Design and construction
You can encourage homeowners and businesses to reduce their heating and cooling costs and impact on the environment.
The amount of energy needed to stay warm in winter and cool in summer can easily be reduced with good design and construction methods.
Designing and building a new home or extension to be energy efficient will cost much less than trying to make an existing building energy efficient.
Homes that include good environmental design can minimise heating and cooling bills and have a lasting positive effect on the environment by reducing greenhouse gases.
Some of these improvements include:
- selecting a building location that has good exposure to the sun
- building a house that has a northerly position to make the most of the sun for that climate zone
- well insulated wall, floor and ceiling
- windows that do not loose heat in winter and reflect heat in summer
- internal and external shading of windows and walls in summer
Energy efficiency needs are dependent on the climate zone in which a house is built. Climate zones are decided on climatic data and there are two Tasmanian zones:
- zone 7 (covering most of the state including the Bass Strait islands)
- zone 8 (covering only alpine areas above 900 metres).
Good solar positioning of a house has the potential to achieve large energy savings when mixed with an efficient design. Houses built with a north facing orientation for the main living areas are more likely to get the required Star rating.
Houses with large areas of glass facing south, west or east may still achieve the star rating but are likely to have higher construction costs and on-going heating costs for the people that live there.
The outside of the house
The design and construction of the house's roof, external walls and floors, will have an effect on the heating and cooling comfort of a house. To achieve the required Star rating the design and build will need:
- insulation of roofs and ceilings
- insulation under raised floors
- selection of appropriate glass windows and doors
- thought to the number and size of roof lights (skylights) and ceiling penetrations including downlights
- closing and filling of openings and gaps to stop draughts and fireplaces that are no longer in use.
Commercial Energy Efficiency
There are compulsory energy efficiency requirements for all types of commercial buildings including
- public buildings
- sleeping accommodation (including single occupancy units)
- health care or aged care buildings.
Included are all Class 2 - 9 buildings within the (NCC) National Construction Code building classification system.
In Tasmania all new commercial buildings, or extensions and alterations to existing commercial buildings, must comply with the compulsory energy efficiency provisions and the Building Act 2016.
For more information read Section J of Volume One of the NCC. Some of the objectives of the NCC are to
- improve the efficiency of heating and cooling a building
- reduce greenhouse gas emissions.
Star ratings - energy efficiency
6-Star energy efficiency in new homes and residential extensions
New constructions of residential buildings, extensions and additions to existing homes must comply with the 6 Star requirement in Tasmania. The higher the Star number, the more energy efficient the home is likely to be when built, using less energy to achieve a comfortable heating level.
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 efficient to heat and cool.
The star rating is assessed using the following accredited software:
- AccuRate Sustainability 126.96.36.199
- BERS Professional 188.8.131.52a
- FirstRate 5 V.5.2.6
All software uses the same underlying Chenath calculation engine designed by the CSIRO
What buildings do the 6 Star requirements apply to?
- all standalone houses or units (Class 1 buildings)
- all sheds and garages (Class 10a buildings) that have a conditioned space. ("Conditioned" means that all or part of that building is heated or cooled)
- units one above the other such as apartments (New Class 2 buildings).
Who can do a Six star energy rating
An energy assessment of homes and extensions may be completed by an architect or a building designer (who is an accredited energy assessor). 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.
- Or 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 given to the building surveyor.
An accredited energy assessor, who is not the responsible designer, can also undertake an energy rating assessment 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.
Form 55 will only be accepted by building surveyor if that independent energy assessor is accredited by:
- Association of Building Sustainability Assessors (ABSA)
- Building Designers Association of Victoria (BDAV)
- Housing Energy Raters Association (HERA).
An energy assessor does not have to be licensed under the Building Act 2016 as a building practitioner in Tasmania.
Star ratings - compliance
How is compliance verified?
The designs of new homes and extensions are assessed by a building surveyor for the Certificate of Likely Compliance. This assessment includes checking for compliance with the 6-Star energy efficiency requirements.
Where to next
- Safe installation of insulation materials
- Guide to 6 Star Energy Efficient Houses in Tasmania (PDF, 752.7 KB)
- Condensation in Buildings - Tasmanian Designers' Guide v2 (PDF, 7.0 MB)
- Condensation Control in Roofs Fact Sheet (PDF, 204.8 KB)
- The Australian Building Codes Board (includes Tasmanian Climate Zone Map) (external link)
- Nationwide House Energy Rating Scheme (NatHERS) (external link)
- Commonwealth Government Department of Climate Change (external link)
- Tasmanian Government Energy Efficiency site "Earn Your Stars" (external link)
- NatHers Accredited sofware, for the nationwide house energy rating scheme (external link)