Quality assurance, construction supervision, commissioning and certification process
Quality assurance through the build
Certification depends on evidence, not intention. The chain includes design review, a thermal-bridge catalogue, site inspections at key stages (foundation, airtight layer, window installation, services) and photographic records. The airtightness test is performed by an independent tester with the building in its final state; the ventilation system is balanced and commissioned with measured airflows.
Commissioning and the certification file
Commissioning covers the ventilation unit (airflows, filters, frost protection, summer bypass), heating and DHW (setpoints, circulation, controls) and owner documentation. The certifier reviews the PHPP, blower-door report, component certificates and completed checklists before issuing the certificate.
Worked example: blower-door result
A dwelling of 350 m³ measured volume shows 150 m³/h leakage at 50 Pa. n50 = 150 / 350 = 0.43 h⁻¹, passing ≤ 0.6. If the same building measured 250 m³/h, n50 = 0.71 h⁻¹ and it fails; the remedy is locating leaks with a smoke pencil or thermography and sealing service penetrations, not simply retesting.
Traps
Testing before the envelope is complete or with openings sealed. Using design airflow instead of measured airflow for ventilation commissioning. Missing component certificates (windows, HRV, membranes) so the certifier cannot verify claimed values. Submitting a PHPP that no longer matches the as-built drawings is the most common cause of a delayed certificate.