the test results from the Council, the EMSD immediately arranged for monitoring tests conducted by a third-party independent laboratory and found that the measured dehumidifying capacity of the 2 models under the STE did not comply with MEELS’s requirements. The EMSD is conducting further tests in compliance to the “Code of Practice on Energy Labelling of Products”. If any product is found to be non-compliant, the reference number of the concerned model may be removed, and the model cannot be sold in Hong Kong.

The daily dehumidifying capacity of these 2 models dropped significantly after installation of HEPA filters, reflecting the impact of HEPA filters on dehumidifying performance. The energy efficiency grading and dehumidifying capacity of a dehumidifier are crucial factors for consumers’ purchase considerations, and when manufacturers provide a filter with the dehumidifier, consumers would naturally install it for use. The Council opines that by displaying the MEELS grade measured without a filter, the manufacturers of these 2 models could potentially mislead consumers into believing that the dehumidifying performance of these 2 models was comparable to that of other dehumidifiers which have obtained Grade 1 energy label.

Manufacturers’ Own Test Environment Potentially Misleading

Consumers Should Refer to Dehumidifying Capacity on Energy Labels

The claimed daily dehumidifying capacity of most dehumidifier manufacturers on the market is measured under the manufacturers’ own test environment (i.e. 30°C and 80% RH), and the measured dehumidifying capacity ranged from 15.0L to 30.1L among the 14 models, about 49% to 83.9% higher than results measured under the STE (i.e. 26.7°C and 60% RH) with an average of about 70.3% higher. The measured daily dehumidifying capacity of compressor dehumidifiers would be higher at higher temperature and relative humidity, yet consumers should note that this does not accurately reflect the actual indoor environment when a dehumidifier is operating with the windows closed. The dehumidifying speed and performance of a dehumidifier is higher during the initial period of operation due to higher relative humidity in the room. However, as the air will become dryer in the room, the dehumidifying speed will slow down accordingly. As such, using test data measured under the manufacturers’ own test environment could potentially mislead consumers into overestimating the product’s performance. The Council has in the past repeatedly urged manufacturers to stop using their own test environment because it does not reflect the actual circumstances of use, but no obvious improvement has been observed so far. When purchasing a compressor dehumidifier, consumers are recommended to study the dehumidifying capacity stated on energy labels rather than relying solely on manufacturers’ promotional leaflets or user manual with claimed capacities measured under non-standard test environments.

Air Purifying Speed of 2-in-1 Air Purifying Dehumidifier Models Varied

Among the 14 test models, 4 were 2-in-1 air purifying dehumidifiers. The tests were conducted at independent air purifying modes for removal of cigarette smoke, dust, and pollen, with reference to US national standards. The results showed that the model with highest and lowest air purifying speed in removing smoke, dust, and pollen varied by 2.3 times, 1.8 times, and 1.7 times respectively. In the test for reducing formaldehyde concentration, which was conducted in accordance with the Chinese national standards, the speed of the 4 models varied by as much as 2.7 times.

Consumers should also consider the cost of filter replacement before buying. Based on the price and the frequency of changing the filter recommended by agents, the approximate cumulative costs for replacing filters were estimated to range from $0 to $2,000 for the first 5 years among models, and from $350 to $4,000 for the first 10 years. However, the actual frequency of replacing filters is subject to conditions of use, for example, if there are more indoor pollutants or the dehumidifier operates for longer periods, filters might require replacement more frequently and the cost would be higher.

While a dehumidifier could cost several thousand dollars, its lifespan could be extended if used and maintained properly. Consumers could refer to the following tips:

  • For a larger living area or more humid living space, consider choosing a model with a higher dehumidifying capacity and speed;
  • The filter of 2-in-1 air purifying dehumidifiers must be cleaned and replaced in a timely manner. Otherwise, the air purifying performance will be greatly reduced;
  • Do not cover the air ventilation grills of the dehumidifier when drying clothes, as this may cause overheating due to poor ventilation. Do not place dripping wet laundry on top of the dehumidifier to avoid risk caused by water dripping into the appliance;
  • Avoid leaving dehumidifiers operating unattended or at night while asleep. When the dehumidifier is not in use, turn off the power to save electricity and ensure safety;
  • Clean the water tank and dust filter of dehumidifiers regularly to prevent bacterial growth and dust accumulation which may hinder heat dissipation. After cleaning, only put the parts back in when completely dry.


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