Compact buildings with good thermal protection
All components making up the building envelope must be well insulated. Edges, corners, connections and penetrations must be planned with special care in order to avoid thermal bridges. All opaque building components should be so well-insulated that their heat transfer coefficients (U-values) do not exceed 0.15W/(m²K), meaning that no more than 0.15 watts of heat energy are lost though the external envelope per degree Kelvin and square meter. For free standing, single family homes, these U-values are often under 0.10 W/(m²K). The more compact the building envelope, the easier and more cost-efficient it is to reach the Passive House Standard.