In the Building Process

In the building process you would be thinking about three things.

1. The design - how much energy is this home designed to use once someone is living in it?  How much of this energy can it produce itself via solar panels and battery?  Decisions made at the design and building stage will have a major impact on the home's lifetime emissions.

2. The materials - what is the carbon footprint of the materials you are planning to use?  Are there less impactful alternatives that can do the same job for a comparable price?  How can you keep the amount of waste during the process to a minimum?  How re-usable or recyclable are they are the end of the building's life?  

3. How energy-intensive is the building process - what tools and machinery are you using on site and is there a way to reduce some of your energy use or source renewable energy to reduce your carbon footprint?

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It's fair to say that Australia is reasonably advanced in its consideration of design issues, but we still have a long way to go on materials and construction processes.  Sustainable building is still very much a boutique undertaking, valiantly promoted by the likes of Renew but more expensive and complex than homes built using standard building methods.

  

Housing Design

The National Construction Code now mandates minimum energy-efficiency standards for new dwellings, and these are generally certified at the design stage.  The Code doesn't specify which certification method builders need to use, and there are a couple of alternatives, all of which, like other aspects of construction, need to be certified by qualified independent assessors.  Each rating scheme is slightly different but essentially they are measuring the 'whole of home' energy requirement and will be considering factors such as orientation, ventilation, shading, outdoor areas, insulation and installation of rooftop solar generation. The most used rating schemes are:

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• The Nationwide House Energy Rating Scheme (NatHERS) is a scheme administered and overseen by the Commonwealth Government and is the scheme used by most builders.  Housing is assessed at the design stage and rated on a scale of one to ten stars (ten being the most energy-efficient) based on a complex set of criteria.  As of 2025, newly built homes must achieve a rating of 7 stars.  ​

• ​NSW, which always likes to be different, has its own home energy rating scheme which is compulsory for new homes.  It’s called The Building Sustainability Index (BASIX) and fulfils a similar role to that played by NatHERS nationally.  BASIX is a set of mandatory minimum standards rather than a variable rating scheme, and considers issues including energy efficiency, thermal performance, water use and the embodies emissions of the building materials.  

• There is also a broader-based scheme, the Green Star Rating Scheme, which has been administered by the Green Building Council of Australia since 2003.  Unlike NATHERS and BASIX, this scheme rates both commercial and residential buildings and focuses on a wider range of environmental sustainability questions.  It involves four types of ratings – for buildings, whole communities, interiors and existing buildings – and rates projects on a six-star scape, with four stars and above being granted ‘Green Star’ accreditation.  While the scheme can operate at multiple levels it is particularly appropriate for larger projects. 

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We consider some more details around energy efficiency here.

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Building Materials

In comparison to energy ratings, carbon impact of materials is a fairly underdone area in Australian building.  Certainly there is plenty of research out there, but in most cases we lack clear certification or standards related to materials, so you or your architect will need to do a fair bit of work to get a clear picture of this.  A handy place to start in getting your head around this is the Fifth Estate's publication, Extreme Green Buildings, which features a series of short chapters dealing with issues related to leadership, materials and measurement, energy services and finance.  Built, the large Australian construction company, has also produced a set of resources including Taking Action on Embodied Carbon, Creating Net Zero Developments and transitioning to a circular economy in the building industry.  On circularity in the building process - that is, what happens to the building materials at the end of the building's life - we are really right at the starting point.  The detailed AHURI research inquiry into the circular economy in housing, published in 2022 essentially produced a list of things we would need to implement this in Australia, most of which we don't have - product standards, lifecycle tracking, product stewardship arrangements,  education for building professionals.  Read more about it here. 

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Construction Methods

If we are still at the starting gate on materials and circularity, we have barely made it to the mustering yard when it comes to the impacts of different construction methods.  We know that high-rise buildings are more energy-intensive to build because of both the increased structural requirements and the height everything has to be lifted to.  Beyond that, more machine use can equal more energy inputs, but can also save time and cost.  Are there technology upgrades in the wings that can make construction processes more energy-efficient?  Pre-fab components and pre-fab housing clearly reduce energy use on site, but there will be more emissions before the materials get there - how do the two balance out?  I'd love to know the answers to these and other questions - if and when I find out I'll let you know!

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I've been exploring these questions on and off via the Climate/Housing Blog - join the mailing list to keep up to date!