A certified Passive House at Blackmans Bay — one of the first in Tasmania to earn the international mark, and the reason a family will heat this home for a fraction of what their neighbours pay, for the life of the building.
The brief
The owners didn’t want a house that merely looked efficient — they wanted one that could prove it. That meant building to the international Passive House standard and having it independently certified, not just “built to Passive House principles.” It was a five-year journey from first conversation to certificate.
The challenge
Certification leaves nowhere to hide. Every junction, every window reveal, every service penetration has to be modelled in PHPP and then built exactly as modelled — because at the end, an accredited certifier measures the result against hard limits. The airtightness target alone (a blower-door result at or under 0.6 air changes per hour) is a number most Australian homes miss by an order of magnitude.
The site made none of it easier. A sloping coastal block with a landslip report over it, a BAL-29 bushfire rating, and a lift. Bushfire compliance wants ember mesh and ventilated cavities; certification wants one continuous, unbroken airtight layer; a lift shaft wants to pass straight through the middle of it. Reconciling those three took more detailing than the rest of the house put together.
The build
Designed with Maxa Design and delivered by our team under site manager Adam Caldwell, the home is a continuous, thermal-bridge-free envelope of 644.8 m² wrapping a treated floor area of 177.3 m², ventilated by a heat-recovery (MVHR) system moving 185 m³/hr of filtered, tempered fresh air. Certification was carried out by Jason Quinn of Sustainable Engineering Ltd, a PHI-accredited certifier.
The specification
Passive House is a performance standard rather than a product list — but performance comes from parts, and these are the ones that delivered it.
The envelope. Timber-framed 140 mm walls insulated to R4.0 (Knauf Earthwool SHD), with a 45 mm service cavity run inside the airtight layer, so electricians and plumbers never have to puncture it. The ceiling carries 290 mm of R7.0 batts (CSR Bradford Gold) beneath a ventilated roof space and Colorbond Traydeck. The floor is a 150 mm concrete raft slab with 50 mm of XPS (Foamex Styroboard, R1.55) laid over the slab and a 75 mm screed above that — insulation between the slab and the room, not buried under the building. Airtightness is a Pro Clima system throughout: Intello internally, Solitex Extasana to the walls, Solitex Mento to the roof, every joint Tescon taped.
The windows. Twenty-one units, 69.7 m² of glass, all Unilux IsoStar2 from Germany — triple glazed at 48 mm, steel-reinforced uPVC with aluminium cladding, seven-chamber frames at 88 mm profile depth. Glass U-value 0.50 W/m²K, whole-window 0.75, solar heat gain coefficient 0.53. For scale, ordinary Australian double glazing sits between 2.5 and 3.5.
The services. A Zehnder ComfoAir Q350 heat-recovery ventilation unit, commissioned and balanced at 185 m³/hr, delivers filtered, tempered fresh air to every room continuously. Hot water is an EvoHeat Evo270-1, a 270-litre air-source heat pump. Heating and cooling — wanted rarely — comes from two 3.5 kW ducted Daikin units.
And no solar panels. The certificate records renewable generation of zero. The 48 kWh/m²·yr renewable primary energy result, against a limit of 60, was achieved on the envelope and the plant alone. Panels would only have improved it.
None of that is unusual hardware. What makes it work is the sequencing and the detailing, which is why we put thirteen of our team through Passive House Institute certification rather than hoping the drawings would carry them.
The result — certified, not claimed
The certificate speaks for itself:
- Airtightness: 0.5 ACH₅₀ — inside the ≤ 0.6 limit
- Heating demand: 10 kWh/m²·yr — against a ≤ 15 limit
- Cooling + dehumidification: 4 kWh/m²·yr — against a ≤ 15 limit
- Primary energy (PER): 48 kWh/m²·yr — against a ≤ 60 limit
That heating figure is the headline: this home needs roughly 80–90% less energy to stay warm than a typical Tasmanian build. See the full technical story on the Bluebush certified Passive House case study, understand what the mark actually means in what “certified Passive House” means, or put your own bills through the Passive House savings calculator. The same standard — the one an independent national panel named 2026 GreenSmart Home of the Year — runs through every luxury home and custom home we build.
