One of the owners works for a supplier of high-performance building components and well understood the “massive benefits” such a house would provide his young family. His professional experience with multiple Passive House projects also contributed to a very smooth design and build process. Although the project was extensively documented in video, there was no drama to see here.
There was excitement though: like when the bulk of the house was erected in just one and a half days. The project used structural insulated wall panels pre-fabricated by Ecopanel near Christchurch. These are a custom-made, modified timber frames that arrive on-site complete with structural facing, a rigid air barrier, insulation, Intello air-tight membrane and service cavity. The panels were erected onsite directly off the back of the loader crane they arrived on. The house stands on a MAXraft concrete slab. Windows were manufactured in Mosgiel using European glazing. As to be expected this far south, triple-glazing was required, in this case with low-e coating and argon fill.
The owners had a modest budget and wanted their house to demonstrate that Passive House performance is within the reach of middle-income families. Its simple form and moderate size (166m² TFA, excluding a detached double garage) helped the building meet Passive House energy targets; it still provides three bedrooms, two bathrooms and a home office. A veranda encircles 70% of the house, softening the rectangular shape and providing outdoor living areas that are easily accessible through 2.2 metre-high by 3.6 metre-wide sliding doors. The owners are enjoying their second winter in their first home. Christchurch can have very low sunshine hours in the winter months, so they are using more heating than they initially expected. However, a small panel heater sized for a bedroom is providing all the additional heat they need to keep the whole house comfortably warm.
Construction Details Average Values:
- U-value External Walls 0.20 W/(m2K)(R5.0)
- Shadowclad, 19mm cavity, Ecoply Barrier, 140mm framing with 90mm R2.8 Knauf and 50mm R1.4 Knauf, Intello, battens with R1.4 Knauf, 12mm plasterboard
- U-value Floor 0.15 W/(m2K)(R6.7)
- MAXRaft insulated foundation system, 100mm concrete over 250mm EPS-s. Tie beam with 250mm concrete and 100mm Expol XPS
- U-value Roof 0.13 W/(m2K)(R7.7)
- colorsteel, 70mm cavity (45mm battens over 25mm counter battens), Proclima Solitex mento, 280mm framing with R6.3 Knauf, Intello, battens with R1.4 Knauf, 40mm cavity, 12mm plasterboard
- U-value Glass 0.55 W/(m2K)(R1.8)
- Thermadura Silverstar
- U-Windows 0.94 W/(m2K)(R1.1)
- Thermadura Natureline
- Ventilation Efficiency 81.50%
- Zehnder - ComfoAir350
- Heating Demand 24.9 kWh/m²/year
- Heating Load 9.4 W/m²
- Frequency of Overheating 2% year over 25°C TFA 166 m²
- Form Factor 3.2
- Air leakage @ 50Pa0.3 ACH/hour
- PER demand55 kWh/m²/year
Passive House Database 5299