The cooling capacity of an air conditioner is clearly the most important factor. This measures the appliance's ability to remove heat from the indoor to outdoor. The higher the cooling capacity, the faster the cooling. The Energy Label which people normally refer to when purchasing an air conditioner gives the appliance an efficiency grade. The higher the efficiency, the less energy it will consume and thus more money will be saved.
It is worth mentioning that the grading standard under the Mandatory Energy Efficiency Labelling Scheme (MEELS) for room air conditioners is based on the Cooling Seasonal Performance Factor (CSPF) which calculates the ratio of the total annual amount of heat that the air conditioner can remove from the indoor air to the total annual amount of energy consumed during the same period. The computation also takes into account other environmental factors and the resultant rating/grade can effectively reflect the actual energy efficiency of an air conditioner.
Apart from choosing an air conditioner with high energy efficiency, you may also need to pay attention to certain factors or situations (such as high humidity level, large room size, west-facing windows, multiple electric appliances in use, and indoor population size, etc.) which may increase the cooling demand and also your electricity bill.
We tend to think that we can conserve energy by lowering the fan speed of an air conditioner. But you will be surprised to learn that a low-fan-speed setting is not conducive to the overall cooling function and thus affects the energy efficiency of an air conditioner. In reality more energy is consumed in the cooling process under this setting. Consumers should try to adjust the fan speed of an air conditioner to its highest setting whenever possible in order to enhance its performance and save energy.
Do you habitually close all the windows and switch off all electric fans before turning on the air conditioner? Well, from now on you can skip the latter. As an electric fan consumes far less energy than an air conditioner, you can actually achieve energy saving by switching on both appliances. This is because with the electric fan’s supplementary effect, you can raise the air conditioner’s set point temperature (and save energy) while still having the sensation of thermal comfort!
A quieter air conditioner is always more desirable as it not only provides for a peaceful living environment but is also “soothing” to your wallet! Imagine that you had an air conditioner which kept roaring and disturbing your neighbours nearby…… Given such noise emission is regulated under the Noise Control Ordinance, you may be prosecuted at any time and liable with a fine of up to $10,000.
If you want to learn more about how to save energy and money(!) while enjoying the comfort of your air conditioner(s), you may want to refer to the article, “Test conducted on ¾ “Horsepower” Window-Type Air Conditioners: Models Using the Eco-Friendly Refrigerants Outperform!”. CHOICE Magazine, Issue 523 (Chinese version only). In the article, the Consumer Council gives an in-depth analysis on the energy efficiency of the various air conditioners in the market and provides useful tips on energy saving.