Designing towards a 7 Star NatHERS outcome begins with understanding how the proposed dwelling will respond to its site and climate. The same window, insulation level or shading strategy can perform differently when applied to another orientation, floor plan or climate zone.

NatHERS modelling considers the documented home as a complete thermal system. The result is therefore influenced by how building form, rooms, openings, construction and solar exposure interact rather than by compliance with a simple product checklist.

This guide focuses specifically on the design methodology used to work towards the target. For guidance on what the benchmark means, when it may apply and how it relates to residential compliance pathways, see the 7 Star NatHERS requirements guide.

Double glazing is frequently presented as a direct route to a higher NatHERS star rating. It can be an effective improvement, particularly where heat transfer through the windows is limiting the dwelling’s thermal performance. It is not, however, a guaranteed or identical solution for every project.

NatHERS does not assess the number of glass panes in isolation. The model uses the thermal properties of the complete window system, including the glass, frame, seals and other relevant components. Window size, location, orientation and shading also influence how that system performs within the dwelling.

This guide focuses specifically on when double glazing may improve the model, what the window performance values mean and which information should be coordinated with the assessor and supplier.

For the broader relationship between climate, orientation, shading, insulation and building form, see How to Design a 7 Star NatHERS Home.

The cost of reaching a 7 Star NatHERS target varies between projects. Some designs may require only focused refinements, while others may need wider changes to glazing, shading, insulation, construction or building form.

The difference is rarely explained by one product alone. A high-cost upgrade may provide limited improvement when it does not address the part of the dwelling creating the dominant heating or cooling load. Conversely, several smaller changes may produce a stronger result without unnecessarily increasing the specification across the entire home.

This guide focuses specifically on how project teams can prioritise expenditure when working towards the target. For the broader relationship between climate, orientation, glazing, shading and construction, see How to Design a 7 Star NatHERS Home.

For guidance on what the 7 Star benchmark means and when it may apply, see the 7 Star NatHERS requirements guide.

Green home loans are intended to support the purchase, construction or improvement of homes that satisfy defined environmental or energy-performance criteria. Depending on the product, the lender may offer a pricing benefit, additional finance for upgrades or another incentive.

NatHERS can provide recognised technical evidence about a new home. Its thermal star rating describes the modelled heating and cooling performance of the dwelling fabric, while a separate Whole of Home rating may record the broader modelled energy performance of household systems, solar generation and battery storage.

Whether either result is accepted for a particular green loan remains a lender decision. Applicants should confirm the lender’s current eligibility criteria before relying on a target rating, specification or certificate.