Although divisive for some, Passive House (Passivehaus) is now proving its worth as a sustainable and high quality housing and building system that can work well in Australian climates. I had the opportunity to stay one night in Australia’s first Passive House Certified apartment building, The Fern, which was recently completed in the inner Sydney suburb of Redfern.
The 11 one-bedroom apartments are the work of Oliver Steele, who is the architect, builder and developer in this instance.
- Read the full profile on The Fern in The Green List The Fern: These Redfern apartments will change your life, and save a motza
There’s a tall green wall that greets you on entry, and a further nod to biophilia with tactile timber handrails and finishes on the exposed concrete staircases.
The first thing I noticed when entering the apartment was how fresh and clean the air inside was, far better than any apartment I’d ever been in before.
The other thing I picked straight away was the quiet. You can hear the busy four-lane motorway on the street below, but it’s a hum rather than a roar.
It was an unseasonably warm evening, considering it’s only the first week in September (eek), but the interior of the apartment remained a very comfortable 20-24 degrees Celcius the whole time.
Good air quality, comfortable temperature and soundproof interior are features you can expect from all Passive House buildings, along with the less perceptible benefits of low energy use, no pollen (great for those with allergies), no pollutants (including toxic dust particles from car brakes) and no unwanted insect visitors (unless you welcome them in by opening the doors and windows).
All these features come down to the extreme airtightness of the building – something that’s confronting for some in the Australian construction industry because people are taught that “buildings have to breathe” (It’s also worth noting that passive house specifications and calculations are adapted for the local climatic conditions, and won’t pass certification unless they are met).
- Read our investigation into the pro’s and con’s of passive house Passive House and three deep dives: Phil Harris, Erwin Boermans, Daniel Kress
A few gaps here and there indeed allow fresh air into a building, which is important in Australia’s hot and humid climatic conditions. This works well to a certain point but if you can actually control what air is flowing in and out, then that can be even better.
Key to Passive House is wrapping a vapour permeable membrane and thick blanket around the whole building so it’s insulated and airtight. This is paired with a heat recovery ventilation system.
This system is pretty simple really and needs very little energy to run. It brings constant fresh air into the living areas and bedrooms and exhausts air from the bathrooms and kitchens.
The air coming in flows past the air going out without mixing physically, but the heat (or cool) is drawn from the stale air to the cold air, which is then fed back down into the pipes and into the rooms. The stale air, without the heat or cool, is then funnelled back outside.
The other critical aspect of Passive House is avoiding any thermal bridging, where there’s penetration of the building envelope for pipes or cables, or between the windows and doors, allowing the transferral of outside heat from the exterior building mass into the interior.
The Fern relies on seamless concrete to create an airtight seal (other materials can be used in timber homes though), which remains largely exposed as part of the design. The concrete finishes are complemented by natural materials such as herringbone timber floors, marble benchtops, and stone bath and basin.
Another important component of Passive House is sealable doors and windows. If you’ve been to Europe, you might have seen these high quality contraptions that make a satisfying click in and out of the seal when opened and closed.
These ones have been imported from Europe and weren’t cheap. But the hope is that once the building standard becomes more common in other parts of the world, these parts will be manufactured closer to home and at a lower cost. The rise of the building method in China suggests inexpensive Passive House componentry might not be that far away.
A sound night’s sleep
As someone who sleeps in a bedroom next to a busy road in your average leaky Sydney terrace house, the undisturbed night’s sleep was a real treat. I woke up feeling incredibly refreshed, despite sleeping in a room with the windows closed.
Another misconception with Passive House is that you need to keep the windows and doors closed at all times. But these buildings are also built for cross ventilation, so if you want fresh air you can “see”, you simply open the windows and doors and let the outside in.
There is a small airconditioning unit because passive house dwellings in temperate climates use them for the hot, humid days at the peak of summer to maintain the narrow thermal comfort range.
At the Fern, the systems use just 350 watts, which is enough to cool the entire apartment even during heatwaves and should only need to go on for half an hour or so at a time.
You perhaps wouldn’t notice the fresh air and temperate conditions if you didn’t know to look for them. But the whole notion of comfort in a home is, after all, largely the absence of discomfort.
Passive House might not be the only way to build sustainably but it ticks a number of boxes. On this tricky site, where the optimal orientation wasn’t possible due to a tall building blocking to the north, the Passive House method seems to have been a successful tool in the development of comfortable, low energy homes.