A packaging system for shipping a temperature sensitive payload, the packaging system comprising: a housing comprising a bottom panel, a top panel located above and in spaced vertical alignment with the bottom panel, side panels extending vertically between the bottom panel and the top panel, and end panels extending vertically between the bottom panel and the top panel, the housing defining a product compartment; one or more bottom cooling layers located in use between the bottom panel and the payload; one or more top cooling layers located in use between the payload and the top panel; wherein the packaging system further comprises: a plurality of hollow vertical posts disposed within the product compartment and adjacent at least one of the side panels or end panels, each vertical post having an open top end and an open bottom end and defining a vertical inner space within the vertical post; wherein adjacent vertical posts define a vertically oriented channel between the vertical posts; and wherein the plurality of vertical posts are spaced from the top panel and the bottom panel a sufficient distance to allow air to flow through the vertical inner space within each vertical post; characterized in that each vertical post has a triangular cross sectional profile, and each vertical post comprises an outer facing side adjacent a side panel or an end panel and two angled sides extending from opposing vertical edges of the outer facing side and meeting along an elongated vertical inner edge. a housing comprising a bottom panel, a top panel located above and in spaced vertical alignment with the bottom panel, side panels extending vertically between the bottom panel and the top panel, and end panels extending vertically between the bottom panel and the top panel, the housing defining a product compartment; one or more bottom cooling layers located in use between the bottom panel and the payload; one or more top cooling layers located in use between the payload and the top panel; wherein the packaging system further comprises: a plurality of hollow vertical posts disposed within the product compartment and adjacent at least one of the side panels or end panels, each vertical post having an open top end and an open bottom end and defining a vertical inner space within the vertical post; wherein adjacent vertical posts define a vertically oriented channel between the vertical posts; and wherein the plurality of vertical posts are spaced from the top panel and the bottom panel a sufficient distance to allow air to flow through the vertical inner space within each vertical post; characterized in that each vertical post has a triangular cross sectional profile, and each vertical post comprises an outer facing side adjacent a side panel or an end panel and two angled sides extending from opposing vertical edges of the outer facing side and meeting along an elongated vertical inner edge. a plurality of hollow vertical posts disposed within the product compartment and adjacent at least one of the side panels or end panels, each vertical post having an open top end and an open bottom end and defining a vertical inner space within the vertical post; wherein adjacent vertical posts define a vertically oriented channel between the vertical posts; and wherein the plurality of vertical posts are spaced from the top panel and the bottom panel a sufficient distance to allow air to flow through the vertical inner space within each vertical post; characterized in that each vertical post has a triangular cross sectional profile, and each vertical post comprises an outer facing side adjacent a side panel or an end panel and two angled sides extending from opposing vertical edges of the outer facing side and meeting along an elongated vertical inner edge.