The design and specification of the dwelle.ings will potentially meet Passivhaus and Code Level 6 of the Code for Sustainable Homes. The exact standard achieved will depend on the specific dwelle.ing size, the site location, orientation of the building, the choice of renewable energy/heating system and whether the triple glazed windows option has been selected.
The U-value of the walls is 0.15 W/m²K, the elemental U-value of the windows is typically 0.76 W/m²K (depending on size) and the air leakage is no more than 0.75 m³/m²hr @ 50 Pa (0.6 air changes per hour).
The design of the smaller dwelle.ings are capable of performing up to Code Level 5, however there are difficulties in achieving the mandatory Fabric Energy Efficiency standards in the ENE 2 category. The difficulty arises due to an apparent anomaly in the SAP methodology that penalises relatively small detached buildings, even though they are highly insulated, air tight and thermally efficient.
The larger dwelle.ings could meet Passivhaus and actually surpass the Code for Sustainable Homes Level 5 and meet Code Level 6, with them also being Lifetime Homes compliant.