A thermal break is a strip of polyamide (a rigid plastic) that separates the inside and outside halves of an aluminium frame, so heat and cold can't travel straight through the metal. In this catalogue it takes a window from about Uw 2.1–2.2 W/m²K (standard frames) to Uw 1.2–1.8 (thermally broken). For new homes in cooler climates it is usually needed to make the 7-star NCC energy rating.
The numbers, series by series
Factory test figures for every window series in our range with a published Uw, lowest (best) first:
Uw is the heat loss through the whole window, frame and glass. Lower is better. The figures depend on the glass, so your energy assessor should use the values for the exact glass on your quote.
When you need it
- Cool climates (Melbourne, Canberra, Hobart, the Adelaide Hills, the Blue Mountains): almost always, for comfort and condensation as well as the energy rating.
- Big glass on any house: large sliding doors and fixed panes lose the most heat, so the frame matters more.
- Tight energy ratings or BASIX targets: often the cheapest way to get the stars back without shrinking windows.
When standard aluminium is fine
- Hot, humid climates (climate zones 1 and 2: north Queensland, the NT, much of Brisbane), where you want airflow more than insulation.
- Sheds, garages, workshops and some granny flats.
- Internal glass walls and doors.
Condensation
Standard aluminium frames get cold in winter and water condenses on the inside of the frame. A thermal break keeps the inside face warmer, which cuts condensation and the mould that comes with it. Double glazing does the same for the glass.
Questions
What is a thermally broken window?
An aluminium window whose frame is split into inside and outside parts joined by a polyamide strip, so heat doesn’t conduct straight through the metal.
How much better is a thermally broken frame?
In this range, standard frames test at about Uw 2.1–2.2 W/m²K and thermally broken frames at about 1.2–1.8, so heat loss through the window drops by roughly 20–45%.
Do I need thermally broken windows for 7 stars?
Often, in cooler climate zones (6, 7 and 8) and on houses with a lot of glass. Your energy assessor decides; send us the window specification from the energy report and we match it.
Are thermally broken windows more expensive?
Yes, the frame costs more than a standard one, but it can save buying thicker glass or cutting window sizes to meet the energy rating.
Does a thermal break stop condensation?
It reduces it a lot, because the inside of the frame stays warmer. Double glazing does the same for the glass.