Sustainable building: 5 ideas for your home

22 November 2022

Home improvement is a national hobby in Australia. We spend billions annually on renovations, while around 50,000 new homes begin construction each quarter. The Block was the only show in the top TV programs of 2021 that wasn’t a major sporting event. 

We hardly need the official stats to tell us this story. Take a walk around most Aussie suburbs and you’ll find houses under scaffolding, kitchens being demolished, back decks in progress and the list goes on.

Yet for many of us, preoccupation with the project itself – and its costs – often means sustainability becomes an afterthought. But to make the most of the opportunities, it should be embedded from the beginning. So, what could we change to make this happen?

We asked two UQ experts, Dr Paola Leardini, Senior Lecturer in Architecture, and Dr Liz Brogden, Lecturer in Design (Built Evironment), at the UQ School of Architecture, to explain the basics and share some ideas.

What's in this story?

  1. Understanding 'sustainable building'
  2. Thinking about building lifecycle
  3. Going beyond passive design
  4. Achieving efficiency and comfort
  5. Building in South-East Queensland

1. Understanding ‘sustainable building’

While sustainable, eco and green language in building has become common, says Dr Brogden, we often don’t have a ‘big picture’ understanding of what it means – or, more importantly, why it matters.

“When it comes to sustainable architecture, what’s crucial is that we ‘design-in’ resilience to our buildings and environment,” Dr Brogden says. 

“This means understanding that climate change is no longer about mitigating ‘one-in-one-hundred-year’ issues. We need to adapt our houses to a different and variable climate for the long term.

“To do this successfully, we must be responsive to local environments. Top-down policy and industry standards will have an impact, but we also need place-based approaches that are highly localised, participatory with the community and responsive to differences in local character.”

  • Where are trends headed? There is a growing awareness that the climate is changing too fast to build based on past weather patterns, if we want architecture to be resilient into the future. Dr Brogden says regulators around the world are considering how to best incorporate predictive climate data into building codes, through initiatives such as the Global Resiliency Dialogue. An Australian Government consultation report released earlier this year explores how this might work with our Nationwide House Energy Rating Scheme (NatHERs).
  • Research focus: Dr Brogden was recently awarded a Churchill Fellowship to further her work in sustainable architecture education. Her new project will connect Australian architects with international initiatives to build climate literacy. She will also be teaching a new subject on sustainable design and climate change, which will be introduced as a core course in the UQ Master of Architecture for the first time next year.
  • What can you do? Understand your own climate region before you start building. The Australian Government Sustainable Homes site breaks down eight climate zones, with different priorities and tips for each. You could also ask your architect or builder about their approach to sustainable design before you engage their services.

2. Thinking about building lifecycle

Dr Leardini also embraces the idea that sustainable building is about more than optimising energy performance.

“Energy efficiency, or ‘operational energy’, is a key factor,” she explains. “But its importance is well understood internationally – if not yet not fully translated into the Australian building codes.

“What is thought about less, however, is the ‘embodied energy’ of a building and its ‘lifecycle assessment’.

“The lifecycle assessment looks much more closely at the amount of energy that goes into construction, maintenance and ‘end-of-life’ of a building, as well as the associated carbon emissions. Embodied energy incorporates issues like the durability, recyclability, and renewability of materials throughout the lifecycle of a dwelling.

“When building from scratch, this means considering carefully the materials you select, and understanding how each different option – wood, concrete, stone and so on – performs in a ‘circular economy’.

“In construction, a circular economy means resources are kept in use for longer by increasing the longevity of a building or re-using materials and components at a building’s end-of-life.

“When renovating, this similarly means assessing what you’re removing and whether it can be re-purposed. Many renovations are purely aesthetic and involve sending materials to waste that are still perfectly functional, not to mention not biodegradable or even highly polluting.”

  • Where are trends headed? Circular design principles are increasingly being embedded into all forms of production from fashion to food packaging, cars to building construction. The main idea is to design waste out of the process. Dr Leardini recommends the Ellen Macarthur Foundation for an introduction to the circular economy and circular design.
  • Research focus: Dr Leardini is a member of the UQ Centre for Future Timber Structures and a chief investigator of a new Australian Government ARC Research Hub. The goal of this industry-led research is to drive the future of timber in the built environment, and Dr Leardini says it will focus on the sustainability of timber in Australia across the whole supply chain, from plantation and forestry strategies to end-of-life options. 
  • What can you do? Research the materials you select for your home. Try to understand their life cycle. Think about why you are doing your renovation. Are you removing elements that are still perfectly functional? Are there ways you can update your home and refresh its look avoiding demolition? Is it possible to safely re-use the existing materials?

3. Going beyond passive design 

If you ask your builder or architect about sustainability, they’re likely to talk about ‘passive design’. This concept can be briefly summarised as solutions that enable a dwelling to maintain a comfortable temperature without the use of additional heating or cooling systems that require energy consumption.

Many commercial architecture or building firms have excellent blogs explaining their application of the concept, and the Australian Government’s Sustainable Homes site contains an extensive educational section on passive design.

As the Sustainable Homes site says, passive design may incorporate a range of features or techniques, depending on the climate. These could include solar gain or shading techniques, thermal mass of materials, insulation, cross ventilation and more. Some of these strategies, as relevant to South-East Queensland, are summarised by Dr Leardini and Dr Brogden in section five, below.

