Windows are where most of the unwanted heat gets into a Queensland home, and where a lot of winter warmth escapes. They're also one of the bigger line items in your energy rating. Pick the wrong glass for a big west-facing slider and you'll be running the air conditioner all summer, no matter how good the insulation is.
The good news is that you only need to understand a few numbers to ask the right questions.
C20 - What You Should Know When You Design Your New Home
$59.00 AUD
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.
U-value: how much heat passes through
U-value measures how easily heat moves through the whole window, glass and frame together. Lower is better.
A low U-value keeps heat out in summer and in during winter. It matters most in cooler climates, but it still affects comfort here, particularly with large glass areas or where you sit near the window.
SHGC: how much of the sun's heat gets in
The Solar Heat Gain Coefficient tells you how much of the sun's heat comes through the window, on a scale from 0 to 1. Lower means less solar heat gets in.
- Most of Queensland is cooling-dominated, so a lower SHGC on east and especially west-facing windows makes a real difference.
- North-facing windows with good eaves can take a higher SHGC. The eaves block the high summer sun, and the lower winter sun comes in and warms the room.
In Australia, winter sun comes from the north. Some imported advice talks about south-facing windows for winter sun. Ignore it.
Visible transmittance: daylight without the heat
Visible transmittance (VT) is how much daylight comes through. You can buy glass with a very low SHGC that also makes a room feel dim. That might suit a west-facing bedroom, but not a living area you want bright and open. Check VT alongside SHGC so you don't end up with efficient windows and a gloomy house.
Use WERS and your energy report
In Australia, window performance is rated under the Window Energy Rating Scheme (WERS). WERS-rated products list the whole-window values, usually shown as Uw and SHGCw.
Your NatHERS assessor will have used specific U and SHGC values for each window to get your home to 7 stars. That's your target. When the window supplier quotes, check that the products match the values in your energy report, not just a brochure figure for the glass alone. If the builder wants to substitute a different window, ask for the WERS values and confirm with your assessor that the rating still stands.
Glazing: single, double or triple
- Single glazing with low-e or tinted glass often meets 7 stars in much of Queensland, depending on the design and orientation.
- Double glazing lowers the U-value and helps with noise. It's most worthwhile in cooler climates, on noisy streets and for big expanses of glass. Our separate post covers whether it's worth it for you.
- Triple glazing is rarely needed in Queensland.
Low-e coatings are thin metallic layers on the glass that control heat. Double-glazed units may also have argon gas between the panes and warm edge spacers, which reduce heat loss and condensation at the edges.
The rule: match the glass to the U and SHGC values in your energy assessment, not to what sounds impressive.
Frame choices
The frame affects heat flow, how well the window stays square and sealed, and how it handles weather.
- Aluminium is the standard in Australia. It's strong, slim and good for big openings, but it conducts heat well. Thermally broken aluminium frames have an insulating barrier inside that cuts heat flow and improves comfort.
- uPVC frames perform well thermally at a reasonable price. Check stability and colour on hot, west-facing walls, and make sure the product suits Australian sun.
- Timber frames insulate well and look great, but need regular maintenance. Poor water management around sills and corners leads to swelling and rot.
- Composite and timber-aluminium frames combine a weatherproof outer face with better thermal performance inside. They cost more.
Installation matters as much as the product
Even good windows perform badly if they're installed poorly. On site, look for:
- Windows set plumb, level and square, with packers where the manufacturer specifies.
- Fixings as per the manufacturer's instructions, not just a few nails.
- Sill flashings and wall wrap correctly lapped so water drains out, not in.
- Gaps between the frame and the wall framing sealed against air leaks.
- Windows protected during construction so glass and frames aren't scratched, splattered or used as a ladder rest.
Windows should also be rated for your site's wind classification and meet AS 2047 for water penetration and structural performance, which matters a lot on exposed and coastal sites.
Quick checklist before you approve the order
- U and SHGC (whole window) match your energy report.
- West and east windows have a low SHGC, or proper external shading.
- North windows are shaded by eaves sized for summer sun.
- VT is reasonable for living areas.
- Aluminium frames are thermally broken if your energy report assumed it.
- The window rating suits your wind classification.
- Any substitution has been checked by your energy assessor.
Further reading
Double Glazed Windows: Benefits for Your New HomeDiscover the benefits of double glazed windows for your new home. Learn about energy efficiency, sound insulation, security, and more.
Home Orientation for Comfort & Energy EfficiencyThe orientation of your home plays an important role in comfort, energy efficiency, and cost-saving potential. In this post we explain how to position your home for maximum benefit, including design considerations, materials, systems, and climate-specific strategies.
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.
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.
