Unpacking the Energy Rating System.

The  NATHERS energy rating system uses computer software to calculate the anticipated energy usage of a home which is represented simply as a Star rating out of a maximum 10 Stars. At present new homes in WA are required to achieve a minimum of 6 Stars which will be raised to 7 Stars towards the end of the year. Most existing housing stock is very energy inefficient and would achieve considerably less than this minimum, possible even in the 1 and 2 Star range.

The Witchcliffe Ecovillage mandated a minimum 8 Stars which has now been amended to 7.5 Stars to help lower costs in these difficult times. At Econests we are taking the view that any savings made on reducing the energy efficiency of the home will be at the cost of future energy savings and home comfort and that it is hard to ‘retrofit’ efficiency after the home is built. There is also ample evidence that a higher Star rated home will hold its value better than one with a lower energy rating. To this end we will continue to ‘reach for the stars’ in our Econests limited edition designs and aim towards a 9 Star home as being the ‘sweet spot’.

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A 9 Star home will use approximately 80 per cent less energy to heat and cool than a 6 Star house, and one tenth of the energy of average existing housing stock.

The holy grail of a 10 star house is near impossible to attain for most people. That’s because it would technically need zero additional heating or cooling. There are high-end one off bespoke designs for 10 star houses, but for most of us these are not feasible.

But 9 star houses are achievable. And this is what we will aim for at Econests as we try and build the most energy efficient, sustainable collection of homes in Australia.

We also realise that Energy Efficiency is only one marker of a ‘sustainable’ home and that there are many more aspects to take into account. That is why it is so pleasing to us that the Witchcliffe Ecovillage have also mandated Life Cycle Assessments  (LCA)  that take into account all the energy used to make the home (embodied energy) to ensure that homes in the Ecovillage are Carbon Negative

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Witchcliffe Eco Village have set a carbon target beyond zero.  That is, each home in the village over its life cycle will avoid or offset more greenhouse gas emissions than it produces.

The specific target that has been set by the Ecovillage is -220kgCO2e/occupant/year which is expressed as a percentage saving versus a benchmark residence , the target being a 105 % saving. At Econests we are again trying to be the leading edge of carbon negative building and are achieving some of the highest results in the Ecovillage including several homes achieving above a 150 % carbon savings.

In summary, while we believe the targets set by the Ecovillage are far beyond most (any?) home developments, we at Econests will still strive to be at the leading edge of even these strict sustainability criteria.