Thornbury Passive House
RESIDENTIAL: single dwelling
PASSIVHAUS CLASSIC CERTIFICATION
THORNBURY, VIC, 2024
This Passivhaus is a double-storey family home located on a standard size lot in Thornbury, designed with both functionality and aesthetics in mind. Created for a family with two teenage children, the design balances efficient, cost-effective solutions with engaging architectural features. The home’s layout capitalises on its orientation, with large north-facing glazing overlooking the garden, ensuring ample natural light and solar heat gain.
The property’s primary views are to the south, while the backyard to the north enhances privacy and outdoor living space. High ceilings in the living areas and thoughtful spatial planning give the home an open, airy feel while supporting energy efficiency. This design approach provides a comfortable, practical living environment that meets Passivhaus standards without compromising the unique character and warmth of the family home.
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AIRTIGHTNESS n50 ACH@50pascals: 0.37
HEATING DEMAND (kWh/m².yr): 15
COOLING DEMAND (kWh/m².yr): 10
HEATING LOAD (W/m²): 14
PRIMARY ENERGY DEMAND (PE) (kWh/m².yr): 77
PRIMARY ENERGY RENEWABLE DEMAND (PER): 34
PRIMARY ENERGY RENEWABLE GENERATION (PER): 0 -
LOCATION: Thornbury, VIC
NCC CLIMATE ZONE: 6 – Mild temperate
NATHERS CLIMATE ZONE: 21
YEAR OF COMPLETION: 2024
TREATED FLOOR AREA (PHPP sqm): 201.5
PROJECT TYPE: New Build
CONSTRUCTION TYPE: Timber Frame
CERTIFICATION LEVEL/ ENERGY STANDARD: Passivhaus Classic
THIRD PARTY CERTIFICATIONS: Nathers -
MHRV SYSTEM: Zehnder Comfoair Q350 HRV
DOMESTIC HOT WATER SYSTEM: Sanden GAUS-315FQTS 315L split heat pump
EXTERIOR WALL TYPE, U-VALUE: 140mmx45mm timber frame with insulation between studs and aerated concrete panel cladding, 0.288
FLOOR SLAB TYPE, U-VALUE: Wafflepod, 0.395
ROOF INSULATION TYPE, MANUFACTURER: Rockwool Ceiling insulation
ROOF CONSTRUCTION: Timber roof trusses
ROOF ENVELOPE U-VALUE: 0.139
WALL FRAME TYPE: Timber
GLAZING TYPE, U W-VALUE, G-VALUE, U G-VALUE: Koemmerling U-PVC frames and Double Viridian Lightbridge, 1.44, 0.6, 1.28
EXTERNAL DOOR TYPE, MANUFACTURER, U D-VALUE: Koemmerling, U-PVC with Obscured Glazing, 1.44
project FEATURES
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This project incorporates several unique features designed to enhance both aesthetic appeal and functionality within the Passivhaus framework. The high ceilings in the living room and entryway create a spacious, open feel, filling these communal spaces with natural light and giving the home a warm, inviting atmosphere. Additionally, the parents’ bedroom includes an interior balcony that overlooks the high-ceilinged living room, providing a sense of connection within the home while maintaining privacy.
To maximize solar gain and natural lighting, large north-facing windows open up to the garden, allowing for beautiful views and enhanced energy efficiency by capturing warmth during cooler months. This not only supports passive heating but also strengthens the connection between the indoor and outdoor environments.
Another distinctive feature is the designated utility yard, which houses all the home’s technical equipment out of sight. By keeping mechanical and maintenance equipment in a dedicated, discreet area, the design maintains a streamlined aesthetic and preserves space for other functional areas. These thoughtful features work together to meet the client’s lifestyle needs while fulfilling the project’s energy efficiency and sustainability goals.
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This project faced several key challenges in meeting the Passivhaus Standard while balancing the client’s preferences and budget constraints. One major challenge was the site orientation. Since the primary views were to the south, we needed to accommodate the client’s desire for large windows without sacrificing energy efficiency. Large south-facing windows can contribute to significant energy loss, so we used a of high-performance glazing to mitigate heat loss while preserving the view.
Another challenge was working within a limited budget. Passivhaus components, such as high-quality windows, superior insulation, and airtight construction, come at a premium cost. Balancing these requirements with the client’s budget meant we had to make strategic choices about material sourcing, prioritize energy-saving elements, and keep the house footprint small to minimize construction and operational costs.
From this project, we gained several valuable insights. One lesson learned was the complexity of heat distribution in large rooms with high ceilings. While Passivhaus aims to create a consistent indoor climate, large spaces can lead to uneven temperature distribution, especially when relying on passive heating strategies alone. This experience underscored the need for precise spatial planning and, in some cases, supplementary heating options for larger, open areas to ensure occupant comfort.
Additionally, we found that while heat recovery ventilation (HRV) systems are essential for maintaining air quality and efficiency in a Passivhaus, they sometimes distribute heat too slowly across spaces, which can delay comfort during colder periods. This taught us that while HRVs are highly effective for fresh air circulation, they may not always be sufficient on their own to meet temperature demands quickly in larger or higher-ceilinged rooms.
Overall, the project reinforced the importance of carefully balancing client desires with Passivhaus principles, as well as the need to account for spatial configurations that can impact comfort and efficiency. These lessons have informed our approach to designing future Passivhaus buildings, particularly in terms of space planning and supplementary heating strategies for larger or more open areas.
Project Members
ARCHITECT/ BUILDING DESIGNER: WURL architects
BUILDER: G-Lux
PASSIVHAUS CERTIFIER: Detail Green
PASSIVHAUS CONSULTANT/ DESIGNER: WURL architects
STRUCTURAL ENGINEER: ARX
WINDOW SUPPLIER: Bluesky
HRV SUPPLIER: Fantech
AIRTIGHTNESS MEMBRANE SUPPLIER: Proclima
INSULATION SUPPLIER: Bradford
BLOWER DOOR TESTER: Passivetech
PHOTOGRAPHER: Sophie Tomaras