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Inverter Models of “1.5 Horsepower” Window-type Air Conditioners 27% More Energy Efficient than Fixed Capacity Models on Average Urging for Strengthened Warranty Period and Maintenance Services to Extend Product Lifespan

  • 2023.04.17

April generally brings warm and humid weather to Hong Kong, and some households may have already turned on their air conditioners for better comfort indoors. The surge in global fuel prices in recent years has affected electricity tariffs around the world, including Hong Kong. According to the Hong Kong Energy End-use Data compiled by the Electrical and Mechanical Services Department (EMSD), air conditioning constituted nearly 40% of total household electricity consumption in Hong Kong in 2020, thus choosing an energy-efficient air conditioner will help save energy and electricity tariff. The Consumer Council tested 13 models of inverter and fixed capacity “1.5 horsepower” (HP) window-type cooling-only air conditioners on the market and found that inverter models were on average 27% more energy-saving than fixed capacity models, with a maximum disparity of 37.1% in energy efficiency. Although 4 models had Grade 1 energy labels, their energy efficiency varied by as much as 12.4%, 2 of which only met Grade 2 standard according to the test results. Besides, the cooling capacities of 8 models were found to be 0.2% to 5.7% lower than claimed. Products with greater disparity may fall short of consumers’ reasonable expectation for product quality. The Council urges manufacturers to proactively improve the quality control and energy efficiency of air conditioners, and has informed the EMSD of the test results.

In addition, all suppliers offered full machine warranty periods ranging from 24 months to a maximum of 39 months. Most of them provided warranty renewal service at an annual fee ranging from $200 to $800, but not all maintenance and repair fees would be waived after warranty renewal, and some providers even declined renewals from consumers living in remote areas. As comprehensive and affordable after-sales services could help extend the lifespan of the product, the Council urges suppliers to extend the warranty period and offer more affordable annual renewal and various maintenance fees to support sustainable consumption.

Inverter Models Had Better Overall Performance

2 Models Scored 4.5 Points Overall

Conventional fixed capacity air conditioners run their compressors at a fixed top speed with automatic pauses and restarts at intervals to adjust the room temperature. On the contrary, compressors in inverter type air conditioners can reduce the speed automatically when the room temperature is close to the target temperature, consuming less power and boasting high operational efficiency, as a result saving energy. In the past, most inverter air conditioners on the market were split-type models, but more window-type models have become available in recent years.

The Council tested 13 models of “1.5 HP” window-type cooling-only air conditioners, of which 10 were inverter models priced from around $4,790 to $9,780 (3 models included basic installation), while the remaining 3 were fixed capacity models priced approximately between $5,340 to $6,650. Test results showed most of the inverter models had a better overall rating than the fixed capacity models, with 2 inverter models receiving the highest score of 4.5 points. As retail prices could vary by hundreds or over a thousand dollars among retailers, consumers should compare prices carefully to identify a model with good value for money.

On Average 27% More Energy-saving for Inverter Models

Energy Efficiency Varied by Up to 37.1%

Energy consumption is a major consumer concern when picking an air conditioner. The Cooling Seasonal Performance Factor (CSPF) is now commonly adopted internationally to indicate the cooling energy efficiency of air conditioners. A higher CSPF value represents higher cooling energy efficiency and better energy-saving performance. The CSPF value of the 13 models ranged from 3.106 to 4.937, and on this basis, assuming the total amount of heat extracted from a room throughout a year was the same for all models, the model with the highest CSPF value would save 37.1% more energy than the lowest model in a year. The CSPF value of all inverter models were higher than that of fixed capacity models, with an average CSPF value of 4.331 for the 10 inverter models, and 3.163 for the 3 fixed capacity models, which means on average the inverter models used 27% less electricity than the fixed capacity models. However, it is worth noting that the cooling efficiency also varied considerably among inverter models, with a maximum difference of 18.1%. Furthermore, the measured cooling capacities of 8 models were found to be 0.2% to 5.7% lower than claimed. Although the discrepancies were still within the 10% acceptable tolerance range under the Mandatory Energy Efficiency Labelling Scheme (MEELS) and common international practice, it was incumbent on manufacturers to improve if discrepancies were large enough to fall short of consumers’ reasonable expectations of the product.

On the other hand, compared to the 15 models of “1.5 HP” fixed capacity window-type models tested by the Council in 2015, 3 fixed capacity models in the current test showed an average 9.2% improvement in energy-saving performance, clearly indicating that product design and production quality control is conducive to better energy efficiency.

