NatHERS Assessment Process
What Documents Are Needed for a NatHERS Assessment?
A NatHERS assessment depends on clear project information. The assessor needs enough detail to model the home accurately, including its layout, orientation, construction, glazing, insulation and shading.
Documents in brief
For a NatHERS assessment, you usually need architectural drawings, site information, window and door details, construction specifications, insulation values, roof colour, shading information and floor, wall, ceiling and roof details. A preliminary review may start with less information, but a final assessment needs confirmed documentation that matches what will be approved and built.
Why documentation matters
A NatHERS assessment is not based on a general impression of the home. It is based on the specific design, construction details and climate context of the project. The assessor needs to understand how the home is shaped, what it is made from and how it responds to sun, shade, heat and cold.
If information is missing, unclear or inconsistent, the assessment may need assumptions or clarification. This can slow the process and may lead to later changes if the final construction details do not match the original model.
Clear documentation helps the NatHERS assessment support the approval pathway, construction documentation and final compliance commitments.
Architectural plans
Architectural plans are usually the starting point for a NatHERS assessment. These drawings help the assessor understand the layout, room sizes, building form, window locations, ceiling heights, zoning and relationship between conditioned and unconditioned spaces.
The most useful drawing set usually includes floor plans, elevations, sections and a site plan. For more complex homes, additional details may be needed to understand roof forms, split levels, voids, raked ceilings, garages, subfloors or exposed floor areas.
The clearer the drawings are, the easier it is to model the home accurately and avoid unnecessary back and forth during the assessment.
The practical point
A NatHERS assessment is only as clear as the information provided.
Good drawings and specifications make the assessment faster, more accurate and easier to align with approval and construction.
Site plan and orientation
The site plan helps confirm the location of the home, its orientation and its relationship to neighbouring buildings, boundaries, landscape and other potential sources of shading.
Orientation is important because each façade receives different solar exposure. A north facing window, west facing window and south facing window can each affect heating and cooling demand differently.
For more detail, see our guide to why house orientation matters for NatHERS.
Elevations and sections
Elevations show the external walls, windows, doors, roof form, eaves and façade conditions. Sections help explain ceiling heights, roof and ceiling construction, floor levels, raked ceilings, voids and how different parts of the home connect.
These drawings can be especially important where the home has split levels, cathedral ceilings, clerestory windows, exposed floors, double height spaces or complex roof geometry.
Without sections, the assessor may not be able to model the ceiling, roof and floor conditions accurately. That can affect the NatHERS result and the construction commitments that follow.
Core drawings usually needed
• Site plan with orientation
• Floor plans
• Elevations
• Sections
• Window and door schedule where available
• Construction details for walls, roof, ceiling and floors
Window and door schedules
Windows and glazed doors can have a major effect on NatHERS ratings. The assessor needs to understand window size, orientation, frame type, glazing performance and shading conditions.
A window schedule is useful because it helps confirm dimensions and specifications. If final glazing is not yet selected, the assessment may begin with a proposed performance level, but the final documentation will need to align with what is assessed.
For more detail, see our guide to how window design affects NatHERS ratings.
Construction details
Construction details describe how the home is built. This includes external walls, internal walls where relevant, roof systems, ceilings, floors, slabs, suspended floors, garage boundaries and any exposed construction areas.
The NatHERS model needs these details because different construction systems transfer and store heat differently. A concrete slab, suspended timber floor, masonry wall, lightweight wall or raked ceiling can each affect the thermal pathway.
If the project has unusual construction, the assessor may need additional sections, notes or material details to understand how the building fabric should be modelled.
Common documentation gap
Plans often show the home’s layout clearly, but not always the thermal construction clearly.
NatHERS needs both: the shape of the home and the way the building fabric will actually be built.
Insulation values and locations
Insulation values are important, but so is the location of the insulation. The assessor needs to know whether insulation is in the ceiling, roof, walls, floor, slab edge or another part of the building fabric.
For example, a flat ceiling under a roof space may be modelled differently from a raked ceiling or skillion roof. A suspended floor over external air may need different treatment from a slab on ground.
For more detail, see our guides to how insulation affects NatHERS ratings and ceiling insulation and NatHERS outcomes.
Shading details
Shading can significantly affect solar heat gain through windows. The assessment should capture eaves, awnings, balconies, pergolas, external screens and other built shading elements where they form part of the design.
The assessor may need dimensions such as eave depth, window head height, projection depth or shading location. Nearby overshadowing from other buildings or site elements may also be relevant, depending on the project.
