Various embodiments of the present invention provide an insulated structural panel including a superinsulating, desiccant-filled, vacuum-sealed insulating panel sandwiched between a pair of composite panels. The composite panels are configured to impart structural strength to the panel without introducing heat transfer pathways through the vacuum-sealed insulating panel. The desiccant material disposed within the vacuum-sealed insulating panel is capable of absorbing moisture within the vacuum established within the vacuum-sealed insulating panel and thereby reducing the degradation of the vacuum-sealed panel's insulating capacity.