NatHERS is updating the climate files to provide a more up-to-date climate data set that is more consistent and provides better accuracy in the assessment of energy use in residential homes. NatHERS Climate Files have not been updated since 2005.
The star bands are being re-calibrated because of the introduction of the updated climate files to NatHERS. This is to limit the impact of change, maintain the integrity of the scheme and avoid burdensome adjustment for industry. The star band re-calibration was based on limiting change to star ratings to an ‘average of zero’ for building types in a climate’s star band.
The updated climate files and re-calibrated star bands could mean that there will be a small change to individual house energy ratings depending on house design, building construction and climate zone.
Thermal bridging can significantly reduce the effectiveness of insulation if not accounted for. If the proposed thermal bridging provisions are adopted in the NCC, NatHERS will introduce thermal bridging to regulatory ratings to align with the other compliance pathways in the National Construction Code.
The proposed thermal bridging provision involves the impact of thermal bridging in steel framed houses to be factored into an energy rating, but only to the extent that it exceeds the thermal bridging impact of a timber framed house. The thermal bridging calculations to be installed in NatHERS only account for the additional impact that steel framing elements have over and above that of timber. The impact of introducing this approach to thermal bridging is expected to be up to 0.5 of a star rating.
NatHERS is being expanded to include Whole of Home assessments and ratings to support the proposed National Construction Code (NCC) requirements for residential buildings in 2022. This includes Class 1 dwellings and Class 2 sole-occupancy units (apartments), but not the common areas of apartment blocks.
The expansion of NatHERS to include Whole of Home assessments and ratings will deliver industry a streamlined and cost effective approach to demonstrate compliance with the proposed NCC 2022 requirements.
The Whole of Home tools allow a wider range of appliances, and energy generation and storage to be assessed, than under the NCC Deemed-to-Satisfy elemental provisions.
The changes will help households improve a home’s energy efficiency and reduce energy use, which provides a range of benefits including lower energy bills, improved comfort and health for occupants, improved resilience of buildings to extreme weather and blackouts (peak demand), and reduced carbon emissions.
NatHERS accredited Whole of Home tools are anticipated to be available for use from September 2022, in line with the proposed National Construction Code (NCC) 2022 coming into effect. The NatHERS AccuRate Whole of Home Benchmark Tool will be available from this date.
A consultation version of AccuRate Whole of Home (WoH) Benchmark Tool is currently available. The purpose of AccuRate WoH is to provide a benchmark that other Whole of Home tools can be measured against as part of the Whole of Home software accreditation under NatHERS. See the NatHERS Whole of Home software developer expression of interest page for more information on the software accreditation process and how to apply.
The accreditation of other tools cannot commence until final decisions on NCC 2022 energy efficiency provisions are confirmed. This means that other tools may not be available by 1 September 2022. The NatHERS Administrator is working closely with potential tool developers and is providing early access to information to help support their development.
NatHERS has endorsed the FirstRate5 Whole of Home Pilot Tool to provide an early indication of other NatHERS accredited tools that may be available in the future. Endorsement means that the tool includes all the key modules for a Whole of Home assessment and is on the right track for NatHERS accreditation. More information about the FirstRate5 Whole of Home Tool is available here.
Endorsed tools demonstrate what is possible for accredited NatHERS Whole of Home tools, by providing an indication of the look, feel and usability. Endorsed tools do not produce a NatHERS Certificate or Whole of Home rating.
It is not expected there will be an increased need to use AccuRate to do Whole of Home assessments and ratings. More tools are anticipated to be available for use from September 2022, when the National Construction Code launches. The FirstRate 5 Whole of Home Pilot Tool was recently endorsed by the NatHERS Administrator and is progressing to accreditation.
You need to know how to use AccuRate Whole of Home including how to generate an AccuRate Thermal assessment to use the Benchmark Tool. A number of training sessions have already been held by the NatHERS Administrator and a video demonstration of how to use the Benchmark Tool is here.
NatHERS tool endorsement provides an early indication that the tool is on the right track for NatHERS accreditation. Importantly endorsement provides the opportunity for the NatHERS Administrator to work with the Software Tool Developer to assist with any issues that may arise during the Whole of Home tool development process. Endorsed tools cannot be used to produce a NatHERS Certificate or a Whole of Home rating.
