Many utilities, facing deployment decisions on advanced metering systems, are considering extending the infrastructure beyond the meter to inside consumers’ homes. Doing so would give utilities a way to facilitate energy conservation and demand response programmes, as well as remote service applications. It would let them provide consumers, via in-home displays, with detailed usage information that could help them better understand and modify their consumption patterns. Utilities could also set back thermostats to reduce load during peak periods.
Future applications could also benefit from in-home connections: For example, smart appliances will soon be able to automatically react to changing energy rate information. Instead of running a dishwasher midday when electricity rates are higher, a service application will either automatically delay the machine until a lower rate period, or let the consumer choose when to operate it.
Any solution that extends from the meter to the home must meet several basic requirements:
- It must not decrease the practical life of the metering infrastructure.
- It must support simple, repeatable, low-cost installation practices.
- It must not restrict consumers’ future choice regarding inhome automation products and services.
- It must work reliably.
Many technologies can be used to enable a no-new-wires connection to in-home services and applications, including radio frequency (RF)-based solutions such as ZigBee™ and Zensys™ and power-line-based solutions such as ANSI/CEA 709 (the basis for LonWorks® technology) and HomePlug®. While some of these technologies have successfully delivered in-home solutions for years, others are just emerging and are, therefore, too new to have a dependable track record.
Much attention has been paid, in particular, to the use of wireless technologies for in-home utility applications, and there has been some interesting debate regarding both its readiness and appropriateness. Clearly, wireless has a role to play in in-home applications; the question, however, is what is that role?
In-home connections must be installed for the long haul
When considering an advanced meter deployment, asset life is a key issue. Today’s meters must be able to stay in the field and support evolving utility, regulator, and consumer needs for 20 or more years while operating in often harsh electrical and environmental conditions. No matter what technology is used to extend the meter to the home, it must not degrade this life.
There are two aspects to degraded life: component life and technical obsolescence. Component life is perhaps more obvious and easier to judge. To achieve long life, advanced meters must be based on robust, industrial-grade components rather than consumer-grade ones. Technical obsolescence, while harder to evaluate, can shorten the life of a meter more profoundly than using consumer-grade components can.
Consumer electronics products are notorious for their increasingly shorter product lifecycles, with each lifecycle representing a new evolution of technology. While consumers may not only be willing but eager to replace their mobile phones every 6 to 12 months to keep up with the latest technology and fashion, regulators and utilities are not so eager to fund 6-to-12-month meter replacement cycles. And while the capability to download new firmware into a meter is often cited as an antidote to the technological risk of building consumer-oriented radios into meters, it’s an incomplete solution. True, firmware download is an essential component of any advanced metering system, but in this case it will only protect utilities against obsolescence due to immature protocol stacks and rapidly evolving vendor-to-vendor interoperable models.
As with any new RF technology, the radios themselves will evolve from generation to generation – and you can’t download a new radio. Just as cellular data radios have moved from GSM to GPRS to EDGE and now to UTMS, as wireless Ethernet has moved from 802.11B to 802.11A to 802.11N, and as portable phones have gone from 900 MHz to 2.4 GHz to 5.8 GHz and now to 6.0 GHz, the radios targeted at consumer-level control applications will evolve. It’s not a question of when but rather, how often. Beyond radio evolution, consumer products must also remain interoperable so that, for example, meters can work with old and new load control devices.
Installation and maintenance cost are the key
In-home connectivity is designed to enhance the business case for advanced meters by providing new benefits, such as demand response through a setback thermostat, at marginal incremental costs. RF, with its promise of no new wires, would at first appear to offer an attractive installation cost. However, as we know from personal experience, wireless coverage is neither universal nor uniform. These truths are so deeply ingrained in most of us that we’ve almost forgotten them.
As our cell phone calls fade in and out, we automatically tilt our heads or walk to new a location. We guess what callers are saying when RF signal impairments garble or momentarily block out their voices. We accept that the availability and reliability of the signal changes not only day by day, but also moment by moment. For us, as humans, that works. We’re mobile and our brains are good at interpolating missing data. Meters and thermostats, however, are both fixed in place and limited to machine rather than human intelligence. Unfortunately, these fixed devices have no practical way of dealing with RF fading and RF interference issues.
Consumer RF technologies such as ZigBee and Zensys acknowledge that they can’t provide universal point-to-point coverage and offer some form of repeating (meshing) to overcome this limitation. While this may be a viable approach for consumers looking to create high-end home automation systems, in a meter-to-thermostat or meter-to-display application, it represents an unknown and ongoing expense stream of service calls and new repeaters to maintain reliable communication as conditions change over the years of system operation.
Home systems will evolve
While the advanced metering market is young, the home control market is in its infancy. The intersection of these two evolving marketplaces has the potential to create a wide range of new applications that bring value to both consumers and utilities. While we cannot with certainty describe all of the applications that will emerge over the next 20 years, we can state with certainty that many technologies will be used. RF plays an important – and essential – role in reaching certain in-home devices.
For a thermostat, it represents the lowestcost retrofit installation option. For other energy-consuming devices such as white goods, furnaces, and electric water heaters, power line communications is a more practical solution than RF since most white goods, which are already connected to the power line, are surrounded by metal, making them a natural cage for trapping RF signals.
The meter may remain unchanged for 20 years, but the in-home products around it will not. Thus, a utility’s investment decisions must not prevent a consumer from taking advantage of these new products. And, conversely, a consumer’s decision to buy a new in-home product must not invalidate a utility’s infrastructure investment. There must be a flexible coupling between the two, allowing each to evolve at its own pace and serve its complete product life.
Building a utility-grade in-home connection
The meter-to-home connection must be longlived, low-cost to install and maintain, and accommodate technological changes inside the home. The best way to achieve these goals is to separate the portion of the solution that is subject to rapid technology change and obsolescence – the consumer grade RF – into a simple, inexpensive home gateway that communicates through a defined interface to that portion of the solution that must be long lived – the meter. This increases system life as well as decreases system installation and maintenance costs by introducing mobility into what would otherwise be a fixed RF network.
A meter with power line communications technology can use this communications channel not only to communicate up into the utility infrastructure but also down into the home. For example, the ANSI/CEA 709 standard, which has decades of proven operating history, can support not only millions of meters in metering applications but can also reach every device in a typical home without needing repeaters.
As such, it represents an ideal no-new-wires backbone for connecting a meter to a lightweight RF gateway: The consumer can easily plug into a suitable outlet to provide reliable RF connectivity to a thermostat. As RF technology evolves, new gateways could simply be plugged into the power line backbone without requiring service visits. Isolating the metering infrastructure through a well-built interface preserves the benefits of RF connectivity to in-home devices, such as thermostats, and avoids the high service costs and rapid churn of the installed metering infrastructure implicit in a monolithic implementation, benefiting both utilities and consumers.
This cost-effective approach offers utilities a more secure, reliable, and flexible advanced metering solution, and gives them the most flexibility in the everchanging home automation market.