Why Australian Homes Overheat in Summer and Freeze in Winter
Climate Change Is No Longer a Future Issue
Many discussions around climate change focus on outdoor temperatures.
But people experience climate primarily through buildings.
Recent climate projections from CSIRO and the Intergovernmental Panel on Climate Change indicate that Australia is already experiencing measurable climate change impacts, including rising temperatures, more frequent heatwaves, harsher fire weather and changing rainfall patterns.
At the same time, many Australian homes were designed around climate conditions that no longer reflect current or future realities.
A recent international review published in Environmental Research reviewed 38 studies examining how housing conditions influence health outcomes during climate related events such as heatwaves, flooding and extreme weather.
The findings suggest that housing is becoming increasingly important not simply as shelter, but as critical infrastructure for health, resilience and climate adaptation.
Increasingly, discussions around sustainable housing are also becoming discussions about healthy homes. Homes that support stable indoor temperatures, fresh air, moisture management and long term wellbeing.
We Experience Climate Through Buildings
The cold bathroom in winter.
The overheated upstairs bedroom after a run of hot days.
The western sun turning a living room into an oven by late afternoon.
The restless sleep during heatwaves when homes struggle to release accumulated heat overnight.
Many Australians have come to accept these experiences as normal.
But increasingly, research suggests they may also reflect how our homes were designed and whether they are equipped for a changing climate.
Research into indoor heat exposure has shown that indoor temperatures can sometimes exceed outdoor temperatures, particularly in poorly insulated or poorly ventilated homes.
Australian studies examining heatwaves and housing have found that poorly insulated or poorly ventilated homes can retain dangerous levels of indoor heat, particularly during prolonged hot periods and warm nights. Vulnerability is often greatest among older residents, renters and households with limited access to cooling.
Importantly, people experience climate primarily indoors.
Many older homes across Australia struggle to maintain comfortable indoor temperatures during both winter cold and summer heatwaves.
Why Australian Homes Often Feel So Uncomfortable
Research suggests the average Australian home built before 2003 performs at only around 1.8 stars under the Nationwide House Energy Rating Scheme, providing relatively little protection from outdoor conditions.
Research comparing temperature related deaths in Australia and Sweden found that Australia experiences higher rates of cold related deaths despite Sweden’s much colder climate. The findings have contributed to wider discussion around the poor thermal performance of many Australian homes, sometimes described as “glorified tents”.
It is not uncommon to hear Australians returning from countries such as Sweden or Finland remark that homes there feel significantly warmer and more comfortable during winter than many Australian homes, despite far colder outdoor temperatures.
Researchers suggest this comes down less to climate itself and more to building performance. Better insulation, airtightness, glazing and heating standards mean Scandinavian homes are typically designed to maintain stable indoor comfort throughout winter.
In many colder European countries, homes are designed to maintain relatively stable indoor temperatures year round. In contrast, many Australian homes still rely heavily on portable heaters or oversized cooling systems attempting to compensate for poor insulation, draught leakage and inconsistent thermal performance.
There is also a strong cultural layer to this conversation. Recent commentary has explored the idea of Australian “winter stoicism”, the tendency to normalise cold and uncomfortable homes because Australia is perceived as a warm country.
For many people, discomfort has simply become part of everyday life. Working from home wrapped in blankets, moving portable heaters from room to room, closing blinds against western heat, or struggling to sleep through increasingly warm nights.
But these experiences are increasingly being linked to building performance, housing quality, rising energy bills and urban conditions.
Climate Is Increasingly Becoming an Indoor Health Issue
The relationship between housing and health is becoming increasingly difficult to ignore.
Studies reviewed in the Home Baked: Housing, Heat and Health report found that extreme heat contributes to more deaths in Australia than all other natural disasters combined, including bushfires and floods.
At the same time, research also suggests that cold indoor temperatures remain a significant health issue in Australia.
A large international Lancet study examining more than 74 million deaths across 13 countries found that moderate cold was associated with far more temperature related deaths than extreme heat. Researchers have linked Australia’s relatively high rate of cold related deaths partly to poor housing performance and inadequate insulation.
Heat exposure and cold indoor temperatures have both been linked to:
- cardiovascular strain
- respiratory illness
- dehydration
- sleep disruption
- mental health impacts
- increased mortality
This becomes especially significant for:
- older adults
- young children
- people with chronic illness
- people with mobility challenges
- and those spending long periods at home
Importantly, vulnerability is not evenly distributed.
People living in poor quality housing, rental accommodation or homes without effective cooling are often more exposed to dangerous indoor temperatures.
Renters interviewed as part of the Home Baked report described bedrooms remaining above 30°C overnight, sleeping on tiled floors to stay cool and feeling powerless to request improvements from landlords.
Some Australian studies have also identified “bill anxiety”, where households avoid using heating despite uncomfortable indoor temperatures due to rising energy costs.
Heatwaves, Sleep and the Home
Sleep is emerging as a particularly important issue in discussions around climate adaptation and housing performance.
Recent Australian research examining heatwaves and sleep found that rising night time temperatures can make it harder for the body to cool itself before sleep, resulting in lighter sleep, more frequent waking and reduced overnight recovery.
As climate change drives hotter nights, in some regions faster than daytime warming, the design of bedrooms, ventilation pathways, shading and thermal performance may become increasingly important to long term wellbeing.
Research increasingly suggests that climate change is not only an outdoor environmental issue, but also an indoor comfort and health issue.
Comfort Is Shaped by Design
The research repeatedly points toward the importance of the building envelope and integrated passive design strategies, rather than relying solely on larger heating and cooling systems.
Factors influencing comfort and resilience include:
- orientation
- shading
- ventilation
- glazing performance
- insulation
- airtightness
- thermal mass
- material selection
- surrounding landscape conditions
Increasing awareness around Passivhaus design has also helped shift broader conversations around indoor comfort, energy efficiency and healthy homes.
Importantly, adaptation is rarely about a single fix.
Adding insulation without considering ventilation can increase overheating risk. Airtight homes without appropriate fresh air strategies may affect indoor air quality. Increased air conditioning use can also place further strain on energy systems during heatwaves.
Future-focused housing increasingly requires integrated thinking, balancing energy efficiency, comfort, ventilation, moisture management and resilience together.
Poor thermal performance not only affects comfort, but can also contribute to rising heating and cooling costs over time.
Designing Homes for a Changing Climate
Designing for climate adaptation does not necessarily mean every home needs to become a highly technical or fully certified performance building.
Often, meaningful improvements can begin with relatively practical measures such as:
- improving draught sealing
- adding external shading
- improving insulation
- upgrading glazing
- improving ventilation
- reducing moisture risks
- increasing tree canopy and landscape shading
- considering how homes respond to both winter cold and summer heat
The goal is not perfection.
It is creating homes that feel healthier, calmer, more comfortable and more resilient over time.
As climate conditions continue to change, the performance of our homes will increasingly shape not just how efficiently we live, but how safely and comfortably we experience everyday life.
Sources and Further Reading
This article draws on research and reporting from:
- CSIRO State of the Climate Reports
- Intergovernmental Panel on Climate Change (IPCC)
- Environmental Research
- The Lancet
- Home Baked: Housing, Heat and Health
- Nationwide House Energy Rating Scheme (NatHERS)
- Research from Australian universities and housing researchers examining thermal comfort, indoor heat exposure and climate adaptation
- Passivhaus research and design principles relating to indoor comfort, ventilation and energy efficiency
