Sustainability WA

Residential Energy Efficiency

Sustainability WA have experience in a large range of residential developments - no matter how big or what materials are being used, we have you covered.

6 Star Certifications (NatHERS)

One pathway for proving that you house or building project has met the minimum energy efficient home design standard is to gain a 6 star rating (The minimum energy efficient star rating) using House Energy Rating Software(HERS).

This sophisticated software analyses your building plans and assesses the heating and cooling loads required to keep your future house at a comfortable temperature.

It takes into account the full building fabric – Roof, Ceiling, Walls, windows and floors – and the heat and cold that can pass through these elements.

The Energy Rating Depends On:

  • The layout of the home.
  • The construction of its roof, walls, windows and floor.
  • The orientation of windows and shading to the sun’s path and local breezes.
  • How well the above factors suit the local climate.
  • Sealing – Vented down lights and gas vents will significantly affect an energy rating.
  • Colours of material – Dark colours are better in cold climates and light colours are better in warmer climates.
  • Floor coverings – Tiles show a performance gain in areas where there are high heating loads or where there are full height windows allowing solar access to the tiles.

Zero stars means the building shell does practically nothing to reduce the discomfort of hot or cold weather, while occupants of a 10 star home are unlikely to need any artificial cooling or heating.

We can also give you advice on how to increase your energy rating in order to achieve a high star rating – whether that be a change in insulation or house orientation.

Verification Using a Reference Building (VURB)

Sustainability WA can work with you to tailor an alternative solution for BCA energy efficiency compliance with the Verification using a Reference Building assessment method (VURB). This alternative gives you flexibility to meet energy efficiency compliance and good energy efficient home design by using both the Deemed-to-Satisfy Elemental Provisions method and the thermal modelling software.

The Verification using a Reference Building assessment method uses the Elemental Provisions as a compliance benchmark. A building is modelled with the Elemental Provisions using thermal modelling software to create target annual energy consumption. The building is then designed with your desired specification and this proposed building is also modelled in the thermal software. If your proposed building uses the same or less energy than the reference target then it is deemed to comply.

Verification Using a Reference Building is a minimum performance standard, meaning any proposed building which can achieve above the reference building benchmark energy heating and/or cooling loads is deemed compliant. This process gives builders, architects and designers the freedom to design buildings that meet (or exceed) specifications while also being cost effective. With VURB a star rating is not given but rather the building complies with the energy efficient home design requirements of the BCA.

A reference building cannot be labelled as 6 stars but can be more cost effective to construct compared to 6 stars.
The VURB Method is the most effective method for energy efficiency compliance for large houses, houses with elevated floors, houses with upside down living or houses with unusual design features.

In general, it can help reduce your build costs, while still achieving energy compliance. As this requires 3 separate ratings to calculate, the assessment cost is higher, however, the outcome achieved is much more cost effective in the building stage.

Elemental Provisions

The elemental provisions, or Deemed To Satisfy as it used to be called, provides the least flexible way to achieve compliance of energy efficient home design elements but can still be useful in some circumstances, particularly light weight constructions.

The elemental provisions dictate the insulation or performance levels you need to comply with for each energy efficient home design element.

For example, a floor will have to have a certain R value, as well as the walls and so on. You cannot increase the R value in the walls to compensate for less insulation in the floor. Each individual component must comply.
This often makes it difficult to comply with this method.

As always energy efficient home design will be easier with Sustainability WA and we will find the correct assessment method for your project.

BASIX Assessment (NSW)

A BASIX assessment is required as part of the planning process (in NSW only) and is needed before plans are lodged to the council. The BASIX assessment measures your proposed development for sustainability against BASIX targets that are based on the NSW home benchmark average. Once your design has complied with BASIX a BASIX certificate can be printed and attached to your development application for submission to the council.

If your proposed design does not comply with BASIX due to conflicts with heritage controls or because it uses a new technology not recognised by BASIX, an alternate assessment can be requested.

Sustainability WA is an accredited assessor which means we can take advantage of the simulation method which gives you more flexibility in the design of your development and is not as prescriptive as the Deemed to Satisfy method of BASIX, handy if you want to make use of a greater amount of glazing or non standard design features.

You get your designer to alter the plans to meet the minimum requirements, or if you wish we can mark up the plans for you after the changes have been approved by you. We issue the final certification along with light and water calculations required. That’s it. You will have your energy efficiency documentation.

Existing House Energy Audits

An accredited Sustainability WA assessor will visit your home to conduct a thorough on-site assessment. They will collect data covering: construction materials, your hot water system, heating, cooling, lighting and any renewable energy sources.

At the end of the assessment our assessor will provide your home’s star rating and rate various elements of your home, such as the building itself and major appliances, along with the performance of your home in hot weather.

We will then provide you with practical options to improve your home’s energy efficiency.