New York--Everyone knows how much mileage they get per gallon simply by looking at the fuel gauge on their car. But what about how much it costs to keep a lamp on throughout the night?

Energy Inc. of Charleston, S.C., Modern Moulds and Tools of the U.K. and a handful of other companies are selling real-time energy monitors that tell you how much it costs to power a TV, keep your microwave plugged in and the energy costs of a plethora of other electronic devices in your home. The devices, which cost around $150, promise to drive down the cost of your electricity bills simply by making you aware.

“It’s definitely a wake-up call and a wonderful behavior modifier," said Dolph Rodenberg, founder of Energy. “It changes your behavior when you see your spending money you don’t need to be spending.”

Rodenberg should know. The idea of a real-time in home energy monitor came out of the frustration Rodenberg had for his wife’s inability to turn off things. “She used to leave things on. If she knew what things were actually costing she wouldn’t do it," he said.

Energy’s monitor, called the The Energy Detective, or TED for short, looks like a small alarm clock and works by connecting to the power line coming into your home. Plug the device into any outlet in your house and it will automatically tell you how much electricity is being used. Rodenberg said the device only consumes 0.4 kilowatts of energy to use.

If you turn on a light, TV or other electric device, the load will automatically change. The display can tell you the current dollar-per-hour cost, the current kilowatt of power being used and a host of other information, like how many kilowatts are being used per week, month or for a specified time. The monitor has a UBS drive attached to it and using Energy’s TED Footprints software, you can isolate certain loads. That would enable you to determine how much your hot water heater is costing you in electricity, for an example.

The product can be bought on the company’s Web site at www.theenergydetective.com, but Rodenberg said the company is in talks with distributors to begin selling it at retailers.

“There’s more and more interest being shown and sales are increasing,’’ Rodenberg said. “I don’t like energy prices going up anymore than the next guy, but I happen to be in right business to address that.”

Energy is currently working on an advanced monitor that will enable you to access the energy monitor from a computer or personal digital assistant or PDA, and turn on or off major appliances like HVACs and hot water heaters.

Flash back a few years ago and most homeowners were more concerned with getting their hands on the biggest TV out there than with worrying about the cost to power it. But high energy costs, coupled with a slowing economy, have brought energy consumption to the forefront of many consumers’ minds. One only has to look at the difference in his energy bill from a decade ago to today to understand. Homeowners’ electricity bills are dependent largely in the cost and availability of fuel, which is constantly setting record highs in terms of cost.

According to the Energy Information Administration, the statistical agency of the U.S. Department of Energy, residential electricity prices are expected to increase by 2.4% in 2008. Those prices are forecast to increase to 2.9% in 2009.

Modern Moulds and Tools out of the U.K., has been selling its energy monitor, called the Eco-Eye, for about two months and said demand is high. While the device isn’t available in the U.S now, the company is gearing up to make a system for U.S. consumers.

Eco-Eye comes with a sensor that clips onto the electricity meter and then emits a wireless signal to a receiver in the home that displays information on how much electricity is being used in kilowatts or cost. The in-home receiver runs on batteries. The company is developing another product to be called the Wi-Eye which will be an add-on unit that downloads data on to a personal computer, letting homeowners produce graphical information. The company is also gearing up to develop a water pipe leak detector for the home. 

“The instance you turn on a light you see exactly what it’s costing you," said Trevor Pumphrey, managing director of Modern Moulds and Tools. “It changes your behavior.”