Products with Grade 1 Energy Labels Showed Over 10% Variance in Cooling Efficiency

Under the requirements of MEELS, the CSPF value of an air conditioner must reach 4.50 or above to be classified as Grade 1 energy efficient. Energy labels for all tested models ranged from Grade 1 to Grade 4, with over 80% of the models achieving the grade matching its labelling. 4 models labelled at the highest level, Grade 1, were all inverter models. However, upon calculation based on the test results, the energy efficiency varied by as much as 12.4% among these 4 models, and the performance of 2 were only equivalent to Grade 2 labelling, although they were still within the acceptable tolerance range under MEELS and common international practice, thus were still in conformance with requirements.

Based on the tariff of $2.0 per unit of electricity for an air conditioner operating with the cooling function for 12 hours per day for 180 days a year, the estimated annual electricity tariff for the tested models ranged from $1,290 to $2,045, with the more energy-efficient inverter models naturally costing less than fixed capacity ones. However, if the total operating hours per year is longer, or if the air conditioner is customarily set to a lower temperature, actual electricity costs would far exceed the aforementioned estimates. Additionally, the electricity tariff could increase as a result of various factors, such as higher humidity, a larger space, west-facing windows, draughty doors and windows, having the ventilation fan on, multiple appliances operating at the same time, and a larger number of people in the room, etc. The Council advises consumers to monitor their electricity bills closely, and adjust their habits when necessary to lower the electricity costs.

1 Model Failed Power Cord Pulling Test

The majority of the 13 models passed all safety tests, including current leakage, earthing continuity, internal wiring and installation, electrical insulation, and power cord fixing device. However, 1 model showed less satisfactory performance in terms of the power cord fixing device, with the power cord displaced 3.7mm after 25 pulls at a force of 100N, failing to comply with the standard requirement of 2mm.

Suppliers Offered Full Machine Warranty from 24 to 39 Months

Parts Might Still Be Charged After Warranty Renewal

Air conditioners are expensive consumables and after-sales service is particularly important to extend their lifespan. High repair and maintenance costs or inferior service quality may drive consumers to dispose of the appliance, creating more e-waste. Of the 13 models tested, suppliers offered a full machine warranty of 24 months to 39 months on new units, while the more durable air conditioner compressors were covered for at least 5 years, among which 2 even offered coverage for 10 years and in perpetuity respectively. All tested models generally waived labour charges for repair, non-human caused damaged parts replacement fees, and basic on-site inspection charges for urban households ($150 to $980 may be charged for remote areas) during the warranty period for new units, after which a basic on-site inspection fee of $340 to $550 would be charged for urban households, and up to $1,530 for remote areas, equivalent to about 20% of the price of this model. It is important to note that 12 models offered warranty renewal at an annual fee ranging from $200 to $800, while 1 model did not offer any renewal at all. However, warranty renewal does not mean repairs will be completely free. Even for damage not caused by human factors, only 7 models offered parts free of charge during the renewed warranty period, while the remaining 5 models only offered discounts. Some suppliers also indicated that renewal of warranty is subject to prior on-site inspection, and if the unit is older than a certain number of years, or if the consumer lives in a remote area, renewal of warranty might not be granted. Consumers should therefore enquire about the details before renewing the warranty. On the other hand, all suppliers offered air conditioner cleaning services but charges varied vastly from $500 to $1,200 for urban areas. For remote areas, additional charges might apply, or cleaning service might even be denied.

The Council calls on suppliers to provide longer warranty periods and more affordable annual warranty renewal and maintenance fees, so as to facilitate consumers to repair products, thereby reducing waste and promoting sustainable consumption. Some tips for installing and using air conditioners:

  • If there is no designated cement space for the air conditioner unit, make sure the window frame and supporting structure are strong and secure enough to hold the unit. Even if there is a designated space, an air conditioner unit must be firmly secured on the cement and not just simply placed on the space;
  • Installation by the air conditioner supplier generally offers better safeguard, as the supplier is responsible for both machine- and installation-related problems, thus saving the hassle. Consumers can also engage a contractor recommended by the supplier as the quality of installation is better guaranteed, and problems can be traced and followed up more easily in the future;
  • Avoid installing air conditioner units in direct sunlight, and do not block the air inlet and outlet;
  • Remember to close curtains while the air conditioner is in use, and keep windows and doors closed to maintain the room temperature;
  • Using an electric fan alongside an air conditioner will make it feel cooler without having to lower the temperature setting of the air conditioner. Save energy by pre-setting a unit turn-off time and remembering to turn it off before leaving home;

During summer months, it is recommended that dust filters, air inlets and outlets be cleaned around once every fortnight to avoid affecting the performance of the unit. Arrange regular inspections, maintenance, and repairs by experienced technicians to ensure proper functioning of the machine.



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