For more detail, see our guide to shading and solar heat gain.
Performance details usually helpful
• Insulation R values and locations
• Window and door sizes
• Glazing and frame performance values where known
• Roof colour and roof material
• Eaves, awnings, balconies and external shading dimensions
• Floor coverings, slab details and exposed floor conditions where relevant
Roof colour and roof details
Roof colour can affect heat gain through the roof, particularly in climates where solar exposure is strong. Roof material, ceiling type, roof insulation and ventilation conditions can also influence thermal performance.
For homes with raked ceilings, cathedral ceilings or skillion roofs, the roof and ceiling details may need to be especially clear. These forms can have less space for insulation and may behave differently from a conventional roof space.
Roof and ceiling details should match the construction that will actually be used, not just a generic note copied from another project.
Floor construction and floor coverings
Floor construction can influence heat transfer, thermal mass and comfort. A slab on ground, suspended timber floor, floor above a garage and floor over external air each behave differently in NatHERS.
Floor coverings can also matter, especially where the home is relying on thermal mass. A polished concrete slab may behave differently from the same slab covered with carpet or timber flooring.
For more detail, see our guide to floor construction and thermal performance.
Can a preliminary assessment start with incomplete documents?
A preliminary NatHERS review can often begin before every detail is final. This can be useful when the project team wants to understand whether the design is likely to reach the required rating before final documentation is completed.
However, assumptions may need to be made if information is missing. Those assumptions should be reviewed later when final construction details, glazing and specifications are confirmed.
For approval or construction documentation, the final NatHERS assessment should reflect the design that is actually being submitted and built.
A useful rule
Send what you have early if you need direction.
But expect the final NatHERS outcome to depend on confirmed plans, specifications and construction details.
Why consistency matters
The plans, specifications, NatHERS certificate and approval documents should be consistent. If the drawings show one construction system and the NatHERS assessment assumes another, this can create confusion during approval or construction.
Consistency is especially important for windows, insulation, roof colour, shading and construction details. These items can affect the rating and may become commitments that need to be followed during construction.
When changes happen after assessment, the NatHERS result may need to be reviewed to confirm whether the rating and compliance pathway still hold.
How documents connect to compliance
The documents provided for NatHERS help support the residential energy compliance pathway. For many new homes, townhouses and apartments, this may relate to NatHERS, 7 Star Rating, Whole of Home and state based systems such as BASIX in NSW.
The same information also helps identify whether the design has thermal performance pressure points. Large areas of glazing, difficult orientation, raked ceilings, exposed floors, dark roofs or insufficient shading may all affect the pathway.
The stronger the documentation, the easier it is to assess the home clearly and avoid late design or compliance surprises.
Design considerations for Australian homes
Project teams should think about NatHERS documentation before the drawings are fully locked in. This helps ensure the thermal performance assumptions are realistic and can be built.
For Australian homes, climate, orientation and building fabric are closely connected. The documents should show enough detail to understand how the home will respond to its local conditions.
The aim is not just to produce a rating. It is to make sure the rating reflects a coherent design that can be approved, documented and constructed consistently.
Working with Certified Energy
Certified Energy provides NatHERS assessments for new homes, townhouses and multi residential projects across Australia. Our team can review your project documentation and identify what information is needed to complete the assessment.
Where documentation is still developing, we can help clarify what is missing and what assumptions may need to be confirmed. We can also help connect the assessment with related requirements such as NatHERS, BASIX, 7 Star Rating and Whole of Home.
For the broader assessment process, visit our guide to what a NatHERS assessment is or explore the NatHERS Knowledge Hub.
FAQ
What documents are needed for a NatHERS assessment?
A NatHERS assessment usually needs floor plans, elevations, sections, site orientation, construction details, insulation values, window schedules, glazing details, shading information and roof colour details where known.
Can a NatHERS assessment start before all details are final?
Yes. A preliminary NatHERS review can often begin before every detail is final, but the final assessment needs enough confirmed information to accurately model the home.
Why are window schedules important for NatHERS?
Window schedules are important because window size, orientation, frame type, glazing performance and shading can strongly affect the NatHERS rating.
Do insulation details need to be confirmed?
Yes. Insulation values and locations should be confirmed because they affect the thermal performance model and may become construction commitments.
What happens if the design changes after NatHERS?
If the design changes after assessment, the NatHERS result may need to be reviewed. Changes to windows, insulation, roof colour, shading, floor construction or building form can affect the rating.
