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Star ratings

6-Star energy efficiency in new homes and residential extensions

6 Stars introduced for new houses

Tasmania has had mandatory energy efficiency requirements for new housing since 2003.

From May 2014 the higher 6-Star energy requirements in the National Construction Code (NCC) have applied in Tasmania to all new detached houses or units, and any attached outbuildings such as a garage.

New extensions and additions to existing houses must also comply with the 6 Star requirement.

A Star rating refers to the expected energy efficiency of a house design.  Stars are awarded on a scale of 1 to 10, with 1 the lowest efficiency level and 10 as the most thermally efficient.  The higher the Star number, the more energy efficient the home is likely to be once constructed, using less energy to achieve a comfortable heating level.

6 Star is the current minimum level for Tasmania while remaining cost effective for consumers to comply with.

What buildings do the 6 Star requirements apply to?

  • All Class 1 buildings (detached house or unit) and all Class 10a buildings (non-habitable outbuildings) that have a conditioned space. ("Conditioned" means that all or part of that building is heated or cooled).
  • New Class 2 buildings (sole occupancy units one above the other such as apartments) have been required to comply with 6-Star measures since May 2013.

What are the main changes made by 6 Star?

They are:

  • a higher level of insulation is needed generally around a building's conditioned space to meet increased minimum total R (resistance) values
  • more stringent glazing provisions to prevent heat loss through windows and doors
  • extra insulation provided in some areas as compensation for ceiling insulation loss caused by openings or penetrations such as exhaust vents and downlights

In addition to achieving a 6-Star level for thermal efficiency and comfort, new houses must also meet new requirements for energy efficient lighting and space heaters.

Residential additions or alterations

REVISED Building Regulation Advisory Note 4-2013 (PDF, 5 pages, 123 KB)includes information on the procedures for the energy assessment of residential additions or alterations.  Tasmania has adopted a simple and practical approach to enable compliance with the NCC without adding extra costs or complexity to the building.

How is compliance verified?

A building permit is required for most new building work to ensure it complies with the NCC.

The designs of new homes and extensions are assessed by a building surveyor for the issue of the Certificate of Likely Compliance. This assessment includes checking for compliance with the 6-Star energy efficiency requirements.

Who can do a 6 Star energy efficiency assessment?

An energy assessment of homes and extensions can be completed by the responsible designer (an architect or a building designer). Energy efficiency is part of their work as an accredited designer.

  • An energy efficiency assessment may be made using the Deemed-to-Satisfy approach (prescriptive construction requirements for thermal comfort) in the National Construction Code.
  • Alternatively the energy efficiency of a design may also be calculated using a computer-based energy rating program operating approved 'second generation' software.  A signed and dated printed verification report and any supporting documentation must then be provided to the building surveyor.

An expert energy assessor, who is not the responsible designer, can also undertake energy rating assessments using the approved software. They must provide a verification report, supporting documents and complete a Form 55 'Certificate of Specialist or Other Person' to provide to the building surveyor. However the Form 55 will only be accepted by building surveyor if that independent energy assessor is accredited by either the Association of Building Sustainability Assessors or the Building Designers Association of Victoria.

There is no requirement that an energy assessor must also be accredited under the Building Act 2000 as a building practitioner in Tasmania.

Approved residential 6 Star energy assessment software

There are currently four software tools accredited under the NatHERS (Nationwide House Energy Rating Scheme) available for use in Australia for rating thermal performance of house designs:

  • AccuRate and AccuRate Sustainability
  • BERS Professional
  • FirstRate 5

All software use the same underlying Chenath calculation engine designed by the CSIRO.  BERS Professional and FirstRate 5 provide designers and assessors with alternative user interfaces.

For more details about these software tools go to the NatHERS website

More information

Designing and constructing an energy efficient residence