Just another post to educate everyone,
(From my personal knowledge,)
Real technology improvement in residential aircon systems only fall under 2 major categories.
1) Improvement in COP (Coefficient of Performance). This is an indicator how much electrical energy is required to remove a certain amount of heat energy. The higher the COP, the more energy efficient your compressor is.
Cooling capacity is the amount of heat the compressor can remove in a certain amount of time. It will definitely affect the amount of electrical energy consumed of course. However, do take note that a lower cooling capacity does not necessarily means it's a bad model. It is simply because different models are manufacturer for different target market. Some people do not need great cooling whereas others do. So, it is paramount that you understand your usage pattern when choosing an aircon system, and do not fall for 'lower is lousier' assumption.
That being said, I am absolutely in disagreement with NEA for using electricity consumption as a gauge for benchmarking. NEA's benchmark factors COP and cooling capacity together, giving an idea of the annual electrical cost. Following that, NEA then attaches a 'tick' rating based on the electrical bill in comparison with similar models in that category. However, this method of calculation disadvantages the more powerful models and gives credit to weaker models simply because weaker models use less electrical energy. If I could decide for NEA, I'd instead look at the COP to decide how much 'bang for buck' I will be getting from the compressor.
2) The second improvement is minor, and related to extra features. Ioninsing technology, air purifier, mobile/wlan control, 2 dimensional blower swing, etc. These, I do not need to explain much. I guess you guys can understand this part easily.
I hope I have helped cleared up some doubts and given you a new perspective in aircon choosing!