FAQ
What is a blower door test, and why is airtightness critical for modern sustainable builds?
SustainaBuilding utilizes in house blower door testing to depressurize and pressurize the structural envelope, allowing us to accurately locate and seal microscopic air leaks before internal linings are installed. Conducting these tests to strict ATTMA standards ensures your building acts as a sealed thermal barrier. Minimizing uncontrolled air infiltration is the single most effective way to optimize your mechanical heating and cooling systems, eliminate incoming drafts, and maintain exceptional indoor air quality.
Explore the mechanics of high-performance sealing in our article: The Airtight Revolution: The Future of Sustainable Building in Australia.
Why does SustainaBuilding recommend a NatHERS 8-star energy rated home with HRV as minimum spec?
The minimum 7-star NCC regulatory baseline on paper function like an insulated sieve in reality. It also ignore structural air leakage and thermal bridging through the framing, leaving Adelaide Hills homeowners with drafty, expensive-to-run properties. True lifetime energy efficiency requires rigorous airtightness and insulation design with independent building science modelling rather than just ticking a regulatory box. Through modelling and building many forever homes we have found we always achieve an airtightness result of less than 5 air changes per hour at 50 pascals, which requires us to have mechanical ventilation under the NCC. A good thermal envelope (high levels of insulation, good window placement and airtightness) is the key to an energy efficient comfortable home.
Learn how to avoid common structural pitfalls in our article: The Performance Gap: Why Your 7-Star Dream Home Might Be a Performance Failure.
I get condensation on my windows, this can lead to toxic mould growth! How do you defend against this?
As modern Australian homes become more heavily insulated, preventing internal moisture accumulation requires advanced hygrothermal analysis and controlled structural ventilation as well as the elimination of thermal bridges like your aluminium window frames. SustainaBuilding uses detailed moisture-movement modelling to predict how water vapor behaves within wall, roof and floor assemblies under localized weather stress. By pairing smart, vapor-permeable membranes with continuous ventilation systems, UPVC double glassed windows, we eliminate the hidden condensation points that cause toxic mould growth and structural timber decay.
Discover our complete structural moisture defence strategies in our guide: The Hidden Enemy: How to Defend Your Home Against Condensation.
What real-world airtightness and blower-door test metrics do SustainaBuilding homes typically achieve?
SustainaBuilding targeted performance metrics are an air permeability of <10 for renovations and additions (whole of home), <5 for new builds and <0.6 for PassivHaus. Unlike other builders, we put these numbers into our contracts (exclusions apply to some renovations and additions).
But in practice we achieve much better results. For instance our worst result for a new home is a air permeability of 1.35, and our best result for an addition (whole of home) is 1.68.
This rigorous quality control ensures an completely draft-free interior and permanently protects the internal building structure from hidden moisture damage.
