The three names are often grouped together because each can influence the design and documentation of a residential development. That does not make them interchangeable. NatHERS is a residential energy-rating framework. BASIX is a New South Wales residential sustainability requirement. BESS is a Victorian planning-stage sustainable design assessment.

The correct starting point is usually the project location, building type and approval pathway. A house in New South Wales may need BASIX together with NatHERS modelling. A Victorian apartment development may need BESS at planning stage and NatHERS as a separate residential energy assessment. A Victorian commercial development may require BESS but would not use NatHERS.

This guide compares the role of each framework without replacing the detailed requirements of the individual pathways. For project-specific guidance, review the relevant council, planning authority and building approval requirements.

Preparing for a BESS assessment involves more than collecting a set of architectural plans. The information entered into BESS must describe the same development shown in the planning documentation, and each claimed credit should be supported by an identifiable drawing reference, schedule, calculation or technical report.

Common problems arise when project areas are entered incorrectly, sustainability measures are nominated before they are documented, or supporting reports relate to an earlier design revision. These inconsistencies may not be apparent from the overall BESS score alone.

This guide focuses on preparing the project information and evidence needed for a credible assessment. For the complete explanation of planning context, assessment scope, scoring and report structure, see the BESS Knowledge Hub.

Indoor Environment Quality, commonly shortened to IEQ, is one of the categories assessed within BESS Buildings. The category does not provide a general rating of whether a building is healthy or comfortable. Instead, it applies defined credits to particular development types and requires project information or evidence to support the responses entered into the assessment.

The applicable IEQ credits change according to the project profile. An apartment development may be assessed for daylight access, natural ventilation, cross-flow ventilation and particular thermal-comfort measures. A non-residential development may instead require daylight, ventilation, shading, ceiling-fan or air-quality evidence relevant to its regular-use areas.

This guide explains how IEQ operates within BESS and what information may be required to substantiate the assessment. For the complete planning, scoring and report pathway, see the BESS Knowledge Hub.