Effective January, 2011, new, more rigorous guidelines are in place for new homes that earn the Energy Star label. The new requirements will make qualified new homes at least 20 percent more efficient than homes built to the 2009 International Energy Conservation Code, slashing utility bills for qualified homes by 15 percent. Key elements of the new guidelines for Energy Star qualified homes include a complete thermal enclosure system, quality installed complete heating and cooling systems, complete water management system, efficient lighting and appliances, and third-party verification.
See http://www.energystar.gov/index.cfm?c=new_homes.nh_features