A BASIX consultant reviews a proposed residential development, identifies the appropriate assessment pathway and prepares the information needed to generate a BASIX Certificate for a New South Wales planning or approval application.
The role can include reviewing architectural plans, entering water and energy information, coordinating the thermal-performance assessment, testing practical design changes and checking that the resulting BASIX commitments are consistent with the project documentation.
A BASIX consultant does not approve the development or replace the architect, engineer, builder or certifying authority. The consultant’s role is to prepare and coordinate the sustainability assessment information required for the proposed residential project.
In Brief
What Is the Role of a BASIX Consultant?
A BASIX consultant translates the proposed residential design into the inputs required by the NSW BASIX assessment tool. The consultant reviews the plans, completes the applicable water and energy sections, determines how thermal performance will be assessed and coordinates any required NatHERS simulation. They may also identify practical design changes where the project is not meeting its requirements, prepare the BASIX Certificate and help keep its commitments aligned with the approval drawings.
What Is a BASIX Consultant?
A BASIX consultant is an industry professional who prepares, coordinates or advises on BASIX assessments for residential development in NSW.
The title describes the consultant’s practical role within the project. It should not be confused with the formal role of an accredited NatHERS assessor, who is authorised through a recognised Assessor Accrediting Organisation to conduct thermal simulations for the BASIX Thermal Comfort Index.
A BASIX consultant may also be an accredited NatHERS assessor. Where that is the case, the same consultant may be able to prepare both the thermal simulation and the wider BASIX assessment. Where the consultant is not accredited for NatHERS simulation, that component must be completed by an appropriately accredited assessor.
The exact service therefore depends on the consultant’s qualifications, the type of project and the thermal-performance method being used.
Important Distinction
BASIX Consultant and Accredited Assessor Are Not Identical Terms
A BASIX consultant may coordinate the complete assessment, including project details, water, energy and certificate preparation. An accredited assessor has a specific formal role: conducting an approved thermal simulation and issuing the associated NatHERS Assessor Certificate.
Before appointing a consultant, confirm whether thermal simulation is included, whether it will be completed in-house and whether the person conducting that simulation holds current assessor accreditation.
What Does a BASIX Consultant Actually Do?
01
Review the Project Scope
Identify the residential project type, review the available plans and determine which BASIX application pathway and assessment information are relevant.
02
Extract Design Information
Read the site plan, floor plans, elevations, sections, glazing schedule and construction details needed to describe the proposed development accurately.
03
Complete Water and Energy Inputs
Record relevant fixtures, rainwater systems, landscape areas, hot-water systems, heating, cooling, ventilation, lighting and other applicable project selections.
04
Coordinate Thermal Performance
Determine whether an available simplified method is appropriate or whether the design requires thermal simulation by an accredited NatHERS assessor.
05
Test Design Adjustments
Review practical changes to glazing, shading, insulation, systems or other inputs where the proposed design is not meeting the applicable BASIX requirements.
06
Prepare the Certificate
Complete the required assessment fields, review the commitments and generate the BASIX Certificate once the applicable requirements have been satisfied.
1. Reviewing the Proposed Residential Project
The consultant’s work begins with the proposed development rather than with the BASIX tool itself. Before entering information, the consultant needs to understand what is being designed and what documentation is available.
The initial review may consider:
- whether the proposal is a new dwelling, multi-dwelling development or alteration and addition
- the number and arrangement of dwellings
- the site location, orientation and surrounding context
- the completeness of the architectural drawings
- whether existing and proposed work is clearly distinguished
- whether pools, spas, common areas or shared services are included
- which thermal-performance pathway is likely to be suitable
This step helps prevent the assessment from being created under the wrong project type or based on incomplete assumptions.
2. Reading the Plans and Specifications
A BASIX assessment is built from information contained in the project documentation. The consultant must interpret that information accurately and identify anything that is missing, inconsistent or not yet resolved.
Depending on the development, the review may include:
- site plans and true north orientation
- floor plans, elevations and building sections
- conditioned and unconditioned areas
- window and glazed-door dimensions
- window orientation, frame and glass performance
- eaves, awnings, balconies and other shading elements
- external wall, roof and floor constructions
- insulation and thermal-break specifications
- rainwater, landscape and hydraulic information
- hot-water, heating, cooling and ventilation systems
Where the drawings and schedules provide different information, the consultant may need clarification before the assessment can be finalised. Guessing unresolved specifications can produce certificate commitments that the project team did not intend to adopt.
