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Staying put

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When a South Australian building couple started revitalising a dilapidated stone cottage, they soon knew this would be their forever home.

Ian Bushnell

Content Writer
South Australian custom builders Sam and Mary-Jane McArdle liked their sustainable house project so much, they decided to make it their own home.

The 1920s stone cottage across the road in Mallala, north of Adelaide, was supposed to become their green makeover show-home where clients could walk through and see sustainability principles and technology in action. ‘But once we drew up the plans, we fell in love with it,’ says Mary-Jane.

They’d lived across from the character-laden but dilapidated four-bedroom home and lean-to for 10 years, and being suckers for old houses, decided to buy it.

They had no real plans for the property, which had been vacant for a couple of years. But after completing the HIA GreenSmart course, the couple was inspired to reimagine it as a working energy and water efficiency model.

Mary-Jane says the starting point is always the design. Specialist architects Goodhouse were brought in. The lean-to was replaced by a modern pavilion extension and the home was rezoned so the new kitchen, dining, living area and a home office could take advantage of the northern aspect.

The north-facing extension with its high vaulted ceiling and tall windows captures the warming winter sun, but in summer, the eaves are calculated to provide shade through the heat of the day.

A tiled floor retains the sun’s heat in the winter and radiates it back out as the house cools. An internal recycled brick wall provides thermal mass, helping to maintain a constant, comfortable temperature range of 18-25°C inside.

In summer, the electric-powered high windows open at night to let hot air escape, while other windows allow cross-ventilation cooling air to flow through the house. Supporting the design are double-glazed uPVC units that reduce heat loss and gain, and high insulation levels keep the house snug in winter and keep out the fierce summer heat.
The McArdles opted for extra insulation, and they try to encourage clients to exceed the minimum requirements to gain the maximum benefit. ‘It’s more of an outlay upfront but it’s not double the cost and the benefits pay back,’ she says.

Combined with a solar PV system, energy-efficient lighting and appliances such as a heat pump hot-water system and induction cooktop, it means their electricity consumption has been slashed to less than half (43 per cent) of what they used in the previous house.

A ducted heating and cooling system in the old part has hardly been deployed, and the extension gets by with ceiling fans. It’s these kind of gains that excite Mary-Jane, who admits she underestimated just how much you could lower energy use and bills by how you build.
She says decisions such as getting the orientation of the house right and where you locate the windows don’t cost anything more but will have a huge impact on how the house performs. And while double glazing and insulation will cost extra, it’s an investment that pays off in spades. ‘You’re going to live in a house that’s just more comfortable and not having to rely on mechanical heating and cooling,’ says Mary-Jane.

The home went from less than two stars to a 6.8-star energy efficiency rating, which takes into account the old stone cottage. In addition, two 30,000-litre tanks harvest rainwater from the roof of the house and shed for use throughout the home which is fitted with water-saving Wells 4-star rated taps, while the garden is mostly drip-irrigated.

Sustainability is now a key part of the McArdles business offering, but Mary-Jane also sees it as a duty to raise awareness and educate clients. ‘When we get a new enquiry, we like to be involved in the planning process. We try to offer that building consultation during the drafting of plans before it’s too late.’

Mary-Jane advises builders to do their research, raise awareness and educate their trades, who may not be up to speed with the latest materials or appliances. 
The nine-month build itself was trouble-free, and they missed most of the supply chain issues plaguing the industry. The only unplanned work was to replace the sagging ceiling in the older section. The result was the best of both the old and the new, including ways to honour the original building’s heritage such as exposed stone walls. ‘It’s a nice visual contrast,’ says Mary-Jane. 

The McArdles have also used as many recycled materials as they can, such as the red bricks for the internal wall and the old water tank iron for garden beds.

The home won the Renovation/Addition Project category at the 2021 HIA Australian GreenSmart Awards, a first-time entry for the McArdles, who say it was validation for what they are trying to achieve.
‘It’s great to have awards where you are identifying projects done well in that GreenSmart environment,’ Mary-Jane says. ‘Sharing that with potential clients and the marketing that comes out of that helps to raise not just our profile but the profile of GreenSmart building itself. It’s been good to see people’s response that a way of building like this even exists.’

And when the McArdles talk about GreenSmart building, it’s not just theory – it’s coming from the family of five’s day-to-day lived-in experience.

For more information, visit McArdle Projects.


2021 HIA Australian GreenSmart Renovation/Addition Project


McArdle Project


Mallala, South Australia


  • Roofing: Heritage Galv Roofing in
  • True Oak profile, Nexteel
  • Wall cladding: Colorbond CGI, Nexteel; Maxline, Nexteel; Australian hardwood timber
  • Windows and doors: uPVC double glazed, Australian Window Solutions
  • Internal brick wall: Recycled red bricks to provide thermal mass to aid temperature regulation
  • Timber benchtops in kitchen, laundry, pantry, bathroom and office: Australian hardwood timber
  • Timber floorboards: Original pine floorboards, rejuvenated with sand and sealed with Loba low-VOC sealant to prolong the life
  • Floor tiles: Dark ceramic to help absorb and retain sunlight in winter, Tile Centre
  • Kitchen benchtop: Low-VOC Essastone, Laminex
  • Paint: Ultra-low VOC Wattyl ID Advanced
  • Solar PV: 6.6kW panels and 5kW inverter
  • Insulation: R6 insulation and reflective foil in the old house. The extension has R6 and reflective foil in ceilings, R4 in external walls, and R.2.5 in internal walls
  • Hot water system: Stiebel Eltron WWK302 heat pump.