Retrofitting Existing Buildings and the Embodied Carbon Imperative
October 2026
This blog post is adapted from a presentation prepared and delivered by Jane Cameron Finlay at the THRIVE 2026 Passivhaus Conference and through the 2026 Passivhaus Incubator Program, as part of the Retrofit Committee’s contribution to both events.
I believe the future of our built environment will be defined by how we transform the buildings we already have.
With Passivhaus, we have shown that it is possible to create buildings that are exceptionally comfortable, healthy and ultra-low energy. The challenge now is to bring those benefits to the places where Australians already live, work, learn and gather.
Our existing buildings represent an enormous opportunity to reduce energy use, extend the life of valuable materials and avoid the emissions associated with replacing them. Retrofitting must become a central part of how we reduce the carbon impact of our built environment.
Why Existing Buildings Matter
A 2021 Australian study estimated that more than 70 per cent of the country’s existing residential buildings would still be in use in 2050. Improving their performance will be essential to achieving meaningful emissions reductions.
For homeowners, this means recognising the potential in the house they already have. An older building may be uncomfortable, draughty or expensive to heat and cool, but these shortcomings do not necessarily justify demolition. A carefully planned retrofit can address performance while retaining the structure, character and qualities that make a home worth keeping.
The same thinking applies to schools, offices, apartments and other buildings across our cities.
Looking Beyond Operational Energy
For many years, the focus of sustainable building design has been on operational energy: the energy used to heat, cool, ventilate and run a building. Passivhaus has demonstrated how substantially this demand can be reduced.
We also need to account for embodied carbon, including the emissions generated by producing, transporting and installing building materials.
The Green Building Council of Australia’s 2025 report, Our Homes Weigh a Tonne, estimated average upfront emissions of around 185 tonnes of carbon dioxide equivalent for a typical new detached house. It compared this with approximately 24 tonnes from operation over an assumed 60-year life, allowing for projected electricity grid decarbonisation.
These figures highlight the importance of decisions made before construction begins. As electricity becomes cleaner, the emissions associated with new materials take on greater significance.
Retaining an existing building makes further use of materials whose production emissions have already occurred. The benefit is avoiding the new emissions that would arise from replacing them.
Measuring embodied carbon should therefore become standard practice. It allows us to compare retention, retrofit and rebuilding on a more informed basis.
Retain Transform Perform
The opportunity can be expressed in three words: retain, transform, perform.
Retain as much of the existing building as practical, particularly its structure and other durable materials. Transform it to meet contemporary needs. Improve its performance through Passivhaus principles so that it provides comfortable, healthy spaces with very low energy demand.
This approach also preserves neighbourhood character, cultural significance and a sense of place. These qualities are found in everyday buildings as well as those on heritage registers.
For me, this is one of the strongest arguments for retrofit. We can improve how a building works while retaining what makes it valuable.
Moving from Individual Homes to Retrofit at Scale
The Australian Passivhaus community has developed considerable expertise in retrofitting individual homes. The next challenge is to apply that knowledge more widely.
The Rifle Range retrofit in Williamstown demonstrates the potential of an ordinary volume-built brick veneer house. Carland Constructions describes the project as a transformation to the EnerPHit standard, the Passive House Institute’s standard for retrofits, while retaining the existing brickwork and roof tiles.
In my view, its significance extends well beyond one house. It demonstrates what could be achieved across the many similar homes in Australian suburbs. The lessons from this work can help make future retrofits more repeatable and accessible.
There are also opportunities beyond housing. At Ballarat Clarendon College’s Junior School, Williams Boag Architects have combined the adaptive reuse of existing buildings with new extensions to create high-performance educational facilities. The project demonstrates how existing places can be adapted to meet new uses and performance expectations.
Social housing also deserves particular attention. Improving the performance of these homes can reduce the burden of heating and cooling costs and improve comfort for people with limited resources to address building problems themselves.
The opportunity extends to apartments, offices, universities, schools and hospitals. Our task is to take what we have learnt from individual projects and make it applicable across this much broader building stock.
What Retaining a Tower Can Achieve
Quay Quarter Tower in Sydney demonstrates the value of retention at a very different scale.
Although it is not a Passivhaus project, its transformation offers an important lesson. Around two thirds of the existing columns, beams and slabs were retained. The Clean Energy Finance Corporation reports that reusing the existing structure saved more than 12,000 tonnes of embodied carbon and an estimated 12 months of construction time compared with rebuilding from the ground up.
For a commercial project, a shorter construction programme can also mean bringing the building back into use sooner and potentially receiving rental income earlier.
Recycling materials after demolition has a role, but retaining a serviceable structure avoids the need to dismantle it and manufacture a replacement. The concrete already in place can continue doing its job.
The same principle applies to a suburban home. Before deciding to demolish, we should understand what can be retained, how it can be upgraded and what replacement would cost in both financial and carbon terms.
Begin by Asking What We Can Keep
Every existing building deserves a considered assessment of its potential.
Retrofitting gives us the opportunity to improve comfort and operational performance, extend the useful life of materials and preserve the history and character embedded in our neighbourhoods.
I believe assessing retention and retrofit should become the starting point for our industry. Demolition should follow a considered evaluation of the alternatives.
Before we ask, “What should we build?”, let’s first ask, “What can we keep?”