The aim of the invention is the reduction of heat loss in the area of the joints in conversion from the cold into the warm zone. This aim is achieved by the structures, the material and the shape of the profiles of the heat insulator, when the desired insulator/profile is constructed from composite materials with low thermal conductivity, thereby the heat loss reduces, and with high strength, thus it is able to transmit all the loads from the panels to the supporting structure of the casing. Thermal insulator, one or multi-chamber is set between the fillings, passes from the cold zone and touches by at least one of its ends into the warm zone between the filling and the supporting profile.