NatHERS and Whole of Home are sometimes described as competing assessment methods. This is no longer an accurate way to understand their relationship.

NatHERS is the wider residential energy-rating framework. Within that framework, a proposed home can receive a thermal star rating out of 10 and a separate Whole of Home rating out of 100. The two results answer different questions about the same dwelling.

The thermal star rating asks how much heating and cooling the home is likely to need because of its design and construction. The Whole of Home rating builds on those thermal loads and considers the energy performance of household systems, solar generation and battery storage.

Preparing for a NatHERS Whole of Home assessment is not simply a matter of adding solar panels or selecting efficient appliances near the end of design.

The Whole of Home result is connected to the thermal performance of the dwelling and to the heating, cooling, hot-water, cooking, lighting, pool, spa, solar and battery information represented in the assessment. When these inputs are incomplete or inconsistent, the project may require additional assumptions, design changes or repeated modelling before certification.

The objective is therefore not only to reach an applicable rating benchmark. It is to reach that outcome using a coordinated design that can be documented, approved and constructed as assessed.