“Homes built before 2003 rate woefully for minimum energy ratings”
The Climate Council does not mince words when it comes to Aussie homes. Their report on home energy performance confirms what many homeowners feel every winter and summer. Most Australian homes built before 2003 were never designed with comfort, efficiency or airtightness in mind.
They were built in an era with almost no insulation standards, no thermal requirements and no expectation that a home should actually retain the heating or cooling you pay for. The result is millions of houses that leak heated and cooled air through the walls, subfloor, and ceiling almost as fast as units can produce it.
These homes are draughty, inefficient and expensive to run. Unfortunately, our earlier building standards did not protect homeowners from rising energy costs or extreme weather.
How Australia’s Energy Standards Actually Changed.
Our standards finally changed in 2003, when the Building Code of Australia introduced the first mandatory energy-efficiency provisions for new homes. It’s been slow to roll out minimum star ratings, but as of 2022, many jurisdictions now require a 7-star performance for new homes, along with stricter rules on building-envelope efficiency.
Why Is My Home So Cold in Winter?
Australian homes lose heat incredibly quickly because they’re not airtight. Heating or cooling a leaky home is like trying to warm a room with the windows left open. Warm air escapes, cold air pushes in, and the temperature never truly settles.
If you’ve ever spent time in a Canadian or American home during negative temperatures, you’ll understand the difference immediately. Those homes stay warm because airtightness is treated as essential, and every part of the building is sealed to keep conditioned air inside.
The Issue With Underfloor’s
Many homeowners don’t realise how much of the air inside their home comes from below their feet. Some building guidance suggests that up to 42% of the air entering a home can originate from the subfloor or crawl space. If that cavity is cold, damp, or filled with outside air, it can move upwards into the living space, making it impossible to maintain a comfortable indoor temperature.
This is driven by the Stack Effect. It works when there’s a substantial pressure differential between the internal and external environment, caused by temperature differences.
During the winter, warm air rises and escapes through gaps at the top of your home, which creates suction that pulls cold outside air in through gaps at the bottom of your subfloor. In the summer, the opposite happens. Radiant heat warms up your ceiling cavity, pushing down your cool air from the AC into the gaps through your subfloor.
Insulation helps, but airtightness is what stops the movement of air that ruins efficiency.
What’s the Solution? The Importance of Underfloor Insulation
If you live in an older, leaky home, improving comfort and efficiency comes down to one principle: you must stop uncontrolled air movement. The only way to do that properly is by sealing the building envelope and using insulation that improves both thermal resistance and airtightness at the same time.
Why Most Insulation Products on the Market Fall Short
Many homeowners assume that simply adding more insulation will fix their temperature problems. This is where things go wrong. Most common insulation products in Australia were designed to meet minimum R-values, not to address the much bigger issue: air leakage.
Here is why traditional products struggle.
Batts (Glasswool, Polyester, Rockwool)
Batts are the most common insulation in Australian homes, but they have significant limitations:
- They only slow heat transfer. They do not seal gaps.
- Air can move freely around, behind and through them.
- They rely on perfect installation, which adheres to manufacturing guidelines (which is nearly impossible to achieve)
- Small gaps around edges can reduce their real-world performance by half.
- They sag over time, especially under floors or in humid conditions.
Batts can improve an R-value on paper, but in a draughty house, they do nothing to stop cold air from entering or warm air from escaping.
Why YetiFoam is so Effective
Traditional insulation only slows heat transfer, but it does little to address the air leakage, moisture movement and draughts that make older homes uncomfortable. This is where polyurethane systems like YetiFoam offer a real advantage.
When applied, YetiFoam expands to fill gaps and cracks and bonds tightly to timber and metal. This creates a continuous air barrier that modernises the building envelope rather than simply lining it with insulation.
The result is high thermal performance, reduced moisture and vapour movement and far more stable indoor temperatures throughout the year.
In older homes, especially those with raised timber floors, underfloor insulation of this type can transform day-to-day comfort by stopping cold air from flooding in from below and keeping conditioned air inside. It remains one of the most cost-effective ways to achieve the airtightness and efficiency of a modern build without needing to reconstruct your entire home.
Why Insulation Matters More in Australia Than Ever
With rising energy prices and more extreme weather patterns, Australians are finally realising that comfort and efficiency are not luxuries. They are essential. It’s estimated that residential energy usage is responsible for about 29% of what’s taken from the grid. If you look at countries like Canada (which are far colder), a recent report estimates that number to be 22%. Our homes need to be better.
Insulation plays a major role in reducing heat loss, improving comfort and lowering bills. But insulation alone is not enough. The real answer is insulation plus airtightness, just like the USA, Canada and Europe have been doing for decades.