The dream of an intelligent home that automatically controls the living environment and responds to individual preferences has been around since the advent of the microcontroller first suggested the possibility. High cost, reliability issues, limited capability, and a lack of standards have imposed major constraints on the market, however, keeping home automation more in the realm of imagination than practice. The advent of wireless technologies, the emergence of home-networking standards, and pull from both the entertainment and the energy markets are now revitalizing efforts to realize that dream, although industry participants are still hotly contesting the implementation methods.

A technology must possess many attributes to be successful in a consumer market such as home automation. These features include:

• Affordability: The technology must provide enough benefits with a low enough price that consumers become willing to invest in it.
• Ease of use: The technology should be simple enough to install that the average consumer can use it out of the box.
• Reliability: Once consumers install it, the technology should work as they expect without interruption and without their attention.
• Flexibility: Consumers expect to use technology where and how they wish without significant restrictions.
• Long operating life: Consumers expect their investment to pay dividends over months or years without fail. In the case of battery-operated devices, long battery life is essential for consumer satisfaction.
• Interoperability: Consumers expect to be able to purchase technology components from a variety of competing sources and have the components work together without effort.
• Capability: Consumers have come to expect that a newly adopted technology will provide several important benefits and useful features and that the technology’s capability and features will steadily increase over time.

Currently, every available home-automation technology falls short in one or more of these areas, although proponents are continuously working to address these shortcomings. Sometimes, the shortfall arises purely from the communications medium. Home-automation systems use one or more of three media: wire and cable, power line, and wireless, typically RF. Each approach has its advantages and drawbacks.

Wire and cable media for home automation include twisted-pair wiring, coaxial cables, and optical fiber. These media have an advantage in their high data capacity and ability to provide a relatively noiseless communications channel for network signaling. Their major drawback is cost. Estimates for the installation of cable in construction range from $65 per linear foot for residences to nearly $300 per linear foot in industrial settings. Costs are lower when installation occurs during new construction but still remain too high for most consumers.

A second drawback of wire and cable media is inflexibility. Consumers are not free to relocate controls or endpoint equipment as they wish. The location of the installed cabling restricts placement, and the cost of new cabling is prohibitive.

Power-line signaling

In response to the drawbacks of cabling, home-automation technologies seek to use one type of wiring in every residence: the power line. As a networking medium, a power-line connection has two advantages. One is that they are in place and run to nearly every location where endpoint devices exist. The second is that endpoint devices need no external power source, such as a battery. Both help satisfy the low-cost and ease-of-use requirements of a consumer technology.

Power-line networking has its challenges, however. The medium is noisy, carrying a variety of voltage spikes that arise as lights and motors switch on and off, loads change, and disturbances on the power grid propagate into the home. As a result of this noise, power-line-networking technologies have either restricted their signaling bandwidths or employed sophisticated and expensive noise- and error-reduction strategies.

Dramatically higher rates have become available over the last few years. The HomePlug Powerline Alliance’s new HomePlug AV standard, using technology from Intellon, employs orthogonal-frequency-division multiplexing to generate signals that attain data rates as high as 200 Mbps. This speed is fast enough for the network to go beyond simple control of lights and power and serve as a communications channel for entertainment media, such as IPTV (Internet Protocol television). It remains to be proved, however, that the cost for this sophistication will drop to the levels needed for widespread adoption.

Power-line signaling also has other drawbacks that can impact its long-term success. In US homes, for instance, power comes to the house as two out-of-phase, 120V feeds with a neutral line. This arrangement allows the wiring of 240V power for demanding appliances, such as furnaces and dryers, and allows regular household power to run at the safer 120V level. The result, however, is that the power lines in the house split among the two phases, and power-line signaling cannot reliably cross between the phases without the help of either a bridge node or a high-frequency shunt between phases. This step adds complexity and cost that consumers may not tolerate to the implementation of a home network.

Power-line signaling also has a limitation to its installation flexibility: It requires that power lines be present at every node in the system. This situation imposes restrictions on the placement of control nodes, such as light switches and thermostats. Ideally, consumers would want to locate anything anywhere with no restrictions.

Technological advances have thus brought a variety of home-networking approaches to levels that will allow the dream of intelligent houses finally to become reality. Two roadblocks still remain, however. One is interoperability. Many companies base their approaches on proprietary technology, which limits the number of suppliers from which consumers can choose. The other roadblock is the lack of a compelling application to jump-start the market.

As exciting as these possibilities seem, however, from the consumer’s viewpoint they represent just the gravy. Alone, they will not fuel the market. The meat of home automation, the killer application, must command widespread acceptance of the technology.

Such an application may be emerging. Power companies in both Southern California and Texas are looking to technologies such as ZigBee to help them implement load control and demand-based pricing in the home. With a ZigBee link from the meter into the home, these companies hope to provide customers with real-time feedback on energy use and cost as well as adjust user demand by remotely turning thermostats up or down, turning off water and pool heaters, and the like.

As energy costs continue to rise, such uses of home-automation technology can become compelling and may become mandatory. It’s a humble beginning and less exciting than an intelligent home that conforms itself to your presence and preferences, but it may be all the home-automation industry needs to gain entry to the consumer’s home. From there, the approaches that best satisfy the many requirements of consumer technology can see the kind of opportunity growth that the PC industry enjoyed in the late 20th century.