The Rifle Retrofit Passive House: A Case Study in Transforming Melbourne Homes

Project Overview: The Rifle Retrofit Passive House project by Carland Constructions is a groundbreaking endeavour to transform a standard 1993 volume-built brick veneer house in Williamstown, Melbourne, into a certified Passive House (EnerPHit standard). This case study highlights the journey, challenges, and innovative solutions employed to achieve a home that is "healthier, optimised, more comfortable," "built responsibly and simply built better," and ultimately "just feels better". Carland Constructions is a Melbourne builder, specialising in Passive House Melbourne and Passive Home builder Melbourne projects.

The Challenge: From "Ugly, Mouldy, Draughty" to High-Performance The existing house was a typical example of Australian volume-built homes from its era – characterised by a "musky smell," discomfort, and signs of mould due to water leaks. It was, in essence, "a leaky tent" with an air exchange rate estimated at 30+ ACH (air changes per hour). The primary goal was to drastically improve energy efficiency, comfort, and indoor air quality without stripping the external brickwork or roof tiles, a significant deviation from typical Passive House new builds. This project aimed to be a leading example of Melbourne Passive House construction and sustainable homes Melbourne.

Key Players & Collaborative Approach: This project's success hinged on strong collaboration, especially given the absence of a traditional architect or building designer as the lead. The core team included:

• The Homeowners: Crucial stakeholders who were already educated in Passive House principles and committed to achieving certification. Their willingness to "go out on a whim" was vital.

• The Interior Design (HeHe Design): Responsible for all internal aesthetics and material selections, ensuring healthy choices.

• The Passive House Consultancy: Cam is the hero on this project. Described as "the rocket scientist," this consultant was instrumental in the project's success, providing critical expertise in building physics, running complex simulations (like WUFI analysis for moisture), and ensuring compliance for certification. They helped navigate the complexities of retrofitting, especially concerning moisture management when not removing external cladding.

• The Certifying Body: This certifier played an impartial role, verifying the Passive House consultant's calculations and ensuring the project met Passive House standards, acting as a crucial check for proper execution. For this project we worked with HIP V. HYPE

• Carland Constructions Team: The in-house carpenters were praised for their "super duper skilled" work and extreme pride in building high-performance homes, adapting to on-the-fly problem-solving given the unknowns of a retrofit. Our team really took sustainable building in Melbourne to another level

• Key Suppliers: Companies that supplied crucial components, such as the triple-glazed windows and airtightness membranes, were vital partners, providing high-quality products and working closely with the team to overcome installation challenges.

Innovative Solutions & Overcoming Hurdles:

1. Airtightness: The .41 ACH Triumph: The existing house started with a massive air leakage rate (estimated 30+ ACH). The team achieved an astounding 0.41 ACH in the final blower door test, well below the 1.0 ACH standard for EnerPHit certification. This was accomplished by relying on an internal air barrier using materials like Intello, meticulously sealing every penetration, especially around existing internal wall junctions. Challenges included working around existing L-brackets for trusses, which were sealed by gluing and screwing a plywood strip to the top plates, providing a continuous surface for the air barrier. This is a prime example of achieving a certified Passive House builder Melbourne standard.

2. Window Installation: A Complex Dance: Replacing existing windows in a brick veneer house without removing the bricks was a major challenge. The original windows were typically installed flush with the brickwork, placing the glazing layer outside the insulation plane. For Passive House, windows needed to be brought back into the insulation layer.

   • Triple Glazing: Initial modelling showed that double glazing wouldn't meet the required U-value (under 1.25). The solution was triple-glazed uPVC windows.

   • Levelling & Flashing: The house slab was found to be 110mm out of level from front to back, complicating window installation and flashing details. A custom sill system with a back dam and XPS insulation was designed to ensure water drainage away from the structure, especially since an external membrane couldn't be installed.

   • The Doggie Door Dilemma: A late homeowner request for a doggie door nearly jeopardised certification due to the inability to get a low-E coating on it, pushing the average window U-value to the very limit.

   • Insulated Front Door: A timber front door was insulated with PIR board to help meet the overall U-value target, a solution now being adopted on every project.

3. Floor Insulation: The Cork Screed Innovation: Insulating the existing concrete slab without reducing the 2.7m ceiling height was a major hurdle. The team opted for a cork screed product imported from Italy. This material, when mixed with water and poured, provided a thermal layer (equivalent to R2 insulation) on top of the slab. While initially perceived as cost-effective, it proved to be the "most stressful thing that I have ever done on a building site". This contributes to the home's low energy homes Melbourne status. There is more to come on this

4. Wall Insulation & Moisture Management: Existing fibreglass insulation was found to be dirty and sagged. Polyester insulation was chosen due to its density (32 kg/m³) and hydrophobic properties, allowing water to shed rather than soak in, crucial given the lack of an external membrane. A hygrothermal analysis was performed to ensure the wall assembly could dry out without an external membrane, confirming the removal of existing metal sisalation was necessary to prevent mould formation. This is key to building healthy homes Melbourne.

5. Electrical & Plumbing Overhaul: The non-compliant and rusting old wiring and copper plumbing were completely replaced. This decision, while increasing budget, was deemed more cost-effective than trying to salvage and integrate old systems, ensuring airtightness and proper insulation of hot water pipes. This all-electric approach is vital for energy-efficient homes Melbourne.

Outcomes and Impact: The Rifle Retrofit Passive House is a "remarkable" achievement, being, to our knowledge, the first certified Passive House conversion of a volume-built home in Australia.

• Financial Savings: The project is estimated to save the homeowners around $8,000 per year on heating bills alone, compared to the original house. That's a massive win for the hip pocket and the planet.

• Enhanced Comfort & Health: The home maintains a stable indoor temperature of around 20 degrees Celsius year-round with minimal effort. Occupants experience superior thermal comfort, noise reduction from the triple glazing, and improved indoor air quality thanks to mechanical ventilation removing dust, pollen, and odours. The elimination of mould and dampness significantly contributes to a healthier living environment. This is the essence of a high performance homes Melbourne.

• Industry Benchmark: This project serves as a "proof of concept" demonstrating that millions of existing Australian homes can be dramatically improved to high energy efficiency standards without demolition. It highlights the viability of deep retrofits and challenges the misconception that high-performance building is prohibitively expensive or aesthetically limiting. This project adds to Carland Constructions' growing portfolio of Passive House projects Melbourne, solidifying our reputation as Passive House specialists Melbourne.

• Team & Process Refinement: The complexity of the retrofit pushed our team to innovate and refine our pre-construction and on-site processes, making us more efficient and knowledgeable for future projects.

Conclusion: The Rifle Retrofit Passive House stands as a testament to what's possible when passion, expertise, and a collaborative spirit converge. It's more than just a renovation; it's a blueprint for a healthier, more sustainable future for Australian homes, proving that "built responsibly and simply built better" isn't just a tagline, but a tangible reality