To prepare a BASIX Certificate in NSW, an assessor needs enough project information to understand the design, building fabric, water commitments, energy systems and thermal performance pathway. The exact documents required depend on the project type, but most BASIX assessments begin with the architectural drawings and then move into the details that affect water, energy and thermal comfort compliance.
BASIX applies to residential development in NSW and forms part of the development application or complying development certificate process. The BASIX standards cover water, energy use and thermal performance, and apply to all new residential developments, as well as renovations over $50,000 and swimming pools or spas of 40,000 litres or more. Because the certificate becomes part of the approval documentation, the information used in the assessment should match the plans submitted for approval.
For most BASIX Certificates, you will need the project address, site plan, floor plans, elevations, sections, roof plan, window and glazing details, construction information and any available details about hot water systems, rainwater tanks, pools, spas, solar panels and major fixtures. The more complete the documentation is, the easier it is to prepare an accurate BASIX Certificate.
The most important documents are usually the architectural plans. These drawings allow the assessor to understand the size, layout, orientation and construction of the proposed development. They also help confirm whether the project is a new dwelling, alteration, addition, secondary dwelling, dual occupancy, townhouse development, apartment project, pool or spa.
For a typical BASIX assessment, the following documents and details are helpful:
Architectural drawings are the foundation of the BASIX assessment. They show the physical design of the project and allow the assessor to calculate or confirm the information required for the certificate. If the plans are incomplete, unclear or inconsistent, the assessment may need to pause while the designer, architect, builder or client confirms missing details.
The plans also help ensure the BASIX Certificate matches the approval package. This is important because BASIX commitments can affect the actual build. For example, a certificate may include specific insulation levels, glazing assumptions, hot water systems, rainwater tanks, ventilation requirements or other sustainability commitments that need to be reflected in the plans or specifications.
Yes. Window and glazing details are often important for BASIX, especially where the project also requires NatHERS thermal comfort modelling. The size, location, orientation and performance of windows can influence the heating and cooling performance of a home. Large areas of glazing, poorly shaded windows or high performance glazing selections may all affect the final assessment.
If a formal window schedule is not yet available, the assessor may still be able to begin with the window sizes shown on the elevations. However, the final certificate should be based on clear and reliable glazing information wherever possible. Useful details include frame type, glass type, U value, SHGC value, window operation, shading devices and any skylights or glazed doors included in the design.
For many new homes and larger residential projects, BASIX is closely connected to NatHERS thermal comfort assessment. NatHERS modelling may require additional detail about construction systems, insulation, glazing, shading, ventilation, floor types, ceiling heights and roof form. If these details are missing, the assessor may need to request further information before the thermal comfort pathway can be finalised.
This is why it is helpful to prepare BASIX and NatHERS together rather than treating them as separate last minute documents. When the two assessments are coordinated early, the design team has a better chance of identifying performance issues before the approval package is lodged.
BASIX also reviews water and energy commitments. Depending on the project, the assessor may need information about fixtures, hot water systems, rainwater tanks, landscaping, swimming pools, spas, ventilation, cooling systems, heating systems and solar panels. Some of these details may not be fully selected at the early design stage, but they still need to be resolved before the certificate is finalised.
For example, a rainwater tank commitment may affect plumbing design and site planning. A hot water system selection may affect energy performance. A pool or spa may affect water and energy commitments. Solar panels may assist with energy targets, but the roof layout, orientation and available area need to be understood before they are relied on in the assessment.
In many cases, a preliminary BASIX review can begin before the plans are fully finalised. This can be useful if the design team wants early feedback on likely compliance issues, glazing risk, insulation assumptions or major system commitments. Early review can be especially helpful for custom homes, complex renovations, duplexes, townhouses and projects with large areas of glazing.
However, the final BASIX Certificate should be based on plans that are sufficiently developed for approval. If the design changes after the certificate is issued, the BASIX Certificate may need to be updated so the commitments continue to match the approved drawings and specifications.
If key documents are missing, the assessor may need to request clarification before the BASIX Certificate can be completed. Missing information can also lead to assumptions, and assumptions may not always match the final design intent. This can create avoidable delays if the certificate later needs to be amended or if the approval documentation does not align.
The best approach is to provide the most current plans available and clearly explain what is still undecided. Certified Energy can then review the information, identify what is missing and advise what is needed before the BASIX Certificate can be finalised.
Before requesting a BASIX quote, it is helpful to prepare the following information:
Certified Energy prepares BASIX Certificates for residential projects across NSW, including new homes, alterations and additions, secondary dwellings, dual occupancies and multi dwelling developments. Our team can review the available plans, confirm what information is still needed and prepare the BASIX Certificate once the project is ready for assessment.
If your project also requires NatHERS thermal comfort modelling, we can coordinate the BASIX and NatHERS components together so the design, certificate and approval documentation remain aligned.
Send your available plans and project details to Certified Energy and our team can confirm what is needed before preparing your BASIX Certificate.
Request a QuoteYou usually need the project address, site plan, floor plans, elevations, sections, roof plan, window and glazing details, construction information and any relevant details about hot water systems, rainwater tanks, pools, spas, solar panels and major fixtures.
A preliminary review can often begin before plans are final, but the final BASIX Certificate should be based on plans that are ready for approval. This helps ensure the certificate commitments match the drawings submitted with the DA or CDC.
Yes. Window sizes, orientation, frame type, glass type, U values, SHGC values and shading can all affect BASIX and NatHERS thermal comfort outcomes.
If documents are incomplete, the assessor may need to request more information or make assumptions. This can delay the certificate or lead to amendments later if the final design changes.