What is a Passive House in Melbourne
You hear it all the time. Passive houses are for european homes.
WRONG
A Passive House in Melbourne is designed for the climate of that location.
There's often confusion about what it means to build a Passive House in Australia. We hear terms like "Passivhaus principles" or "designed to the standard," but what does this actually mean? As Passive House construction experts, we know that true performance requires more than just a passing nod to the standard.
What is a Passive House?
The Passivhaus Standard is a rigorous quality assurance standard for energy-efficient buildings. It is based on extensive scientific research and testing, and buildings that achieve this standard are renowned for their energy efficiency, comfort, and high quality of design and construction.
For a building to be a true Passive House, it must meet four measurable criteria:
Specific Heating Demand: ≤15 kWh/m2.yr or a Specific Heating Load of ≤10 W/m2.
Specific Cooling Demand: ≤15 kWh/m2.yr.
Primary Energy Renewable (PER) demand: ≤60 kWh/m2.yr.
Airtightness: n50≤0.6/h⊆50pa.
The best way to demonstrate these requirements have been met is through official certification by an accredited Passive House Certifier. This is the only way to be completely sure the building performs as intended.
The Pitfalls of Misrepresentation
Unfortunately, there are times when builders or developers might claim a project meets the Passive House Standard when it doesn't. Claims that a building is "designed to Passivhaus Principles" because it has high insulation or airtightness are incorrect and misleading. The standard is a holistic system, and meeting one or two of its requirements is not enough to qualify.
Unless a building has been officially certified, it should not be described as a Passive House. It is acceptable to describe a non-certified building as an "uncertified Passivhaus Standard building" only if all quality assurance requirements have been met and there is full documentation to prove it. However, this still carries a risk of performance gaps emerging later on.
Our Certified Passive House Projects
We have built a number of certified Passive House projects that demonstrate our expertise. These include:
Parade Passive House
Forrest Passive House
Champion Passive House
Rifle Range EnerPHit, which is a certified Passive House retrofit
Pigeon Passive House (Under Construction and targeting certfication)
Flemington Passive House (Under Construction and targeting certfication)
We also have two more Passive House projects currently on-site: our Pigeon and Wellington projects.
These projects show what can be achieved when a builder and client commit to the rigour of the Passive House Standard. As specialists in Passive House construction, we're dedicated to building homes that are built responsibly and simply built better.
The Benefits
The true value of the Passive House Standard lies in the benefits it provides to the consumer, which include:
Excellent thermal comfort.
Minimised energy bills.
High standard of indoor air quality.
Avoidance of mould growth.
High levels of user satisfaction.
Optimised lifecycle costs.
By committing to certification, clients are protecting themselves from nasty surprises and ensuring their investment performs as intended. It is the best way to get the home you paid for.
But then theres the people who say “you don’t need a passive house in Melbourne” - well let’s put that comment to bed.
Averting the Melbourne Climate Conundrum
Melbourne's climate is often described as "four seasons in one day." It is a cool-temperate climate zone, which presents a unique challenge: we need to keep buildings warm in a cold, damp winter and cool during a hot summer. Many conventional Australian homes are poorly equipped for this. They leak heat in winter and gain it relentlessly in summer, forcing us to rely heavily on active heating and cooling systems.
Winter Warriors: A Passive House building is designed to be very well insulated and airtight, minimising the flow of heat between the inside and the outside. This means that once the indoor air is warm, it stays warm. For our Melbourne winters, where we see long periods of cold and sometimes damp conditions, this is revolutionary. It allows for comfort without a traditional, energy-hungry heating system. The small amount of heating still required can be delivered by heating the fresh air supplied by the ventilation system.
Summer Sanctuary: But Passive House is not just for cold climates. For warm climates, the principles are similarly applied for cooling and dehumidification. In a Passive House, passive cooling concepts like high-performance glazing, strategic shading, and night ventilation are a primary line of defense. The thick, well-insulated building envelope resists heat gain from the scorching sun, while shading prevents solar radiation from entering in the first place. This approach minimises the need for active cooling, which can be a huge energy draw during Melbourne's heatwaves.
The Power of Building Science: From Principles to Performance
Passive House isn't a checklist of materials; it's a science-based performance standard. This means every component and design choice is carefully considered for its contribution to the whole. Key principles include:
Superior Insulation & Thermal Bridge-Free Design: To meet the standard, exterior building elements must have a very low U-value, typically below 0.15 W/(m2K). This is far beyond the conventional building code and is crucial for limiting heat transfer. A "thermal bridge-free" construction is also highly recommended, as these weak points can compromise the performance of an otherwise well-insulated building.
Air-Tightness: The building envelope must be exceptionally airtight to prevent uncontrolled drafts and air leakage. This is verified with a blower-door test, aiming for a result of no more than 0.6 air changes per hour at 50 Pascals of pressure (0.6 h−1 at 50 Pa). This is the wizard's spell that locks in comfort.
High-Performance Windows: Glazing and windows are often the weakest point of a building's thermal envelope. Passive House demands high-performance glazing with U-values below
0.8 W/(m2K) to minimize heat loss, while also having a high solar energy transmittance (g-value) of at least 50% to maximize solar heat gains in winter.
Heat Recovery Ventilation (HRV): A high-efficiency ventilation system with heat recovery is essential, especially in our cool-temperate climate. This system constantly supplies fresh air and extracts stale air, recovering at least 75% of the heat from the outgoing air and transferring it to the incoming air. It provides exceptional indoor air quality without the energy penalty of opening windows in winter.
The Path to a Sustainable Future
Beyond comfort and energy savings, Passive House is a powerful tool for a more sustainable future. By drastically reducing operational energy demand, these buildings lessen our reliance on fossil fuels and the associated carbon emissions. As the Passive House Planning Package (PHPP) shows, new versions of the tool now include frameworks to evaluate buildings based on renewable primary energy (PER) and to assess energy generation from sources like photovoltaics (PV). This aligns perfectly with the broader move towards a renewable energy grid, ensuring that a building is not only efficient but also a net contributor to a sustainable energy system.