One aspect of the invention relates to an insulation and ventilation system for a building envelope (e.g. a building wall and/or a building roof).The system includes: one or more interior building envelope layers; an insulation panel having an interior side abutting against at least one of the one or more interior building envelope layers and an exterior side having a plurality of transversely spaced and continuously longitudinally extending grooves interspaced between a plurality of transversely spaced and continuously longitudinally extending protrusions; and one or more exterior building envelope layers located exterior to the insulation panel to provide a plurality of transversely localized venting channels defined at least in part by an interior surface of the one or more exterior building envelope layers and the grooves of the exterior side of the insulation panel.