Tool accreditation means tools are formally recognised by the NatHERS Administrator as being ready to use for Whole of Home assessments and ratings. See the NatHERS Whole of Home software developer expression of interest page for more information on the software accreditation process and how to apply.
Sustainability Victoria has developed the FirstRate5 Whole of Home Pilot Tool and recently it has been endorsed by the NatHERS Administrator. The pilot tool is intended to help designers become familiar with undertaking NatHERS Whole of Home assessments, which are expected to form part of Performance Requirement 2 (PR2) in the proposed changes to the National Construction Code in 2022 (NCC 2022).
Please note that the FirstRate5 Whole of Home Pilot Tool cannot be used to assess compliance with NCC 2022. An updated version of the tool will be released in 2022, once all requirements for NCC 2022 are known.
The FirstRate5 pilot tool works by importing the heating and cooling load data from a FirstRate5 project file and then adding on the additional appliance and distributed energy modules. The user interface is simple to use, and it is expected it will only take 10-15 minutes to enter the necessary details to complete a Whole of Home assessment.
The FirstRate5 Whole of Home Pilot Tool has limitations at this stage:
The ‘Solar Panels and Battery Storage’ module is currently limited to 13 Victorian NatHERS climate zones (20, 21, 22, 24, 25, 27, 60, 61, 62, 63, 64, 66, 69), which have minimal crossover with climates zones along the NSW & SA borders.
Heating/cooling equipment efficiency and type can only be specified for two main zones: 1) the conditioned living (primary) zone, and; 2) the conditioned other (secondary) zone.
The efficiency level of the solar-electric, gas boosted solar and heat pump water heaters can be specified as either ‘standard’ or ‘high efficiency’.
An assessment can only be undertaken with a FirstRate5 project file.
Sustainability Victoria is offering free online one hour training sessions to interested parties. It is mandatory to attend a training session before Sustainability Victoria will grant you access to the pilot tool.
Visit Eventbrite to select a training session. If you cannot attend any of the listed sessions, please register your interest here and Sustainability Victoria will inform you about upcoming training sessions. Once you have been granted access to the pilot tool you can access it here.
To use the FirstRate5 Whole of Home Pilot Tool, you will also need to have an active FirstRate5 account. If you are not already a registered FirstRate5 user, you will need to visit the FirstRate5 website and create an account for free.
The NatHERS star rating and the Whole of Home rating will both be used to meet compliance with the NCC.
The NatHERS star rating will be used to meet compliance with the proposed Performance Requirement 1 (thermal performance) for Class 1 dwellings and J1P2 for Class 2 sole occupancy units (apartments).
The Whole of Home rating will be used to determine compliance with the proposed Performance Requirement 2 (annual energy use budget) Class 1 dwellings and J1P3 for Class 2 sole occupancy units (apartments).
The Deemed-to-Satisfy (DTS) point on the Whole of Home rating scale to meet the stringency proposed for NCC 2022 has not yet been set.
The rating scale aims to provide a point that can be used as the DTS provision for NatHERS, to demonstrate compliance with the NCC’s proposed Performance Requirement 2 (annual energy use budget) for Class 1 dwellings and J1P3 for Class 2 sole occupancy units (apartments).
The Australian Building Codes Board (ABCB) is consulting on a proposed new minimum NatHERS star rating of 7 stars for NCC 2022, with allowances for outdoor living area and/or ceiling fans in NCC climate zone 1 and 2.
Thermal bridging can significantly reduce the effectiveness of insulation if not accounted for. If the proposed thermal bridging provisions are adopted in the NCC, thermal bridging will be introduced to NatHERS to align with the other compliance pathways in the NCC. Thermal bridging will be based on calculation methods in NZS 4214.
When conducting a NatHERS energy assessment, the star rating is based on the total amount of energy predicted to be needed to keep that house comfortable. That total is broken down into the amount required for heating and cooling and is displayed on the NatHERS Certificate as well as the star rating.
To meet NCC requirements, a house design must meet the minimum energy requirements for a given location (total energy use) and must not exceed either the heating or cooling load limits for that star band and location.
