Situated on a 106-acre swath of land in Dover, Massachusetts, Powisset Farm provisions more than 300 member families with fresh fruit and vegetables. In 2014, the land preservation group Trustees of Reservations renovated the century-old barn, adding a net-positive teaching kitchen and building the lower level into a root cellar. "It was a drafty New England barn with old wood floors, single-pane windows, and doors that didn’t close well," recalls architect Stephanie Horowitz of Boston’s ZeroEnergy Design, the firm hired to reimagine the structure. Today, the state-of-the-art kitchen hosts public classes on everything from jam-making to food security.