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Almost two years ago, my husband and I bought our dream home on the Gold Coast of Queensland, Australia: a 1980s brick house with three bedrooms, two baths, and 2,900-square-foot space. It has all the hallmarks of the era it came from — single-glazed windows, gaps that leaked air, gas appliances, and no insulation in the ceiling or internal walls — but we fell in love with it at first viewing.
The house had high ceilings, north-facing light pouring into the main living areas, and a sprawling backyard with space for all our garden plans. But living in a hot, humid climate, we knew the house wouldn’t cope with long summers or rising energy demands without changes. Gold Coast summers routinely push into the mid-80s with humidity hovering above 80% for much of the year. Even modest temperature increases feel oppressive. This past spring to summer was Australia’s second hottest on record, with temperatures well above average, and more days over 95°F than the years before.
With that in mind, our priority was to make our home comfortable and energy efficient, while preparing it for a harsher climate in the years ahead. Here’s how we did it.
We Added Insulation and Airtightness
Typical for older Australian homes, our house had zero insulation and heat transfer was a major issue. This means that in the winter, rooms that had been warm during the day would plummet to single digits overnight, and in the summer, the brick walls soaked up heat and released it long after sunset, keeping us much toastier than we’d like.
Overall, around 25% to 35% of heat is lost or gained through the roof, and another 15% to 25% through the walls, according to Sustainability Victoria. We knew insulation was the most affordable and effective way to make the house more comfortable and drive down our energy bills.
For insulation, we looked at a few options — natural wool was too expensive. Natural wool with the recycled polyester batts was appealing, but we were worried about the acoustic performance as we both worked from home, and cellulose fiber was messy to install, which was not ideal in a partial renovation. But ultimately we chose R3.5 Ecowool, a glass-wool insulation that uses a natural binder to keep volatile organic compounds low — meaning no off-gassing over time.
The first winter after installation, we noticed an immediate difference in our home. Queensland winters are mild — typically 50°F to 68°F night and day — but in a poorly designed house, the cold is trapped, and it feels freezing inside. The house now holds at 64°F to 68°F overnight without running heat, and in the mornings it takes minutes, not hours, to bring the house up to a comfortable 75°F.
Sealing gaps around doors and windows helped, cutting the draughts and leaks. Our previous rental — a similar-size 1980s brick home with no insulation — cost us around $400 to $500 AUD a quarter in power bills. In our new home, our bills have dropped to about $150 a quarter, even with both of us working from home. And we expect that to reduce to almost nothing in the coming months.
We Replaced Single-Pane Windows and Invested in Simple Shading
The home came with the original single-pane glass on all the windows and doors, another weak point for heat gain and loss. Replacing every window with double glazing wasn’t realistic for our budget, or suitable for our climate. Double glazing is excellent for trapping heat in colder regions, but it offers less benefit in a subtropical setting where ventilation and shading are often just as effective.
Instead, we upgraded the north-facing windows and doors — the kitchen, living room, and my home office, all of which are belted by morning and midday sun. We chose low-emissivity glass that reflects radiant heat in summer and helps retain warmth in winter. In the hottest months, it’s already 86°F outside by 8 a.m., so these spaces needed the most protection. The bifold and sliding doors came in at around $4,000 each, and the windows ranged between $1,500 and $2,500 AUD.
We prioritized spending the money we had in these high-use living areas and turned to more affordable fixes elsewhere. On the south side of our home, where direct sun is less intense, we went for honeycomb blinds in the bedrooms and secondary spaces. These create an insulating air pocket against the glass, cutting heat gain in summer and retaining warmth in winter. Together with the draught sealing and new door seals, these changes stopped the worst of the leaks.
Credit: Kseniya Ovchinnikova / Getty Images
We Invested in Electrification and Energy Independence
From the outset, Dave and I knew we wanted to shift the house off gas and go all electric. Gas heating and cooking is still used in millions of Australian homes, but it’s increasingly expensive and a major source of household emissions. But that doesn’t mean electricity is cheap. The average family in Australia spends at least $500 (33 cents per kWh). Energy prices keep rising (household electricity costs have risen by about 20% in the past year), so really the long-term goal is to bring our bills as close to zero as possible.
