A better way to keep cool

With energy costs high and rising, and an electrical grid that threatens to blow a fuse every time it gets hot, the decisions you make about keeping cool this summer matter. So what's really the most efficient way to cool your home?

Positioned between the extremes of window-mounted units and central systems is an air conditioning technology that's still new to most Canadians. Generically called ductless, mini-split systems, this newer approach was developed in Japan and uses a type of heat pump technology to efficiently deliver cooling action to independently controlled zones in your home.

Ductless air conditioners are usually called mini-splits because the two main halves of the equipment are separated by distance. One half is the compressor and it sits outdoors all the time, just like the compressor on a central air conditioner. The other half of the ductless system - the indoor air-handling unit - is wall-mounted and connected to the compressor via a pair of hidden pipes. This is the unique feature of the mini-split approach.

Think of the indoor component like a radiator that delivers cold instead of heat. It can be located as far as 75 feet from the compressor and still work fine. Noise and vibration never gets anywhere near the inside of your home, and cooling action can be delivered high up on any wall for maximum benefit. Typical mini-splits include two or three indoor air-handling units to deliver cooling action around your house.  Hook-up is technically easy, requiring no ductwork and only a three or four inch hole drilled through an exterior wall.

Besides offering an air conditioner option that's sized to fill the gap between central systems and window air conditioners, ductless systems have another advantage, too. They save money through lower electricity consumption. This happens in two ways.

Since the cooling action of a mini-split is delivered to several independently controlled areas in your home, it's possible to selectively cool different zones optimally, depending on the time of day. By focusing cooling action in bedrooms at night, for instance, and living areas during the day, you can save substantially by reducing the amount of total air-cooled.

On top of this, there's another energy advantage, too. According to the U.S. Department of Energy, typical residential duct systems can lose a staggering 25 to 40 per cent of the heating and cooling energy supplied to them by a furnace or air conditioner. This happens because of leaks within the ducts, especially those drawing warm air back into the system to be cooled. Add to this the fact that the metal ducts themselves must also be cooled before you feel any benefit, and you'll see where these huge energy losses come from.

Operating without all that sheet metal has its advantages. For duct-free houses heated with electric baseboard heaters or radiant in-floor heating, mini-splits offer cooling action that simply can't be achieved with central air. Ductless systems also eliminate the risk of criminal intrusion into the home that window air conditioners create. Some systems are even designed to operate in reverse, supplying heat efficiently during cool weather.

At the moment, ductless, mini-split air conditioners are relatively new, and this means that more than the usual profit margin is built into their sales and installation. Currently, the cost per unit of cooling capacity is roughly one third more than you'll pay for central air. But as with any new technology, competition will eventually kick in, lowering the price to consumers. Before that happens the cost advantages and efficiencies of mini-splits mean they're still worth a close look.