What exactly is energy rating?

Energy Rating is the assessment of the efficiency of the design of the building envelope. We calculate how much energy is used to heat or cool the house; thereby establishing the heating and cooling loads. As heating and cooling is the most significant contributor to greenhouse gas emissions (and costly energy bills), it is important to address this issue first, before tackling water heating, appliances and lighting.

We energy rate with complex software tools, which factor in different building materials, floor/wall/ceiling/glazing areas, insulation, draught, orientation & climate zone. These tools can appear relatively simple, but have taken over 20 years to develop and contain thousands of formulas and computations to reach the level of accuracy they now employ.

An accredited rater, skilled in modeling different designs using these software tools, can provide you with an accurate assessment and give you sensible and economical recommendations for improving the efficiency of your home. This will save you time, fuss and money on construction phase.

Why do I need an energy rating?

The Building Code of Australia requires all new dwellings in Australia to achieve a 6 Star rating. Your Registered Building Surveyor will need this assessment in order to issue a building permit. Extensions and Alterations have different requirements, so contact us for the specific regulations for your job.

More importantly though, you need to know your home will be as energy efficient as possible – a 6 Star rated home, will negate the need to install large energy guzzling heating and cooling systems, because it will be a comfortable home to live in all year around!

More information on the benefits of an energy efficient home is available on the following websites:







How long will it take?

Typically we work towards an 8 day turn around from quote acceptance.

Once the preliminary assessment is complete, if the home achieves 6 Stars we can send your documentation straight away. If it hasn’t reached 6 Stars, then we will provide you with recommendations, which you may need to consider before getting back to us.


What information do I need to provide?


  • Site plan, showing any adjacent structures
  • Detailed floor plans
  • Elevations
  • Sections
  • Electrical plan
  • Window schedule, showing glazing and frame preferences
  • Construction material specifications

What makes Blue Lotus different?

 We have rated almost every almost every conceivable design. We have assessed some homes using multiple orientations, with and without eaves and with alternate facades. We have worked with all kinds of clients and can offer you a service that is tried and tested. We are up-to-date with new products, and have knowledgeable contacts to provide us with any further information we need.

Blue Lotus can save you money by offering recommendations that have worked for other clients, and that’s what keeps them coming back and recommending us to others.

What if my design doesn’t rate 6 Stars?

No problem, we will offer you sensible recommendations. More often than not we will give you a choice of different recommendation options. Included in our price is consultation by email, so you can keep track of the different scenario’s that have been tried. You can use this to communicate with clients, architects, and builders to ensure that you select the best option for your design.

Why is it harder to achieve 6 Stars in a Melbourne climate zone?

Melbourne, as we know, has all kinds of weather – sometimes, on the same day! Melbourne has some high ‘peaks’ in summer but for most of the year it can be cooler outside the home than inside. An energy efficient home is one that retains a comfortable temperature inside - regardless of the temperature outside. Due to such variable weather, Melbourne residents need to design for all conditions.

What are some helpful tips?

  • Ask for an assessment in the design stage, as it can help save money by ensuring the design is as efficient as possible before things are ‘set in concrete’.
  • Always insulate the ceiling, (timber) floors and walls well (We will advise you on the ‘optimum’ levels of insulation, as part of our service).
  • Seal all draughts - ask for our handy document detailing draught sealing.
  • Place your glazing thoughtfully, to maximize the northerly aspect, minimize glazing to the south and use adjustable external shading to the north and west. Careful placement of glazing is as important as getting the proportions of glazing to floor area right.
  • Note: Single glazing has no resistance to heat transfer, so the more glass there is, the less efficient the design will be.

What do I need to do, to design for 6 Stars or more?

Talk to us before you start, or send us some working drawings so we can maximize the design before things become hard to change. It’s not difficult to design for 6 stars or more, but you will need to consider the site orientation and overshadowing of adjacent structures. Building materials and glazing areas need to be chosen carefully.

Who can perform an energy rating?

All assessors need to be accredited to perform assessments.

Each state has slightly different accreditation requirements, contact us and we will let you know if we can help, or we’ll refer you to someone who can.

Blue Lotus is fully accredited in 1st & 2nd generation tools.

What are the benefits of an efficient design?

Want a home where you are comfortable all year round – in any room in the house – without fighting the cat/dog/kids for the heater?

Want a home that doesn’t need air-conditioning in summer? (You might need a fan for a couple of the hottest days in a Melbourne summer, but only if you really feel the heat!)

Want to spend more money on things, other than heating and cooling?

And most importantly, do you want to reduce your carbon footprint and help reduce climate change?

What tools will be used to rate my design?

FirstRate5®house energy rating software

I understand that as well as an energy rating, I also need to provide either a rainwater tank or solar hot water system?

Yes, this is a separate regulation from the energy rating and does not factor in the assessment at all, but you will need to provide your Registered Building Surveyor with details of either a rainwater tank or solar hot water system when applying for your building permit. See Plumbing Industry Commission www.pic.vic.gov.au website for further information.