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Practical and affordable home automation: Part three – Putting it all together

At Agilent, we've been talking about "The Next Frontier" for a couple of years, as we listen and respond to the test challenges our customers face. We have watched huge advances in development and adoption of mobile communications, the borderless office and home automation. We thought you might be interested to see how one Agilent employee applied the notion of "The Next Frontier" to his own home, in a real-world example of home automation

In the November and December issues of the go/semiconductor newsletter, we introduced you to Pete O'Neill, an engineer with Agilent's Semiconductor Products Group – now Avago Technologies – who explained the overall design of his home automation system and the design and implementation of the control system. This month, in the final of this three-part series, O'Neill explains each of the automated components of his home automation system, from lighting to security.

Lighting control

In conjunction with heating/ventilating/air conditioning and security, lighting was one of the key systems O'Neill wanted to control when he decided to automate. Lighting has been the most extensively automated aspect of home automation for years, yet at about $100 per switch, it is prohibitively expensive to automate all the lighting in the house.

O'Neill chose OnQ Advanced Lighting Control for his lighting system, which uses an RS-485 two-wire bus for all the load switches. Then a 3-wire bus from each of the load switches enables up to 9 auxiliary switches, which provides easy multi-way switching. For example, a switch in O'Neill's upstairs hall is a 6-way switch: a load switch and four auxiliary switches, so that from any room upstairs, the switch operates the upstairs hall light. Any of these switches, which are also dimmers, can be operated either manually or from the controller.

HVAC control

Energy conservation was a key objective for O'Neill's home automation, which made a zoned heating system ideal for his needs. The house is split into three zones, upstairs, main floor and basement, with thermostats regulating each zone.

With the zone system, the air flow can be directed to the floor that needs it, whether it's heat or air conditioning. No more complaining that it's too hot upstairs, when the temperature is perfect on the main floor. Mechanical vent dampers are electrically controlled by the zone controller to open and close the vents as needed. A central computer controls the three zone thermostats simultaneously, and a manual override is available at the thermostats.

To deliver hot water faster at the tap, O'Neill installed a pump-driven hot water recirculation loop. However, circulation increases standby heat loss, even with insulation, which makes it an ideal system to regulate for greater efficiency so his control computer switches off the recirculation pump when hot water is not anticipated to be needed. With an electric-ignition gas water heater, O'Neill can, theoretically, time the heater's operation. Unfortunately, because of liability concerns, the manufacturer will not provide the information needed to install a regulating switch on the gas unit, so O'Neill is unable to integrate the water heater into his home automation system.

An air-to-air heat exchanger (heat-recovery ventilator) exchanges the heat from the exhaust air with the incoming air, to replace the house air without losing the heat (or cold) it contains. In the winter, this pre-warms the cold outside air before it reaches the furnace, and in the summer, it pre-cools the incoming hot outside air before it reaches the air conditioner. Because the house is designed to be air-tight, active ventilation is needed. This ventilator system replaces the need for bathroom exhaust fans. It does make some noise and is not perfectly efficient, so it is not in constant operation. However, it is tied into the home automation system for timed operation and as part of the emergency response in case of fire (it is shut down to prevent additional air flow), or carbon monoxide poisoning (it goes on to dilute the CO with fresh air).






















Sensors for security and automation

Security systems have existed for years, but usually they are comprised of cheap motion sensors with passive infrared, which produces a high rate of false detection. O'Neill's security system uses sensors with a combination of passive IR and microwave motion because they are far more reliable. If someone trips the alarm, the control computer is programmed to know when and where to reach either O'Neill or his wife based on the time of day and day of week.

O'Neill recommends recessed magnetic switches over wireless options for window and door security. Wireless is typically considered the way to go, however O'Neill recommends the tiny recessed magnetic switches, because they fit into a 5/8-inch diameter hole drilled into the window sash, and therefore, are completely invisible. A wireless switch requires a much bulkier cover for the battery that runs it.

Getting settled

O'Neill's hierarchal design really paid off at move-in. The automation system wasn't complete when the O'Neills moved into their new home; however, each system worked independently, without the control computer, until O'Neill was able to complete the wiring and installation.

He focused first on controlling the thermostats, followed by the lighting. Telephones and the Internet were next in priority. After only 3 weeks, most systems were up and running. The O'Neills moved into their dream home on October 1, 2004, and by December 5 it was fully automated. The following are actual dates of completion for the various stages of the project:

  • Sept. 29 smoke alarms engaged
  • Oct. 1 move in
  • Oct. 14 phone network operating
  • Oct 17 data network operating
  • Oct. 29 video network operating
  • Nov. 4 HAI consoles installed
  • Nov. 5 first ALC light operating
  • Nov. 6 thermostats communicating with controller
  • Nov. 12 all ALC lights work
  • Dec. 5 security system complete

Wider adoption gaining momentum

Interestingly, price, not technology, has been the primary barrier to wider adoption of home automation. Many consider it too specialized to make the investment.

However, standardization and volume manufacturing are driving down the price, and the high cost of energy is inspiring many to consider greater efficiency of their home systems, which automation can enhance. O'Neill observes, "People who automate their homes are no longer considered early adopters. The creation of home theaters and the desire to network digital devices have been driving, and will continue to drive, the automation movement."

References and tips

Few books are available to assist those who want to automate. O'Neill has found the series by Robert N Bucceri to the most helpful: Structured Wiring Design Manual, Latest Technology in Automated Home Control., and How to Automate both New and Existing Homes. O'Neill adds, "Document everything. Buy good tools. And run much more wire than you think you will need."

Additional references:

Part 1 and Part 2 of the series are viewable in the go/semiconductor Feature Articles archive.

Author: Pete O'Neill is a Research and Development engineer previously with Agilent, now with Avago Technologies, the new company formed by KKR and Silver Lake Partners from Agilent's divested Semiconductor Products Group. His area of expertise is IC test. O'Neill received his BSEE and MSEE from Purdue University. To complement his work on chips he can't see or touch, O'Neill enjoys building houses and the gadgets that go into them.





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