NatHERS Certificate & Assessment Services

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What is a NatHERS Certificate?

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NatHERS Certificate & Assessment Services

The Nationwide House Energy Rating Scheme (NatHERS) evaluates the thermal performance and overall energy efficiency of new homes and apartments across Australia. Working with a qualified NatHERS consultant helps your design meet the National Construction Code (NCC) requirements, which from 2022 mandate a minimum 7-star Thermal Rating and a Whole of Home score of 60 for houses and 50 for apartments.

A NatHERS energy assessment helps architects, builders, and homeowners optimise designs, select efficient appliances, and enhance occupant comfort while reducing long-term energy use. With around 90 percent of new dwelling designs now assessed through NatHERS, these standards support both compliance and cost savings, with updated NCC requirements helping new homeowners save an average of $183 annually.

What is a NatHERS Certificate?

A NatHERS certificate is an official assessment that measures how energy-efficient a new home or apartment is. Instead of relying on complex building rules, NatHERS assessors use computer modelling to estimate how much energy the dwelling will need for heating, cooling, appliances, and on-site energy systems. This makes it easier for designers and builders to understand where improvements can be made for comfort and efficiency.

For homeowners, a higher NatHERS rating means lower energy bills, better indoor comfort, and a home aligned with Australia’s sustainability goals. Importantly, achieving a minimum 7-star rating can also qualify homeowners for green loans from selected insurers and lenders.

Thermal Star Rating

The Thermal Star Rating scores a home from 0 to 10 based on how well it maintains comfortable temperatures without relying heavily on heating or cooling. Factors such as layout, insulation, window design, and orientation affect the score. A 7-star home performs efficiently, while 8 to 10 stars indicate exceptional energy performance. This rating supports smarter, energy-efficient home design and aligns with NCC requirements.

The Whole of Home Rating

The Whole-of-Home rating evaluates the energy use of major appliances, including heating and cooling systems, hot water, cooking loads, plug loads, and any on-site solar or battery storage. Scored out of 100, it shows whether a dwelling meets or exceeds the NCC energy budget. This broader assessment helps homeowners understand the total impact of their appliance choices and supports more sustainable performance across the entire home.

Why You Need a NatHERS Consultant

Role of a NatHERS Assessor

NatHERS assessors play a crucial role in evaluating and certifying the energy efficiency of new dwellings. The accredited professionals possess the expertise to assess and optimise the thermal performance of residential designs, guiding compliance with energy efficiency standards.

Technical Expertise

Trained to use accredited software, NatHERS assessors model the thermal performance of residential buildings. They understand how insulation, window placement, and building orientation affect energy efficiency.

Assessment Process

Assessors collect detailed information about the new dwelling’s design, materials, and location. They input this data into NatHERS-approved software to simulate its thermal performance and determine its star rating.

Efficiency Recommendations for Better Ratings

In addition to providing a star rating, assessors often offer suggestions for improving a new dwelling’s energy efficiency. These recommendations help homeowners, designers, architects, and builders make informed choices to enhance comfort and sustainability.

By collaborating with Afogreen Build as a NatHERS assessor, you can significantly enhance your building’s design to comply with energy ratings. We will analyse your plans and provide tailored recommendations. This proactive approach helps achieve the desired energy rating and creates a more comfortable and sustainable living environment.

Feel free to schedule an initial consultation today for expert guidance and to learn how we can help you optimise your home design for superior energy performance

Our NatHERS Assessment Process

At our NatHERS Assessment Services, we follow a thorough step-by-step process to offer accurate and reliable energy efficiency evaluations for buildings.

Step-by-Step Guide

  1. Initial Consultation

    We begin with a consultation to understand your project requirements and goals. This includes discussing your design plans and any specific energy efficiency targets.

  2. Documentation Review

    Our assessors review the plans, specifications, and any relevant documentation, which helps us gather the necessary information for the assessment. In addition, if the information or specific details to undertake a detailed assessment are not available or have not yet been made, default settings have been developed to be used in these situations.

