Found in: News

The '6 STAR' House Energy Rating System

If you’re in the process of building a new home, or completing alterations and additions to an existing home, it’s likely that you’ve already heard about the ‘6 Star Energy Rating’ relating to the energy efficiency requirements of your project. As outlined in the National Construction Code (NCC, formerly the Building Code of Australia), all local government authorities in Australia require patrons to meet certain energy efficiency regulations before they can be granted a building permit. For residential buildings, there are 3 accepted methods in use that demonstrate energy efficiency compliance in Australia, and 1 new method that is being introduced in 2016.

Firstly, let’s take a look at the four methods for energy efficiency standards;

1. 6-Star method

The House Energy Rating (6 Star Rating) method is the most common form of assessment for its ease of understanding and quantifiable assessment rating. The assessment process involves modelling the proposed building using thermal modelling software. The final result is a star rating, which correlates to the amount of energy required to heat and cool the building to a comfortable temperature year-round. The higher the star rating, the less energy is required by the building. Since 2010, a 6 star minimum efficiency rating has been the requirement in most of Australia, however variations of 5 and 4 star standards have been in place since 2003. The house energy rating method is the fastest and easiest method for demonstrating energy efficiency compliance.

2. DTS method

The Elemental Provisions method, previously known as the Deemed-to-Satisfy (DTS) method, came into usage in 2003 when energy efficiency provisions were first introduced in the Building Code of Australia (BCA). The assessment process involves comparing the proposed building's construction to the standards prescribed in the NCC. The assessment results in a strict pass or fail result with no flexibility.

3. VURB method

The Verification Using a Reference Building (VURB) method has become an increasingly popular method of assessment that combines the practices of the House Energy Rating method and the Elemental Provisions method. The assessment process involves modelling and comparing the proposed building to a reference building that is compliant with the elemental provisions. The benefits of the VURB method are its flexibility and cost effectiveness for compliance for certain building types. Due to its increased complexity, the assessment does take a little while longer to complete than the other methods.

4. VUSV method

The Verification Using a Stated Value (VUSV) method is rolling out in 2016 as a simple assessment method that compares a building’s efficiency against a baseline thermal load metric. Similar to the house energy rating method, the process for a VUSV assessment involves modelling the proposed building using thermal modelling software. Unlike the house energy rating method however, the final outcome of a VUSV assessment is simply a pass or fail result.

How is the 6 star method assessed?

Nationwide House Energy Rating Scheme (NatHERS)

NatHERS Logo

The Nationwide House Energy Rating Scheme, better known as NatHERS, is the national administrator of the House Energy Rating Scheme (6 star rating method) as part of the Federal Government, Department of Industry, Innovation and Science in the Energy Division. The state government authorities that oversee the NatHERS scheme in each state include:

  • WA - WA Building Commission
  • SA - Department of Planning, Transport & Infrastructure
  • NT - Department of Lands Planning and the Environment
  • NSW - BASIX/Department of Industry Resources and Energy
  • VIC - Sustainability Victoria
  • TAS - Department of Justice
  • ACT - ACT Planning Land Authority

It’s important to note that only buildings that achieve a 6 star rating using NatHERS method can claim to have a ‘6 Star’ efficiency rating. If a building project has reached compliance using any other provision or verification method, it does qualify as meeting energy efficiency standards however it doesn’t by default mean it has achieved a 6 Star rating.

House Energy Ratings (HERs)

The ultimate aim of the House Energy Rating Scheme is to create more environmentally friendly houses that consume less energy to heat and cool, are more comfortable to live in and also comply with state building regulations. Despite the popularisation of the term ‘6 star rating’, HERs are actually assessed on a scale of 0 to 10. A house with a rating of 10 would require no artificial heating or cooling throughout the year, whereas a rating of 0 would require considerable energy to make the home comfortable. As a point of perspective, the average home in the 1990’s had an equivalent rating of 0 where homes did not have any ceiling insulation or many other modern features. A 6 star home is considered to be a relatively economic home to run, so the 6 star rating is considered the minimum passing grade throughout Australia. There are certain unique situations when a 5.5 or 5.0 star rating could comply, however this only applies in specific areas with unique circumstances.

What is assessed for a 6 Star Energy Rating

For the 6 star energy rating and all other types of assessment, the following is considered in evaluating a building’s thermal performance:

  • Location (climate zone)
  • Orientation (with respect to North)
  • Building materials (floor type, wall type, roof type etc.)
  • Windows/glazing (size/location/frames material/type of glass etc.)
  • Insulation (ceiling/roof/wall/floor, the type, the thickness, the brand etc.)
  • Roof and Wall Colours
  • Ventilation
  • Ceiling Fans
  • Lighting
  • Floor Coverings
  • ...and much, much more!

Upon provision of detailed plans, an a qualified assessor, such as Thermarate, will model the building using the NatHERS accredited software to determine it's thermal performance. The software calculates how much energy would be required to head and cool the home over a year and this energy level is converted into an assessed efficiency rating or 'star rating'. Should the building not achieve the minimum 6 star rating, the assessor can then recommend the best course of action to meet the minimum standard using the most cost effective solutions.

How do I obtain a 6 Star Energy Rating?

Finding accredited assessors

To obtain a 6 star energy rating you’ll need to be assessed by a professional with appropriate training and Certificate IV in NatHERS assessment. Assessors can either be accredited or unaccredited by AAOs (Assessor Accrediting Organisations) as long as they have the necessary qualifications to carry out the assessment, however accredited businesses are best positioned to provide a professional and reliable service due to the extensive training and quality control that is managed by AAOs. The Association of Building Sustainability Assessors (ABSA, based in Sydney) and the Building Designers Association of Victoria (BDAV, based in Melbourne) are the only two organisations qualified by NatHERS to provide accreditation to independent businesses such as Thermarate.

Who can request House Energy Ratings

Home owners are able to request a HERs assessment without the intervention of a builder, architect or private certifier. All you require for an assessment are the architectural drawings of your building in a PDF format.

For more information about the 6 Star Rating standard, please visit the official NatHERS website or visit the Assessor Accrediting Organisations websites, ABSA and BDAV.

To submit your drawings and request a HERs assessment, contact Thermarate for a free quote today.