14 Dehumidifiers with Grade 1 Energy Labels Varied by up to Over 50% in Energy Efficiency Disparate Performance for Air Purifying Models Calling for Strengthened Disclosure to Protect Consumer Rights

With the humid climate in Hong Kong, many families rely on dehumidifiers to keep the indoor environment dry all year round, and air purifying dehumidifiers have burgeoned in the marketplace in recent years. In collaboration with the Electrical and Mechanical Services Department (EMSD), the Consumer Council tested 14 models of compressor-type dehumidifiers, including 8 models which could be equipped with High Efficiency Particulate Air (HEPA) filters for air purification. The dehumidifying performance tests were conducted under a standard test environment (STE) and manufacturer’s test environment (MTE) respectively, and with basic filters installed. Under the MTE, the measured daily dehumidifying capacity ranged from 19.8L to 29.8L among all models, around 56% to 82% (average of 69.7%) higher than that measured in the STE. As the MTE generally differs from the conditions of the actual indoor environments, the Council once again urges manufacturers not to use dehumidifying capacity measured under the MTE which does not reflect real-life usage conditions in labelling and promoting their products. Under the STE, the measured daily dehumidifying capacities of 5 models were slightly lower than their claims by 0.5% to 6.8%. Although all tested models were labelled with Grade 1 energy rating, those models with similar dehumidifying capacities were found with significant variance in their energy efficiency (EE) performance, with the highest EE being 50.2% higher than the lowest EE. The model with the lowest EE was calculated to be only Grade 2 based on its energy factor, yet its discrepancy was still within the acceptable tolerance range (+10%) under the Mandatory Energy Efficiency Labelling Scheme (MEELS).

The tests also found that for 8 models that could be used with HEPA filters for air purification, there were huge discrepancies in their speed of purifying particulates and reducing formaldehyde concentration, with the latter varying by up to 6-fold. Besides, even though 2 models had satisfactory dehumidifying performance when HEPA filters were not installed, once HEPA filters (additionally purchased or given as a free gift) were installed, their dehumidifying capacities dropped by 18.4% and 30.1% respectively, the dehumidifying EE also decreased by 26.2% and 40.7% respectively, whereas the air purifying performance was also inferior. When selecting dehumidifiers that could be installed with HEPA filters for air purification, the Council recommends consumers to not only pay attention to changes in dehumidifying performance under different configurations, but to also consider the costs of regularly replacing HEPA filters. The Council also recommends the EMSD to disclose whether the products were installed with HEPA filters (if any) when the energy efficiency tests were conducted, to assist consumers in comparing products and making informed choices.   

Among the 14 models of dehumidifiers, 8 could be equipped with HEPA filters for air purification, with prices ranging from $3,698 to $7,580, of which 6 models came with HEPA filters as basic accessories, whereas in 2 models the HEPA filters had to be additionally purchased or was provided as a free gift. The remaining 6 models were priced from $2,400 to $3,998. The claimed daily dehumidifying capacities of the 14 models ranged from 12L to 19L under the STE (26.7°C and relative humidity of 60%), and from 20L to 31L under the MTE (most were 30°C and relative humidity of 80%). The tests compared the models’ dehumidifying performance, accuracy of dehumidifying capacity claims, noise level and ease of use, as well as the air purifying performance of the 8 models that could be equipped with HEPA filters for air purification, while EMSD tested the models’ safety performance.

5 Models with Slightly Lower Measured Dehumidifying Capacity than Claimed Under the STE 

Greatest Variance in Energy Efficiency Exceeded 50%

In choosing a dehumidifier, a consumer’s primary concern is its dehumidifying performance. Conducted with reference to the MEELS of EMSD and US national standards, the tests compared the consistency between the measured dehumidifying capacity and their claimed value as the assessment benchmark[1]. According to the results under the STE, the measured daily dehumidifying capacities of 5 models were slightly lower than their claim values by 0.5% to 6.8%, though still within the acceptable tolerance limit of the MEELS; whereas under the MTE, the measured daily dehumidifying capacities of 7 models were slightly lower than claimed, with the discrepancy being less than 8% which is still within the acceptable tolerance limit  (+10%) adopted internationally. The measured daily dehumidifying capacities of all models under the MTE ranged from 19.8L to 29.8L, around 56% to 82% (average of 69.7%) higher than those measured in the STE. Having in the past repeatedly urged manufacturers to stop publicising claims based on tests conducted in their own test environment, because it does not reflect the actual circumstances of use, the Council hereby once again advocates for manufacturers to improve.

As dehumidifiers usually operate for prolonged hours, energy efficiency is an important factor when making a purchase. Despite all models being labelled with Grade 1 energy efficiency ratings under the STE, some models with similar dehumidifying capacities vastly varied in terms of their EE, with the highest one being 50.2% higher than the lowest one. The model with the lowest EE was calculated to be only Grade 2 based on its energy factor, yet its discrepancy was still within the acceptable tolerance range under the MEELS. After the Council submitted the test results to EMSD, they had reminded the manufacturer of the importance of quality control, to ensure that the product complies with MEELS.

