The Passive House standard (PHI, Darmstadt) defines: heating energy demand <15 kWh/(m²a), air tightness n50 <0.6/h, U-value opaque components <0.15, triple glazing with U_g <0.8.
Passive House insulation materials require λ-values ≤ 0.032. For existing buildings, KfW-40 or -55 are often more cost-effective. See topic portal.