  3. Energy Modelling

    We use software tools to simulate the building’s thermal performance. This involves inputting data and other essential details into the assessment software. 

  4. Rating Calculation

    The simulation generates a star rating under the NatHERS framework. Our assessors analyse the results and identify opportunities for improvement if the initial rating does not meet the desired standards.

  5. Certification

    Upon completing the assessment and making any necessary modifications, we issue the NatHERS Certificate with the logo, confirming the building’s energy efficiency rating.

At Afogreen Build, our assessors use NatHERS-accredited software tools to generate official star ratings and issue relevant certificates.

HOW NATHERS STAR RATINGS ARE CALCULATED

NatHERS star ratings are generated using sophisticated thermal performance modelling. In simple terms, accredited NatHERS software analyses the building’s design, construction materials, orientation, and climate zone. The software then simulates how much heating and cooling the home will need throughout the year.

Based on these simulations, the home is assigned a star rating. A lower rating means the home requires more energy to stay comfortable, while a higher rating reflects efficient design with minimal heating and cooling demand. Working with a NatHERS consultant helps these simulations are interpreted accurately, allowing homeowners and designers make informed decisions that support energy-efficient home design and long-term sustainability.

IMPROVING YOUR DESIGN TO ACHIEVE HIGHER STAR RATINGS

Even small design improvements can significantly increase a home’s NatHERS star rating. Upgrading insulation, choosing better wall construction methods, improving window glazing, and incorporating effective shading all reduce the amount of energy required for heating and cooling. These changes enhance thermal performance and help achieve better results.

At Afogreen Build, our NatHERS consultants provide tailored recommendations based on your home’s climate zone, site conditions, and construction approach. By modelling different design scenarios, we help homeowners, architects, and builders refine their plans to reach 7-star performance or higher, aligning each project with modern expectations.

Benefits of a NatHERS Certificate

A NatHERS certificate provides numerous advantages for homeowners, architects, and builders:

Compliance with Regulations
The NatHERS Thermal Star Rating and the Whole of Home Rating can both be used to meet compliance with the new NCC energy efficiency provisions.

Higher Property Value and Enhanced Disclosure and Rental Standards
A NatHERS certificate boosts a property’s appeal to buyers, especially those prioritising energy efficiency and environmental impact. It also supports energy efficiency disclosure and rental standards, helping to improve the overall performance, comfort, and sustainability of new dwellings.

Cost Savings
Improved energy efficiency leads to long-term savings on utility bills, making a new dwelling more economical to live in.

Support for Green Loans
A minimum 7-star rating can qualify homeowners for green loans from certain insurance companies.

Improved Energy Efficiency
It rates a new dwelling’s energy efficiency, helping to reduce reliance on heating and cooling, lower energy bills and greenhouse gas emissions, and improve overall energy performance. It also supports industry and homeowners in achieving zero energy (and carbon) ready homes.

Increased Comfort
Higher ratings maintain consistent indoor temperatures, improving comfort by reducing reliance on mechanical heating or cooling.

Wider Range of Options
Unlike the NCC Deemed-to-Satisfy provisions, NatHERS allows for a broader selection of appliances, energy generation, and storage solutions. This flexibility supports new dwellings that exceed the minimum standards and can even generate more energy than they use.

Trade-Offs Between Technologies
NatHERS enables a trade-off between various technologies and appliance efficiencies. For instance, using more efficient appliances might eliminate the need for solar PV installation while still meeting the NCC 2022 minimum requirements.

Tailored Recommendations
To further enhance sustainability, NatHERS suggests energy improvements, such as insulation or window placement.

Certified NatHERS Consultants

With extensive experience conducting thorough energy assessments and providing tailored design advice, we help your projects comply with the NatHERS rating system and meet NCC 2022 requirements. Our consultants work closely with you to identify opportunities for improvement. Contact us today to enhance your building’s energy efficiency with our expert guidance.

