An analysis in the Portland,OR area found that green-certified homes sold for up to 8% more on average. The study analyzed sales data for May 2010 through April 2011. Certifications came from Energy Star, LEED for Homes, Earth Advantage or combinations of these programs. The difference in sales price was even higher for existing homes, with an average premium of 30%. Another trend noticed in the study was that third-party certification resulted in a higher sales price. In many cases, the builders’ homes earn a HERS rating of less than 40, which can translate into a savings of 60-80% in energy bills.