The building and construction sector is responsible for almost 40 per cent of global carbon emissions, according to a 2021 report from the Clean Energy Finance Corporation. Decarbonising the design and construction process offers a clear-cut path to reducing emissions. But what can be done beyond adding solar panels and green walls to our homes and offices? 

From embracing low-carbon building materials to tapping into real-time weather data, architects in Australia and New Zealand are finding innovative ways to minimise the environmental footprint of our built environment.

Natural selection

Forget any preconceived notions you had about straw bale buildings being ramshackle oddities favoured by fringe dwellers. Contemporary straw bale passive houses are modern marvels capable of dramatically reducing household energy bills.

Wanaka-based architecture, design and construction firm Hiberna are blazing a straw bale passive house trail in New Zealand. 

“It’s an easy place to make big improvements. Currently, buildings are so poorly designed. We have the solutions for building right now, so why wouldn’t we?” says Jessica Eyers, environmental building consultant, architectural designer and director of Hiberna.

So, what is a passive house anyway?

“Passive houses are comfortable year-round and use virtually no energy to achieve that,” Jessica explains.

Design principles of a passive house, according to the Australian Passive House Association, include airtightness, thermal insulation, high-performance windows, thermal bridge-free design and ventilation systems that ensure air circulation with minimal heat loss. The Passive House Institute of New Zealand and the Australian Passive House Association will model, test and verify passive houses before certifying them.

Having built the southern hemisphere’s first certified straw bale passive house as their own home, Jessica and her builder-husband Ben recently worked on the development of Luggate Hall, New Zealand’s first certified passive community building. 

Jessica’s favourite insulation material is straw – one of the oldest and carbon-friendly building materials in the world, thanks to its low level of embodied carbon. Embodied carbon is the term the World Green Building Council uses to describe emissions associated with materials and construction processes throughout the whole lifecycle of a building or infrastructure. Concrete is a high emitter of carbon, whereas straw has extremely low embodied carbon levels.

“[Straw] is a local material, it’s carbon negative, compostable and completely non-toxic,” Jessica says. “At the end of the building’s life, it’ll go back into the ground.” 

Europe, she says, is leading the way in straw bale construction and in many facets of sustainable building.

CopenHill is a futuristic waste-to-energy power plant in the Danish capital Copenhagen, which also features a dramatic, slanted roof used as a ski slope and recreation facility. In France, a strong cohort of builders is championing straw bale for the construction of medium and high-density residential developments. 

“They’ve built seven-storey apartment buildings out of straw panels in France. There’s a real opportunity to make this material mainstream,” she says, adding that straw bales are inexpensive and have a surprisingly good fire rating. 

Since the Queenstown Lakes District experiences sub-zero temperatures, homes that provide a stable, comfortable temperature are hugely advantageous.

“Living in a building that’s just above freezing is a miserable and stressful experience. Waking up in a house that’s 21 to 22 degrees every single day, all year round – and knowing the heating hasn’t even been on – is such a liberating feeling,” she says. 

Adopting automation   

Based in Sydney’s North Alexandria Industrial Heritage Conservation Area, Smart Design Studio certainly lives up to its name. The multidisciplinary design practice occupies an energy-positive building that uses technology to drive a sustainable approach to its day-to-day operations. 

With no air conditioning, the building harnesses passive solar design, natural ventilation and automation to remain cool in summer. It also drastically reduces its reliance on electricity from the grid thanks to 260 solar photovoltaic panels and battery storage.

Automation plays an important role in the building’s temperature management system, controlling the fans, blinds, windows, lighting and underfloor heating and cooling. 

“The weather station on our roof, which also monitors the weather bureau’s forecast, ensures that the rain, wind and hot or cold air does not come into the studio,” explains William Smart, founder and creative director of Smart Design Studio. 

Unsurprisingly, the building has won a slew of architectural awards. William envisages that technological advancements will continue to enhance the sustainability of buildings in the future.  

“In the next 10 years we’ll see continual improvements in solar and wind power generation systems and battery storage. Just like in the car industry, technology is making this equipment more efficient, more affordable and therefore more popular,” William says.

He believes that natural building materials like timber, bamboo and green concrete (made with fly ash and other waste materials) will also grow in popularity. 

“Timber and bamboo are very sustainable and capture carbon as they grow,” he explains. “They produce very little carbon emissions in their production and delivery. Concrete is a strong and durable material that is quite sustainable if made with recycled steel and the cement is composed and made in the right way.”

A star is born 

Building a home without heating or cooling is a somewhat radical idea in a city like Adelaide known for its scorching summer heat waves. But that’s exactly what Jim Woolcock has done. As director of Adelaide sustainable building design consultancy SUHO, he’s recently fulfilled an ambition to create Adelaide’s first home to achieve the maximum 10 stars on the Nationwide House Energy Rating Scheme (NatHERS).

“I’ve spent 20 years telling people they should build more energy-efficient houses… so here’s a good example to show that it’s possible,” Jim says.

The project was a huge undertaking. Everything from the choice of insulation materials to the colour of the flooring, and the aspect of the block was scrutinised to maximise energy efficiency, he says. 

Located in Woodforde, within the Adelaide Hills region, Jim says SUHO designed the house to be resilient to temperature fluctuations, a claim they have tried and tested on days that reach 40 degrees and above.

“The monitoring shows that there isn’t a need for air-conditioning if people are willing to have a comfortable temperature up to 26 degrees in summer,” Jim says. 

A heat recovery ventilation system enables a constant flow of fresh air to circulate through the home, which also stops mould growth.   

Among its many accolades, the 10-star home was named the 2021 winner of the Master Builders Excellence Award for Environmental and Sustainable Construction in the residential category, and the 2021 People’s Choice Award in the Design Matters National Building Design Awards.

Jim is realistic about the fact that achieving a 10-star rating can be cost prohibitive for many homeowners. He believes an 8-star rating is the sweet spot when analysing the cost-to-benefit ratio and is hopeful that this ground-breaking design will encourage more Australians to build energy-efficient homes in the future.

“You can get 90 per cent of the benefit from meeting 8 stars,” he says. “It’s costly to get to 10 stars, so you’re probably better off spending more on solar panels or buying an electric car,” he says.

Beyond energy efficiency, the home’s triple-glazed windows buffer traffic noise while the airtightness coupled with the filtering system stops dust accumulation, a bonus for people with allergies. 

“It’s nice to think about it as a feel-good house. It not only feels nice to live in a more energy-efficient house, but it also feels good to not worry about bills while doing something good for the environment,” says Jim.

By Jo Stewart