However, while the classic passive design principles will always be relevant, Dr Brogden says, climate management now means thinking beyond individual dwellings. She notes again the importance of not just ‘what’ is designed, but ‘where’.

  • Where are trends headed? Projects must intentionally meet the needs of their location, rather than developers rolling out a templated design in as many locations as possible, Dr Brogden stresses. Incorporating this kind of thinking into architecture education and professional development at every level is vital for transforming building sustainability into the future, she reiterates, speaking again to UQ’s new Masters course and her Churchill project. Dr Leardini also notes contemporary urban landscapes and small blocks make the execution of many passive design principles challenging (for instance, ideal orientation may not be achievable, cross ventilation may be blocked). Developers must work with local councils, researchers and climate experts if sustainable communities are to be achieved.
  • Research focus: Dr Brogden has explored how climate impacts a city’s architectural and building outcomes with Dr Kirsty Volz, through a 2021 Architecture Media Politics Society conference paper. Dr Leardini also focuses on climate response at the neighbourhood and city scale, and is currently leading a research team working on energy and water resilience in Brisbane suburbs.
  • What can you do? Consider the site you are buying, from both a climate risk and optimisation perspective. Check resources like local flood plain maps, bush fire ratings and other weather data. What will sustainable design be able to help mitigate? If you are buying off the plan, or from a developers’ catalogue, will all of their advertised passive design features actually be effective on your site?

4. Achieving efficiency and comfort

Of course, one of the most important considerations when building or renovating your home is comfort. Too often, sustainability and comfort are seen as incompatible, but this doesn’t have to be the case, both Dr Leardini and Dr Borgden assure us.

“Ultimately, buildings are for people, and so when we talk about designing sustainable, energy efficient spaces, we also need to take into account their thermal comfort,” Dr Leardini says.

Dr Brogden agrees, saying sustainable solutions must recognise that, in most areas, people will also want some form of active climate control at the extremes of seasons. 

“But by focusing on the right passive strategies for your location, you can really minimise the use of air conditioners or artificial heating,” she says.

The key is to maximise passive principles, while also enabling other indoor climate control solutions to be used efficiently, Dr Leardini explains. 

“Successful sustainable design must understand, accept and reflect human behaviour. Traditionally, the debate has been about active versus passive, but we have to move past that,” she says.

Australian figures from 2014 already showed that 75% of houses had active cooling systems (up from fewer than 20% in 1990). And the International Energy Agency predicts that at least two thirds of the world’s households will have an air conditioner by 2050. 

“When active systems are required (which is true for most locations in Australia), houses must be designed to bring active and passive strategies together effectively,” Dr Leardini emphasises.

  • Where are trends headed? If we want to design passive houses that also work well with air conditioning, we need to think much more about moisture management and the overall air- tightness of the dwelling, Dr Leardini says. Air leakage of the building envelope reduces air conditioning efficiency. Poor moisture management also exacerbates the risk of condensation within walls and ceilings due to the low temperature setting of air conditioning, which can lead to mould growth. Some changes have been introduced in the new National Construction Code, but Dr Leardini says Australia lags leading international markets in house performance.
  • Research focus: Last year, Dr Leardini contributed a column to sustainable architecture publication, The Fifth Estate, providing an evidence-based review of why both passive design and climate control may be needed in Queensland homes to secure not only energy efficient, but comfortable and healthy, buildings.  
  • What can you do? Retrofitting traditional Queenslander homes for air tightness and good moisture management is challenging but not impossible, Dr Leardini says. Air leakage is typically hard to avoid in older homes, as they were not designed to be efficient with air conditioning. However, their overall performance can be largely improved with new lining, insulation and effective shading. In new builds, an integrated strategy addressing insulation for thermal performance (this works in hot climates too!), ventilation and air tightness to achieve higher performance standards should be made mandatory, Dr Leardini believes, especially in relation to moisture control for mould-free, healthy houses.

5. Building in South-East Queensland

Both Dr Leardini and Dr Brogden offer a toolbox of tips for home builders and renovators striving to achieve greater sustainability in South-East Queensland.

Their top five passive design principles, applied locally, include:

  • Ventilation: build windows and doors that allow for natural and cross ventilation, wherever possible. Keep air moving through different parts of the house to create a cooling effect
  • Shading: design window shading and roof overhangs that are the right shape and size to keep the sun out of your home as much as possible. Shading is also key in your garden or outdoor area, where research has shown trees can significantly reduce the ‘heat island effect’ of concrete patios, driveways and other common urban landscape features
  • Insulation: instal roof and/or wall insulation when viable to minimise the flow of heat in and out of your home. It’s often the case in South-East Queensland that homes are not well built for the cooler months and insulation can make a big difference to your energy bills in all seasons
  • Orientation: if you have the option, build your home north facing. This means constructing the longest façade and all your main openings towards the north, with smaller openings to the east and west, to make the most of the morning sun while reducing indoor exposure to the hotter afternoon climate
  • Position of glass panels: avoid or reduce as much as possible the number of windows or large glass doors facing west. It can be hard to build shade overhangs large enough to combat the low angle of the late afternoon sun, and glass generally will be the weakest part of your passive solution, so keep it out of direct sun as much as possible.

Where to next?