Proper weatherization was undertaken to ensure that the house retained as much energy as possible. The two biggest factors of building weatherization are energy loss through air leakage and energy loss through thermal conduction.  The attic was sealed and insulated with R40 GreenGuard certified insulation.  The underside of the rear flat roof was insulated with R30 closed cell foam. Closed cell foam (min R21) was used to insulate the walls and joist pockets. The crawlspace was also sealed to prevent infiltration.