“A married household actually uses resources more efficiently than a divorced household,” said Jianguo Liu, a sustainability expert with Michigan State University. He and fellow researcher Eunice Yu concluded that in 2005, in the United States alone, divorced households could have saved 38 million rooms, 73 billion kilowatt-hours of electricity and 627 billion gallons of water if their “resource-use efficiency” had been comparable to that of married households. Liu’s analysis of the environmental impact of divorce appears in this week’s online edition of Proceedings of the National Academy of Sciences. Besides the United States, Liu looked at 11 other countries, including Brazil, Costa Rica, Ecuador, Greece, Mexico and South Africa between 1998 and 2002. In the 11, if divorced households had combined to have the same average household size as married households, there could have been a million fewer households using energy and water in these countries. “People have been talking about how to protect the environment and combat climate change, but divorce is an overlooked factor that needs to be considered,” Liu said.