Tue, Apr 22, 2008
my paper
Why no savings from inverter air-conditioner?

HOPING to save on energy bills, Mr D Tan, forked out $700 more for a popular brand's multi-split inverter air-conditioner in November last year.

The 33-year-old, who recruits workers for the construction industry, reasoned that long term savings would defray the initial expense. He was thus blase about turning on the air-conditioner in every room, whenever he was home.

But five months later, his electricity bills are still similar to his pre-inverter days - $150 a month.

Mr Tan lamented: "What's the point of installing the inverter then?"

When all units are operating simultaneously every day, energy consumption sky-rockets.

Perhaps, Mr Tan was under the impression he could save on power bills even if he uses the multi-tick, energy efficient labels, for long periods.

That may not be the case.

It all boils down how to long on the air-con is used. If it is on 24/7, savings could be minimal or nothing.

Sales staff at two electronics shops my paper visited recommended inverter air-conditioners.

Considered more energy efficient, inverters vary the compressor speed to achieve the desired temperature.

Traditional systems, or non-inverters, start and stop the compressor to maintain temperature.

Since an inverter cuts the number of stop-start repetitions, less power is consumed, lowering electricity bills.

According to Mr Sonny Chuah, the General Manager of LG's Air-Conditioning Division, heavy users could "end up paying more compared to using a non-inverter". He pointed out that inverters are energy efficient when they operate at partial load.

So using only two out of four air-con units for a few hours daily trims monthly bills.

While this is the case for all air-cons, people tend to buy multi-system inverters to enjoy cool comfort in different rooms most of the time.

The National Environment Agency (NEA) estimated that homeowners may save up to $730 annually by switching from a conventional air-conditioner (with no ticks) to an inverter (with four ticks), provided only some units are turned on for eight hours or less a day.

The picture changes drastically at full load, when all units operate at the same time.

However, Mr Victor Yu, marketing manager of Toshiba's Air-con Division, points out that inverter air-conditioners seldom operate at full load.

He said: "That only happens when owners install a smaller-sized equipment, which requires the compressor to keep running to maintain the set temperature."

Economics aside, inverters appear to be winning fans.

Electronics retailer Harvey Norman did not disclose exact numbers, but revealed that inverter sales doubled in

March this year compared to last year. Non-inverter sales rose by 30 per cent.

Of the 48 air-con related complaints filed with the Consumers Association of Singapore since January this year, none groused about inverter efficiency.

So, whether you plump for an inverter or stick with a non-inverter, Mr Chuah cautions to "always consider your lifestyle" to make smart technology work for you.

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