A method of retrofitting a home includes providing a structural base on a ground surface adjacent to and outside the outer walls, the structural base comprising one or more air passages; installing insulation adjacent to an outer surface of the outer walls, the insulation being supported by the structural base; and installing siding material on an outer surface of the insulation, the siding material and the existing outer walls enclosing the insulation and defining a flow path, a top of the flow path comprising one or more air passages into the attic space such that air flows along the insulation in the flow path between the structural base and the attic space. A plurality of new trusses may be supported at an apex of the existing roof that overhanging the existing outer walls and the insulation, the trusses sloping direction of the slope of the existing roof.