McMansion Lite

Supersized homes have supersized footprints, and some U.S. counties aren't waiting to be trampled by the environmental consequences. In Marin County, California, according to a recent MSN.com report, new homes must meet the energy budget standards set for a 3,500-square-foot abode, which means builders can only go as big as they can be efficient. In Pitkin County, Colorado, there's a green building checklist with point values assigned to various efficiency measures; the bigger the house, the more points required for a permit. The environmental incentive is steep: Over its expected life span, a 10,000-square-foot McMansion puts 5.4 million pounds more carbon dioxide into the air than the average U.S. home at 2,400 square feet, according to Adbusters (March/April 2006).