3. Completing the Water Assessment
The consultant records the water-related information required for the project. This does not involve designing the complete hydraulic system, but it does require the assessment inputs to match the proposed plans and specifications.
Relevant information may include:
- the efficiency of taps, showers and toilets
- rainwater-tank capacity
- the roof area connected to the rainwater tank
- the internal and external uses supplied by collected water
- garden, lawn and low-water-use landscape areas
- swimming-pool or spa information where applicable
- shared water measures for multi-dwelling developments
The resulting commitments may affect the architectural, landscape and hydraulic documentation. The consultant therefore checks that nominated measures can be carried through into the approval set.
4. Completing the Energy Assessment
The energy section records the proposed systems and services that influence operational energy use and associated emissions within the BASIX assessment.
The consultant may review and enter information relating to:
- hot-water-system type and energy source
- heating and cooling systems
- mechanical ventilation and exhaust systems
- ceiling fans
- lighting selections
- cooking energy source
- photovoltaic systems and other applicable measures
- shared services within multi-dwelling developments
The consultant may identify more than one way to achieve the required outcome, but the final selections should reflect systems the client and design team are prepared to document and install.
5. Coordinating the Thermal-Performance Assessment
Thermal performance is one of the most technically detailed parts of the BASIX process. The consultant first needs to establish which assessment method is available and appropriate for the proposed design.
Some eligible single-dwelling designs may use the BASIX Thermal Comfort DIY Method. Other projects require or benefit from the Simulation Method, which uses approved NatHERS software and must be completed by an accredited assessor.
For a simulated assessment, the work may include:
- constructing a thermal model of the proposed dwelling
- entering geometry, orientation and room zoning
- modelling glazing, shading and external obstructions
- assigning wall, roof and floor constructions
- applying insulation and thermal-bridging details
- testing heating and cooling loads
- issuing the NatHERS Assessor Certificate
- entering the certified simulation results into BASIX
Where the BASIX consultant is also the accredited assessor, these tasks may be delivered as one coordinated service. Otherwise, the BASIX consultant and NatHERS assessor need to exchange consistent plans, specifications and results.
Who can perform a NatHERS assessment? →
6. Identifying Practical Design Improvements
Where the project does not meet an applicable BASIX requirement, the consultant can help identify which part of the assessment is driving the result.
The appropriate response depends on whether the issue relates to water, energy, heating performance, cooling performance or the coordination of multiple inputs. A generic upgrade is not always the most effective solution.
Possible adjustments may include reviewing:
- glazing area, orientation or performance
- eaves, awnings and external shading
- roof, wall or floor insulation
- thermal bridging through steel-framed construction
- natural ventilation and ceiling fans
- hot-water, heating and cooling systems
- rainwater storage and connected catchment
- fixture and appliance efficiency
The consultant should explain the consequence of each proposed change so the architect, designer, builder or homeowner can make an informed decision. The objective is not simply to add the highest available specification, but to find an appropriate response for the actual design.
Explore design optimisation and BASIX →
7. Aligning BASIX Commitments with the Plans
A BASIX Certificate contains commitments that must be reflected in the project documentation. Preparing the assessment is therefore not only a data-entry exercise. The consultant must also check that the certificate and drawings describe the same proposed development.
Coordination commonly includes checking:
- window sizes and identification numbers
- glazing U-values and solar heat-gain coefficients
- wall, roof and floor insulation
- roof and wall colours where nominated
- shading dimensions and projections
- rainwater-tank size and connected uses
- hot-water and mechanical-system selections
- photovoltaic-system capacity where relied upon
Where the plans change after the assessment, the consultant should determine whether the BASIX Certificate or supporting thermal assessment also needs to be revised.
8. Generating and Delivering the BASIX Certificate
Once the applicable assessment requirements have been met and the project inputs have been reviewed, the consultant can generate the BASIX Certificate through the NSW Planning Portal.
The final consultant package may include:
- the issued BASIX Certificate
- a NatHERS Assessor Certificate where thermal simulation was used
- stamped or associated thermal-assessment drawings where applicable
- a summary of key project commitments
- clarification of specifications that need to appear on the drawings
- advice about outstanding coordination items
The BASIX Certificate is then submitted with the relevant development or complying development documentation. The applicant and project team remain responsible for ensuring the final approval set incorporates the required commitments.
