Being a very populous country, India needs electric power in huge quantities even when its average domestic consumption is much lower than the developed nations. As per the 2012 data, the average domestic power consumption per year was about 750 units (KWh). This translates into about 3500-4000 units per family on the average per year or about 290-330 units per month per family. Since this is an average value, the higher income families must be consuming much higher as the a good percentage of lower income group families might be consuming zero to 30 units per month. It is also interesting to note the wide disparity of domestic electric power usage across the various regions and states of India.
Most people are not very clear about the working principle of a common air conditioner unit. Any one who is thinking of purchasing and installing an air conditioner for home or small office purpose should try to understand the essential principle of working of an air conditioner.
In my opinion rotary type window air conditioners should be the first choice for small and medium homes and offices having rooms which are not so big. It is also better to limit its size to 0.75 TR or 1 TR. This is because, the lower TR machine draws much lower current from the house hold electric circuit. For example, a 0.75 TR window a/c consumes less than 1000 W of electric power if it is a rotary compressor type with at least 2 star rating. It may cost around Rs.15000/- while a 1.5 TR machine of similar rating would cost around Rs 26000/- and consumes about 1800 W of electric power. Obviously the lower rated ones are better both on account of initial costs and running costs. The higher rated ones would start and stop more making your home's electric wiring prone to higher sparking and burn outs. Again, the machines with reciprocating compressors for the same TR rating draws much higher electric power. Such second hand and reconditioned a/c machines are available in the grey markets in India at throw-away prices. However, their running costs would be very high if they are regularly to be used.
In places where humidity is low and water supply is not a big issue, the evaporation type coolers are much preferable both on account of initial and running costs. As the summer heat goes up with lowering of humidity in the air, these coolers give very comfortable cooling. However, they are not useful when humidity goes up during the onset of rains after summer. They are also not very effective in the coastal areas of India due to high humidity.
It is also not a very prudent decision to spent much money for fancy features of air conditioners. Of course, such fancy features are for those for whom money is not a big issue.
The best brands in air conditioners in India are Voltas, LG, Carrier Aircon, Samsung, etc. Voltas is totally an Indian brand and the current market leader.
Though I have advocated for window a/c of one or 0.75 TR, such machines are apparently in short supply as the traders normally do not seem to be keen in selling these for obvious reasons. So, if you are thinking of low tonnage AC, you have to be a little persuasive with the dealers.