Clare Parry, who will be a panellist at The Fifth Estate’s Flick the Switch event on 5 August, is a director of the Australian Passive House Association (and founding chair). She’s been weathering the lockdown periods in her recently built Passive House in Melbourne, and is thrilled not to be in the “dumb” double brick house she lived in before.
For Parry, who is also director and principal consultant at Grün Consulting, achieving Passive House standard was a non-negotiable in the same way that marble benchtops are for other people.
The energy savings are clearly a huge part of the appeal but like any real Passive House enthusiast, Parry is hooked on the luxury of impeccable comfort.
“Now that I live in a Passive House, I never want to move, because I look at a typical home and think ‘that looks really cold and uncomfortable’.”
She describes her home as “small but perfectly formed”. “Everything is deliberate, there are no accidental inclusions.”
Thanks to a simple streamlined design, it was able to be built with 90 per cent carpentry, forgoing the likes of plaster and most joinery. She says the design lent itself to a pretty standard skill set, but that didn’t mean the team didn’t “challenge the building code where it needs challenging”, such as on ventilation.
Many Australian builders don’t mind leaving a few gaps here and there to allow fresh air into the building, helping to prevent humidity and odours, but Passive House goes one better by controlling exactly how much air is flowing in and out by pairing an airtight membrane with an ultra efficient heat recovery ventilation system.
Her home is fitted with a small split system that provides heating and cooling, which she typically only needs to turn on for short spurts. The building is so good at regulating its own temperature that sometimes she wakes up in the morning and wonders if she’s left the heater on.
Bitten by the Passive House bug
A mechanical engineer by training, Parry first got into Passive House when she was working on a Passive House project for Umow Lai. Her passion blossomed from there, and she now spends about 95 per cent of her working hours on PH projects at her ESD consultancy and other endeavours.
Right now the company is is super busy, working on 120-plus projects, including a retrofit that will see a building wrapped up in an external cladding layer (made from a low embodied carbon material) like a blanket.
There’s been a flurry of Passive House activity in Australia of late, including in commercial, schools and the tertiary sector, it’s still a tiny fraction of the entire market, Parry says.
She’s aware the emerging Passive House revolution is happening against the backdrop of a building and construction industry that still isn’t overly concerned with quality control.
In fairness, builders are up against it with tight budgets and deadlines. But it’s the enduring status quo that leads to systemic quality issues.
Budget constraints prompt builders to choose cheaper materials that don’t perform as well, such as lower quality glazing, and turn a blind eye to edges that don’t meet up.
Overall we’ve had falling standards over the past 20 years but it’s not just in construction, Parry says. Our society increasingly chooses more, faster and cheaper over quality in pretty much all we do.
In construction we end up with buildings that fall short of the minimum NatHERS rating – sometimes as low as two stars when the minimum is six. And yet the modelling used for the calculations banks on near-perfect execution.
One of the obvious discrepancies is that NatHERS accounts for a certain amount of air changes per hour, but when the airtightness falls far short of expectations, this blows the energy performance way out.
The result is, “It’s also impossible to keep that home comfortable.”
It’s not just the residential sector that suffers from a performance gap on sustainability. There are countless buildings that haven’t met their sustainability targets. Parry says there are big numbers of legal actions underway by unhappy clients who don’t think they’ve got what they were promised. Sustainability is a lot about promises, she says.
This performance gap can give sustainability a “bad name”. This is starting to improve though, especially as more work is going into addressing the performance gap in different rating tools, including Green Star.
A really tricky area, Parry says is the less tangible area of biophilia and its impact on mental health for instance.
Energy efficiency can be tricky enough but this field makes the job of ESD professionals considerably more complicated and why successful ESD professionals need to be “good storytellers”.
One pilot home project shows there’s a long way to go
When there’s something like Passive House to aspire to, it can be intimidating to think about how far the rest of the industry has to go to consistently meet a similar standard.
Parry is watching this play out through her involvement with a pilot project underway to test the economic and comfort benefits of a Certified Passive House home for the mass market, which involves building one certified home among a conventional estate.
The contrast couldn’t be greater; Parry says it’s such a departure from what the contractors have done before. For instance the use of underfloor insulation, or the need to be extremely careful not to puncture a wall for instance, because this would PH airtightness outcome but mean nothing at all in a conventional build.
In the end the site was declared a strict “no-go zone” for anyone without the right training and accreditation.
Parry says it’s easy to feel overwhelmed by the scale of the task, and the prospect of “telling builders that they need to be careful about every tiny thing”. But she hopes the exemplars in Passive House and sustainable design will start to “shine through” and attract a dedicated following.
“People will start to see what can be done and start asking ‘why aren’t we doing this?’”
She also says people are attracted to Passive House for different reasons. Schools, for example, might not care that much about saving $200 a month on energy bills but want indoor environments that keep children healthy and preforming at their best.
Lingering misinformation about Passive House
Parry says there’s a lingering misunderstanding that PH always needs to be a hermetically sealed box. However, that’s in direct contradiction to the system’s requirements that there needs to be operable windows and doors to allow fresh air in whenever the outdoor conditions are comfortable.
She says there’s plenty of flexibility in the standard to build for different climatic conditions, and that this is actively encouraged.
Parry does recognise, however, that Passive House might be more attractive to somewhere like Melbourne compared to Sydney, where the climate is more temperate and doors and windows can be kept open more often than not.
However, it’s actually easier to achieve certification in a climate like Sydney, and then occupants get all the other benefits of a Passive House, such as acoustic comfort and clean air free of allergens and pollutants.
Get your tickets to the Flick the Switch event here
This article is from an original interview with Clare Parry by Tina Perinotto for a podcast that could not be produced due to technical difficulties.