Lambda Value (λ)

Thermal conductivity of an insulation material in W/(m·K) — the lower the value, the better the insulating effect.

The λ-value (lambda) describes the thermal conductivity of a material. For insulation materials, it is the central performance metric.

Typical values: mineral wool 0.032–0.040 W/(m·K), EPS 0.030–0.040, PIR 0.022–0.028, wood fiber 0.038–0.042, vacuum insulation panel 0.006–0.008. The λ-value is combined with thickness to determine the U-value.

For passive house standards, λ-values ≤ 0.032 W/(m·K) are required.

Lambda Value (λ) – Thermal Conductivity of Insulation — Building Materials Radar