Double glazing gets sold as a must-have for any energy-efficient home. In Canberra or Melbourne, it often is. In south-east Queensland, the answer is "sometimes". Here's how to work out whether it's worth it for your home.
C20 - What You Should Know When You Design Your New Home
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Last updated 28 Oct 2026 · Revision 3 · Free updates for life
Checklist Type: Minor
Form Factor: Fillable, print-ready PDF (A4, 42 pages)
When to use: Design stage: before the plans and specification are finalised and before you sign
A 134-check guide to work through with your designer while the plans are drawn. Settle the block, the sun, the layout, the energy rating, the services and the contract early, so a change costs a redraw, not a variation.
What double glazing is
A double glazed window has two panes of glass sealed together as one unit, with a gap between them, usually filled with air or argon. The gap slows heat moving through the glass, in both directions. In summer, it slows heat getting in. In winter, it slows heat getting out.
The two numbers that matter
Every window's performance can be rated under the Window Energy Rating Scheme (WERS). Two numbers matter most:
- U-value: how easily heat conducts through the whole window. Lower is better. This is where double glazing shines.
- SHGC (solar heat gain coefficient): how much of the sun's heat comes through the glass. Lower means less heat gain.
In a Queensland home, the main problem is usually the sun's heat pouring in, not heat conducting out on a cold night. That makes SHGC, and shading, just as important as U-value. A clear double glazed unit can still let in plenty of solar heat. A tinted or low-e single glazed window can sometimes do better against the sun for less money.
Compare windows using their WERS ratings, not the sales brochure.
What double glazing does well
- Reduces heat transfer, which makes rooms more comfortable and reduces heating and cooling.
- Reduces noise. If you're near a main road, railway line or flight path, this alone can justify it. For the best noise reduction, ask about laminated glass and different pane thicknesses.
- Reduces condensation on the inside of the glass in cold weather. This matters more in cooler areas than on the coast.
- Helps meet 7 stars. Under NCC 2022, most new homes need a 7-star NatHERS rating. On large glazed areas or west-facing walls, better glazing (sometimes double glazing) can be what gets the design over the line.
What it doesn't do
It isn't automatically more secure. Security comes from laminated or toughened glass and good locks, not from having two panes. If security matters, ask for laminated glass in at least one pane.
It doesn't fix bad design. A big unshaded west-facing window will still overheat the room, double glazed or not.
Frames matter too
The frame can lose as much heat as the glass.
- Aluminium is the most common frame in Australia. It's strong, low maintenance and affordable, but it conducts heat well, so it performs worst.
- Thermally broken aluminium has an insulating strip separating the inside and outside of the frame. It performs much better than standard aluminium.
- uPVC performs well thermally and is common overseas, and increasingly available here.
- Timber performs well and looks great, but needs regular maintenance.
Your frame choice may also be limited by your site's wind rating and, in bushfire-prone areas, the bushfire attack level (BAL). Check both before you fall in love with a product.
The cost
Double glazed windows cost noticeably more than equivalent single glazed windows, and the gap grows with better frames and specialty glass. On a whole house, it can add up to a significant sum. Get your window supplier to quote both options on your actual plans, and ask your energy assessor how much each option changes your star rating. Then you can see what you're actually buying.
Is it worth it for you?
Double glazing is likely to be worth it if:
- You're near a noisy road, railway or flight path.
- You're in a cooler climate, like the Darling Downs or the Granite Belt.
- The house has large glazed walls or big west-facing windows that can't be shaded.
- You need the extra performance to reach your star rating without compromising the design.
It's less likely to be worth it if:
- You're in a mild coastal climate with good orientation and shading.
- The windows are modest in size and well shaded by eaves.
My recommendation
For most south-east Queensland homes, I'd spend on shading and better glass on the west and north first: wide eaves, awnings, external screens, and low-e or tinted glass where the sun hits. Then use double glazing where noise or big glazed walls make it pay.
Whatever you choose, look after the seals. Clean the windows and tracks regularly and check for damage. A failed seal on a double glazed unit shows up as fogging between the panes, and the unit will need replacing.
Further reading
Glazing for Your Home: Comfort, Energy, and Cost InsightsGlazing greatly impacts your home’s comfort, energy efficiency, and costs. Understanding glass types, frame materials, and installation can help you optimise thermal performance, lower energy expenses, and improve sustainability in your new home.
Smarter Housing Assessments: Reduce Emissions and Future-ProofFind out why your home’s energy rating might be fooling you—and what you can do about it. From cutting emissions to slashing bills, we’ll show you how smarter assessments and upgrades can future-proof your home and wallet.
Mastering Energy Efficiency: Air Sealing & Insulation TipsBuilding an energy-efficient home is more than just a trend; it’s a responsibility. Dive into the intricacies of air sealing, insulation, and the importance of thermal mass. Discover how these elements can drastically reduce energy consumption and promote sustainability.
As-Designed vs As-Built: Why Efficiency Falls ShortMany new homes promise energy efficiency on paper but fall short once built. In this post we look at the MDPI Sustainability Review and its main takeaways. Its good to know what’s going on, what to expect and how to position yourself to achieve the best outcome.
Optimizing the 4 Control Layers for High-Performance HomesBuilding an energy-efficient home requires a good understanding of the four control layers: water, air, vapour, and thermal. In this post we look into how project builders can optimise these layers, ensuring homes are comfortable, sustainable, and cost-effective.
Home Insulation Guide: Improve Comfort & Lower Energy CostsInsulation is one of the most important factors affecting the comfort and energy efficiency of your new home. This guide explains why insulation matters, what materials to consider, and how correct installation can lead to lower energy bills and a more comfortable living environment.
