Is Passivhaus a Scam in Australia?

You'll hear it said, sometimes loudly, that Passivhaus in Australia is a giant scam. Overkill for a mild climate. Expensive marketing dressed up as building science. Some of that criticism is fair, and I'll say so plainly. But the scam headline is wrong, and it's wrong in a way that keeps Australians living in cold, leaky, mouldy houses and calling it normal.

No, Passive House isn't a scam. It's the only building standard in Australia that tests whether the finished house performs, with an independent blower door test and certification. The critics are right that it costs more than the legal minimum. They're wrong that the legal minimum is worth aiming for.

Carland Proof Point: Our own Pigeon Passive House in Yarraville tested at 0.26 ACH50 and held 22°C inside with clean, filtered air during January's 42°C heatwave, while bushfire smoke choked the street outside.

Does a Passive House really only save 30% on energy?

Here's a point where the sceptics are half right, and I'll give it to them. The marketing line that a Passive House is 90% more efficient is sloppy, because the honest answer depends entirely on what you compare it to. Line it up against an already decent home and the energy gap narrows. Argue about the exact percentage and you can make it look modest. Fair enough.

But energy percentages are a distraction, and fixating on them misses what the standard actually delivers. The numbers that matter are the ones you can test. A Certified Passive House has to hit airtightness at or below 0.6 air changes an hour. The average Melbourne home leaks at around 19 (CSIRO and Australian Building Codes Board, 2016 airtightness study). Our Pigeon Passive House came in at 0.26. It has to model a heating demand at or below 15 kWh per square metre per year. Pigeon models 9.0. Those are not marketing lines. They came off a blower door machine and a certified PHPP file.

And the real payoff isn't a number on a power bill, it's what the house feels like. Stable temperature, no cold floors, no condensation, filtered air. Argue the percentage all you like. Would you rather live in the 30%, or in the house that was never tested at all?

Isn't a Passive House just far more expensive than a normal home?

Yes. Compared to a house built to the Building Code minimum, a Certified Passive House costs more, and any builder who tells you otherwise is having you on. This criticism is fair, and pretending it's free would be exactly the marketing fluff I can't stand. So let's have the honest version.

Two things. First, the premium is smaller than most people assume once you're comparing like with like. An independent cost study by Altereco Design across 18 projects found a Certified Passive House came in about 3.21% more than an already high performance home. Not double. A few per cent. Second, and more important, the code minimum is a terrible thing to measure against. The World Health Organisation ranks Australian homes among the coldest in the developed world relative to what it's doing outside (WHO Housing and Health Guidelines). The legal minimum in this country gives you a cold, leaky, untested house, and then you pay for that gap every winter in energy bills, and sometimes in your health.

So the real question isn't why does it cost more than the minimum. It's why is the minimum so bad that a tested, comfortable house looks expensive next to it? If the cheapest legal house is cold and never checked, what exactly is it the benchmark for?

Doesn't NatHERS already do what PHPP does?

This is the argument that falls over hardest, and it's the whole reason I build the way I do. NatHERS and PHPP are not doing the same job. NatHERS rates a design. PHPP predicts a performance that then gets tested on the finished building. One is a drawing-stage star rating. The other is a promise you have to prove.

Here's the part people miss. A NatHERS rating is calculated off the plans and, in the vast majority of Australian homes, nobody ever tests whether the finished house matches it. No blower door. No verification. The star rating describes a house that exists on paper. Passive House certification requires an independent blower door test on the actual built home before it can be certified, and a certifier checks the PHPP model, the airtightness result and the construction details against the standard. That is the difference between a house that was designed to be good and a house that was proven to be good.

Calling PHPP redundant because NatHERS exists is like saying you don't need to weigh yourself because you wrote down what you hoped to weigh. If your builder models a design but never tests the result, what did the modelling actually guarantee you?

Can't you get airtightness and no mould without a certification?

Technically, yes, and I won't pretend certification is the only path to a good house. A brilliant builder could hit these numbers without a certificate on the wall. That's true in principle. In practice, almost nobody does, and that's the whole point.

Airtightness only counts if someone tests it. Mould only stays away if the vapour control and ventilation are designed properly and checked. Without certification, all of that rests on trusting that the builder knew what he was doing and did it when no one was looking. Certification is what drags it into the daylight. It forces a blower door test, an independent certifier, and a paper trail that holds the whole team accountable, the architect, the builder and the trades. It's not a magic ingredient. It's the referee that makes sure the promises got kept.

You can build a tested, airtight, mould-free home without certification. You can also drive without a seatbelt. If your builder says he doesn't need certification because he's good enough, who checks that he actually was?

Are Passive Houses stuffy because the ventilation needs babysitting?

You'll hear that Passive Houses feel stuffy, and that the fresh air depends on someone fiddling with the system rather than it just working. I'll push back hard here, because stuffy air in a Passive House isn't the standard failing, it's a system that was set up badly or never maintained. A blocked filter or a unit an owner has quietly turned down will make any home feel flat, and one stuffy house tells you about that house, not about the standard.

A properly commissioned heat recovery unit delivers a constant supply of fresh, filtered air, and pulls the warmth out of the stale air on its way out. Ours run at up to 87% heat recovery. When it's set up and serviced right, the air is the best thing about the house. During January's bushfire smoke, when Melbourne's outdoor air was thick with it, the sensors in our Pigeon Passive House had indoor particulate levels sitting near zero. That's not stuffy. That's the cleanest air in the suburb. And you can still open a window whenever you like. Opening one doesn't break anything, it just means you fancied a breeze.

Judge the concept by a well-commissioned system, not a neglected one. If a Passive House has bad air, is that the standard failing, or the setup and the servicing?

Isn't passive solar design cheaper and just as good?

Passive solar design is excellent, and I use it on every build. Orientation, north-facing glazing, shading that keeps summer sun out and lets winter sun in, thermal mass. It's cheap, it's clever, and anyone championing it is on the right track. But framing it as an alternative to Passive House is a false choice, because Passive House already includes all of it.

Here's the difference. Passive solar gets the sun working for you. Passive House gets the sun working for you and then makes sure the heat you've gained doesn't leak straight back out through a draughty, thermally bridged envelope. You can orient a house perfectly to the north and still lose all that lovely solar gain overnight through gaps and cold walls, because passive solar on its own doesn't require airtightness testing, continuous insulation, or mechanical ventilation. Passive House is passive solar plus a tested, sealed, ventilated shell. It's not the rival to good passive design. It's what happens when you refuse to waste it.

So it was never passive solar versus Passive House. It's passive solar on its own, or passive solar with the leaks sealed and the result actually measured. Which one would you want keeping your family warm in July?

So is Passive House a scam, or not?

Let's be fair to the doubters, because they land a couple of real hits. Passive House does cost more than a code-minimum home. Certification isn't the only conceivable path to quality. Bad ventilation setups do exist. All true, and worth saying out loud.

But a scam is when you pay for something that doesn't do what it claims. Passive House is the opposite. It's the one standard here that refuses to take the builder's word for anything and tests the finished house instead. The thing being sold as a scam is the only thing in Australian housing that actually proves it performed. If measuring whether your home works is a scam, what does that make the millions of houses nobody ever bothered to test?

By Matthew Carland, certified Passive House builder and director of Carland Constructions. Five certified Passive House and EnerPHit projects in Melbourne, every one independently blower door tested.