How does the insulation calculator work?
This calculator determines the thermal resistance (R-value) of your van's insulation build-up and calculates the total heat loss in Watts. This helps you choose the right materials, thickness and heating system.
R-value calculation
Each insulation layer has a thermal resistance: R = thickness (m) / λ (W/m·K). The total R-value of a surface is the sum of all layers plus the internal and external surface resistances (Rsi and Rse) per EN ISO 6946. For walls: Rsi = 0.13, Rse = 0.04. For a roof: Rsi = 0.10 (heat flows up). For a floor: Rsi = 0.17 (heat flows down).
U-value and heat loss
The U-value is the inverse of the R-value: U = 1 / R. It indicates how many Watts of heat flow through 1 m² per degree temperature difference. The heat loss per surface is: Q = U × area × ΔT. The total heat loss is the sum of all surfaces plus windows.
Uninsulated comparison
A bare steel panel (approximately 2 mm) has a U-value of about 5.88 W/m²K. The calculator compares your insulated build-up against this baseline to show how much heat loss you save. Even a thin layer of insulation makes a huge difference.
Quellen und Normen
Die R-Wert-Berechnung folgt EN ISO 6946 (Wärmedurchlasswiderstand von Bauteilen). Oberflächenwiderstände (Rsi/Rse) stammen aus derselben Norm. Lambda-Werte (λ) der Dämmstoffe basieren auf Herstellerangaben und EN 12667/EN 12939 (Messverfahren für thermische Eigenschaften). Typische Werte: PIR 0,022 W/m·K, XPS 0,034 W/m·K, Armaflex 0,036 W/m·K, Steinwolle 0,035 W/m·K. U-Werte der Verglasung (Einfach 5,8 / Doppelt 2,8 W/m²K) sind Richtwerte aus EN 673.
Frequently asked questions
What is a good R-value for a camper van?
For walls, aim for R ≥ 1.5 (e.g. 30 mm PIR + 19 mm Armaflex). For the roof R ≥ 2.0 is recommended since heat rises. The floor can be slightly less, R ≥ 1.0, because the ground acts as a buffer. These values keep a diesel heater comfortable down to about -5°C.
Does adding more layers always help?
Yes, R-values are additive: each layer adds its R to the total. However, the benefit of each additional centimetre decreases. Going from R 0.5 to R 1.5 saves far more heat than going from R 2.5 to R 3.5. Thickness and weight are often the limiting factor in a camper van.
What about thermal bridges?
Metal ribs, screw points and window frames act as thermal bridges — they short-circuit the insulation. This calculator does not model individual bridges, but as a rule of thumb, thermal bridges increase heat loss by 10–20%. Covering ribs with Armaflex or foam tape helps significantly.
How big a diesel heater do I need?
Match the heater output to your calculated heat loss. A 2 kW heater is fine for a well-insulated medium van (Ducato L2H2) down to about -5°C. For larger vans, poor insulation, or extreme cold, a 4 kW unit is safer. The heater should be able to run below maximum for comfort and fuel economy.
Wie viel Isolierung brauche ich für den Wintereinsatz?
Für komfortablen Wintereinsatz (bis -10°C) brauchen Sie mindestens R-Wert 3 in den Wänden und R-Wert 4 im Dach. Das entspricht z.B. 40mm Armaflex oder 30mm PIR.
Ist Armaflex besser als PIR?
Armaflex ist flexibel und füllt unregelmäßige Formen gut, hat aber einen niedrigeren R-Wert pro mm. PIR ist dünner bei gleichem Isolierwert aber starr. Viele Ausbauer kombinieren beides: PIR auf Flächen, Armaflex in Ecken.