Windows, Heat, and Sunlight: How They Impact Sustainable Living in Darwin
Windows do far more than frame a nice view - they shape how a building interacts with heat, sunlight, and shading. Get them right, and you can reduce energy costs, improve comfort and make the most of natural light. Get them wrong, and you’ll be battling heat gain, glare, and wasted energy.
In the tropics, a cool home contributes to a healthy home and the wellness of its residents. In Darwin’s hot and humid climate, well-designed windows and effective shading are key to reducing cooling costs and improving a home’s sustainability and liveability. By controlling how much heat enters the building, the right window and shading solutions can help lower reliance on air conditioning, reduce energy use, and create a more comfortable, naturally cooled space.
Yes please!
I’ve been putting shading to the test to see just how much cooler I can make the glass in my east-facing upstairs bedroom. My Millner townhouse, built in 1979, still has its original aluminium sliding door with 3mm clear glass—standard for Darwin homes but an absolute heat trap!
To make things more challenging, the neighbouring townhouse has a long west-facing wall that reflects the afternoon sun straight onto my bedroom glass, giving it one final blast of heat before the evening. Not exactly the recipe for a comfortable night’s sleep!
Before I get to the testing and results, let’s talk about the nitty gritty of windows and how they work for us up here, north of the Tropic of Capricorn.
How Windows Transfer Heat
Windows allow heat to move between indoors and outdoors through conduction, convection, and radiation, making them one of the weakest points in a home’s insulation. Poorly performing windows let heat in year-round, leak air-conditioned air, and drive up energy costs while adding to greenhouse gas emissions. In fact, according to Your Home, up to 87% of a home’s heat is gained through windows - which likely includes glass doors too. "When sunlight hits glass, its radiant heat pours inside, where walls, floors, and furniture absorb it. These surfaces then release the heat back into the room, but because re-radiated heat has a longer wavelength, it struggles to escape - trapping warmth indoors where you least want it!
Source: Your HomeDarwin and the Sun’s Path
Darwin sits north of the Tropic of Capricorn, which means it experiences high sun angles all year round. Unlike in temperate climates, where the sun moves lower in the sky during winter, here it’s often directly overhead or even slightly to the south (burning our eyeballs and sucking away our joy!) during the tropical summer.
In Darwin’s wet season, the sun is almost directly overhead at midday. This means all sides of a house can be exposed to direct sunlight, increasing heat gain. In the dry season, while the sun shifts slightly north and is weaker, it’s still intense enough to require careful shading to prevent overheating. Shading is essential in Darwin—not just for north-facing windows, but for all sides of your home.
The Role of Shading in Sustainable Cooling & A HEALTHIER HOME
Shading is one of the most effective ways to control heat gain and reduce cooling costs. External shading - such as deep eaves, pergolas, and vegetation—can lower indoor temperatures by up to 10°C, significantly reducing the need for air conditioning (YourHome), or at least being able to set the air conditioner to a higher temperature (every 1 degree higher reduces energy consumption by approximately 10%).
Key shading strategies for Darwin include:
✔ Deep eaves and verandas - ideal for keeping walls and windows shaded throughout the day.
✔ Adjustable external blinds or shutters - offering flexibility based on the time of year.
✔ Louvres and breezeways - allowing for natural ventilation while blocking harsh sunlight.
✔ Trees, shrubs and pot plants - use them to shade windows and glass doors wherever you can. Not only do they still allow breeze and light through, but they enhance your connection to nature.
By reducing direct solar heat gain, shading not only improves comfort and energy efficiency, but also contributes to sustainable living in Darwin by cutting energy consumption and lowering greenhouse gas emissions.
CASe STUDY: TRANSFORMING A JULIETTE BALCONY with a bamboo blind & plants
TRANSFORMING A JULIETTE BALCONY
Shading windows and glass doors for sustainable living and a healthier home in Darwin, NT.
Watch the heat drop and liveability improve with just a few minor changes!
My east-facing Juliette balcony was a major source of heat gain, turning my bedroom into an oven each morning. Rather than relying on air conditioning to counteract the problem, I took a more sustainable approach—using shading and greenery to keep the space cooler naturally.
I installed a bamboo blind, choosing it over plastic alternatives for its durability and eco-friendliness. Made from just three simple materials—bamboo, cotton string, and a metal pulley—it’s biodegradable or recyclable, unlike plastic blinds, which trap heat and eventually break down into microplastics. To make sure I got the best coverage, I went for a blind wider than the balcony, ensuring it fully shaded the glass and framing while also keeping it from swinging in the wind. A few bits of wire secured it neatly to the balustrade—quick, easy, and effective.
To boost the cooling effect, I carefully selected plants suited to the space, opting for native species where possible. Choosing plants of varying heights helped increase shade, reduce heat reflection, and, as a bonus, made the balcony a lot more inviting. The plants also work to cool the air through transpiration, creating a fresher microclimate around the glass doors.
Beyond reducing heat, this setup also improves privacy, shielding my space from the neighbouring balcony without blocking all the light or airflow. And since the internal blinds don’t have to be closed all the time, I can now enjoy the outdoor view while keeping the heat at bay.
The only downside? My bedroom is now so much cooler, darker, and more relaxing in the mornings that getting out of bed is harder than ever! But overall, this simple, low-cost solution has made a huge difference—proving that thoughtful material choices and strategic planting can keep a home more comfortable without relying on extra energy use.
further steps to improve the passive cooling of this room
There is much more that can be done to improve the passive cooling and energy efficiency of this room, the first of which will be installing bulk ceiling insulation to reduce the cool air loss when the room is air conditioned. There is also the opportunity to upgrade the glass door to a new aluminium door with a thermal barrier and low-emissivity (Low-E) glass which reflects heat while still allowing natural light through.
Final Thoughts: Windows and Sustainable Living in Darwin
Windows do more than add to a home’s design - they shape how it handles heat and light, directly impacting energy use, comfort, and sustainability. In a hot, humid climate like Darwin’s, well-designed windows and shading can cut cooling costs, reduce a home’s environmental footprint, and improve resident health and wellbeing. Making smart choices in window design and shading means your home works with the climate, not against it - leading to lower power bills and a more comfortable, sustainable living space.
Did you know
I offer Sustainable & Healthy Home consultations?
Providing advice on sustainable materials, non-toxic finishes, and energy-efficient solutions to help create a healthier, more sustainable home. Whether you’re adding window shading or tackling a full renovation, I offer practical steps to make your space more sustainable, healthier and aligned with your values.
Got a project in mind? Let’s chat about the solutions for your home!