Australia’s building sector has long been recognised as both a challenge and an opportunity in the transition to a low-carbon economy.
Homes and commercial properties are responsible for a large share of the country’s energy use and emissions, both from the electricity and gas that run them and from the carbon embedded in their concrete, steel and insulation.
Many of Australia’s homes remain some of the least efficient in the developed world, often cold in winter, hot in summer, and powered by fossil gas.
The government’s updated Trajectory for Low Energy Buildings, released in August 2025, signals a significant shift in policy and a broader understanding of how to align buildings with the net zero target by 2050.
The first version of the Trajectory, agreed in 2019, was built around a “fabric first” mindset. Its goal was to make new buildings “zero energy and carbon ready” by 2050. The way to get there was by tightening National Construction Code requirements for insulation, glazing and airtightness and by pushing thermal performance higher over time.
New residential standards were stepped up in NCC 2022, moving from 6-Star to 7-Star energy ratings, with a “whole-of-home” energy budget layered in. An addendum later that year extended the focus to existing homes and offices, recommending training, information, energy performance disclosure for buyers and renters, and minimum standards for rentals.
The 2019 plan assumed that efficiency had to come first, while electrification of heating, cooking and hot water was only vaguely acknowledged as part of a “zero carbon ready” outcome.
That strategy made sense on paper but it underestimated the limits of efficiency as a climate tool. International evidence has shown again and again that insulation and sealing often deliver smaller reductions than expected.
In the United Kingdom’s Warm Front program, low income households who received insulation upgrades did not reduce gas use over time. Instead they chose to live in warmer conditions. Germany spent hundreds of billions of euros on retrofits over two decades with no net fall in gas demand for heating.
A major US study found retrofit savings at less than half the modeled level. France saw insulation upgrades cut emissions by less than 20%, while replacing fossil heating with clean electric alternatives cut them by more than 80%. Rebound effects and comfort gains eroded the emissions payoff of efficiency when it was not paired with fuel switching.
The 2025 update responds to this experience. It keeps efficiency improvements as a core element but broadens the frame. It makes fuel switching to electricity explicit. It recognizes that shifting demand in time is as important as cutting total demand. It adds embodied carbon in materials to the agenda.
It points to the need for climate resilience in buildings so that they can keep people safe in extreme heat and flooding. It emphasizes equity through green finance and fair access. It also singles out refrigerant emissions from heat pumps and cooling systems as an area to manage carefully. Where the 2019 strategy was narrowly focused on fabric, the 2025 strategy reflects a wider systems perspective.
The differences are clear. What stayed is the drive to raise construction code standards and reduce operational energy use. What was added is a recognition that how buildings are powered matters as much as how well insulated they are. Electrification of space and water heating and cooking is now at the center.
Demand flexibility through smart controls and pricing is prioritized to smooth peaks and align loads with renewable generation. Cutting embodied carbon in steel, cement and insulation is now part of the plan.
Refrigerant management is recognised for the first time. Equity is brought forward with finance tools to make upgrades accessible. The strategic language has shifted from efficiency first to efficiency plus electrification and systemic decarbonization.
This shift aligns closely with what evidence and analysis have been showing. Heat pumps cut emissions much faster than insulation. Demand management can shave peaks more effectively than chasing 9-Star fabric upgrades.
Embodied carbon and refrigerants are large enough pieces of the puzzle that they cannot be ignored. The trajectory of global climate policy in other countries points the same way.
In the United Kingdom, the Climate Change Committee has reduced its emphasis on deep retrofits and now sees electrification plus targeted efficiency as the most cost-effective path. Time-of-use tariffs and thermal storage are being used to shift heating loads into daytime solar windows or nighttime valleys. Australia’s strategy is catching up to these insights.
The strengths of the updated strategy are significant. By embracing electrification, it points directly at the fossil gas network that must be wound down. By calling out demand flexibility, it addresses grid concerns with modern tools rather than overbuilding the fabric of every house.
By adding embodied carbon and refrigerants, it takes a comprehensive view of building emissions. By framing equity and green finance as part of the plan, it increases the chance that households of all income levels can participate. By including resilience, it acknowledges that climate change is already here and buildings must protect their occupants.
The weaknesses lie in how it might be implemented. If governments and regulators cling to a “fabric first” sequence, requiring costly insulation upgrades before allowing electrification, adoption of heat pumps could be slowed. If there are no clear national mandates to stop new gas connections or sales of gas appliances, then momentum could falter.
If the target is framed only around 2050 without firm milestones for 2030 or 2040, urgency may be lost. If modeled savings from efficiency are overestimated without accounting for rebound, emissions may not fall as quickly as projected. These are risks that could blunt the impact of what is otherwise a forward-looking strategy.
The path forward for Australia is to make electrification unambiguous. New buildings should be all-electric on a short timeline. Replacement of gas heaters and cooktops should be accelerated with incentives and standards.
Efficiency upgrades should be pursued, but in a pragmatic way that makes homes comfortable and right-sizes heat pumps without chasing perfection. Green finance should be scaled so that households can afford the transition. Embodied carbon targets should be embedded into procurement and codes, and refrigerant leakage should be tightly managed.
The updated Trajectory for Low Energy Buildings is a major step for Australia. It acknowledges that reducing energy demand is not enough, that the fuel source matters, and that the full lifecycle of buildings must be addressed. It recognises that buildings must serve people, not just carbon metrics, by providing health, safety and comfort in a hotter, more volatile climate.
The lesson of international experience is clear. Insulation and efficiency matter, but they are not the main event. Electrification is.
If Australia follows through on that insight, its buildings can become clean, affordable, and resilient far sooner than 2050. The decisions taken in the next decade will determine whether the sector is still clinging to gas or fully part of the clean energy future.
