In late 2011, the Department of Energy (DOE) announced increases in the minimum efficiency standards of residential furnaces and air conditioners. In the 30 northern states, the minimum efficiency rating of new furnaces was to be raised to 90 percent from its current level of 80 percent, starting May 31st, 2013. In the 20 southern states, the minimum efficiency of air conditioners is set to be raised from 13 SEER to 14 SEER starting January 1st, 2015 (SEER is the estimated BTU’s of cooling provided by each watt-hour of electricity, so a 14 SEER unit will use about 7 percent less energy than a 13 SEER system). These changes were expected to reduce greenhouse gas emissions by 113 to 143 million tons, and to reduce residential energy consumption by one-fifth.