Spend Smart. Cool your air-conditioning cost

The cool comfort of your air-conditioned room is a blessed relief from the scorching summer. But as the temperatures soar, so does your power bill.

Now, you can’t really part ways with your air-conditioner. But following a few practical steps can help you cut down on the power that’s consumed and thus lower your bill. If you’re looking to buy a new air-conditioner, it pays to do a thorough evaluation. Here’s how.

Buying right An energy-efficient AC will consume lesser power. When you’re buying an AC, look for the Bureau of Energy Efficiency’s star label, an indicator of power efficiency. The more the stars the AC sports, the more energy efficient it is. The star rating ranges from one to five, with a five star indicating highest efficiency.

But most of you may already be aware of star ratings. What you need to also pay attention to is the year of the star label. Star ratings get updated every two years. So, an AC which was labelled with a four star rating in 2008 would be equivalent to a one star now, explains Avikal Somvanshi, Senior Research Associate, Sustainable Buildings and Habitat Programme, Centre for Science and Environment.

So, how much of a difference can a star or two make to your power bill? On an average, each star offers 6-7 per cent greater efficiency, says Somvanshi.

To arrive at how much your power bill can amount to based on star labels, you can check the Energy Calculator on www.saveenergy.co.in . The calculator allows you to select the flat size (small, medium or large), choose from one star to five star ACs for different rooms, the usage time and the state where your house is located. The calculator will then indicate your energy consumption.

Let’s assume you use three-star rated 1.5-tonne ACs for eight hours a day, six months a year. Then, completely switching over to five star ACs could save you about ₹13,400 in UP and ₹17,000 in Tamil Nadu over five years, assuming you fall in the above 300-unit electricity slab. A five star AC can cost you around ₹4,000-5,000 more than a three star one.

You can also select ACs based on inverter technology. They are among the most efficient ones and can offer even greater savings than the BEE five star ACs.

In an inverter AC, the speed of the compressor is adjusted according to the requirement of the room unlike in other ACs. This reduces power consumption; inverter ACs offer a power saving of 20-25 per cent compared to a five star AC. But an inverter AC is pricier than a five star one by around ₹5,000. The additional cost incurred can be recovered in about a year’s time if the AC is run for six-eight hours a day, says A Radhakrishnan, Director, Clima-cool Systems, an air conditioning service provider. Finally, you can also check the Energy Efficiency Ratio (EER) at the time of buying an AC. The EER, or the ratio of cooling capacity to power input, tells you how much of a power guzzler the AC is. The higher the EER, the more efficient the AC.

Size it right Another factor worth considering while choosing an AC is its size, which depends on the room. Avikal Somvanshi provides a thumb rule you can follow — for every 100 square feet of room, a one tonne AC is needed.

You can also try the online tool on the LG website http://www.lg.com/in/support/ac-tonnage-calculator to calculate the appropriate AC tonnage for a particular room. The correctness of the room size is, however, not of much concern when it comes to an inverter AC.

Tips to follow Even if you’re not buying a new AC, you can still reduce your power consumption. For instance, the temperature at which you set your AC affects the power usage. ACs are designed to work efficiently and economically if the temperature is set at 27 degree centigrade or higher. Every degree reduction in the temperature setting from this 27-degree mark can lead to a 3-10 per cent increase in power consumption.

Here’s an example. A three star 1.5 tonne AC running eight hours a day on a temperature setting of 17 degree centigrade can consume 200 kWH (units) more in a month than it would have if the temperature was set at 27 degrees.

The age of an AC too matters, as it becomes less efficient as it ages. Avikal Somvanshi provides an example. A 4-star AC bought in 2008 would have been consuming around 470 kWH a month (if it’s run for eight hours a day). Today, it would take up 155 kWH more each month, assuming an annual 2 per cent depreciation in efficiency.

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