Sustainable House Day 2025

Near the beach in Newcastle, New South Wales, this new build makes the most of a tiny subdivided site for truly inspired urban infill. Designed around existing mature trees on the block, the house is orientated to the laneway on the west and also engages with the street to the north, taking on a role of passive surveillance and fostering a sense of community in its coastal suburban surroundings.

At only 120 square metres, the three-bedroom, single-bathroom home employs design tricks and careful detailing to ensure that it feels larger than it is. A raised deck built around a feature olive tree connects two small interior living rooms, almost doubling the living space when the weather is fine. Built-in furniture allows for smaller rooms and more storage, and a hallway to the extra toilet has a second function of doubling the size of the laundry.

Future adaptability was also a key consideration. The second bedroom has been designed to accommodate bunk beds down the track, when the children grow. The third bedroom, downstairs, is currently doing duty as a study, but space is available upstairs for a study nook when that bedroom is needed.

“This house has been designed to challenge the Australian norm of housing,” says architect and homeowner Jo Bastian. “It’s half the size of an average Australian home, sits on a site half the size of an average site, and provides flexible rather than large living spaces.”

Mark Lavis and his partner Hannah Lord’s typical ‘ex-govie’ home in the Canberra suburb of Watson wasn’t serving their family well anymore. The old house was poorly orientated, sparingly insulated and rundown, but they loved the area and wanted to stay. With the assistance of Mark’s sister, architect Claire Lavis from Paper Seven Architecture, they designed a modest 161-square-metre three-bedroom new home for their block, and went about constructing it as owner-builders.

“The existing house on the site was slowly dismantled rather than demolished, and valuable, recyclable materials were diverted from landfill,” says Mark. “We’ve used them for joinery, furniture and architectural detailing in the new build.”

With passive solar design firmly in mind, the 8.2-Star, all-electric new home has its living areas and bedrooms placed to take advantage of northern sun in winter. It’s of insulated reverse brick veneer construction, the brick layer acting as thermal mass to help regulate the internal temperature.

With a 10.5-kilowatt solar PV system, electric vehicle charging, heat pump hot water, and energy-efficient lighting and appliances, the house is not only net positive for operational energy across the year; the family accounts are also in credit for their home and transport (EV) energy costs. An impressive feat.

In Scarborough, Western Australia, a young family is enjoying far greater comfort and liveability after the significant upgrade of their 1960s double brick house.

“The clients came to us wanting to renovate and extend their home, providing some more living space, increasing the energy efficiency, and removing the gas,” says builder Jason Tincey. “Our plan of attack was to improve the thermal envelope and make it continuous, fit uPVC double-glazed windows, install a mechanical ventilation system and increase the airtightness of the home.”

Most of the existing house was retained, minimising the need for new materials, and the materials from the deconstructed sections were salvaged and reused or rehomed where possible.

The team decided to aim for the Passive House EnerPHit standard for renovations, meeting the target and achieving an impressive airtightness of 0.82 air changes per hour at 50 pascals pressure (ACH50). The house also achieved a 9.6-Star NatHERS energy rating.

Neil Fearby renovated his timber home in Toowoomba, Queensland, a regional city that experiences cool winters and moderately hot summers. “It’s an ordinary house for its time, in a suburb of other ordinary 1960s houses,” says his partner, Kushla Gale.

What made the biggest difference to the home’s liveability was adding insulation. During the renovation, Neil removed the masonite interior wall lining and insulated all interior and exterior walls as well as the ceiling. The couple report that although they installed an energy-efficient reverse-cycle air conditioner, they never use it because the house is now so comfortable thanks to the insulation. The transpiration and shade provided by the trees they have planted also help cool the house and its surrounds in summer.

While the house does still have a gas cooktop and gas water heating, they use a portable induction hotplate for cooking and plan to install an electric heat pump water heater when the current system needs replacement. “At the time we installed the gas appliances we didn’t realise how terrible gas is for the climate,” says Kushla. “If we were renovating today, we’d make the house all-electric to reduce its emissions and make the most of the solar PV system we installed.” With solar generation, their electricity account is always in credit, but they still have gas bills.

Designed by building designer Rogier Voorhoeve (whose own home nearby has featured in Sustainable House Day in past years and also in Sanctuary 62, p40), Middleton Beach House is a response to the clients’ wish for “something different”. “It’s a ‘beachy-Scandinavian’ home crafted from local materials,” Rogier explains. “It’s highly sustainable, achieving a 7.5-Star energy rating, and features a rammed earth wall and waffle-pod concrete floor that function as thermal batteries, maintaining a stable indoor temperature year-round.”

Of course, the orientation is also carefully considered, with north-facing living areas and main bedroom. There is appropriately shaded double glazing and good cross ventilation, all contributing to its great passive solar performance.

Rogier is very pleased with the project and the collaborative approach to its construction. “Both the builder and I prioritise strong, functional designs that are built to last for many decades, using local materials and minimising construction waste,” he says. “Maintaining open communication with clients and stakeholders is key to fostering a positive working relationship.”

An “uninsulated concrete box” built as part of the 1956 Olympic athletes’ village wouldn’t sound like a dream home for many, but after looking for a long time, Alex Childs and Aiden Varan jumped at the chance to buy this fixer-upper in Heidelberg West, Melbourne. “It had enough land for our chooks, ducks, and food production,” says Aiden.

Fans of the high-performance Passive House standard and the only slightly less rigorous EnerPHit standard for renovations, they were interested to see whether it could be done on their “tired old concrete beast”. Stripping the house back by removing the floor, ceiling, roof and several internal walls, the couple rejigged the layout slightly, added cathedral ceilings, and paid particular attention to airtight membranes and draught-proofing. Outside, they applied a layer of rendered EPS panel insulation to the concrete.

They updated the plumbing and electrics, installed a mechanical ventilation system, got rid of the gas and added a solar PV system. The couple did the work themselves wherever possible, and prioritised the use of reclaimed materials. “In combination with the off-plumb walls, this proved hugely challenging when trying to achieve airtightness,” says Aiden. However, after much work, they achieved near-EnerPHit standard and are delighted with their comfortable, beautiful home. “From a poky, dark, worn-out concrete kit home, we created an eclectic country cottage with sustainability at the forefront.”