Until now the generally applied aluminium distance frames, an essential element in double glazing, with ever improving window frame and glazing heat conductivity coefficient values were shown to be the weak point in combined pane construction. Aluminium has significantly greater heat conductivity than the remaining window components. The aluminium frame around the edge of the pane is the last route of excessive heat penetration from the room to the exterior. This effect has been taken into account in the new approach to calculation of the coefficient Uw of the window and has been described with coefficient Psi (Ψ). The solution to this problem may be the application of a distance frame, called warm frame, executed from compound insulation material or fine steel.
The use of „warm edge” improves thermal insulation at the edges, which ensures higher temperature of glass in this area and reduced risk of temporary water vapor condensation. The effect is that permissible relative air moisture, which in given conditions forms water vapour, may due to the application of “warm frames” be higher by approximately 10-15{cae6c5075036641cf5600fc8c8efcf6a097e71654492c69f785b7526fa8c80cb} and shall not cause the occurrence of water vapour condensation. The permissible external minimal temperature, at which water vapour condenses on pane surfaces, is also reduced.