Off Old Farm Road in Chilmark at the end of a dirt road sits the new house of Dardanella and Sean Slavin and their two small children. Over the past year this house has become a home for the young family but it has also become a laboratory. Here, and in 32 other houses across the Island, General Electric and the Vineyard Energy Project have been testing out the next generation of so-called smart appliances and gauging the response of customers whose energy demands have been tempered by the energy load capacity of utilities.