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Power supply companies are blaming the increased use of air conditioning units for electricity shortages, amid fears of power blackouts in New South Wales and other states this summer. But the air conditioning manufacturers dispute these claims and insist they are working hard to ensure that systems are designed to work efficiently.
“We seem to have this issue with the people who supply the power who tend to say power usage is due to the growth in the use of air conditioners,” Bernie Bugdalski, marketing and sales manager at manufacturer Fujitsu ’s specialist and commercial division, explains. “But we are responding to a market demand for comfort and a good lifestyle in the sort of fairly extreme conditions we live in here, especially in the summer time. As an industry we’ve been extremely dynamic over the past five or six years. If anything we’ve probably broadened the use of air conditioners from being a summer respite to an all-year round product. There tends to be the suggestion that it’s the air conditioning companies’ fault that this [power shortages] is all happening but there’s things like the design of housing to be considered.
“We also tend to think that the power supply problems are because the poles and wires aren’t up to speed.”
There are several ways to ensure that air conditioning units are run more efficiently. The first is to ensure that homes are properly insulated, for example with batts. According to Guy McGrath, national business manager, residential at CSR Bradford Insulation, “Homes can be turned into ‘Comfort Zones’, preventing up to 42 per cent of heat transfers through the ceiling and up to 24 per cent through walls.”
Product manager at Fujitsu Bill Yankos agrees. “The first thing I ask customers is how well their property is insulated,” he says. But there are ways to ensure that air conditioners are used more effectively and the push for this is coming from government. “As of October 2004, the Australian standards will be changed to included Minimum Energy Peformance Standards (MEPS) for single phase air conditioners,” Yankos explains. “These include the single box units you see in windows, wall hung systems and smaller ducted systems. Up to now, for the past two years we’ve had MEPS only for large three phase air conditioners. The next step will come in 2007 where MEPS will be raised and it is said that 75 percent of current units in the marketplace will not pass that bar, so there’s a long term goal to make products more efficient.”
One of the techniques employed in commercial and larger residential applications to reduce power consumption is zoning. “This is where, using a duct system, you stop air going to a particular room if no one is in it,” Yankos says. “So instead of cooling the entire house if everyone is in the living room, you’d have ‘day zone’ on, for example, then when they go to bed at night, you flick a switch and the unit sends all the air to the bedrooms and turns it off from the living room. “It uses less power because it only has to cool so many cubic metres of space.”
Among technological advancements enabling residential air conditioners to drastically reduce power consumption is the inverter. “A normal air conditioner will, when it requires cooling, turn on the compressor,” Yankos explains. “When it does this, it draws a sudden surge of power and that costs energy to turn the compressor over. The significance of the inverter is that it can reduce or increase the speed of the compressor, therefore it will reduce or increase the capacity of the system.
“An analogy would be driving your car with your foot either fully on the floor or fully on the brake - imagine how much petrol your car would go through and the pressure on the brakes and tyres. So the inverter modulates the compressor speed to meet exactly the amount of energy required to cool or heat the property.”
Power is also saved when the unit is initially switched on, Yankos adds. “The inverter enables the compressor to start at a slow speed and then build up. Depending on the manufacturer, some will start at 16 per cent of the top speed, some may start at only five percent. Some will continuously ramp up and some will take steps up until the cooling effect has been achieved. If a compressor goes bang to 100 per cent it uses a whole lot of energy to get there and then if it runs at 100 percent power usage, that’s a lot of power. When an invertor turns it on, it continually ramps up so it has negligible power usage when it starts up and once it sits there it may be using only 50 percent power as it runs more efficiently at its partial load.”
The latest evolution in the industry is to use a refrigerant (gas) called R410A, which is not only zero ozone depleting but also gives air conditioners a very high co-efficient performance. “That means for example on a normal air conditioner you may have a two, three or even four star energy rating. We have one model in our wall mounted systems whose star rating goes off that scale as it is over six, because it uses this refridgerant combined with inverter technology.”
The use of inverters in commercial systems is growing but more slowly, says Yankos. “The commercial sector is more likely to refurbish an old system to make it work as it’s expected to have a greater lifespan than a residential unit,” he notes. “The cost of commercial air conditioning units is 100 times more than residential ones, so that is also a factor.”
Nevertheless some commercial models have energy efficient design features built into them, such as multiple compressors whereby the system selects which combination to run to be most effective and efficient. Yankos expects to see inverter driven units for commercial use in the future. “Many large buildings such as shopping centres that require constant amounts of cooling or heating use chillers as part of the air conditioning system,” he says. “To give an idea of the scale, if you need 10kw to do a house, chillers start at 150kw and go to many thousands of kilowatts, and inverter technology is starting to be included in the chiller.”
Source: Building Products News
4-Sep-2003
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