Lord Kelvin said it more than a century ago: “If you cannot measure it, you cannot improve.”

Today, it’s become a business cliche: “What you don’t measure you can’t manage.”

In that light, and against the backdrop of the UN climate negotiations unfolding here in Copenhagen, Google, GE, The Climate Group and NRDC came together to call on governments around the world to provide people with real-time information on their home energy use.

Simply getting useful and timely information (as opposed to a monthly bill) about their electricity usage drives people to curb usage and reduce their greenhouse gas emissions by 5 to 15%, the companies said and studies show. When their usage is compared to their neighbors’, they cut back even more.

“This simple but bold call to action makes common sense,” said Steve Fludder, who oversees GE’s EcoMagination efforts.

The technology to deliver real-time information about electricity consumption — essentially, a meter and software — exists today and it’s not expensive.

GE makes so-called smart meters that it sells to electric utilities.  It is also developing a wireless home energy monitor to be sold to consumers that will measure electricity usage, let consumers know which gadgets or appliances are using power, and communicate with so-called smart appliances so that dishwashers or dryers can run during times of the day when electricity is cheaper. All this is part of the smart grid and smart home you’ve probably heard about.

“We ultimately have a vision of a zero net-energy home,” Fludder said. Of course, that would require the homeowner to install solar panels, or a small-scale wind turbine, or some other form of distributed power generation.

Google’s Power Meter is free software developed by google.org, the company’s philanthropic arm. It’s being tested by about 10 utilities around the world. The software also works with a number of home energy devices. Google partners that make devices include a British company called AlertMe and a company called Energy Inc. that makes The Energy Detective.

Dan Reicher, director of climate change and energy for Google, said  devices today are “available in the range of about $200 and the word on the street is that there are several devices that are on their way that are in the $50 to $100 range.”

“A smart meter in every home” makes sense, even if it doesn’t have quite the resonance of “a chicken in every pot” or “a car in every garage.” (Thanks, by the way, to Dan for the headline on this blog.) Below is a brief video from San Diego Gas & Electric, one of Google’s utility partners.