Passive House Certification: What It Involves
Passive House certification is a performance standard with measured criteria and independent verification. For builders considering it, this is what it actually involves.
The criteria
Certification requires meeting all of the following:
Heating demand not exceeding 15 kWh per square metre per year, or a peak heating load under 10 W/m².
Cooling demand with an equivalent limit, adjusted for climate. In Australian conditions cooling and dehumidification frequently drive the design more than heating.
Primary energy demand within the specified limit for the whole building.
Airtightness of 0.6 air changes per hour at 50 pascals or better, verified by blower door test.
Thermal comfort, with limits on overheating frequency and on internal surface temperatures.
The airtightness figure is the one that separates Passive House from ordinary good construction. Well built conventional homes reach 3 to 5 ACH50. Passive House requires 0.6.
The process
Design stage. The building is modelled in PHPP, the Passive House Planning Package. Every assembly, window, thermal bridge and ventilation component is entered, and the model predicts whether the criteria are met. Changes made at this stage are free.
Construction. Detailing follows the model. Thermal bridge free construction and continuous airtightness are the two demanding parts. Components with certified performance data simplify the modelling.
Testing. A blower door test at lock-up, when the air barrier is complete and linings are not, so leaks can still be reached. A final test for the certified result.
Certification. An independent certifier reviews the documentation, the as-built model and the test results.
What it demands of the builder
Detailing discipline. The airtightness target cannot be achieved by fixing leaks at the end. It requires the air barrier to be planned, drawn, communicated to every trade, and checked continuously.
Sequencing. Penetrations sealed as made. Testing before linings. Trades briefed on which layer is the air barrier and what happens if it is breached.
Documentation. Product performance data, photographs, and test results.
Time. The first certified project takes longer than an equivalent conventional build. Later ones are closer.
EnerPHit
For existing buildings, EnerPHit applies the same approach with criteria adjusted for retrofit constraints, including a less demanding airtightness target of 1.0 ACH50.
It exists because achieving new-build Passive House performance in an existing structure is often impossible without demolition, and a standard that nobody can meet does not improve anything.
Is it worth doing?
That depends on the client and the project, and there is no general answer.
What is worth saying is that the skills transfer. A builder who has completed one certified project details every subsequent build better, whether or not those builds are certified. The airtightness discipline, the control layer thinking and the junction detailing all carry across.
Passive House trade certification is available as a training qualification without committing to a certified project, and it is the more accessible starting point for most builders.
In Australian conditions
Two things differ from the European context the standard came from.
Cooling frequently drives the design. In much of Australia the summer condition determines the assembly, not the winter one. Shading, glazing specification and dehumidification matter more than heating.
Climate variation is extreme. A Passive House in Hobart and one in Cairns are different buildings solving different problems with the same standard.
Both are reasons the modelling matters. Intuition developed in one climate does not transfer.