Frequently Asked Questions (FAQs)

How long does the assessment process take?

The timeline can vary depending on the complexity of the project. For further information, please get in touch with us.

The cost of a NatHERS assessment varies depending on the project’s complexity and the new dwelling’s size, location, and compliance requirements. Please get in touch with us for a detailed quote tailored to your specific needs.

Several core principles of thermal performance influence your NatHERS Thermal Star Rating. Consultants may use thermal modelling software to evaluate how these principles interact in your specific climate zone and construction method, helping you understand which design choices will improve your outcome.

  • Maximise solar gain in cool months and minimise solar gain in hot months
    Solar gain is heat transferred into a building from sunlight, and controlling it involves factors like building orientation, window placement, shading, external color, and insulation. Proper orientation maximises sunlight for heating in colder climates, while window placement, especially north-facing, can enhance solar gain but may lead to heat loss if not balanced. Shading devices are essential, with adjustable options providing control in different climates. Lighter exterior colors reflect heat, helping manage indoor temperatures, while insulation reduces heat loss or gain, enhancing comfort by minimising air leakage.
  • Maximise or minimise energy transfer
    Energy transfer happens through conduction, where heat moves from warm to cool areas in walls, floors, roofs, glazing, and skylights. It can be controlled by improving insulation and design. Factors include dwelling shape, less external wall area reducing heat transfer, and grouping similar zones to minimise internal energy transfer. Insulating between different temperature zones, like bedrooms and garages, also helps reduce energy transfer.
  • Maximise ventilation and optimise infiltration
    Ventilation is air movement through a dwelling, controlled by air paths like doors, windows, and fans. Factors include dwelling orientation for cooling, window and door placement for cross ventilation, and internal zoning for temperature control. Unsealed downlights can cause air leakage and reduce insulation, while window type affects airflow, with casement windows providing more ventilation than double-hung ones.

Yes! If your new dwelling doesn’t achieve the desired rating, Afogreen Build will guide modifications to improve energy efficiency. Here are some options to improve a rating:

  • Improve thermal rating: Enhancing thermal performance reduces the need for heating or cooling, boosting the Whole of Home rating.
  • Use efficient appliances: Choose higher efficiency appliances and size them appropriately.
  • Change appliance type: For better efficiency, consider switching from ducted air conditioning to room reverse cycle air conditioning.
  • Switch fuel technologies: For example, switch from gas water heaters to solar electric ones.
  • Install load-shifting technologies: Use systems like batteries or PV panels oriented to the west to reduce energy demand during peak hours or run heat pumps off-peak.
  • Add onsite renewable energy: Install solar PV systems to generate renewable energy.
  • Reduce home size: Encourage the client to reduce floor area, as Whole of Home calculations are based on floor space (m²).

NatHERS assessments primarily apply to residential buildings, including houses and apartments, for new construction and major renovation while the existing scheme is being released. However, commercial buildings may require different energy rating frameworks, such as a JV3 assessment.

There are currently four software tools in Australia that are accredited to assess compliance with the requirements of the National Construction Code:

  • AccuRate Home Version v1.3.3.24 (using Chenath v3.24) includes Thermal ratings, Whole of Home ratings, Thermal and Whole of Home Certificates, and WERSLink Default Window Library.
  • BERS Pro Version 5.2.4 (using Chenath v3.23) includes Thermal ratings, whole-of-home ratings, Thermal and whole-of-home certificates, and WERSLink Libraries.
  • FirstRate5 Version v5.5.5a (using Chenath 3.22) includes Thermal ratings and Thermal Certificates but excludes WERSLink (the new Windows library).
  • FirstRate5 Whole-of-Home (Version 1.0.1) includes Whole-of-Home ratings and Whole-of-Home Certificates but excludes PV Diverter hot water systems.
  • Hero Version 4.1 (NCC 2022 profile using Chenath v3.23), which includes Thermal ratings, Whole of Home ratings, Thermal and Whole of Home Certificates, and WERSLink Libraries and excludes PV Diverter hot water systems.

