Articles - Certified Energy

Common BASIX Issues in NSW

Written by Team CE | May 23, 2026 3:22:39 AM

Thermal Comfort and BASIX in NSW

Thermal comfort forms a major part of BASIX compliance for residential developments across New South Wales.

The thermal performance of a home can significantly influence:

  • indoor comfort
  • energy efficiency
  • heating and cooling demand
  • long-term building performance

BASIX assessments evaluate how effectively a home is expected to maintain comfortable indoor temperatures throughout different seasons and climate conditions.

For many residential projects, thermal comfort assessments are completed using NatHERS modelling software alongside the BASIX assessment process.

What is Thermal Comfort?

Thermal comfort refers to how effectively a building maintains stable and comfortable indoor temperatures throughout the year.

A thermally efficient home may:

  • remain cooler during summer
  • retain warmth during winter
  • reduce reliance on mechanical heating and cooling
  • improve occupant comfort
  • lower long-term energy demand

Thermal comfort performance is influenced by how the building responds to:

  • sunlight
  • outdoor temperatures
  • ventilation
  • seasonal climate conditions

Thermal Comfort and BASIX Assessments

Within BASIX assessments, thermal comfort performance is evaluated as part of the overall residential building assessment.

This may involve analysis of:

  • glazing performance
  • insulation
  • orientation
  • shading
  • ventilation
  • thermal mass
  • building materials
  • passive solar design

The assessment aims to determine how efficiently the proposed home is expected to perform under local climate conditions.

NatHERS and Thermal Modelling

NatHERS assessments are commonly used to evaluate the thermal comfort component of BASIX compliance in NSW.

NatHERS modelling analyses:

  • heat gain
  • heat loss
  • seasonal indoor temperatures
  • building envelope performance

The software estimates how much heating and cooling may be required to maintain comfortable indoor conditions throughout the year.

This modelling process can help identify opportunities to improve:

  • glazing performance
  • insulation strategies
  • shading design
  • ventilation pathways
  • orientation outcomes

Glazing and Solar Heat Gain

Windows and glazing systems can significantly influence thermal comfort outcomes.

Large glazing areas may improve:

  • daylight access
  • views
  • winter solar gain

However, excessive or poorly positioned glazing can also increase:

  • unwanted summer heat gain
  • heat loss during winter
  • overall cooling demand

Thermal performance assessments often consider:

  • glazing orientation
  • SHGC values
  • U-values
  • shading systems
  • frame performance

Balancing glazing performance with passive solar design is often a key part of achieving strong BASIX outcomes.

Insulation and Building Envelope Performance

Insulation plays a major role in reducing heat transfer through the building envelope.

This may include:

  • roof insulation
  • wall insulation
  • floor insulation
  • reflective membranes
  • sealing and draught reduction

Well-designed insulation systems can help stabilise indoor temperatures and reduce overall heating and cooling demand.

The overall building envelope performance may also be influenced by:

  • construction methods
  • thermal bridging
  • material selection
  • air leakage

Orientation and Passive Solar Design

Building orientation can significantly influence thermal comfort performance in NSW homes.

Passive solar design principles may include:

  • northern solar access
  • controlled western glazing
  • seasonal shading
  • cross ventilation
  • thermal mass placement

Well-considered orientation can often improve:

  • winter solar access
  • summer heat protection
  • indoor comfort
  • energy efficiency

These design decisions are often most effective when integrated early during concept planning.

Ventilation and Air Movement

Natural ventilation can assist with maintaining indoor comfort and reducing cooling demand.

This may involve:

  • operable windows
  • cross ventilation pathways
  • stack ventilation
  • airflow management
  • window placement strategies

Ventilation performance can vary depending on:

  • site orientation
  • surrounding buildings
  • room layout
  • climate conditions

Good ventilation design is often closely connected to overall passive design performance.

Common Thermal Comfort Challenges

Some of the most common thermal comfort issues affecting residential developments include:

  • excessive west-facing glazing
  • inadequate shading
  • poor orientation
  • insufficient insulation
  • limited ventilation
  • thermal bridging
  • oversized glazing areas
  • late-stage design changes

These factors can often lead to increased heating and cooling demand and more difficult BASIX compliance outcomes.

Improving Thermal Performance Early

Early-stage thermal planning can often improve both BASIX compliance and long-term building performance.

This may help:

  • reduce redesigns
  • improve occupant comfort
  • optimise glazing design
  • lower operational energy demand
  • improve passive solar outcomes
  • strengthen overall building efficiency

For many residential projects, decisions made during concept design have the greatest influence on thermal comfort performance.

Thermal Comfort and Different Climate Zones

Thermal comfort requirements can vary significantly across NSW climate zones.

Design strategies suitable for cooler climates may differ substantially from those used in warmer coastal or western regions.

Factors commonly influenced by climate zone include:

  • insulation levels
  • glazing requirements
  • shading design
  • ventilation strategies
  • thermal mass performance

As a result, thermal comfort assessments are generally tailored to the local conditions of the proposed project site.

Frequently Asked Questions

What is thermal comfort in BASIX?

Thermal comfort refers to how effectively a home maintains comfortable indoor temperatures throughout different seasons and climate conditions.

Is NatHERS used for thermal comfort assessments?

Yes. NatHERS modelling is commonly used to assess the thermal comfort component of BASIX compliance in NSW.

Can glazing affect thermal comfort performance?

Yes. Glazing size, orientation, SHGC values and shading systems can all significantly influence thermal comfort outcomes.

Why is orientation important for BASIX?

Orientation can affect solar heat gain, ventilation performance and overall energy efficiency throughout the year.

When should thermal comfort assessments begin?

Early-stage thermal planning during concept design can often improve BASIX outcomes and reduce redesigns later in the project.