The gas cooktop, water heater, and aging dryer were replaced with efficient electric alternatives — an induction cooktop, an electric hot water heater, and a heat pump dryer. We also upgraded the fridge and dishwasher to more energy-efficient models and took advantage of any rebates. Appliances are one of the biggest drivers of household energy use — roughly 30% (or more) of the total. A heat pump hot water system uses 60% to 70% less energy than a standard tank, saving $300 to $700 a year. Heat pump dryers cut electricity use in half, while older fridges can use up to three times more power than modern units.
With the house fully electrified, a few months after moving in, we installed a 6.6kW solar system on the roof. With only two of us in the house, this size system is more than enough to cover our needs and a home of this size. To get the most from our system, we shifted routines so the washing machine and dishwasher run during daylight hours, while the solar panels are producing.
Just this month, we’ve installed a BYD solar battery to store excess power and provide backup during outages. Storms on the Gold Coast are hitting harder and more often, and widespread blackouts are becoming more common. After a recent summer storm from a nearby cyclone left much of the Gold Coast without power for days, and some suburbs for weeks, the battery already feels like money well spent for the peace of mind of keeping the lights and fridge running.
We’re not off-grid. Any excess power is exported back for a small feed-in tariff, which doesn’t make you rich but does help offset bills. It’s still early days, but eventually the combined solar and battery system should comfortably cover most of our annual use.
Credit: Elliott Kaufman/Getty Images
We Invested in Passive Design Adjustments
We also looked at how to make the most of what was already there. We adjusted the floor plan to work with existing doors and windows to improve airflow and cross-ventilation. On warm days, we close off south side rooms to block the sun and open windows on the eastern side to catch breezes. Ceiling fans help move the air, and the air conditioner runs on the hottest parts of the year when the humidity becomes too much. We also close off one side of the house, the rooms we don’t use day to day, to halve the area we need to cool.
Credit: Susan Hodgson/Shutterstock
We “Rewilded” the Garden
When we first bought the house, the 941 square-meter block was mostly lawn — kept neat and green by years of pesticides — fringed with overgrown clumps of over 100 golden cane palms, clusters of agaves, and introduced tropical plants. The soil was compacted and lifeless, and the garden almost devoid of biodiversity.
We spent months removing the golden canes as well as the invasive introduced trees — the cocos palms and umbrella trees. We kept some of the older Bangalow palms and shade trees that help cool large areas of the house. Bit by bit, we’ve been replacing the lawns with new gardens filled with water-wise native plants like Westringia, Banksia, Chrysocephalum, and Prostanthera. Over 60 species so far that are native to South East Queensland, thrive in our climate and build structure for a layered habitat.
As the plants mature, they’re helping cool the block, buffer erosion after heavy rain, and link into a wider habitat corridor in the neighborhood. To help us through the drought years and keep the gardens alive, we have one 5,000-liter rainwater tank, and plan to install a second water tank further down the track.
What I Learned About Making a House Sustainable
We did a lot of research before we started, and that helped us focus on the upgrades that would have the most impact. The biggest surprise was how much difference insulation and sealing draughts made. Those simple fixes delivered the most comfort and savings for the least cost and effort. At the same time, moving away from gas has unlocked the benefits of solar and made it easier to run the house on clean energy and help us start saving money.
I feel incredibly fortunate that we’ve been able to make these changes, and reassured knowing our home is better prepared for a changing climate and whatever comes next. Of course, you can never fully prepare for the unpredictable, but working with nature rather than against it feels like a step in the right direction both for our own comfort and for the part we play in the bigger picture.
Further Reading
Big College Energy: 12 Dorm Room Essentials That Do the Most (Partner)
Dorm Goals: 10 IKEA Finds That Just Make Sense (Partner)
How to Set Up a Dorm Room That Works Really Hard — and Looks Really Good (Partner)
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