Abstract: A prefabricated panel for forming walls and roofs of buildings includes a concrete planar portion having a first face and a second face, at least one concrete rib projecting from the first face, at least one block of insulating material fitted adjacent to the first face and the at least one rib, a plastic stud channel secured over at least one of the at least one rib, anchors for securing the panel to a foundation. A polystyrene strip is preferably contained within each plastic stud channel. The anchors preferably include a first angle-iron plate having first and second planar portions, the first planar portion being contained within one of the concrete ribs and the second planar portion being exposed and parallel with the exterior of the rib, a second angle-iron plate having first and second planar portions, the first planar portion being fastened to the second planar portion of first angle iron plate and the second planar portion being secured to the foundation.