New South Wales now has two Passive House certified buildings. The experience of the designers and builders behind these projects shows that the building standard isn’t easy to follow but it’s worth it to get ultra-low energy homes that are comfortable, quiet and secure.
There’s now a certified Passive House in Thornleigh, on Sydney’s upper north shore, and another in the Blue Mountains.
Airtight construction is at the heart of the Passive House building standard, which was developed in Germany (Passivehaus). This is paired with a reliable mechanical ventilation system with heat recovery, guaranteeing great indoor air quality, ultra-low energy usage (typically less than 80 per cent of the energy used for heating and cooling an average home) and minimal noise penetration from outside.
Joe Mercieca of Blue Eco Homes, the design and build team behind the Blue Mountains display home, says he “was looking for his next challenge” in sustainable homes, which led him to Passive House.
“It’s sustainability on steroids.”
Mercieca has since skilled up – he’s now a certified passive house tradesman – and had a crack at his first project, the Sapphire Passive House in the Blue Mountains.
It wasn’t easy, he says, especially as the building standard comes up against what’s traditionally taught in carpentry.
For example, carpenters in Australia are generally taught that houses “have to breath” but a passive house needs to be airtight, he says.
The Sapphire home is so tightly sealed that the gaps for air to escape are collectively no larger than the head of a pinkie finger. Mercieca says most of the air is leaking out of keyholes.
It’s also tricky creating a “breathable but non permeable membrane so that water can’t get in but it still breathes”.
He says this is a matter of using the right materials in the right location.
“If you’re not using the materials properly it can make it worse.”
The result is total power consumption per day (without factoring in solar) that’s less than the cost of a takeaway coffee.
The home’s internal temperature is constantly kept at a comfortable level, ranging from 20 to 25 degrees, with minimal reliance on artificial heating or cooling. A ventilation system pushes filtered clean air throughout the house so there’s no carbon dioxide build-up inside.
The house also has a 5.2kW LG solar PV system with battery storage, and is built to the highest Bushfire Attack Level regulations.
Both homes were built using conventional Australian construction techniques.
Peace and quiet
The Thornleigh house is the work of Envirotecture architect Andy Marlow.
“With a third of all our new projects now being delivered to the Passive House standard, Envirotecture are very pleased to see this first project completed and certification received,” Marlow says.
The airtight construction and quality windows will critically shield residents from the noise from busy local roads and nearby train line.
The two-storey home also wraps around a large tallowwood tree that will provide shade in summer.
The house has 10 internal water tanks that help regulate internal temperature. They will act as a room divider while capturing the sun through a huge north facing window that has a retractable shading blind to control the amount of sun during the summer months.
The tanks will be filled after construction and are not connected to the other rainwater tanks, as the temperature of rainwater can be problematically low and pose a condensation risk if put straight into a building.
Although the windows – uPVC with an aluminium external skin – are imported, they come triple glazed as standard, which is more cost effective than a special order of double glazing.
The final result is a home that is 44 times less leaky than the average Australian home.
Passive design can work in Australia
Blue Eco Homes’ Mercieca says the newly certified homes should put to bed any doubts that Passive House isn’t suitable for the Australian climate. This is because the calculations for Passive House are specific to each climate.
“It can be built anywhere… we can build a passive house in Darwin.”
Now he’s done it once, Mercieca expects the next project will be easier. The company has already signed a contract for its next one.
“We’re very proud to have completed the first Certified Passive House in the Blue Mountains. We hope to build all our future projects this way.”
The certification of these two buildings brings the total number of Passive House Certified buildings in Australia to 18. There is a pipeline of hundreds of Passive House buildings in various stages of planning and construction.