'Smart home' systems allow householders to foil intruders, check the weather and put the dinner on without having to cross the threshold

A few days after Christmas, while friends were at work, their house in New Jersey was broken into. The police believed the burglars were only in their house a matter of minutes - yet in that time managed to ransack the place and get away with money, jewellery, cameras and a laptop computer.

Needless to say, our friends were devastated. Their options, they now say, are either to get a dog or to install a home security system.

Research has shown that most people choose to get an alarm system after they or someone they know has been burgled. Most people still buy home security systems to prevent burglaries and sales tend to be highest during the summer, when the number of break-ins increases.

It is estimated that about three million home security systems were installed last year, up from 1.9 million in 1991.

There are several security manufacturers throughout the United States and all offer different plans at different rates. Normally, a home security system means putting in place motion detectors, door and window monitors, smoke detectors, gas detectors and emergency buttons to summon help from the local ambulance, fire department or police station.

The average cost for this type of installation is around $1,000 (€1,132) with a monthly service fee for monitoring services linked to a central station run by the alarm company. Some home security companies, however, will install the equipment for free if the homeowner will sign a contract for monitoring services, usually for a minimum of two to three years.

Nowadays, some alarm companies are offering packages that include features going beyond basic home security. These options give rise to a "smart home" that can let people control household functions from a central location. Last May, ADT Security Services of Boca Raton in Florida, which has three million commercial, residential and federal customers in North America and Europe, introduced the ADT Safewatch iCenter.

The iCenter is a four-by-four inch computer touchscreen that can be programmed to allow the homeowner to do much more than simply activate the alarm.

Using the iCenter, the homeowner can control lighting both indoors and outdoors, retrieve e-mail, leave or retrieve voice messages (like a telephone answering machine) for other family members or screen incoming telephone calls. The person can also customise the system so that, via the internet, the latest weather, sports scores and news headlines will pop up on the screen. The iCenter security system can also control the garage door and check whether small household appliances such as the stereo, coffee maker or iron are turned on or off.

Not only can the system be checked and activated from inside the house, but also when someone is away from home. When on the road, a homeowner can access the iCenter remotely via ADT's website, or over the phone. The person can check if the system is activated and, by using a high-speed internet connection, can decide to arm or disarm the entire system, individual security zones or just the perimeter of the house.

The cost of the ADT Safewatch iCenter begins at $3,000 and rises as more sophisticated sensors are added. In addition, ADT charges a monthly monitoring fee of $49.99 for the iCenter, compared to about $26.99 for its other systems. Soon, ADT expects to offer customers remote access to thermostat and closed circuit television cameras and, further down the road, the system might even be able to monitor temperature levels in hot water heaters and fridge freezers.

Obviously, the more money someone is willing to spend on securing a house, the more sophisticated the technologies. One security company can even install a system that will interrupt the homeowner's television viewing with a picture of the person who is ringing the doorbell.

In the past, marketing by home security companies used the fear factor to urge homeowners to get security systems to protect their properties and families. Now, with the help of the internet, the focus is on comfort and convenience in allowing a homeowner to control many of the household gadgets - even when halfway around the world.

Given the fact that only about 1 per cent of American households has an alarm system, it is an area with plenty of room for growth.