“Energy efficient”, “carbon neutral” and “net zero” are buzzwords we hear more and more as we face the impact of climate change. But do we think about them enough in building?
Globally, a move towards sustainable housing is growing. In Europe, efforts to move to greener homes hope to combat rising energy costs and be better for the planet. But 40% of global carbon dioxide emissions still come from the real estate sector.
In Australia, off-grid electric homes are becoming more common. A recent report by the University of New South Wales is pushing the built environment industry to reach net zero by 2040, and according to a 2024 study by Domain, energy-efficient real estate is attracting more interest than conventional homes.
But even if net zero housing – which means your home releases no net carbon – is not yet the norm, many architects are beginning to champion sustainable design, aiming for high energy ratings and future-proofing homes to adapt with the changing climate.
By reducing their carbon footprint, and using passive design – which focuses on conditions like sunlight and layout instead of artificial climate control – these net zero homes make it clear that going back to basics is key to making the switch.
Huff’n’Puff Haus, Strathbogie ranges, Victoria
Once upon a time a big bad wolf could huff, puff, and blow the straw house down. But not any more – in rural Victoria, Envirotecture’s Huff’n’Puff Haus is here to stay.
Asked to create an off-grid, all-electric, energy-efficient home, architect and director Talina Edwards set out to build a house that would let two empty nesters age in place for years to come.
Huff’n’Puff house is made from prefabricated, structurally insulated straw bale panels about 300-350mm thick and has “passivhaus premium certification”, which means it generates more renewable energy than it uses.
As a waste product, straw not only sequesters CO2 – reducing the embodied carbon of the project – but is an under-utilised material in building. Edwards says the amount of straw burned in paddocks annually would be enough to insulate 40,000 homes in Australia every year.
Envirotecture also aimed to use sustainably sourced timber, reduce use of plastic during building and focused on good ventilation strategy for healthy air quality. The house needs hardly any heating and cooling, instead relying on orientation, cross ventilation, passive shading and natural light.
“The cost of building anything is expensive, but not the cost of building well,” says Edwards.
“If you reduce the size and maybe you don’t have so many built-in pieces of joinery … you can choose how to prioritise.”
Despite Australia’s “obsession” with large homes, the 200 sq metre house is flexible and functional – a corridor opens out into spaces instead of whole rooms. A breakfast bar can become a study space; a window seat, a place to look at the view.
“On a regional site it always looks a bit odd if you’ve just got this tiny little house, but we did keep it a modest size,” says Edwards. “I think that’s the first tip for anyone building no matter where.”
The project has won many awards since its completion and is shortlisted in the sustainability category in the House awards. But for Edwards, it is not about accolades.
“Everyone kept saying, it’s so beautiful … but it’s not about what it looks like,” she says.
“… The beauty of it is beyond skin deep. What’s hidden behind? What’s the true heart of what this is doing?… It’s honest beauty, not just considering the aesthetics.”
39S House, Brisbane, Queensland
On a 240 sq metre block in Brisbane, architect Andrew Noonan has breathed new life into a dilapidated Victorian-era timber cottage, giving the five bedroom family home a net zero future.
Aiming for a “whole-of-life net zero” home – one that takes as much carbon out of the system through energy production and materials as it takes to build – Noonan went back to basics, applying passive-design principles to literally turn the house around.
“The house originally ran north-south. It had a very long west-facing facade,” says Noonan.
“100m away there is Suncorp stadium … and a main road, so quite noisy on that same western side … it became quite an opportunity to do one big move to solve a couple of problems.”
Noonan removed a 1930s extension at the rear of the home and added a new extension to achieve east-west orientation. It’s a five bedroom home, with four of them occupied, but Noonan says necessity must be questioned when building.
“Do we all need media rooms? Do we all need three, four or five bathrooms?” he says, adding that key to the net zero approach is letting the climate dictate material choice to ensure a lifespan beyond the 55-year average for a home.
If you have high-quality doors and windows “they’ll very much last beyond the life of the building,” Noonan says.
“If they’re made in a way that’s designed to be thermally efficient – not cheap, single piece aluminium frames with very thin glazing in them … but something that is thinking about performance – that will have an ongoing value.”
39S House also has no heating or cooling, instead relying on heavily insulated timber framing and orientation to cater to Brisbane’s humidity.
And while Noonan recommends electrifying everything by switching to induction appliances, air source heat pumps and getting photovoltaic panels– which are slightly different to solar – he says gadgets “won’t solve the problem if it’s not worked out in a more simple way first”.
Green space occupies 50% of the site, reducing external heat. The air temperature directly outside the doors and windows is 15 degrees cooler than it would be if the area was paved with no trees.
And the home also considers Brisbane’s propensity to flood, lifting the house above ground and aiming to absorb flood waters into the soil, slowing the run-off rate downstream.
“Just because it’s doing some really interesting sustainability things doesn’t mean it has to look like a tree house,” says Noonan.
“It can look like it can look like any house … the aesthetic doesn’t really tie into the performance.”
Farrier Lane House, Perth, Western Australia
Architect Matt Delroy-Carr set out to build an affordable, high performing family home. But when a lifecycle assessment partway through the project came back carbon neutral, he added net zero status to the list.
His home, Farrier Lane House, now acts as a demonstration project on how to build sustainably for his practice MDC Architects.
“A 180 sq metre-house might have exactly the same things in it as an 140 sq metre-house like mine,” says Delroy-Carr. “It’s just got 40 sq metres of wasted area that’s inefficiently designed.”
Farrier Lane House has large windows to open up the space. Its house-to-garden ratio heavily favours green space, filling 60% of the site to extend the liveability of a smaller-footprint home.
Inside, it has a double brick ground floor, providing a solid thermal mass, a hybrid upper floor with reverse brick veneer and timber-framed floors throughout.
But Delroy-Carr says often the more you focus on carbon neutrality through material use, the harder it is to get a high NatHERS star rating.
“The rating system heavily favours masonry construction … it loves brick and concrete, because they’re high thermal mass materials,” he says.
“The more concrete and bricks you put into the project, the higher the star rating, but inevitably, the higher the carbon footprint.”
While we are creatures of habit, Delroy-Carr says younger generations are beginning to focus more on sustainability and smaller footprint. But his advice to clients is “don’t try to do everything.”
For him, the first thing to try is orientation. Even with MDC’s off the plan homes, all are intended to face north.
Among three things – carbon footprint, thermal performance and liveability – coexisting, responding to your climate is paramount and something you can do on a modest budget.
“That’s our basic design philosophy … you don’t need to up-spec a house with too many add-ons to make it comfortable.”
