Buying an Air-Conditioner for first timers and repeat buyers

As salaries have increased since the early 1990’s, the prices of the ACs have also fallen, what was a ultra luxury item has now came within the reach of middle class in India. Buying and properly operating an AC is not something that comes naturally to most of the middle class people in India. Though over the past decade, increasing number of people have become used to having air conditioners at home.

In today’s market, air conditioners come with many variants in functionality and feature, which are quite confusing for both first time and repeated buyers to make the right choice unless they have a proper idea on common terms like tonnage and star rating. Tonnage is the common unit for cooling capacity and the star rating gives efficiency of the air-conditioner.

What Cooling requirement is necessary?

The AC tonnage will decide the cooling effect of the desired area which is based on the size of the room, number of people living in the room, number of walls exposed to sun light directly and number of windows and their area.

Broadly, the following chart will assist you to pick the right size for your room:

Room Size in Sq.ft Tonnage required
Up to 120 Up to 0.75
121 – 150 1 Ton
151 – 250 1.5 Ton
251 – 400 2 Ton and above

If you feel that 1.5 ton is extra for your need then you can even choose a 1.2 ton air conditioner for your room. It is also not a good idea to buy a bigger AC than required because you end up paying more on electricity bills and also suffer with inconvenience of extremely cold wind from the AC when the compressor is switched on.

Which Star rating is more power efficient?

Star rating in an AC is given by calculating amount of EER or COP (Energy Efficiency Ratio or Coefficient of Performance). This system in India was introduced by BEE where EER is the ratio of cooling effect provided by AC system in Watts to the power rating of the system. (1 ton has a cooling effect of 12000BTU/hr in Watts it is 3516 Watts). Typically, EER is specified based on the standard indoor temperature of 800 F with 50% humidity and outdoor temperature of 950 F.

For better understanding check the star rating descriptions below:

  • 3 star rated
    These ACs have lower price and save only minimal amount of power. 3 star rating for an AC is given when efficiency is between 3.1 to 3.29.
  • 5 star rated
    These ACs have relatively higher price than 3 star, but are efficient in power savings. When compared to one star, a 5 star AC is usually 5000 to 10000 Rs higher in price because its efficiency value is more than 3.29.

  • Ratings in green color are accurate
    ACs with green color sticker are more accurate because it represents 2012 BEE standards. It is better to avoid buying ACs with red color stickers as they are 2011 BEE standards. Note that, 2012 BEE standards are less than that of 2011 i.e a red sticker with 5 star rating has efficiency equivalent to 4 star rating of green sticker.
  • ACs with the same star rating:
    In case, if you have to choose between AC systems with the same star rating, it is better to go with the accurate numbers. The higher the efficiency value the better the performance would be. For instance, an AC with 3.21 rating is better than the AC system with 3.1.

Over the years, AC systems have transformed to become more energy efficient to suit the needs of various customers. Previous AC models consumed large amount of electricity and gave less cooling effect whereas, present generation systems have digital displays, remote control and many other advanced features. Many developments were integrated into the AC system to progressively increase the minimum efficiency standards, and optimize it for low power consumption.

You may also like to read:
Indoor Air Quality
Advantages of Inverter Air Conditioners
AC and Ventilation for India – White Paper
Why Measure Indoor Air Quality

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