Hero, FirstRate5, BERS Pro, and AccuRate Home are all fully accredited, including certificates, and can be used for National Construction Code (NCC 2022) regulatory assessments.

It’s helpful to have your architectural plans and specifications ready. At Afogreen Build, our building and sustainability consultants can provide you with any additional information needed for the assessment. Contact us now for further info. 

Here are the top tips for building for 7 Stars:

  • Involve a NatHERS assessor early in the design process
    Working closely with a NatHERS consultant from the beginning of your design process will help you identify and implement the strategies to meet a 7-start rating.
  • Orientation is key
    Design for the local climate, ensuring proper shade and solar access. Repositioning the house plan can significantly improve performance.
  • Improve glazing
    Custom windows provide better flexibility for performance. Window sizing, placement, and shading should suit the climate.
  • Increase zoning
    Adding more internal doors helps NatHERS provide more accurate heating and cooling estimates. Consider placing doors at corridor ends, the bottom of stairs, or closing off infrequently used rooms.
  • Insulate more
    Improve ratings by increasing the R-value of wall, floor, and ceiling insulation or adding insulation to new areas like slab edges, garage walls, and internal walls. Be mindful of condensation risks.
  • Plan for fans
    Installing ceiling fans in all rooms boosts your NatHERS rating and enhances homeowner comfort.
  • Check your colours
    Adjusting roof and external wall colors can improve NatHERS ratings, especially by avoiding dark roofs in warmer climates. Some software even adjusts window frame colors for a noticeable difference. Discuss color choices with clients early.
  • Look at lighting
    NatHERS rewards homes with fewer ceiling penetrations with higher ratings. Consider whether your design can delete downlights that aren’t IC4 rated, roof windows, and skylights, and replace these with other lighting options that allow for continuous ceiling insulation.

 

With Afogreen Build’s expertise, we will help you achieve the highest energy efficiency standards for your new dwelling.

To achieve a higher Whole of Home rating, consider selecting energy-efficient appliances, increasing solar PV on your home, and adding a battery to reduce energy imports during peak periods. These choices help lower energy consumption and improve your rating, with homes exceeding seven stars being rewarded for their efficiency. In some states, such improvements also strengthen outcomes in related frameworks such as a BASIX assessment, supporting broader compliance and sustainability goals.

The Whole of Home assessment must be revised, and a new certificate must be issued whenever project specifications change.
Examples of revisions that require re-rating include:

  • An updated NatHERS thermal assessment.
  • Changes in appliance technology include replacing a room reverse-cycle air conditioner with a ducted reverse-cycle air conditioner, replacing a gas instantaneous hot water heater with a gas storage heater, switching from a gas cooking appliance to an electric one, replacing a lithium-ion battery with a lead-acid battery, and changing a variable pool pump to a single-speed pool pump.
  • A decrease in appliance efficiency, such as replacing a 6-star gas heater with a 5-star model.
  • Suppose an appliance or technology is replaced by a higher-efficiency version of the same type (e.g., a 6-star hot water system replacing a 5-star system). In that case, re-simulation isn’t necessary, though it may improve the rating.

 

Other revisions requiring re-simulation include:

  • A decrease in Small-Scale Technology Certificates (STCs) for solar hot water and heat pumps, especially if the STC value falls below the substitution range noted in the certificate. Note that STCs reflect system efficiency or size, not just efficiency.
  • A reduced PV system size or changes in its orientation or slope.
  • An increase in pool or spa volume.

