BASIX is not limited to new homes.

Many renovations and additions in NSW also require BASIX compliance as part of the development approval process.

Unlike new builds, however, renovation projects often involve working with existing structures that were never originally designed around modern thermal performance principles.

This creates a different type of architectural and thermal challenge.

Rather than designing an entirely new building envelope from scratch, renovation projects often involve carefully integrating new performance requirements into homes with existing constraints, materials and spatial conditions.

Quick Answer

Does BASIX apply to renovations in NSW?

Yes.

Many renovations and additions in NSW require BASIX compliance depending on the project scope and development application requirements.

BASIX assessments for renovations may involve:

• thermal comfort
• energy performance
• water efficiency

Common renovation challenges include:

• integrating old and new construction
• existing glazing limitations
• insulation upgrades
• orientation constraints
• balancing thermal performance with existing conditions

Early planning generally creates smoother compliance outcomes.

Why renovations are different from new homes

New homes are typically designed as complete systems from the beginning.

Renovations are different.

Existing homes may already contain:

• older glazing
• limited insulation
• fixed orientation constraints
• outdated construction methods
• thermal weaknesses
• restricted ventilation pathways

New additions must often work around these existing conditions rather than replacing them entirely.

This means BASIX for renovations is often less about ideal performance and more about improving the thermal behaviour of the home within realistic project constraints.

Existing homes and thermal performance

Many older Australian homes were not designed around current thermal performance standards.

Some homes may overheat during summer, lose heat rapidly during winter or rely heavily on mechanical heating and cooling systems.

Common existing conditions may include:

• single glazing
• uninsulated roofs
• poorly sealed openings
• western solar exposure
• limited shading
• lightweight construction

When new additions are introduced, the thermal relationship between old and new areas becomes increasingly important.

The project begins functioning as one interconnected building system.

Integrating old and new construction

One of the more complex aspects of renovation projects is balancing new performance expectations with older building fabric.

New additions may involve:

• higher insulation levels
• improved glazing
• better sealing
• stronger passive solar response

Meanwhile, the existing parts of the home may continue to perform very differently thermally.

This can create uneven internal comfort conditions if the transition between old and new areas is not considered carefully.

Good renovation design often focuses on improving the overall balance of the home rather than simply upgrading isolated components.

Orientation limitations in renovation projects

Orientation plays a major role in thermal performance, but renovation projects often have less flexibility than new homes.

Existing room layouts, neighbouring buildings, structural limitations and site conditions may already be fixed.

This means renovation projects frequently involve working with compromise conditions.

Even so, relatively small design decisions may still improve thermal performance significantly.

This may include:

• refining glazing placement
• improving shading
• adjusting internal layouts
• increasing ventilation opportunities
• reducing western solar exposure

In many renovation projects, thermal improvement happens incrementally rather than through complete redesign.

Glazing upgrades and existing windows

Existing glazing is often one of the weaker thermal elements within older homes.

Large unshaded windows may contribute to:

• overheating
• winter heat loss
• thermal instability
• increased cooling demand

Some renovation projects involve replacing windows entirely, while others retain portions of the existing glazing system.

Balanced decisions are important.

Simply introducing large new glazing areas without passive shading or orientation control may create additional thermal pressure rather than improving performance.

Good glazing outcomes generally emerge when windows work together with shading, ventilation and the broader architectural response.

Insulation and retrofit challenges

Insulation upgrades can significantly improve the thermal performance of existing homes.

However, retrofit conditions are often more complicated than new construction.

Existing homes may contain:

• inaccessible roof cavities
• limited wall access
• suspended floors
• inconsistent construction methods
• thermal bridging conditions

This means insulation strategies often require project-specific assessment rather than standardised solutions.

Even relatively modest insulation improvements may still create meaningful changes in thermal stability and comfort.

Ventilation and airflow in existing homes

Natural ventilation can become especially important in renovation projects.

Older homes sometimes contain fragmented airflow pathways or poorly functioning room layouts.

Renovation design may improve ventilation through:

• operable window placement
• cross ventilation pathways
• spatial reorganisation
• airflow separation
• connection to outdoor spaces

Ventilation improvements may help reduce cooling demand while improving indoor comfort during warmer months.

Heritage and architectural character

Some renovation projects also involve heritage or character-sensitive conditions.

In these situations, thermal upgrades may need to balance:

• performance
• architectural identity
• planning controls
• material preservation
• visual character

This often requires careful integration rather than aggressive replacement strategies.

The strongest outcomes usually emerge when sustainability improvements respect the existing architectural language of the home.

Why early BASIX integration matters

One of the most common renovation problems occurs when BASIX is considered too late in the design process.

Late-stage compliance adjustments may require:

• glazing redesign
• shading changes
• insulation revisions
• specification upgrades
• planning amendments

Early integration allows thermal performance to become part of the architectural strategy from the beginning.

This generally creates smoother compliance pathways and more balanced long-term outcomes.

Renovating for long-term liveability

Good renovation performance is not only about achieving approval.

Homes with stronger thermal behaviour often feel:

• calmer
• more stable across seasons
• less dependent on mechanical systems
• more comfortable to live in over time

Many successful renovations achieve these outcomes through relatively simple but carefully integrated design improvements.

In many NSW homes, thermal comfort is strengthened not through complexity, but through a more thoughtful relationship between the existing building and its evolving environment.

Related Reading

To understand how homes maintain stable indoor temperatures, explore understanding thermal comfort in BASIX.

For a broader overview of climate-responsive architecture, read passive design and BASIX.

For the full overview, return to the BASIX Knowledge Hub.