Al Gore, who was criticized for high electric bills at his Tennessee mansion, has completed a host of improvements to make the home more energy efficient, and a building-industry group has praised the house as one of the nation's most environmentally friendly.

The former vice president has installed solar panels, a rainwater-collection system and geothermal heating. He also replaced all incandescent lights with compact fluorescent or light-emitting diode bulbs.

"Short of tearing it down and staring anew, I don't know how it could have been rated any higher," said Kim Shinn of the U.S. Green Building Council, which gave the house its second-highest rating for sustainable design.

Gore's improvements cut the home's summer electrical consumption by 11 percent compared with a year ago, according to utility records reviewed by The Associated Press. Most Nashville homes used 20 percent to 30 percent more electricity during the same period because of a record heat wave.

Shinn said Gore's renovations are impressive because his home, which is more than 80 years old, had to meet the same rigorous standards as new construction.

"One of the things that is tremendously powerful about what the Gores have done is demonstrate that you can take a home that was a dog, and absolute energy pig, and do things to correct that," Shinn said.

Gore bought the mansion in the Nashville suburb of Belle Meade in 2002 for $2.3 million. It houses his offices and those of his wife, Tipper, as well as a commercial kitchen for formal events.

Cost prohibitive for most

Gore spokeswoman Kalee Kreider declined to say how much the couple spent on the improvements.

"The Gores decided to take a series of steps over time that might be logistically or financially out of reach for many Americans," she said. "But they were fortunate enough to have the ability to do so.

"But everyone can get started, whether it's changing light bulbs or purchasing green power."

This fan atop the Gore home gets its power from solar panels.

In February, a conservative think tank criticized Gore for using an average of 16,000 kilowatt hours a month for an average monthly bill of $1,206 in 2006. The typical Nashville home uses about 1,300 kilowatt hours a month.

Gore has said the criticism was unfair because the 10,000-square-foot mansion was undergoing extensive remodeling. He said this week that "global warming denier" groups were trying to discredit him because they don't like the attention he has given to climate change.

"You're going to have people try to attack the messenger in order to get at the message. They have not been able to succeed," Gore told CNN from Norway, where he picked up the Nobel Peace Prize for his environmental work.

"The only way to solve this crisis is for individuals to make changes in their own lives," he said.

One of 14 'gold' homes

The Green Building Council's certification program has four levels, with platinum being the highest followed by gold. Gore's home was one of 14 to earn gold status and the only Tennessee home to earn any certification.

Electricity usage at the home remains well above regional averages, but Gore's power consumption decreased by 6,890 kilowatt hours, or 11 percent, between June and August, despite the heat wave.

Gore's electric use increased again after he had to take his solar panels off-line in August so his new geothermal system could be integrated into the system. But his natural gas use has dropped 93 percent in the three months since the geothermal pump was activated.

When the Gores' heated pool is hooked up to the system later this month, their energy use is expected to decline more, his spokeswoman said.

Gore has also said he invests in renewable energy such as solar and wind power to balance 100 percent of his electricity usage.

Stephen Smith, executive director of the Southern Alliance for Clean Energy, said the size of Gore's house limits how much he can cut his energy consumption.

"We all need to evaluate what we legitimately need in square footage," he said.

Still, another owner of the same house likely would not have been as dedicated as Gore to reducing energy consumption, said Smith, who also serves on the advisory committee for Gore's Alliance for Climate Protection.

"I promise you the energy use would be as high, if not higher," he said.