Is Double Glazing Necessary for BASIX and NatHERS in NSW?

Double glazing has a reputation as the magic fix for energy ratings. Sometimes it is exactly the right call. Often it is an expensive answer to a problem that orientation and shading could solve for a fraction of the cost. Here is how to decide.

What double glazing actually does

Two panes with a sealed gap slow the flow of heat through the window. That reduces winter heat loss and summer heat gain, and it dampens condensation and noise. The benefit is real, but windows are only one part of the thermal picture.

When it is worth it

• Cold climate zones such as the Blue Mountains, where winter heat loss dominates.
• Large glazed areas that cannot be reduced for design reasons.
• Difficult orientations where west or east glass cannot be avoided.
• Comfort and noise priorities on busy roads or exposed sites.

When you can avoid it

In much of Sydney and the warmer coastal zones, a well-oriented home with good eaves, sensible window sizes and quality single glazing or high-performance single glazing can reach 7 stars without going double everywhere. The smarter move is selective: better glass only on the faces that need it.

A cost-effective glazing strategy

1. Right-size windows to the orientation before changing the glass.
2. Shade north and west glass properly.
3. Upgrade glazing on the worst-performing faces first.
4. Reserve full double glazing for cold zones or large unavoidable glass areas.

Frequently asked questions

Will double glazing guarantee 7 stars? No single product guarantees a rating. It is the combination of orientation, shading, insulation and glazing that gets you there.

Is it ever required? It can become necessary where the design leaves no other option, which is why testing early matters.

Want to know if your design actually needs double glazing? Send us your plans and we will model it both ways.