Considerable Discrepancy in Air Purifying Speed

Speed of Removing Formaldehyde Varied by up to 6 Times

In recent years, many dehumidifiers promote themselves as also having air purifying functions. Naturally, consumers would expect these new products to have outstanding performance, but the test results revealed huge discrepancies in the speed of removing particulates and formaldehyde concentration for the 8 models that could be equipped with HEPA filters. For the model with the fastest removal speed, its respective speed in removing smoke, dust, pollen and formaldehyde were 4 times, 3.7 times, 4.4 times and 6.4 times faster than the slowest model, reflecting the significant disparity in air purifying performance among models. As for the 2 models for which HEPA filters had to be additionally purchased or was provided as a free gift, their performance was inferior.

2 Models with Additionally Purchased or Free HEPA Filters

Dehumidifying Performance Dropped After Installation

Consumers should be mindful that dehumidifiers operating under different configurations might affect their dehumidifying performance. Of the 8 models that could be equipped with HEPA filters for air purification, 2 models had the option to install HEPA filters or not, and both models had consumer reminders in their user manual and on the HEPA filter packaging that installation of the gifted or additionally purchased HEPA filters might adversely affect or lower the dehumidifying performance. The tests showed that under the STE, the overall dehumidifying performance of those 2 models was fairly good without HEPA filters, yet after HEPA filters were installed, the daily dehumidifying capacity and EE reduced significantly. The measured daily dehumidifying capacity dropped by 18.4% and 30.1% respectively, while the dehumidifying EE also dropped by 26.2% and 40.7%. It is estimated that the annual electricity cost for dehumidifying would go up by 10.6% and 18.3% respectively.

Since consumers would reference the dehumidifying capacity and energy efficiency gradings when selecting a compressor-type dehumidifier, the Council recommends the EMSD to disclose information on whether HEPA filters (if any) were installed when the dehumidifiers were undergoing tests for energy efficiency, so as to assist consumers in making comparisons and making an informed choice. At the same time, manufacturers could also provide information on their packaging on the dehumidifying performance before and after HEPA filters were installed, as well as the standards of the test environment, to enhance consumers’ understanding of the product’s performance. When selecting, consumers should examine the energy label for the dehumidifying capacity and EE, rather than simply relying on the data provided by manufacturers on their promotional pamphlets or product user manuals which are derived from tests conducted in a non-standard environment. 

Up to 54% Discrepancy in Electricity Costs

Pay Heed to the Cost in Replacing Filters

  Even though the EE reflects a dehumidifier’s energy-saving performance, different home environments have different dehumidifying needs, affecting the actual electricity expenditure. For an annual usage of 450 hours (about 90 days, 5 hours daily), at $1.70 per unit of electricity, the electricity cost for the 4 models with higher dehumidifying capacity claims would be approximately $194 to $218, while that for the 10 models with lower claimed dehumidifying capacities would range from $127 to $196, representing a difference of about 54% between the highest and lowest models in the latter category.

For dehumidifiers that could be fitted with HEPA filters for air purification, it should be noted that such filters need to be replaced regularly to avoid lowering the air purifying performance. The Council reminds consumers that in selecting such dehumidifiers, the future costs of replacing the filters should also be considered. The cumulative cost of changing filters for the various models in the first 10 years ranged from $0 to $7,410, which, added to the cost of the appliance (from $3,698 to $7,580), would amount to total costs from $5,280 to $12,590. If there are more indoor pollutants or if the dehumidifier needs to operate for longer periods, then more frequent change of filters might be required. If air purification is the main demand, such as at a location with a larger area or worse indoor air quality (for example near roads, eateries or with many people smoking indoors), or if there are asthma sufferers, patients with allergy, then buying an air purifier with better capabilities might be a better option.

Making a smart choice when selecting a dehumidifier coupled with proper maintenance could prolong the product lifespan and support sustainability. Consumers may refer to the following recommendations:

• Dehumidifiers should not be used in the bathroom. Do not cover the air ventilation grills of the dehumidifier when drying clothes nor place dripping wet laundry above the dehumidifier, to prevent poor ventilation or water dripping into the appliance, leading to overheating or posing safety hazards;
• Clean the water tank and air filter regularly to prevent bacterial growth and accumulation of dust which could hinder heat dissipation; after cleaning, components must be completely dry before putting them back in the appliance. When using models that could be equipped with HEPA filters, consumers should follow the user manual and clean and replace them regularly;
• Make good use of the timer function and always switch off the appliance after use to lower power consumption. Also, refrain from leaving the dehumidifier operating whilst unattended or during sleep, to save electricity and to ensure safety.