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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 \u2014 single-glazed windows, gaps that leaked air, gas appliances, and no insulation in the ceiling or internal walls \u2014 but we fell in love with it at first viewing.<\/p>\n
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\u2019t 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\u2019s second hottest on record<\/a>, with temperatures well above average, and more days over 95\u00b0F than the years before.<\/p>\n 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\u2019s how we did it.<\/p>\n Typical for older Australian homes, our house had zero insulation and heat transfer was a major issue. This means that\u00a0in 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\u2019d like.<\/p>\n 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<\/a>. We knew insulation was the most affordable and effective way to make the house more comfortable and drive down our energy bills.<\/p>\n For insulation, we looked at a few options \u2014 natural wool was too expensive. Natural wool with the\u00a0recycled 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>, a glass-wool insulation that uses a natural binder to keep volatile organic compounds low \u2014 meaning no off-gassing over time.<\/p>\n The first winter after installation, we noticed an immediate difference in our home. Queensland winters are mild \u2014 typically 50\u00b0F to 68\u00b0F night and day \u2014 but in a poorly designed house, the cold is trapped, and it feels freezing inside. The house now holds at 64\u00b0F to 68\u00b0F overnight without running heat, and in the mornings it takes minutes, not hours, to bring the house up to a comfortable 75\u00b0F.<\/p>\n Sealing gaps around doors and windows helped, cutting the draughts and leaks. Our previous rental \u2014 a similar-size 1980s brick home with no insulation \u2014 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.<\/p>\n 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\u2019t 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.<\/p>\n Instead, we upgraded the north-facing windows and doors \u2014 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\u2019s already 86\u00b0F 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.<\/p>\n 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<\/a> 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.<\/p>\nWe Added Insulation and Airtightness<\/h2>\n
We Replaced Single-Pane Windows and Invested in Simple Shading<\/h2>\n