An insulating panel 1 comprises a first sheet 2, a second sheet 4, and a body of insulating foam 5 between the sheets 2, 4. The foam 5 has a plurality of longitudinally extending conduits 7 through which a heat exchange medium such as air is circulated. A barrier 10 is used to create an enlarged void space for air circulation. The barrier is located below profile crowns 3 to prevent foam from entering the crowns 3 and to create additional foam-free voids below the crown. Heat transfer efficiency is increased.