Energy conservation: Meter's running

When a car has a fuel-efficiency gauge -- a continuous display on the dashboard showing the rate of consumption -- it tends to promote frugal driving. Nissan, the Japanese carmaker, has calculated that fuel-efficiency gauges can reduce fuel consumption by an average of 10 percent, so it has decided to put them in all its cars.

What if you did the same thing to houses? A variety of products can provide real-time information about electricity consumption. Working out how much energy a house is using is harder than with a car, because electric meters are generally hidden away in cupboards or basements, and many people find them hard to understand. So an easily understood real-time readout, akin to a car's fuel-efficiency gauge, could make a big difference.

The simplest such devices can be plugged in between an appliance and a wall outlet, to display how much electricity the appliance is using. Plug in your toaster, hair dryer or radio and turn it on, and you can see how much power it draws.

There also are more elaborate devices that can measure the power consumption of an entire household, using a current sensor that clamps around the electric cable running into the breaker box. The rate of consumption is then sent wirelessly to a portable display unit. By carrying this unit around the house and switching things on and off, you can see how much power each draws.

The Owl, available in the United Kingdom, is one device that works this way. Its portable display can be configured to update every six seconds or once a minute, which helps extend the battery life of the transmitting unit next to the meter. Total household consumption can be displayed in a number of ways: in kilowatts or in cost per hour (provided you enter the cost per kilowatt-hour into the device).

Shocked, and shocked again

After you have set up the device you get the first shock: Why is the house using so much electricity?

Walking around and switching things off soon reveals where savings can be made: lights left on during the day, a television the children are not watching and a surprising number of power supplies for cell phones, portable phones and the like keeping themselves warm while the things they are connected to are in standby mode.

It's next to impossible to get a house down to zero -- there's always a fridge and a freezer running.

Having switched things off, the second shock comes when you walk around turning things on. Washing machines, dryers, dishwashers and electric ovens produce alarming figures.

The Wattson -- considered the iPod of such devices -- does a similar job, but also makes more detailed analysis possible. Contained within a stylish case, it can remember four weeks' worth of electricity-consumption data, which can be downloaded to a computer for further scrutiny. Besides showing usage patterns, it can produce colored "mood" lights that change according to energy consumption: blue when you are being frugal, red when consumption soars.

The British government has raised the idea that free electricity-display units could be given to all households to encourage energy conservation. But not everyone likes the idea. Energywatch, Britain's energy watchdog, has some concerns: Such units do not measure gas consumption, for one thing, and although they may initially change people's behavior, the novelty could soon wear off.

Smart meters

Another conservation approach is the use of "smart meters." These often include a display unit, but also can do clever things behind the scenes. Unlike simple displays, they also can be read remotely, either via a network connection that runs back to the utility company, or from nearby using a short-range radio link.

And if your house has solar panels or a wind turbine, smart meters can ensure that you are credited for any excess power that you sell back to the grid.

Reliant Energy, the Texas-based utility, has been testing smart meters in Houston and Dallas. They can communicate with energy-hungry household appliances such as air conditioners, water heaters and swimming-pool pumps. The idea is that when the supply becomes tight, the power company can remotely toggle off the power consumption of such items to reduce demand.

In Minnesota, Xcel Energy's Ralph Dickinson, a product developer in Minneapolis, has tested off-the-shelf energy monitors. But the company has not progressed past the research stage when it comes to modifying consumer behavior with such devices.

Behavior modification "is pretty new for utilities and for regulators," Dickinson said, although utilities have long encouraged energy conservation through hardware -- insulation, more-efficient appliances and lighting, he said.

In a separate but related move, Denver-based Xcel on Wednesday announced a pilot project to install a "smart grid" system in nearby Boulder that ultimately will provide customers more capability to monitor and control energy use.

In an ideal world, every home would have a smart meter. But they are not the sort of things that you can go out and buy -- let alone install yourself. Even if they were given away, it would take years to replace the millions of existing meters around the world.

No doubt, some of the novelty of monitoring your power consumption will wear off, but the evidence from fuel-efficiency gauges in cars suggests that, when something clearly shows people how to save money, they will follow its advice. So small, relatively cheap devices such as the Owl and the Wattson can be useful in the meantime.

Staff writer John J. Oslund contributed to this report.