Twizel House

This holiday house was to be a base for its owners to explore the outdoors with their young family.

They wanted something minimal, industrial, and inspired by south island high country huts. They wanted good connection to the outdoors, plenty of storage and overflow sleeping space for family and friends, hard-wearing durable finishes, a big mud room for wet and muddy gear and a warm comfortable efficient space. The Hiberna team worked with national Passive House experts eHaus to design and build a simple energy efficient house that was hard wearing but none the less outstanding in its performance and appearance.


Location:

Twizel

Year of construction:

2017

Construction type:

115mm SIPs panel walls, 165mm SIPs roof, Maxraft floor, Timber triple glazed windows, airtight construction: n0.42ACH

Space Heating Energy Demand:

21kWh/m2.a

Renewables:

Zehnder Comfoair 350, hot water heat pump for water heating, 5kW Bionic fire

Project Team:

Architecture: Hiberna Ltd (with Julien Chazal)/ehaus Ltd
Construction: Hiberna Ltd/ehaus Ltd
Engineering: NZSIP
Interior Design: Hiberna Ltd

Publications:

“All-Black Lumberjack: South Island Timber Home Puts the NZ into nZEB”
Passive House Plus Magazine Issue 24

“How We’ll Live in the Future” NZ House and Garden, November 2017

“We hardly ever light the fire…we don’t even have any matches”

CAPTION: Outside exterior cladded in metal tin + timber joinery
CAPTION: Outside exterior cladded in metal tin + timber joinery

One of the main challenges was the wind. Both for the design and on site during construction 155kmh gusts one night in january: Thats a force 2 hurricane. The site is in one of the highest wind zones in NZ and we needed significant extra structure LVL to cope with the high wind load. The design does include some sheltered outside sitting space to the east as the wind comes mostly from the north-west.

CAPTION: Inside interior, concrete flooring and ply walls
CAPTION: Outside exterior cladded in metal tin + timber joinery

We kept the Auckland clients up-to date with an app called Trello. We uploaded photos and gave regular updates so that they could follow the progress of the build from a distance.

CAPTION: Inside interior, concrete flooring and ply walls

We achieved an air change rate of 0.42 ACH – well below the Passive Housestandard of 0.6

CAPTION: Inside interior, concrete flooring and ply walls
CAPTION: Inside interior, concrete flooring and ply walls

The house passed an air tightness test using a blower door to make sure there are no leaks.
The final key is a heat recovery ventilation system that ensures fresh, dry air 24/7. We used the Passive House Planning Package (energy modelling software) which will ensures that the house will perform.