Click on the image to see the as-built SAP/EPC scores for Edge O Cliff house and the ridiculously low air permeability test result of 0.229 (Q50 – [m³/h/m²] at 50 Pa). South West Air Energy also calculated the air changes/hour (N50) at 0.242ACH (the Passive House standard requires less than 0.6ACH). We think that Umbazi (builders) may have constructed the most airtight house in the UK to date.