Red, gold, and purple are among the colors associated with the English monarchy, including today's House of Windsor. But Charles, the Prince of Wales, has added another color to the palette at his country estate: green.

The prince, known for his efforts on the environmental front, cut greenhouse-gas emissions at his 37-acre Highgrove estate in Gloucestershire (shown) by 18 percent from 2007 to 2008 and will use more recent savings and a carbon-offset program to make himself carbon neutral, according to this story from the Telegraph. Here's how the prince became a pauper on the polluting front:

• Eco-friendly insulation and energy-efficient windows were installed to cut heat loss. Solar panels and wood-chip boilers were installed to provide electricity and heating. (Look for our report on solar water heaters and pellet stoves in the October 2009 issue of Consumer Reports, online and on newsstands later this month.)

• Rainwater is now used for the toilets (report and ratings available to subscribers) and irrigation.

• Ground- and air-source heat pumps were installed provide heating and hot water.

• A green-energy supplier provides the balance of electricity needed for the estate.

• Staffers are encouraged to bicycle to work or drive hybrids. The prince's Aston Martin is fueled by waste leftover from wine production.—Gian Trotta | e-mail | Twitter | Forums | Facebook

Essential information: Learn how to save up to $2,000 a year on your energy bill. See how the Google PowerMeter and Microsoft Hohm can help you analyze and optimize your home energy use. And read more about Highgrove in this post on Treehugger.com.