BASIX for Alterations and Additions in NSW

BASIX requirements apply to many residential alterations and additions across New South Wales.

Renovation projects can still significantly influence:

• energy efficiency
• water use
• thermal comfort
• overall residential building performance

Depending on the scale and value of the proposed works, BASIX assessments may form part of the NSW planning and approval process for alterations and additions.

Understanding these requirements early can help reduce redesigns, streamline approvals and improve long-term building performance outcomes.

Do Alterations and Additions Require BASIX?

Many residential alterations and additions in NSW require a BASIX Certificate where the value of works exceeds planning thresholds.

This may include:

• home extensions
• major renovations
• additional storeys
• substantial internal reconfigurations
• large glazing additions
• attached secondary dwellings

Requirements can vary depending on:

• project scale
• development pathway
• local council controls
• climate zone
• thermal comfort obligations

Some smaller works may be exempt from BASIX requirements, while larger renovations often require more detailed compliance assessments.

BASIX Requirements for Renovations

BASIX assessments for alterations and additions evaluate how the proposed works affect the environmental performance of the home.

This may include consideration of:

• thermal comfort
• glazing performance
• insulation
• ventilation
• water efficiency
• energy performance

Unlike new homes, renovation projects often involve balancing existing building conditions with updated compliance requirements.

This can sometimes create additional design and performance challenges compared to entirely new residential developments.

Thermal Comfort and Existing Homes

Thermal comfort is often one of the most complex aspects of BASIX compliance for renovations and additions.

Older homes may contain:

• outdated insulation
• poor orientation
• inefficient glazing
• limited shading
• inconsistent construction methods

New additions can significantly influence how the existing home performs thermally.

For many projects, NatHERS modelling is used to assess thermal comfort compliance and identify ways to improve building performance outcomes.

This may involve:

• upgraded glazing systems
• additional insulation
• improved shading
• ventilation strategies
• passive solar design adjustments

BASIX and Home Extensions

Large extensions can substantially change the thermal performance and energy demands of a home.

This may include:

• increased glazing areas
• altered orientation exposure
• additional conditioned floor area
• modified ventilation patterns

As a result, BASIX assessments for extensions often require careful coordination between:

• architectural design
• glazing selection
• thermal comfort modelling
• planning documentation

Early-stage assessment can often help identify compliance issues before plans are finalised.

Water and Energy Requirements

Alterations and additions may still need to satisfy BASIX water and energy performance targets.

This can involve:

• water-efficient fixtures
• rainwater systems
• upgraded hot water systems
• efficient lighting
• improved insulation
• appliance performance

The level of compliance required can vary depending on the scale and nature of the renovation.

Common BASIX Challenges for Renovations

Some of the most common BASIX issues affecting alterations and additions include:

• retaining large existing glazing areas
• poor existing orientation
• insufficient insulation
• inconsistent documentation
• thermal comfort failures
• late-stage design changes
• balancing existing and new construction

Renovation projects often involve more design constraints than new homes, making early coordination particularly important.

BASIX and the NSW Approval Process

BASIX assessments for alterations and additions are generally completed alongside the NSW planning approval process.

Depending on the project, approvals may proceed through:

• Development Application (DA)
• Complying Development Certificate (CDC)

pathways.

The process may involve coordination between:

• architectural plans
• BASIX Certificates
• NatHERS reports
• planning documentation
• glazing schedules
• specification documentation

Preparing this documentation early can often help streamline approvals and reduce delays.

Early Planning Considerations

For renovation projects, early-stage BASIX planning can often provide greater flexibility during design development.

This may help:

• reduce redesigns
• improve thermal comfort
• optimise glazing performance
• improve energy efficiency
• streamline approvals
• strengthen long-term building performance

Many BASIX challenges become more difficult and costly to resolve once architectural plans are fully finalised.

Frequently Asked Questions

Do renovations require BASIX in NSW?

Many alterations and additions in NSW require BASIX assessments where the value of works exceeds planning thresholds.

Are NatHERS assessments used for renovations?

Yes. NatHERS modelling is commonly used to assess thermal comfort performance for alterations and additions.

Can extensions affect BASIX compliance?

Yes. Extensions can significantly influence glazing performance, thermal comfort and overall energy efficiency outcomes.

Do older homes need to meet current BASIX standards?

Alterations and additions are generally assessed based on the proposed works and how they affect overall building performance.

When should BASIX assessments begin for renovations?

Early-stage BASIX planning during concept design can often help reduce redesigns and improve approval efficiency later in the project.