Small impact

When a builder takes on a project to build a mere 184-square-metre house with just one bedroom, they don't usually imagine, 'This is the way to win a prestigious national award.'

However, a building company in Victoria took on this challenge and applied for the 2021 HIA Australian GreenSmart Awards. When the awards were announced last September, Ovens & King Builders scored not just the prestigious 2021 HIA Australian GreenSmart Custom Built Home Award but also the GreenSmart Energy Efficiency Award and the GreenSmart Home of the Year Award.

'It was really unexpected,' says Lachie Gales, director of Ovens & King Builders, which is based in Wangaratta, a rural city in the northeast of Victoria. 'We'd won a GreenSmart custom built home award back in 2013, but never in my life did I think I'd achieve the other two prizes. It was a little surreal but very satisfying.'

In some ways, the winning house in Beechworth has its own otherworldly beauty. Owned by a retired couple who have a passion for community responsibility, they were determined to be a little different from other locals in the area. 

Apart from introducing bold design elements, they were keen to have a Passive House built home. They turned to Ovens & King Builders, a company that specialises in sustainable construction and energy efficiency. For Lachie and his team, creating a Certified Passive House was a first for the company. 

'The decision to downsize was one thing, but it took real courage to build a Passive House in this area,' says Lachie. In fact, when the house was built in 2019, this was only the second accreditation in Northeast Victoria. 'The clients wanted the house to stand out in the community so locals can see what's possible.'

Lachie and his team employed the rigorous Passive House standard of construction to achieve a comfortable temperature year-round despite minimal energy consumption. 'The thermal layer on a passive house is so effective. The temperature is not lost,' he says. 'And in summer, that works to keep the heat out.'

In Northeast Victoria, the winter diurnal range – the difference between the daily maximum and minimum temperature – can range from -6°C overnight to 12 to 14°C during the day. 

'Your building design has to cope with this great fluctuation,' says Lachie. 'When the sun streams in during the day, you can take advantage of it. Because the house is so well insulated, any heat gain through the glazing or the couple's activities, such as cooking, boiling the kettle or running hot water in the shower, is retained. Overnight the temperature seldom goes below 16°C.' 

When building this home, Lachie and his team introduced new, innovative materials and products. They installed Logikhaus aluminium/timber composite windows that are triple-glazed and airtight. The thermal performance of the windows, minimising air movement and heat gain and loss, is a critical factor in the success of the building. Canberra-based LogikHaus imports these windows from a manufacturer in Poland, and they are certified for Passive House construction.

'We had to stage our construction process,' says Lachie. 'The installation of the windows and keeping the airtight membrane and the thermal installation layer intact was a challenge in order to seal it effectively. We couldn't have any thermal bridging that conducted energy in an uncontrolled way. You have to use a lot of foresight to make it work seamlessly.'

Other elements that assist Passive House performance include a grid-connected 4kw photovoltaic power supply system; and external wall insulation of 100mm PIR foam, battened and fitted with 'Enseam' wall claddings from Lysaght.

The home's thermal insulation provides effective separation between the heated or cooled inside environment and the outdoors. Heat recovery ventilation brings a constant fresh air flow into the relatively airtight environment, allowing premium indoor air quality while saving energy. The airtightness of the building increases comfort while reducing energy bills.

The build includes a waffle pod slab on an insulated base of 100mm PIR foam and hand-framed stud walls in H2 termite resistant Laminated Veneer Lumber timber. Walls are sealed internally and externally with Pro Clima intelligent breather membranes. 

Apart from implementing the Passive House building performance, Ovens & King Builders also worked closely with the clients to achieve a strong design aesthetic. The exterior of the house was clad entirely in metal. 'Since it has a strong geometric design, we had to execute it precisely,' explains Lachie. 

The team also custom-blended a concrete mix for the polished floor. 'The clients had a distinct finish they wanted, and they had a sample of an overlay masonry floor that was white with flecks of stone.' Lachie selected a blend of local white stone from the Wodonga and Yarrawonga areas. 'With the help of Mawson's Concrete & Quarries, we came up with a concrete blend mix that really met their need,' he says. 'We went with a full exposure polished concrete rather than the overlay. And this was so effective, my next client saw it and repeated the look.'

After completing this stylish, energy-efficient home, Lachie knows the value of winning awards, such as the triple HIA GreenSmart gongs.

'It's been very good for us on a number of levels. I've had a client in the wings for several months now trying to decide which builder he'd choose. After we won the award, I sent out a general notice to a lot of people and, a week later, they were in touch. We are their builder. 

'It validates what we do – and what we do is different to most other builders in our region,' says Lachie. 'It also helps our staff as they see how others value their work. It gives our existing clients extra confidence that they're with a team that can walk the talk. Sustainable buildings and thermally efficient construction are what we live and breathe.'

Materials:

• Custom cabinetry featuring oak cabinets and composite stone Benchtops
• Lysaght 'Enseam' wall claddings in Colorbond matt and metallic finishes
• EzyJamb door finishes along with square set plaster junctions for the same minimalist effect
• LED lighting including directional downlights for highlighting effect
• H2 termite-resistant laminated veneer lumber timber for wall frames, H2 treated plantation-grown pine for roof trussers
• Pro Clima intelligent breather membranes for airtightness: Intello for an internal membrane, Extasana for a weather-tight membrane, all sealed with Extora tape
• Triple-glazed, aluminium /timber composite windows, certified for Passive House construction and imported from Poland by Logikhaus. Powdercoated external frames and European oak internal finishes. European hardware for tilt and turn function. Lift-and-slide doors for airtightness
• R10 Ceiling insulation over the ceiling, overlapping the wall insulation to create a continuous thermal envelope
• Zender Q350 heat recovery ventilation system delivering outstanding performance, including efficient heat recovery (up to 96%), low noise generation and reduced power consumption
• Rainwater tank made from BlueScope galvanised Aquaplate corrugated iron