Pursuing Passive House Prefabrication Perfection by Pro Clima

Prefabricated wall panels complete with facing, rigid air barrier, insulation, vapour control membrane, and service cavity were erected on-site in just one day.

When Amy and Steve Tankard waved goodbye to Auckland for a better lifestyle in Waihi, little did they know that Passive House would be a permanent part of their personal and professional lives. But a Superhome event with Bob Burnett, and a radio interview with New Zealand’s first Passive House Certifier, Jason Quinn, would spark Amy and Steve’s passion for Passive House.

Though a spark may be better described as a raging fire!

Steve subsequently become a qualified Passive House consultant and Amy has been appointed CEO of the Passive House Institute of New Zealand (PHINZ). Maybe that’s just what happens when you bring together possibility, practicality, and perseverance. There is another ‘p’ in their lives, but more on that a little further in this piece.

Steve is the consultant for their family home build which he and Amy are undertaking on a 2,500 square metre section, which is plenty of space for their growing family.

They’ve chosen to go with a 207 square meter home, designed by Toni-Rose Brookes of Borrmeister Architects (now of Common-Good Architects), which includes 3 bedrooms, 2 bathrooms and a living room upstairs, a guest bedroom and bathroom downstairs, as well as a double garage and living-dining-kitchen.

The idea of prefabrication (see, there is another ‘p’) always appealed to Amy and Steve due to the benefits of speed and precision. The panels were erected on-site directly off the back of the loader crane they arrived on in just one day.

The wall elements were modeled in 3D by Offsite Design and manufactured in Christchurch through Ecopanel. These were custom-made, modified timber frames that arrived on-site complete with structural facing, a rigid air barrier, insulation, pro clima INTELLO® airtightness, and vapour control membrane, and a service cavity.

Cladding is a combination of brick veneer and weatherboard with a long-run metal roof along with a fully insulated rib raft polished concrete floor system. A Zehnder ComfoAir 350 will ensure that stale damp air is removed and replaced with dry fresh air. The efficiency of the heat recovery has been calculated to 85.5%.

Construction Details Average Values:

U-wall (avg): 0.226 W/(m2⋅K) – Knauf Earthwool R-5.5 – R-4.1 (140 mm) R-1.4 (45 mm service cavity)
U-floor (avg): 0.342 W/(m2⋅K) – R-4.5 Fully Insulated Rib Raft
U-roof (avg): 0.136 W/(m2⋅K) – R-8.4 – Knauf Earthwool 210 mm R-5.2 between the rafters and 135 mm R-3.2 above the rafters
U-windows: 0.86 W/(m2K) – Neuffer Aluplast uPVC/Alu
Treated floor area: 138.4 m²
Heating Demand: 11.6 kWh/m²/year
Heating Load: 10.7 W/m²
Frequency of overheating: 1%

Ricki Helagi of Passive House Builders based in Omokoroa is undertaking this build and Amy and Steve hope to be in their Passive House prefabrication paradise by Christmas.