BASIX & NatHERS FAQ

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A BASIX certificate is mandatory for all new residential developments in NSW. It proves your design meets sustainability targets for energy, water, and thermal comfort. Without it, you cannot lodge your DA or CC. Check our article in our knowledge hub for more information. 

With Assessify, most BASIX certificates are delivered within 24–48 hours, depending on project complexity.

Costs vary by project type (house, granny flat, duplex). Assessify provides transparent pricing with no hidden fees. Check out our services page to organise a complimentary quote for your project.

Yes. BASIX applies to new homes, granny flats, and major renovations over $50,000 

BASIX certificate is triggered when the estimated cost of work exceeds $50,000, or when pools and spas have a combined capacity over 40,000 litres. 

Secondary dwellings like granny flats also require compliance.

Only the new work is assessed for the BASIX certificate—this includes added walls, ceilings, floors, windows, and any new plumbing fixtures. Existing parts of the home are not reassessed.

New lighting must include at least 40% energy-efficient fixtures. If a pool is added, the pump and filter must be timer-controlled. Solar hot water or PV systems may be recommended.

New taps, showerheads, and toilets must meet minimum WELS ratings. Rainwater tanks may be required for outdoor use or pool top-up, depending on the scope of work.

Thermal comfort is evaluated based on insulation, glazing, shading, and orientation of the new work. The goal is to ensure the addition performs efficiently in summer and winter.

You can generate a BASIX certificate online via the NSW Planning Portal or work with a consultant like Assessify to streamline the process and ensure accurate commitments.

NatHERS (Nationwide House Energy Rating Scheme) is a star rating system that assesses the thermal performance of residential buildings across Australia, from 0 to 10 stars.

NatHERS measures the thermal performance of your home design on a scale from 0 to 10 stars. A higher rating means lower energy bills and greater comfort. Check out our article in our knowledge hub titled NatHERS assessments at design stage. 

Smart design choices—like glazing, insulation, shading, and orientation—help boost your rating. Assessify’s guides and checklists make this simple. 

Yes. In most states and territories outside NSW, significant alterations and additions must meet minimum energy efficiency standards under the National Construction Code (NCC), often assessed using NatHERS software.

NatHERS is typically required when:

• The renovation adds new habitable floor area

• The building envelope is altered (e.g., new walls, roofs, windows)

• The project is subject to a performance solution under the NCC

Under NCC 2022, the minimum NatHERS rating for new dwellings and major additions is 7 stars in most jurisdictions. Some states may allow alternative compliance pathways for existing homes.

Only the new or altered building elements are assessed—this includes insulation, glazing, orientation, and thermal bridging. The existing structure is generally not reassessed unless it’s significantly modified.

A qualified NatHERS assessor like Assessify uses accredited software to model the home’s thermal performance. The certificate is submitted with your building application to demonstrate compliance with the NCC.

We would recommend to engage us early in the design to ensure this does not happen. 

Assessify provides clear recommendations to adjust your design (e.g., insulation upgrades, window changes) so you pass without costly redesigns.

Yes. Early compliance checks save time, reduce costs, and avoid delays. 

Assessify specializes in design‑stage compliance.

Homes above 7 stars are more comfortable, cheaper to run & are future‑proofed against stricter regulations.