9. Revising the Assessment When the Design Changes
Residential designs often continue to develop after the first BASIX Certificate is issued. Windows may change, construction systems may be substituted or different services may be selected during documentation or procurement.
The consultant can review changes involving:
- floor area or dwelling geometry
- window dimensions, locations or specifications
- wall, roof or floor construction
- insulation levels
- shading structures
- rainwater systems
- hot-water, heating or cooling equipment
- photovoltaic or ventilation systems
Some changes may have little effect, while others can alter the project’s water, energy or thermal-performance result. The assessment should be checked before revised plans are lodged or substituted products are installed.
What Information Does a BASIX Consultant Need?
Plans
Architectural Documentation
- site plan with orientation
- floor plans
- elevations
- building sections
- window and door schedule
- shadow or obstruction information where relevant
Fabric
Construction Information
- wall constructions
- roof and ceiling build-ups
- floor and subfloor systems
- insulation specifications
- frame types and thermal breaks
- glazing performance data
Systems
Water and Energy Selections
- rainwater-tank details
- fixture efficiencies
- hot-water system
- heating and cooling systems
- ventilation and fans
- solar-photovoltaic information
What Is Not Included in the BASIX Consultant’s Role?
The BASIX consultant supports one defined part of the wider design and approval process. Unless separately engaged and appropriately qualified, the consultant does not replace other project professionals.
A standard BASIX service does not generally include:
- architectural design or preparation of the complete drawing set
- structural, hydraulic, mechanical or electrical engineering
- planning advice about all development controls
- approval or determination of the DA or CDC
- certification that construction work has been completed correctly
- product installation supervision
- a lifecycle assessment or project-specific embodied-carbon report
- legal interpretation of planning legislation
Where an issue falls outside the BASIX assessment, the consultant may identify the coordination requirement and refer it back to the architect, engineer, planner, builder or certifying authority.
Common Misunderstandings About BASIX Consultants
“Every BASIX consultant is automatically a NatHERS assessor.”
No. NatHERS simulation must be completed by an appropriately accredited assessor. Confirm whether the appointed BASIX consultant also holds that accreditation or coordinates the simulation through another assessor.
“The consultant decides whether the project is approved.”
No. The consultant prepares assessment documentation. The relevant consent authority or certifying authority determines the planning or approval application.
“The BASIX Certificate can be prepared without final design information.”
A preliminary assessment can begin before every selection is final, but the issued commitments must ultimately align with the proposed development. Unresolved information may need to be confirmed before the Certificate is generated.
“The consultant always specifies the most expensive upgrade.”
A well-coordinated assessment should identify why the project is not meeting a requirement and consider suitable responses. Higher-cost glazing or equipment is not automatically the only or best solution.
“Once issued, the Certificate never needs to change.”
Relevant changes to the design, glazing, construction or systems may require the BASIX assessment and supporting thermal documentation to be revised.
Frequently Asked Questions
BASIX Consultant FAQs
What does a BASIX consultant provide?
A BASIX consultant typically reviews the residential plans, completes the applicable assessment inputs, coordinates thermal performance, identifies any required design changes and generates the BASIX Certificate. The exact deliverables depend on the project and agreed service scope.
Is a BASIX consultant the same as a NatHERS assessor?
Not necessarily. A NatHERS assessor must hold current accreditation to conduct thermal simulations. Some BASIX consultants are also accredited assessors, while others coordinate that part of the work with a separate accredited professional.
Does the consultant submit the development application?
Not usually as part of a standard BASIX service. The consultant prepares the BASIX documentation for inclusion with the application. The applicant, architect, planner or another appointed party generally coordinates the wider DA or CDC submission.
Can a BASIX consultant change the design?
The consultant can recommend performance-related changes and test alternatives, but design decisions remain with the client and appointed design team. Proposed changes should be incorporated into the drawings before the assessment is finalised.
When should a BASIX consultant become involved?
The assessment should begin while the plans are sufficiently developed to provide reliable geometry and construction information, but before all documentation is locked. This leaves time to resolve performance issues without disrupting a completed approval set.
What happens if the BASIX assessment does not pass?
The consultant should identify which part of the assessment is not meeting the applicable requirement and review suitable changes. The response may involve water measures, systems, glazing, shading, insulation or another project-specific input.
Can a BASIX consultant revise an existing Certificate?
Yes, subject to access to the project and sufficient documentation. The consultant can review the proposed changes, update the relevant assessment information and generate revised documentation where required.
Related Knowledge
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