A star rating is a computer simulation that assesses an entire building’s heating and cooling loads. The 7-star NatHERS requirement is for whole buildings, not just windows and doors. Everything in the ‘building envelope’ must contribute – with each separate component doing its job.

A combination of window and door types, e.g. single and double glazed in a single building, is allowable; as long as it meets the 7-star NatHERS requirements.

Glass has a significant impact on the thermal performance of windows and doors. However, other components, such as frames and seals, also influence the energy efficiency of windows and doors.

These components and their design determine the energy efficiency of windows and doors.

Most importantly, the Window Energy Rating Scheme (WERS) rates whole windows and doors, not just the glass.

According to NCC Volume 2, the U-value must be equal to or less than the specified value. The SHGC must fall within a tolerance of the specified value, either (+/-) 5% or 10% range, depending on the energy rating software used.

Heat loss and gain can occur by infiltration through gaps in the window and door assembly. The lower the air infiltration figure, the less air will pass through the cracks in the window and door assembly, improving the energy rating.

No. You must use an accredited energy rater to model a building’s thermal performance.

Yes. PVC windows and doors are other options if you are interested in energy efficiency.

However, you need to consider whether they can satisfy the conditions in Australia, which are different from those in Europe.

A window and door system in Australia must cope with cyclones, bushfires and extreme summer heat. Aluminium windows and doors have a long and proven track record for such compliance.

Timber is an excellent material thermally; however, that is only part of the story. Aluminium products are easier and more cost-effective to maintain over their lives than timber products.

In addition, timber only comes in ‘timber’, unlike the flexibility offered by the myriad of available aluminium finishes.

A thermal break is a non-metallic resin or plastic material installed in an aluminium window/door frame that physically separates the interior part of the window/door from the exterior part. Hence, the pathway for heat or cold transfer through the frame is broken.

It all depends on the house’s orientation, shape and layout, the construction materials and insulation used and other passive cooling and heating design principles, e.g. amount of shading around the house.

The ABCB has a map of Australia, which shows all eight climate zones. It is accessible from:

https://www.abcb.gov.au/resources/climate-zone-map

Alternatively, the NatHERS map is much more detailed. Currently, it has sixty-nine climate zones. The map can be viewed at:

https://www.nathers.gov.au/nathers-accreditedsoftware/nathers-climate-zones-and-weather-files

A vital feature of Bradnam’s thermal break range is its visual symmetry with other Bradnam’s windows and doors.

You can mix and match products from any of Bradnam’s ‘Essential, ‘Signature’, ‘Commercial’, or ‘Thermal Break’ ranges and be confident that there will be architectural symmetry among the windows and doors.

The ‘thermal breaks’ are not visible when the windows and doors are closed except for the sliding door. A ‘thermal break’ is visible on the track when the sliding door is closed.

‘Thermal breaks’ are visible on the sashes and frames when the windows and doors are open.