Is Passivhaus Right for You?
Your dream house just got better: how utilising Passivhaus design can up the comfort factor and slash energy costs
Statistics show that at least one-fifth of Australia’s greenhouse gases are generated by households. So when it comes to reducing our collective carbon footprint, anything we can do to reduce our consumption of energy at home has the potential to make a huge difference. Passivhaus design – which can slash a home’s energy use by a massive 75 per cent, has the potential to make a huge difference. As well as being ecologically sound, a passive house is more comfortable to live in than a standard home, and cheaper to run – so it’s also beneficial at an individual level too.
In Australia, the Passivhaus movement is still in its infancy. In fact, the first certified passive house was built in South Australia by Bernward Bucheler, director of Passivhaus Australia, in 2014. Today, there are seven certified passive houses in Australia and 11 in New Zealand.
“It’s definitely gaining momentum,” says Marc Bernstein-Hussmann, director of Melbourne Design Studios and certified passive house designer. “Before me there were three certified Passivhaus designers in Australia; I think we now have about 40. So it’s something that people understand more and more.”
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“It’s definitely gaining momentum,” says Marc Bernstein-Hussmann, director of Melbourne Design Studios and certified passive house designer. “Before me there were three certified Passivhaus designers in Australia; I think we now have about 40. So it’s something that people understand more and more.”
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How much energy can a passive house save?
According to the Australian Passive House Association, passive houses allow for energy savings of up to 90 per cent compared with typical existing buildings, and over 75 per cent compared with average new best-practice constructions. Similar energy savings have been demonstrated in warm climates where buildings require more energy for cooling than for heating.
Extras such as incorporating solar passive design, PV roof panels, and energy-efficient appliances will further reduce a passive house’s consumption of grid power.
According to the Australian Passive House Association, passive houses allow for energy savings of up to 90 per cent compared with typical existing buildings, and over 75 per cent compared with average new best-practice constructions. Similar energy savings have been demonstrated in warm climates where buildings require more energy for cooling than for heating.
Extras such as incorporating solar passive design, PV roof panels, and energy-efficient appliances will further reduce a passive house’s consumption of grid power.
Does it suit the Australian climate?
You may be thinking that Passivhaus design is only suited to the chilly climes of Europe. And it’s true that because a passive house will retain all its lovely warmth through winter, it’s a brilliant solution for cold regions. But Andy Marlow, director of sustainability-focused architecture firm Envirotecture, says Passivhaus principles perform equally well in hot and temperate climates. “It’s perceived as a cold-climate solution, but it was designed as a way to keep houses comfortable; it just happened to originate in a cold climate,” he says.
In fact, certified Passivhaus designers model each home design using site-specific climate data, so the insulation requirements and other design features are adapted accordingly.
You may be thinking that Passivhaus design is only suited to the chilly climes of Europe. And it’s true that because a passive house will retain all its lovely warmth through winter, it’s a brilliant solution for cold regions. But Andy Marlow, director of sustainability-focused architecture firm Envirotecture, says Passivhaus principles perform equally well in hot and temperate climates. “It’s perceived as a cold-climate solution, but it was designed as a way to keep houses comfortable; it just happened to originate in a cold climate,” he says.
In fact, certified Passivhaus designers model each home design using site-specific climate data, so the insulation requirements and other design features are adapted accordingly.
Passivehaus vs solar passive
You’ve probably heard of ‘solar passive’ home design before. It involves orienting a home to the north, and positioning windows to let the sun warm the interiors during winter, while using shading to keep it out during summer. It’s a great concept and, when applied correctly, negates or lessens the need for mechanical heating and cooling.
You’ve probably heard of ‘solar passive’ home design before. It involves orienting a home to the north, and positioning windows to let the sun warm the interiors during winter, while using shading to keep it out during summer. It’s a great concept and, when applied correctly, negates or lessens the need for mechanical heating and cooling.
Including solar passive design features in a passive house will further enhance its thermal efficiency – in some cases there will be no need for additional sources of heating or cooling. “We try to combine passive houses with traditional passive solar design,” Bernstein-Hussmann says. “We say ‘OK, so a few months of the year this house works like a traditionally well-designed, sustainable Australian home, where you leave your windows and doors open, you get good cross-ventilation through, it’s all nicely shaded. All those sort of things work beautifully.’”
“But then for those months where it gets too warm or too cold, you close your windows and you get your heat recovery ventilation system running. That way you can benefit from both worlds.”
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“But then for those months where it gets too warm or too cold, you close your windows and you get your heat recovery ventilation system running. That way you can benefit from both worlds.”
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Design flexibility
Sometimes, site restrictions mean that northerly orientation is either impractical or impossible. Because it doesn’t rely on solar access, Passivhaus affords a design flexibility that can’t always be achieved when using solar passive techniques. High levels of energy efficiency and comfort can be attained on any site, regardless of orientation or the architectural style of the house.
