Most of us don't think of the larger consequences when we crank up the air conditioner on a hot summer afternoon, but for the utility companies those spikes in demand can cause a major headache.

Utility companies buy their energy in advance- they estimate their requirements based on long term weather predictions. If they get it wrong, they pay dearly by buying what is available on the spot market, often paying as much as 16 times more than their regular price. In the worst possible case, the utility company fails to meet demand, and brownouts or even blackouts occur.

Meanwhile, homes and businesses waste enormous amounts of energy and money in the summer by needlessly cooling empty houses and offices, and by setting thermostats at unnecessarily low levels. One or two degrees of difference is barely noticeable to most people, while, taken across a customer base of hundreds of thousands or even millions, it will make a huge difference in energy usage for the utility company.

The management of peaks in demand has long been an issue for utility companies. Load management has been extensively practiced for years with high-usage, industrial and heavy engineering customers, but until recently, the technology hasn't been available to extend that concept to residential and small commercial consumers. Now Carrier Corporation, in conjunction with emWare, Silicon Energy and AT&T has developed a unique and very cost- effective solution.

The ComfortChoice Solution

Carrier Corporation is the world leader in heating, air conditioning and refrigeration systems, and supplies a complete line of electronic non-programmable and programmable thermostats. Its new generation of Energy Management Interface (EMi) thermostats has a new application- demand-side management. EMi thermostats are Internet-enabled-they allow the utility company to adjust the homeowner's temperature setpoint during peak energy time to reduce energy usage. They also allow the homeowner complete freedom to override the utility company's settings and to control the thermostat remotely via a Web browser interface on a PC.

Carrier's EMi thermostat has been introduced through the ComfortChoice program, which is jointly marketed to utility companies by Carrier and Silicon Energy, the leader in e-business enterprise energy management solutions, to help utilities reduce demand and save energy.

Carrier had been working with Silicon Energy for some time. But they were having a problem with finding a device-networking solution that was small and efficient enough to work with the microcontroller in a residential thermostat. Carrier didn't want to increase the development and manufacturing cost of the thermostat, and for all of its other functions, the existing microcontroller in the thermostat was sufficient.

When Carrier met with emWare, the synergy was immediately obvious. emWare's EMIT device networking software is the perfect fit for this kind of project. The portion of the EMIT software that has to be embedded in the device firmware is very small, and EMIT also offers significantly superior support of lightweight networks, such as RS232, dial-up modem, RF (radio frequency), Powerline, or Infrared.

"emWare's EMIT architecture is ideal for electronic devices with 8- or 16-bit microcontrollers, like our thermostats, which enables us to bring Internet technology into the home in a cost-effective platform," said Kenneth Fox, vice president and general manager of Carrier Electronics.

How it works
The EMi thermostat is connected to an external modem that accesses the Internet via the regular telephone supply of a home or small business customer. When the utility company wishes to initiate a supply curtailment, it sends a call to the modem using a distinctive ring pattern that will activate the modem. The modem then calls a central utility curtailment dispatch station, from where it downloads the new settings to the thermostat. Silicon Energy designs and hosts the web site through which the dispatcher at the utility company can monitor and manage energy curtailment, and Carrier designs the web application through which the customer can view the status of their thermostat and control its settings. If the customer chooses to change the thermostat settings, then a message is transmitted via the Internet back to the utility company.

The connection is enabled through AT&T's network services and emWare's EMIT software, which, in addition to providing the networking software on the device itself, provides the gateway between the lightweight network, in this case a dial-up modem, and the server at Silicon Energy.

"Energy management is one of the key applications which will take advantage of the networked, embedded intelligence that's finding its way into the items of everyday life," said Dan Greenberg, Director of Embedded Internet and Pervasive Computing Practice for Harbor Research.

"As Carrier, Silicon Energy, emWare, and AT&T have recognized, only a cross-industry alliance can bring these applications to market. The ComfortChoice program brings together devices and software with providers of applications services and advanced networking to provide a complete solution for utilities. We anticipate a warm welcome by utilities and energy services companies that want to offer leading-edge packages to their customers," added Greenberg.

Saving energy and the environment
The ComfortChoice program offers wider benefits than simply saving money for the utility companies. As Kenneth Fox says, "This program offers cost savings to utilities, more reliable comfort and control to residential customers and greater energy conservation to all of us who are committed to protecting the environment. By reducing demand during peak hours this summer, utilities could realize substantial savings. Homeowners can enjoy lower than normal electric bills. This reduced power consumption will lead to more reliable power supply and mitigate the need for increased production capacity, which reduces investment, preserves natural resources and lowers harmful air emissions."