A blank for forming an insulated carton including a front panel hingedly attached to a first side panel, the first side panel hingedly attached to a rear panel, the rear panel hingedly attached to a second side panel along a longitudinal axis of a blank, wherein each panel includes a central portion disposed between and hingedly attached to at least one flap arranged transverse to the longitudinal axis an end tab hingedly attached to the central portion of the second side panel, wherein the blank defines an interior space of a carton when folded along each hinged attachment and at least one surface of the blank includes a reflective barrier which has a higher thermal radiation reflectance than an under-lying layer for energy-insulating the interior space of the carton.