Essentially, the Passivhaus method shifts the architectural focus back onto aesthetics, rather than having the design constrained around accessing prevailing breezes or optimising solar access. Likewise, a passive house can be built using almost any construction system (timber, steel or concrete, for example) so long as the requisite levels of insulation (including for glazed windows and doors) and air-tightness are met.
In this Cottesloe beach house, the quintessentially Australian architecture takes a starring role, while the Passivhaus features work silently in the background. The home, designed by Roger Joyner of Passivhaus Perth and built by Consortium Builders, was completed last year, making it WA’s first passive house.
Sometimes, site restrictions mean that northerly orientation is either impractical or impossible. Because it doesn’t rely on solar access, Passivhaus affords a design flexibility that can’t always be achieved when using solar passive techniques. High levels of energy efficiency and comfort can be attained on any site, regardless of orientation or the architectural style of the house.
Essentially, the Passivhaus method shifts the architectural focus back onto aesthetics, rather than having the design constrained around accessing prevailing breezes or optimising solar access. Likewise, a passive house can be built using almost any construction system (timber, steel or concrete, for example) so long as the requisite levels of insulation (including for glazed windows and doors) and air-tightness are met.
In this Cottesloe beach house, the quintessentially Australian architecture takes a starring role, while the Passivhaus features work silently in the background. The home, designed by Roger Joyner of Passivhaus Perth and built by Consortium Builders, was completed last year, making it WA’s first passive house.
Passivhaus in the city
The flexibility of Passivhaus also means that highly efficient, sustainable housing can be achieved in dense inner-city or established suburban areas, where site constraints can often compromise the effectiveness of solar-passive design.
Sydney architects Steele Associates are currently working on Australia’s first Passivhaus-certified apartment project in the inner-city suburb of Redfern. “The purpose of this development is to show the industry generally what can be done within the constraints of conventional development to achieve better outcomes for the environment and people,” says Steele Associates director Oliver Steele.
The building, which will comprise 11 one-bedroom units, is due for completion next March. Steele says the Passivhaus principles have allowed him to overcome efficiency obstacles that would otherwise be insurmountable. “We only have east- and west-facing glazing, which means you get a lot of morning and afternoon sun in summer,” he says, as an example. Ordinarily, this would result in uncomfortably hot rooms that occupants would simply cool with air-conditioning.
The Passivhaus solution? “We’re having triple glazing to keep the sun out, as well as automated external blinds that will come down on the east in the morning and in the west in the afternoon to keep the heat load off.”
The flexibility of Passivhaus also means that highly efficient, sustainable housing can be achieved in dense inner-city or established suburban areas, where site constraints can often compromise the effectiveness of solar-passive design.
Sydney architects Steele Associates are currently working on Australia’s first Passivhaus-certified apartment project in the inner-city suburb of Redfern. “The purpose of this development is to show the industry generally what can be done within the constraints of conventional development to achieve better outcomes for the environment and people,” says Steele Associates director Oliver Steele.
The building, which will comprise 11 one-bedroom units, is due for completion next March. Steele says the Passivhaus principles have allowed him to overcome efficiency obstacles that would otherwise be insurmountable. “We only have east- and west-facing glazing, which means you get a lot of morning and afternoon sun in summer,” he says, as an example. Ordinarily, this would result in uncomfortably hot rooms that occupants would simply cool with air-conditioning.
The Passivhaus solution? “We’re having triple glazing to keep the sun out, as well as automated external blinds that will come down on the east in the morning and in the west in the afternoon to keep the heat load off.”
Steele says Passivhaus is particularly well suited to medium-density city living. “As well as the energy efficiency, a real benefit is the acoustic insulation and the dust-proofness. Because living in the inner city, when you rely on doors and windows for ventilation, you also get noise and dust coming in. So here you can have lovely natural light and fresh air, in a perfectly clean, quiet and dust-free environment.”
How skylights have risen up the architectural ranks
How skylights have risen up the architectural ranks
Andy Marlow agrees: “I think that Passivhaus solves a couple of really big issues that mainstream design isn’t currently solving. There are certain locations which are ideally suited to this; under flight paths, in dense urban areas, places where your desire to open a window is really not that great. Passivhaus ends up becoming a very, very sensible response.”
“It also happens that dwellings in those areas tend to be smaller,” he adds, “so the costs associated with building in this way are made easier by the fact you don’t need
so many square metres.”
“It also happens that dwellings in those areas tend to be smaller,” he adds, “so the costs associated with building in this way are made easier by the fact you don’t need
so many square metres.”
So will a passive house cost more to build?
Short answer: yes it will – for the time being, at least. “The challenges for someone wanting to build a Passivhaus in Australia are the additional costs of quality windows and doors,” Marlow says. Most off-the-shelf products currently on the market, he says, would not meet Passivhaus standards.
The need for air-tightness also requires very specific attention to detail during construction, which will add to labour costs. And then, to have the home actually tested and certified is another – not insignificant – expense.
“In Europe [to build a passive house] would cost six or eight per cent more, but their standard of housing is already extremely high. Here it’s a bit more,” says Bucheler. “However, if you are intending to get an architecturally designed house, they usually are around $3,000 per square metre anyway, you could build it to Passivhaus standard for maybe 10 or 15 per cent more.”
