An energy absorber for use in an opening of a wall of a building, the opening defined by a perimeter surface, the wall supporting a closure substantially filling the opening, the closure having respective edges which are substantially parallel to the perimeter surface of the opening. The energy absorber having a planar wall connecting portion, a planar closure connecting portion and a plastically deformable deforming surface therebetween. The connecting portions being substantially parallel to one another and, the deforming surface adapted to absorb, by plastic deformation, a force applied to the closure.