Blowerdoor testing (also known as airtightness testing or air leakage testing) is a diagnostic process that measures how airtight your building is by identifying unwanted air leaks. During the test, we install a calibrated fan into an exterior doorway to create a pressure difference between inside and outside. This allows us to measure the air leakage rate and identify where drafts are occurring. Airtightness is critical for energy efficiency, thermal comfort, indoor air quality, and achieving building certifications like Homestar, Green Star, Passive House, and H1 compliance in New Zealand. Testing is essential for ATTMA accredited projects and helps ensure your ventilation systems (like HRV) work effectively.

H1 compliance refers to meeting the requirements of Clause H1 of the New Zealand Building Code, which governs energy efficiency in buildings. H1 requires buildings to have adequate thermal insulation and limit uncontrolled airflow to conserve energy. There are three main compliance pathways: Schedule Method (using minimum R-values from tables), Calculation Method (using building physics calculations), and Verification/Modelling Method (using energy modelling software). All new buildings in NZ must comply with H1 requirements for insulation, thermal bridging, and airtightness. Our building science team can help you achieve H1 compliance through thermal calculations, energy modelling, and verification reports. For a step-by-step breakdown of the three H1 pathways and when to use each, check out our H1 compliance service.

ATTMA (Air Tightness Testing and Measurement Association) is the leading UK-based organization that sets technical standards for airtightness testing. ATTMA has two main levels of accreditation: Level 1 for residential buildings and Level 2 for large commercial buildings. ATTMA Level 2 (TSL2) testing is required for Green Star projects in New Zealand and Australia, which require rigorous building envelope commissioning and airtightness verification. Our testers are ATTMA Level 2 certified, meaning we follow internationally recognized standards (ISO 9972) for measuring building airtightness on commercial projects, apartments, and large residential developments. This certification ensures accurate, reliable testing that meets the stringent requirements of sustainable building rating systems.

Airtightness testing is a key component for achieving higher Homestar and Green Star ratings. Homestar (for residential buildings in NZ) awards points for measured airtightness - the tighter your building, the more points you earn toward your rating. A typical new code-compliant home achieves 2-4 Homestar, while well-sealed homes can achieve 6-10 Homestar. Green Star (for commercial buildings) requires mandatory airtightness testing as part of Building Enclosure Commissioning (BECx). To earn airtightness credits in Green Star, testing must comply with ISO 9972 or ATTMA standards. Blowerdoor testing provides quantifiable proof of building performance, helping you meet sustainability targets and demonstrate energy efficiency to certifying bodies.

Condensation occurs when warm, moisture-laden air comes into contact with cold surfaces, causing water vapour to convert to liquid water. This commonly happens on windows, walls, and within building cavities when there's insufficient insulation or ventilation. Condensation can lead to mold growth, timber rot, and structural damage if left unaddressed. Building science helps prevent condensation through proper building physics analysis, including thermal calculations to identify cold spots (thermal bridges), condensation risk assessments using methods like the Glaser method, proper insulation design, air barrier and vapour control layer specification, and adequate ventilation design. Our condensation assessments help you understand dew point temperatures, relative humidity levels, and how to maintain healthy, dry indoor environments through proper building design and H1 compliance.

A standard residential blowerdoor test typically takes 1-2 hours, depending on the size and complexity of the building. Commercial or large-scale ATTMA testing may take longer. Before we arrive, your building should be at practical completion - all exterior doors, windows, and penetrations should be installed and sealed. Interior doors should be open, and mechanical ventilation systems should be switched off. All designed openings (like vents and flues) will be temporarily sealed during the test. We measure air leakage at multiple pressure differentials, identify problem areas using smoke pencils or thermal imaging, and provide you with a detailed report showing your air changes per hour (ACH) and any areas requiring attention. The test results help determine if your building meets H1 compliance, Passive House standards, or certification requirements for Homestar and Green Star.