Short answer: yes it will – for the time being, at least. “The challenges for someone wanting to build a Passivhaus in Australia are the additional costs of quality windows and doors,” Marlow says. Most off-the-shelf products currently on the market, he says, would not meet Passivhaus standards.
The need for air-tightness also requires very specific attention to detail during construction, which will add to labour costs. And then, to have the home actually tested and certified is another – not insignificant – expense.
“In Europe [to build a passive house] would cost six or eight per cent more, but their standard of housing is already extremely high. Here it’s a bit more,” says Bucheler. “However, if you are intending to get an architecturally designed house, they usually are around $3,000 per square metre anyway, you could build it to Passivhaus standard for maybe 10 or 15 per cent more.”
Can an existing home be turned into a passivhaus?
Yes, it’s possible. Marlow says the Passivhaus Institut – which oversees the Passivhaus certification program worldwide – has introduced a retrofit approach called enerPHit. It has some slightly reduced performance criteria, because sealing the building envelope and optimising insulation performance can be more difficult in existing buildings. “But there’s no reason why you can’t do it,” he says. “It’s a bit fiddly, but renovating’s fiddly anyway.”
In 2015, Passivhaus Australia renovated this 1950s villa in the Adelaide hills (pictured), which is situated on a steep, windswept slope. Bucheler and his team successfully preserved the home’s charming stonework and unique character, while incorporating a number of insulation treatments. The finished home, which also includes solar power and a geothermal heating/cooling system, uses virtually no power, and despite the harsh weather extremes of its location, the inside temperature remains stable and comfortable.
Yes, it’s possible. Marlow says the Passivhaus Institut – which oversees the Passivhaus certification program worldwide – has introduced a retrofit approach called enerPHit. It has some slightly reduced performance criteria, because sealing the building envelope and optimising insulation performance can be more difficult in existing buildings. “But there’s no reason why you can’t do it,” he says. “It’s a bit fiddly, but renovating’s fiddly anyway.”
In 2015, Passivhaus Australia renovated this 1950s villa in the Adelaide hills (pictured), which is situated on a steep, windswept slope. Bucheler and his team successfully preserved the home’s charming stonework and unique character, while incorporating a number of insulation treatments. The finished home, which also includes solar power and a geothermal heating/cooling system, uses virtually no power, and despite the harsh weather extremes of its location, the inside temperature remains stable and comfortable.
Points to consider
Bernstein-Hussmann cautions that when embarking on a Passivhaus project, education and knowledge in both design and construction are key. The building methodology is completely different to current Australian practices, and if the sealing and ventilation procedures aren’t carried out correctly, moisture can build up inside the walls, which could potentially lead to structural damage.
“You want to build with someone who understands what they’re doing, otherwise they might put all the airtightness membranes in and then the plumber and electrician come and punch holes through it because that’s what they always do,” he says. “A certified tradesperson will understand the whole Passivhaus concept and what’s important in terms of the detail.”
Bernstein-Hussmann cautions that when embarking on a Passivhaus project, education and knowledge in both design and construction are key. The building methodology is completely different to current Australian practices, and if the sealing and ventilation procedures aren’t carried out correctly, moisture can build up inside the walls, which could potentially lead to structural damage.
“You want to build with someone who understands what they’re doing, otherwise they might put all the airtightness membranes in and then the plumber and electrician come and punch holes through it because that’s what they always do,” he says. “A certified tradesperson will understand the whole Passivhaus concept and what’s important in terms of the detail.”
Marlow says the certification process exists to ensure passive houses are structurally sound and functioning correctly. “As part of the certification process, there’s a blower door test at the end of construction, so you know that it’s airtight,” he says. “Ultimately, if you did everything else the same but didn’t do the certification, the risk is that little things get missed. If there’s an undetected leak, depending on how bad it is or where it is, it could allow moisture to get in and ruin a wall assembly and you’d end up with mould and condensation in the wall.”
Pictured here is the blower door test underway on Bucheler’s passive house renovation project.
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Pictured here is the blower door test underway on Bucheler’s passive house renovation project.
Your say
If you enjoyed this story, like it, bookmark it, save the photos and share your thoughts below. Join the conversation!
Building for comfort and energy efficiency
Passivhaus (or passive house) home design originated in Germany in the early 1990s. It is a voluntary building standard aimed at improving energy efficiency. So far, about 50,000 houses around the world have achieved Passivhaus certification – most of these in European countries.
Passive houses – which must be designed by a Passivhaus-accredited architect who understands the concept – are heavily insulated, and designed and built to be airtight. This keeps the internal temperature stable in all weather conditions, minimising or negating the need for heating or air-conditioning.
The technique pivots around the inclusion of a heat recovery ventilation system, which removes the stale air and transfers its heat (or coolness) to fresh air, which is ducted through the home. In this way filtered, temperature-controlled fresh air is continuously brought inside, without any uncomfortable draughts.