The Challenge

The owners of a heritage-listed home in Ainslie, Canberra sought to dramatically improve their home’s energy efficiency without altering its architectural character. Traditional insulation methods would have required major deconstruction and risked damaging the heritage fabric. The mixed structure of brick veneer and lightweight cladding, combined with Canberra’s cold climate, made achieving airtightness, condensation control, and NCC 2022 compliance particularly complex.

Methodology

The project adopted a performance-based approach supported by advanced hygrothermal modelling (WUFI) and blower door testing. Dynamic simulations assessed moisture behaviour, mould risk, and long-term durability across wall and roof assemblies. Strategic coordination between insulation and services ensured airtightness was maintained while preserving access for trades. The insulation was applied prior to rough-ins, allowing clean service cavities and optimal integration with HVAC and ventilation systems.

Solution

Using Heatlok® Closed-Cell Spray Foam from Huntsman Building Solutions, supplied and supported by Pacific Urethanes, the team achieved a seamless, high-performance building envelope. The foam was applied directly to internal brick veneer and roof surfaces, creating a continuous air and moisture barrier that exceeded NCC 2022 requirements.

A blower door test recorded an exceptional result of 1.56 air changes per hour (ACH), far outperforming the industry benchmark of ≤10 ACH under NCC verification standards. This confirmed airtightness levels comparable to international passive house standards, demonstrating that heritage preservation and modern efficiency can successfully coexist.

Phase II will capture completed photography, conduct a final blower door test, and gather testimonials from the homeowners, builder, and certifier, concluding the project’s full performance and lived-experience story.

Conclusion

The Ainslie Heritage Retrofit sets a new benchmark for sustainable building upgrades in heritage contexts. By combining modern spray foam technology with scientific validation and precision installation, the project achieved airtightness performance rarely seen in Australian retrofits. It proved that deep energy transformation can be achieved without sacrificing architectural legacy. This project now stands as a model for future retrofits across Australia, where comfort, efficiency, and heritage can truly align.