Yes, every dwelling must have its own individual NatHERS certificate, as outlined in the NatHERS Technical Note. This applies to all Class 2 houses in a single building or development, even if the design is repeated across multiple projects. Each dwelling must be assessed and rated based on its specific characteristics, ensuring an accurate energy efficiency evaluation for each unit.
When multiple Class 2 multi-unit buildings are located close together as part of the same development, or when the strata plan identifies separate lots, a separate summary certificate must be completed for each building or lot.

No, NatHERS software tools cannot be used to rate only a part of a dwelling. When assessing an addition or extension to an existing dwelling, the rating must include both the existing and proposed areas of the home to ensure an accurate and comprehensive energy efficiency assessment.

To reduce a high heating load and improve the Whole of Home rating, several design improvements can be made, including:

  • Roof and External Wall Colors: Select dark colors for the roof and external walls to absorb more heat.
  • Dwelling Sealing: Improve sealing with weather seals and draft stoppers, especially on exhaust fans (ensure compliance with NCC requirements).
  • Insulation: Increase insulation in walls, ceilings, and roofs, and remove downlights that create gaps in ceiling insulation. Internal wall insulation between conditioned and unconditioned spaces, such as between the house and garage, can also help. Consider underfloor insulation and soft floor coverings like carpet or cork to reduce energy transfer further.
  • Glazing: Maintain a moderate glazing-to-floor area ratio, use glazing units with low U-values (less than 4.0) and high solar heat gain coefficients (greater than 0.5), and limit south-facing glazing while increasing north-facing glazing for better solar gain.
  • Shading Devices: Reduce the width of the shading device to allow more heat during winter or install operable shading devices to maximize solar gain in winter while providing shade in summer.
  • Ventilation: Minimise roof and subfloor ventilation to reduce heat loss while complying with NCC requirements for ventilation.
  • Thermal Mass: Decrease thermal mass if the climate doesn’t provide enough sun to heat materials effectively.
  • Slab Insulation: Use slab edge or under-slab insulation, or consider a waffle pod slab, which provides both insulation and ground coupling.
  • Repositioning and Orientation: Reposition the dwelling’s orientation or windows to maximize north-facing windows in living areas or re-design to optimize northern orientation and zoning.

 

These adjustments can help reduce heating demand, increase comfort, and improve energy efficiency, ultimately enhancing the Whole of Home rating.

To reduce a high cooling load and improve the Whole of Home rating, consider the following design improvements::

  • Dwelling Sealing: Improve sealing with weather seals and draft stoppers, especially on exhaust fans (help to comply with NCC requirements).
  • Insulation: Increase insulation in walls, ceilings, and roofs, and remove downlights that create gaps in ceiling insulation. Internal wall insulation between conditioned and unconditioned spaces, such as between the house and garage, can also help. Consider underfloor insulation and soft floor coverings, such as carpet or cork, to further reduce energy transfer.
  • Glazing: Maintain a moderate glazing-to-floor area ratio, use glazing units with low U-values and high solar heat gain coefficients, and limit south-facing glazing while increasing north-facing glazing for better solar gain.
  • Shading Devices: Reduce the width of the shading device to allow more heat during winter or install operable shading devices to maximise solar gain in winter while providing shade in summer.
  • Ventilation: Minimise roof and subfloor ventilation to reduce heat loss while complying with NCC requirements for ventilation.
  • Thermal Mass: Decrease thermal mass if the climate doesn’t provide enough sun to heat materials effectively.
    Slab Insulation: Use slab edge or under-slab insulation, or consider a waffle pod slab, which provides both insulation and ground coupling.
  • Repositioning and Orientation: Reposition the dwelling’s orientation or windows to maximise north-facing windows in living areas or re-design to optimise northern orientation and zoning.
  • Daylight modelling: software can also help determine what other changes need to be made.

 

These adjustments can help reduce heating demand, increase comfort, and improve energy efficiency, ultimately enhancing the Whole of Home rating.

Ready to enhance your building’s energy efficiency and obtain your NatHERS Certificate?

Contact us today to schedule your NatHERS assessment!
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