When requirements are demonstrated
The energy performance of a new building must be demonstrated when applying for building approval. The building certifier will require proof that a building will meet the mandatory minimum energy efficiency standards as part of determining whether to give building approval.
How requirements can be demonstrated
Energy efficiency requirements (EER) for building approval can be demonstrated a number of ways. Before you design and prepare plans you might like to discuss with your designer the most appropriate method of demonstrating your building has met the requirements.
Some appropriate ways to demonstrate EER include:
- using a current accredited software model (this is done by a suitably trained and competent accredited energy assessor)
- comparing your building with a reference building - this involves verifying the plans for the new building are the same as those for a reference building which complies with the EER
- the deemed-to-satisfy method - the Building Code of Australia (BCA) specifies design features which, when adopted in the design of a building, are sufficient to meet the EER
- accepting a nominated expert's report.
For most residential buildings, certifiers are likely to accept using a current accredited software model. You will need to employ a trained energy assessor who will interpret the various energy efficiency factors specific to your design and will produce an Energy Efficiency Rating for the property.
If you are demonstrating energy efficiency using thermal calculation by energy modelling or rating software, you should be aware ratings will be based on the thermal performance of the building fabric.
This software is performance-based rather than prescriptive, which means it doesn’t tell you the types of building elements (such as double glazing, insulation etc) required to achieve a certain rating. Instead, it uses the building elements present in a building design and models the thermal performance based on those elements.
This means that in theory, where one building may require higher performance windows and a high level of insulation to achieve a high star rating, another design may be able to achieve a similar star rating without double-glazing by reducing the size of the windows and orienting the building to take advantage of passive solar heating. On the other hand, if large windows were oriented to the south or west for example, a house may struggle to achieve a high rating even with double-glazing and high levels of insulation.
Software also does not currently take into account hot water systems, photovoltaic systems, lighting or other energy-generating or consuming appliances. Separate new standards for water heaters installed in new homes have been in place since 31 January 2010.
The software predominantly used for undertaking energy efficiency ratings has been developed under the Nationwide House Energy Rating Scheme.
Since 1 May 2009 only the 2006 Australian Building Codes Board Protocol for House Energy Rating Software has been referenced in the BCA. All ratings using a stated value must be produced on second generation software accredited under this protocol. Use of first generation software is no longer permitted to demonstrate compliance under this verification model.
Use of EER for sale of new residential property
The new ACT House Energy Rating Scheme Guidelines allow for rating and other energy efficiency information to be used for disclosure in some circumstances so that people who want to sell a property don't have to both obtain an energy rating (as required under the Civil Law (Sale of Residential Property) Act 2003 and demonstrate compliance with the energy efficiency requirements of the BCA.
For example a seller might have had an energy efficiency rating done on second generation tools to demonstrate compliance with the BCA and can use this rating for the sale of the premises.
These provisions only relate to incomplete premises being sold off the plan or newly completed premises that have not yet been occupied.