"Smart" appliances for an energy-efficient future

Sam Newman is an analyst with the Energy and Resources Team at Rocky Mountain Institute.

For years, Hollywood has sold us images of futuristic houses filled with "smart" appliances. Think of the coffee machine that can make as many drinks as a Starbucks barista, the refrigerator that tells you when you're out of milk, or the clothes drier that can talk.

Real attempts at such devices have long been constrained to trade shows and demonstration homes. These devices have been portrayed as artificially intelligent, user-friendly, and capable of two-way communication with us and other appliances.

Today's smart appliances have a new benefit that goes far beyond novelty and will finally bring them to the shelves of Home Depot: energy efficiency. Their adoption will be part of a response to the urgent need to modernize the ways that we buy and consume electricity.

More than a third of electricity generated in the United States is used in households. Air conditioners use 16% of that electricity; refrigerators use another 14%. Hot water heaters and other home appliances -- including clothes dryers and dish washers -- consume an even more: 29%. Using existing technology, each of these machines can be made "smarter," lessening our environmental impact.

Every time your air conditioner kicks on during a hot summer afternoon, it contributes to a larger problem. When many air conditioners turn on at the same time, they force up the demand for power from the local utility, putting stress on the system.

To meet this demand, utilities rely on peak generating plants, which might only be used on the hottest days of the year. Power from these plants is carbon-intensive and expensive to generate.

Smart appliances will respond to price signals from the grid to lessen these peak loads. Under a "real-time pricing" system, energy used during peak hours will cost more than energy used at night, when demand is low. This price structure allows residential energy users to optimize their energy usage habits to save energy and reduce emissions.

Imagine setting your air conditioner to save money by remaining off during weekday afternoon hours when power is expensive. It would turn on in the late afternoon, so the house would still be cool when you returned from work.

Similarly, a clothes dryer could be programmed to an "economy" setting which would turn its heating element on and off to take advantage of the cheapest power rates. The dry cycle would take a bit more time, but it would allow the household to respond to variations in electricity supply.

For instance, if a cloud passed in front of the sun, reducing the output of a solar power array, the price of power would increase, signaling the dryer to turn off until the cloud moved away.

Studies have shown that consumers conserve energy when provided with real-time feedback and improved control systems via a computer or appliance smart meters. Just as car owners drive more efficiently when provided with real-time fuel economy data, residences with smart meters use less electricity.

In a recent study in Washington state, overall energy usage fell 10% following the implementation of smart water heaters and dryers. If used nationwide, these technologies could save $70 billion and eliminate the construction of 30 new coal-fired power plants over 20 years.

The next step toward getting smart appliances in each of our homes is taking these pilot programs to scale.

In March, Xcel energy, one of the United States' largest utilities, chose Boulder, Colorado, for an innovative smart city project.

Residences will be fitted with smart appliances, and the utility infrastructure will be upgraded to enable real-time demand response and power pricing. Predicted benefits include lower peak demand on summer afternoons, reduced overall carbon emissions, and improved system reliability.

Appliances that can talk back to you are unlikely outside of Hollywood fantasies any time soon. But smart appliances that save money and reduce carbon emissions are not science fiction. These technologies offer a market-based approach to energy efficiency that will help reduce your environmental impact.

For more information see:

• Gridwise Program at Pacific Northwest National Lab
• Xcel Energy's Smart Grid City project