What is NatHERS?
Nationwide House Energy Rating Scheme
Nationwide House Energy Rating Scheme (NatHERS), is a national government regulatory framework that sets the performance standards for building thermal assessment computer software packages to rate the thermal comfort performance of residential developments across Australia. The rating is based on a scale of 0 to 10 stars, with a higher number of stars indicating a more energy efficient home. The NatHERS rating is calculated using a computer model that takes into account factors such as the size and orientation of the home, the type of heating and cooling systems it has, and the type and amount of insulation it has. The NatHERS rating is used to help homeowners and builders understand the energy efficiency of a home and to identify opportunities for improvement. This star rating may be replaced by specific heating and cooling load requirements in certain jurisdictions. It can also be used as a tool to help homeowners and builders make more informed decisions about the design and construction of new homes.
By provision of a national regulatory framework, NatHERS delivers consistent and reliable energy efficiency ratings for a dwelling regardless of the software package for the assessment and the climate conditions of the development. NatHERS also sets the standards for training provider organisations and assessment procedures to train and test qualified accredited assessors to work with NatHERS thermal simulation software tools. Compared to complying with the directive statements of volume 2 of the Building Code of Australia, a NatHERS assessment provides superior flexibility and delivers a much more educated and customised solution based on the specifics of the dwelling, locality, surrounding conditions and many other considerations using a sophisticated thermodynamic simulation engine developed by CSIRO.
A NatHERS thermal comfort model allows the building owners and developers to trade off between undesirable and expensive building components and replace them with more effective and practical building solutions that serves the economy and sustainability of the building better.
A NatHERS Certificate is a document that shows the results of a NatHERS assessment, which is a computer simulation of the thermal performance of a home. The assessment takes into account factors such as the orientation of the home, the materials used in its construction, and the local climate. The NatHERS certificate provides a star rating for the home, with higher ratings indicating a more energy-efficient home.
The certificate is in the form of a multi page PDF file which summarises the most important information about the building, its overall performance and the performance requirements of each relevant element of the building. The NatHERS certificate can be downloaded from the government portal individually for each dwelling in a multi unit development and there is also an option to download a summary certificate which lists the performance figures of all units of a multi unit residential development.
NatHERS certificates are required for most new homes in Australia, and they can be used to help homeowners save money on energy bills and to reduce their carbon footprint. They can also be used as a marketing tool for builders and designers, as energy-efficient homes are becoming increasingly popular with buyers.
Australian Government introduced NatHERS regulatory framework to provide legal and technical guidelines for computer thermal simulation packages for residential developments to deliver consistent and auditable results and to be accredited in a transparent and fair fashion. It requires computer software packages to simulate how heat enters and leaves the residential spaces of a dwelling based on the standardised building material thermal properties and normal behavioural patterns of regular families operating in the space. To be accredited by NatHERS, a software must meet certain standards and requirements, including the ability to accurately model the thermal performance of homes and to produce reliable and consistent results. Accredited software must also be regularly tested and updated to ensure that it remains accurate and up-to-date.
There are several NatHERS accredited software currently accredited to be used in Australia. We have been historically used BERS pro as our primary NatHERS software however, since availability and successful accreditation of HERO, we now use this software exclusively for all our thermal comfort modellings and simulations.
By defining guidelines for training and evaluation of NatHERS assessors, NatHERS scheme ascertains professional and educated use of thermal simulation software packages. These NatHERS accredited assessors can use and report a dwelling’s thermal loads by use of a NatHERS accredited computer software. They are professionals who are trained and accredited to perform energy ratings of residential buildings in Australia using the Nationwide House Energy Rating Scheme (NatHERS). NatHERS assessors use computer simulations to predict the thermal performance of a home, taking into account factors such as the orientation of the home, the materials used in its construction, and the local climate.
NatHERS assessors can be building designers, energy assessors, or other professionals with the knowledge and skills required to perform NatHERS assessments. In order to become a NatHERS assessor, an individual must complete a NatHERS training course and pass an accreditation exam. To practise as a NatHERS Accredited Assessor, one must maintain their accreditation with an Assessor Accrediting Organisation (AAO). There are currently 3 AAOs active in Australia who are compliant with the Protocol for Assessor Accrediting Organisations being DMN, ABSA and HERA.
NatHERS Simulation Procedures
Certain temperature and environmental conditions are required in a building space for human beings to feel comfortable. NatHERS defines inside thermal conditions of a dwelling which brings comfort to the occupants of the dwelling. NatHERS thermal simulation packages then measure the amount of heat that must be added or removed from each zone of the house in order to keep the house comfortable throughout the year. Standard materials referenced in the NatHERS accredited software packages are used to model the geometry of the building and its orientation, climate zone and exposure conditions introduced to the software. A NatHERS star rating of 0 to 10 is then assigned to each zone as well as the whole dwelling which must be under a certain limit to satisfy the energy efficiency requirements of that dwelling based on the BCA and local and state government codes and regulations.
Optimised NatHERS Assessment Reduces Construction Costs
By using wholistic computer energy modelling programs, an experienced NatHERS assessor can fine tune the thermal comfort modelling of a house and provide a BCA compliant solution with the least cost and most effectiveness. Optimizing a NatHERS assessment can help reduce construction costs by identifying cost-effective solutions for improving the energy efficiency of a home, and by avoiding the need for additional measures that would add to the cost of construction. By achieving a higher star rating, builders and developers can also increase the market appeal and value of the property.
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