Thermal insulation capacity
Finnfoam's thermal conductivity:
|Nominal thickness||20...30 mm||40...70 mm||80...120 mm|
U value, which is calculated using the thermal conductivity of the materials, does not reveal the entire truth regarding the insulation capacity of the structure. The structure's leakage rate n50 also has a significant effect on the insulation capacity of the structure. Increased impermeability means higher thermal insulation capacity! Finnfoam's completely consistent and closed cell structure is impermeable. The U value does not consider the internal convection of the structure, which intensifies as the temperature difference increases. Finnfoam's structure does not allow internal convection.
Finnfoam's thermal insulation capacity is nearly independent of the working conditions. The closed and completely consistent cell structure effectively retains pure air that functions as cell gas, whose thermal conductivity (λ10) is 0.026 W/(m K).
Air flow is unable to weaken the insulation capacity of the insulation and thus it can also function as a wind shield where necessary. Finnfoam's thermal conductivity (λ10) is 0.029–0.034 W/(m K), depending on the panel type. The waterproof Finnfoam will also retain its insulation capacity in moist conditions, which is very important for frost protection.
A structure that only uses Finnfoam for thermal insulation does not require separate wind shielding. However, due to moisture control, Finnfoam cannot be used as a lightweight wind-protective panel with wool-insulated walls for example.
Finnfoam's cell gas is air, which means that its insulation capacity is not reduced over time. Because the thermal conductivity of air weakens as it cools, Finnfoam’s insulation capacity actually increases as the temperature reduces. Finnfoam's insulation capacity is at its highest in freezing conditions. The design temperature of frost protection is -5 °C, at which point Finnfoam's insulation capacity has already increased. As water is unable to permeate Finnfoam, the frost insulation's design thermal conductivity in accordance with the current CE marking and the European standard is even better (0.034 or 0.036) than in dry conditions (0.035 or 0.037). In dry conditions the design thermal conductivity is often the same as the lambda declared value. Due to its consistency, Finnfoam doesn't allow for harmful airflow or reduction of thermal conductivity over time, as air is used as the cell gas.