Software and user interface accreditation

The software accreditation protocol (SAP) and user interface protocol (UIP) outline the requirements and processes for the accreditation and re-accreditation of software tools and user interfaces that produce NatHERS energy ratings for Australian homes. The SAP applies to NatHERS ratings for the desktop version of the tool used for new homes assessments, and the UIP applies to user interfaces that will export data into the CSIRO managed cloud-based tool, AccuRate Enterprise (AE). 

New homes – software accreditation protocol

The Software Accreditation Protocol (SAP) includes a series of documents that stipulate the essential requirements for software tools and developers to model energy ratings and obtain and maintain accreditation under NatHERS.

The SAP uses up to eleven different dwelling designs which comprise of class 1 and class 2 dwellings of various sizes and floor plans. 

To access the SAP dwelling designs, you should submit a written request to admin@nathers.gov.au titled: ‘Application for access to NatHERS SAP dwelling designs’. A completed Guidelines for using NatHERS SAP Designs form must be included.

Minimum software requirements

All software must:

  • be based on well-established models that are in accordance with the principles of thermodynamics and fluid mechanics
  • include hourly calculations of heat flux across the building’s surfaces for every day of the year
  • include zoning of enclosable conditioned and unconditioned areas in a dwelling by function as described in the NatHERS Technical Note
  • produce hourly calculations aggregated to specific reporting requirements
  • use NatHERS climate zones and data
  • accord with NatHERS Energy Load, area adjustment and starbanding modelling requirements
  • provide appropriate user training and support; and
  • meet all NatHERS software testing and accuracy requirements.

Key modelling inputs

Calculations must be accurate, representative of Australian conditions and comparable across different types of housing. The Software Accreditation Protocol requires all NatHERS accredited software tools to meet strict performance standards and requirements for variables including (but not limited to):

  1. Local climate and weather (including temperature, humidity, wind and sun)
  2. Thermal resistance and capacitance of building materials
  3. Window glazing values
  4. Occupancy patterns (including internal heat loads, typical occupancy times and occupancy behaviour)
  5. Window coverings (which are standardised for all ratings, noting they are likely to change over the life of the building)
  6. Different types of zones in the house and whether they are conditioned or unconditioned
  7. Thermostat settings (temperatures at which artificial heating/cooling is no longer required to achieve thermal comfort, noting this varies depending on climate zone)
  8. Shadowing/overshadowing by adjacent buildings and features
  9. Size of the building being assessed (noting smaller buildings generally have a larger wall surface area than bigger buildings).

For more information about some of these parameters, see:

 
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Accuracy Requirements

In order for new software to become NatHERS accredited, it must be rigorously tested. During testing the NatHERS Administrator (or their agent) compare the results of multiple simulated NatHERS ratings against the benchmark software tool, AccuRate Home.

Each simulation (one for each specified dwelling in each NatHERS climate zone) is run using the software tool developer’s own procedures and processes, as specified in its user manuals and guidance materials.

The results of each simulation are then compared against the results obtained by the benchmark tool when performing the same simulation.

All the individual simulations must achieve the following minimum result:

  1. The simulated heating load is within either ±10 per cent or ±10 MJ/m2.annum of the benchmark load; and
  2. The simulated cooling load is within either ±10 per cent or ±10 MJ/m2.annum of the benchmark load.

Furthermore, at least 95 per cent of the individual simulations must achieve the following more stringent result:

  1. The simulated heating load is within either ±5 per cent or ±5 MJ/m2.annum of the benchmark load; and
  2. The simulated cooling load is within either ±5 per cent or ±5 MJ/m2.annum of the benchmark load
    OR
  3. The Energy Rating must not be more than 0.2 stars different from the Energy Rating of the Benchmark Software.

Existing homes – User interface protocol

Software developers can develop third-party user interfaces (UIs) to be connected to AccuRate Enterprise (existing homes mode) to undertake energy ratings for existing homes.

The user interface protocol (UIP) sets out the necessary requirements for user interfaces and software developers to model energy ratings and obtain and maintain accreditation under NatHERS. A thermal standardisation and specification document outlines the required thermal input fields and settings that must be incorporated into all user interface tools to ensure consistency and accuracy in assessments for existing homes. 

There is an expression of interest (EOI) process for software developers to seek accreditation of UIs for existing homes ratings. 

Read about the user interface protocol and the EOI process.