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Cooling Capacity of 5 Models of “1 Horsepower” Window-Type Inverter Air Conditioners Lower than Claimed Energy Efficiency Varied by 13% Among Models with Grade 1 Energy Labels

  • 2024.05.16

Hong Kong’s summers are hot and humid. While a high-performance air conditioner can improve comfort and regulate the humidity indoors, an energy-efficient model could save more on electricity fee. The Consumer Council tested 14 models of “1 horsepower” (HP) window-type cooling-only inverter air conditioners on the market, and results revealed discrepancies between the labelled and actual cooling capacity and energy efficiency grades for some of the tested models. The measured cooling capacity of 5 models was lower than claimed, with the largest variance being nearly 5% for 1 model. The energy efficiency also varied considerably among models, with a maximum disparity of 23.4% in annual energy savings. Although 11 models had Grade 1 energy labels, their energy efficiency varied by as much as 13.3%, 3 of which only met the Grade 2 standard with their measured Cooling Seasonal Performance Factor (CSPF) value, though the discrepancies were still within the 8% acceptable tolerance range under the labelling scheme and common international practice. The Council has informed the Electrical and Mechanical Services Department (EMSD) of the relevant test results, and urges manufacturers concerned to proactively improve designs and ensure quality control so that their products’ performance could live up to consumers’ expectations.

The 14 models of “1 HP” window-type cooling-only inverter air conditioners tested were priced between $3,669 to $7,650, some inclusive of basic installation, while the others charged an additional rate of $340 to $560 for basic installation. 2 models with the highest overall score received 4.5 points, and the majority of the other models scored 4 points. Since prices could vary by several hundred or even over a thousand dollars among different retailers, consumers should carefully compare prices, services, and warranty plans before making a purchase.

Cooling Capacity of 5 Models Lower than Claimed with Variance up to 4.9%

Many consumers prioritise an air conditioner’s cooling power, expecting a fast cooling speed to quickly discharge indoor heat to outdoors. Tested at their maximum load and in accordance with international standards, the results revealed that the measured cooling capacity of the models ranged from 2.511kW to 2.852kW, among which 5 models failed to meet their claimed cooling capacity, with a discrepancy ranging from 1.7% to 4.9%. In particular, 3 models had a more notable discrepancy of 3.6% to 4.9% between their actual and claimed cooling capacity values. Although the discrepancies of these 5 models were still within the 10% acceptable tolerance range under the Mandatory Energy Efficiency Labelling Scheme (MEELS) and common international practice, the disparity still fell short of consumers’ expectations. Manufacturers concerned ought to enhance their quality control to ensure the precision of their products’ cooling capacity performance.

Energy Efficiency Varied by as Much as 23.4%

According to the EMSD’s latest Hong Kong Energy End-use Data, air conditioning constituted close to 40% of the total household electricity consumption in Hong Kong in 2021, thus the energy consumption of air conditioners is a significant concern for consumers. The CSPF value of an air conditioner reflects its cooling energy efficiency – the higher the value, the better the efficiency and the higher the energy savings. According to the test results, the CSPF value of the 14 models ranged from 3.899 to 5.092. On this basis, assuming the total annual amount of heat extracted from a room was identical for all models, the model with the highest CSPF value would save 23.4% more energy than the lowest model per year. If an air conditioner was to operate for 12 hours a day, 180 days a year, given the electricity tariff is $1.6 per unit, the estimated annual tariff for the 14 models would range from $763 to $1,029. The 2 models with the best energy efficiency both achieved a CSPF value of above 5, and they also received the highest overall ratings in this test. In 2018, the Council tested 15 models of “1 HP” window-type air conditioners, all of which were fixed capacity models. In comparison, the inverter models in this year’s test were 33.9% more energy-efficient on average. Despite the improvement in energy efficiency, the test results indicated that it is technically feasible to create products with better energy efficiency.

3 Models with Grade 1 Energy Labels Only Met Grade 2 Standard in Test

Under the requirements of MEELS, the CSPF value of an air conditioner, regardless of window- or split-types, must reach 4.50 or above to be classified as Grade 1 energy efficient. 11 models were labelled as Grade 1, but 3 models achieved only the Grade 2 standard in the test, and the worst-performing model had a CSPF value of 4.417, which was 13.3% less energy-efficient than another Grade 1 model with a CSPF value of 5.092. Nonetheless, the discrepancy in CSPF values between the test results and the values listed in the accredited laboratories’ test reports submitted by the importers to the EMSD (5.0%, 7.8%, and 7.9% for the 3 models respectively) did not exceed the 8% tolerance range allowed by MEELS and common international practice, and hence these 3 models were not in violation of MEELS requirements, but the manufacturers concerned should further improve the product quality.

Operating an air conditioner in humid weather certainly helps the indoor environment stay dry and comfortable. The test found that in cooling mode and at the highest fan speed setting, the models utilised 28% to 34% of the cooling capacity for dehumidification at maximum load, but when operating at half load, the dehumidifying effect would range from 2% to 21%. Furthermore, consumers are reminded that the outdoor noise produced by air conditioners is regulated by the Noise Control Ordinance. Causing noise which is a source of annoyance to any person is an actionable offence with a maximum fine of $10,000. From the test results, 8 tested models were found with relatively low outdoor noise levels.

Longest Full Machine Warranty Is 4 Years

2 Models Offered No Warranty Renewal

When purchasing an air conditioner, in addition to its performance, it is also important to consider the after-sales maintenance service. Of the 14 models tested, a full machine warranty of 2 to 4 years on new units was provided, while the more durable air conditioning compressors were covered for a minimum of 5 years, with 2 even offering a 10-year and lifetime warranty respectively. Within the warranty period, 13 models waived basic on-site inspection charges, labour charges for repair, and replacement fees for non-human-induced damaged parts (excluding remote areas). Except for 2 models, most suppliers offered warranty renewal at an annual fee from $450 to $800, but not all maintenance fees would be waived after warranty renewal, and there may be a need to pay for parts at a discounted price. The suppliers of all 14 models offered air conditioner cleaning services for improved machine performance, but their charges varied considerably, ranging from $400 to $1,200 in urban areas and from $500 to $1,600 in remote areas within the warranty period. The Council urges suppliers to offer longer warranty periods, as well as more affordable annual warranty renewal and maintenance fees to consumers, so as to encourage consumers to continue using the appliance, thereby reducing waste and promoting sustainable consumption.

Consumers may refer to the following safety and energy-saving tips when using and maintaining air conditioners:

  •  Avoid installing air conditioner units in direct sunlight, and ensure the air inlet and outlet are unobstructed;
  • When the air conditioner is in use, draw the curtains to keep the sunlight out, and close the doors and windows to maintain the room temperature. Electric fans consume far less power than air conditioners. Using an electric fan alongside the air conditioner to direct the cool current towards users will make it feel cooler and thus the air conditioner could be set to a higher temperature to save power;
  • Pre-set a unit turn-off time to prevent the air conditioner from prolonged operation or forgetting to turn it off. Remember to turn off the air conditioner before leaving home, and refrain from turning it back on right after turning off;
  • During summer, it is recommended to clean the dust filter, air inlet and outlet about every 2 weeks to ensure unobstructed airflow and performance. Arrange regular inspections, maintenance and repairs by qualified technicians;
  • The refrigerant of an air conditioner is stored in a sealed pipe, and there is generally no need to replace it or add more unless the pipe is broken, or if maintenance such as compressor replacement is needed. Relevant inspections and repairs should be performed by professionals as these require specific skills and handling.


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