The ABCB Standard that sets out the NatHERS split heating and cooling load limits will be updated in NCC 2022, to reflect the changes to NatHERS climate files and the associated changes to star bands. These updates mean the amount of energy corresponding to each star band is changing, so the accepted split of that energy into heating and cooling limits must also be adjusted.
The split loads will be updated using the same principle, whereby they will exclude the worst 5% of houses, based on historical data recorded in the Australian Housing Data portal.
NatHERS In Home assessments and the National Scorecard tool can be used in all Australian climate zones.
The National Scorecard tool has been piloted and trialled nationally to ensure it is suitable to cover a diverse range of built forms, appliances and locations.
Over 5,000 Scorecard assessments have been formally completed to date across Australia, with more than 70 assessors accredited across states and territories.
For tropical climates, the National Scorecard tool has been tested in the field by skilled assessors with local knowledge in locations including Cairns, Broome, Darwin and Townsville. It was found to be suitable for use in all of these locations.
The National Scorecard tool has been specifically designed to incorporate features important to tropical performance, including cross flow ventilation and ceiling fans.
The National Scorecard Initiative enables energy performance assessments to be conducted on existing homes of any age or location, without the need for house plans and specifications.
Accredited assessors have access to a government supported National Scorecard tool designed to be used on-site. Assessors provide a certificate with a star rating out of 10 indicating the cost to run the home, a rating for comfort and the main energy using features of the home.
Accredited National Scorecard assessors assist home owners to better understand their home’s energy performance and what steps they can take to improve the comfort of their home. The assessment certificate provides expert advice on upgrades that householders can make to improve energy efficiency, and reduce their bills and running costs.
The National Scorecard tool, training, accreditation of assessors and quality checks will initially be delivered by the Victorian government across Australia, with the support of all jurisdictions.
Over time there will be further alignment of the National Scorecard with NatHERS processes, including transition of elements of delivery to third parties. For example transitioning accreditation to Assessor Accrediting Organisations.
The National Scorecard Initiative, consisting of an assessment tool, assessor training and assessor accreditation, was endorsed by meeting criteria and standards set by the NatHERS Steering Committee. The NatHERS Steering Committee is a government body that oversees NatHERS.
The National Scorecard Initiative submitted documentary evidence for each criterion, the NatHERS Administrator assessed the evidence and the NatHERS Steering Committee endorsed the National Scorecard Initiative as having met the requirements.
In Home assessments are designed for existing householders who wish to learn more about their home’s energy performance, cost, greenhouse gas emissions or comfort. These assessments rate the home by collecting information from a visit to the home (in-home assessment). These assessments are designed to inform home owners about the energy performance of their home and guide decisions for energy upgrades that can improve comfort, energy efficiency and minimise running costs and greenhouse gas emissions.
The Commonwealth, state and territory governments are extending the Nationwide House Energy Rating Scheme (NatHERS) to include ‘Whole of Home’ and ‘In Home’ energy assessments. Each assessment suits a different need.
Whole of Home assessments will be an extension of the current NatHERS (thermal) assessment of new house designs. It will incorporate thermal heating and cooling for the building shell, and hot water systems, artificial lighting, pool/spa pumps, on-site energy generation, and cooking and major plug-in appliances e.g. air-conditioners. These assessments will use house plans and specifications to assess the home. They can be used for assessing the designs of new builds and major renovations and are intended to be a pathway to comply with the requirements of the National Construction Code.
The National Scorecard star rating represents the average energy cost to run a home. It covers the home’s building shell and its major fixed appliances, as well as any on-site energy generation from solar panels. Separate comfort ratings are also provided for the home’s hot and cold weather performance.
Currently NatHERS (thermal) star ratings only indicate the energy performance of a home’s thermal shell based on house plans and specifications. Work is underway to expand NatHERS (thermal) to include the energy performance of major appliances in the home (e.g. heating and cooling systems, hot water system, etc.).
Once NatHERS ‘Whole of Home’ and ‘In Home’ are fully established, the National Scorecard ratings will be transitioned across so there is one national home energy rating system to cover both new and existing dwellings.