Energy Efficiency performance requirements for residential buildings
The National Construction Code (NCC) provides a number of options to demonstrate compliance with Energy Efficiency performance requirements.
Note: There are alternative ways of achieving energy efficiency: by using Deemed-to-Satisfy (DTS) provisions, formulating an Alternative Solution or using the Verification Method.
Class 1 Buildings:
- New Class 1 buildings must achieve a minimum of 6 Star Rating and have either a rainwater tank or a solar water heater system installed. (See NCC Volume Two, Part 3.12 for full requirements including any exemptions that may apply).
Class 2 Buildings and Class 4 part of a building:
- Class 2 buildings must achieve an average of 6 Star Rating collectively for all sole-occupancy units (SOU) and not less than 5 Star Rating for each individual SOU.
- Class 4, part of a building, must achieve a minimum of 6 Star Rating.
For more information, refer to Practice Note 2014-55 – Residential Sustainability Measures.
Thermal Performance Assessment
The NCC requires minimum Energy Efficiency performance requirements for new buildings.
To determine the compliance with energy efficiency requirements of the building fabric of a residential building, a thermal performance assessment (viz. Energy Rating) must be undertaken.
The thermal performance assessment is a comprehensive evaluation of building envelope performance which includes:
- construction materials
- window glazing specification and orientation
- insulation details
- orientation of the building
In addition, thermal performance assessment also takes into consideration the services of a building (for e.g. heating and cooling loads, insulation of heating and cooling ductwork, artificial lighting, and swimming pool or spa pool heating).
This may be demonstrated in a number of ways including Deemed to Satisfy (DTS), a verification method or an alternative solution.
The NCC requires the use of House Energy Rating software accredited under the Nationwide House Energy Rating Scheme (NatHERS) when conducting a thermal performance assessment using the NatHERS DTS pathway.
There are three software programs accredited by NatHERS:
- BERS Professional
Accredited Thermal Performance Assessors
Thermal Performance Assessors (TPAs) are qualified professionals who are eligible to conduct a thermal performance assessment of a residential building. TPAs are also known as "energy assessors", "energy raters", or "NatHERS assessors".
Accreditation of Thermal Performance Assessors (TPAs) is nationally recognised within the NatHERS governance framework to maintain validity and quality of Energy Rating for residential buildings.
TPAs are accredited by Assessor Accrediting Organisations (AAO) authorised by NatHERS to conduct the thermal performance assessments required for NCC compliance purposes.
TPAs must have completed Certificate IV training in NatHERS Assessment and adhere to comprehensive protocols in order to maintain accreditation.
There are two AAOs authorised under NatHERS:
- Association of Building Sustainability Assessors (ABSA)
- Building Designers Association Victoria (BDAV)
Note: The ABSA and BDAV have a list of Accredited Thermal Performance Assessors on their websites.
It is recommended that building surveyors ensure NCC compliance assessments are provided by accredited TPAs to ensure:
- that services are provided by a suitably qualified professional with adequate Professional Indemnity Insurance
- accurate and consistent energy ratings are achieved
- a comprehensive quality assurance regime that includes a Code of Conduct and periodic performance audits
- a recourse to an AAO in the case of complaints or problems with any assessment disputes or quality assurance.