This little Australian Passive House pushes a lot of buttons
It's tiny! It's shiny! It's prefab! It's passivhaus!
Passivhaus, or Passive House for those who hate all things European, is a performance standard that is being used all over the world. In North America it is being questioned by many; over at Green Building Advisor, Martin Holladay summarizes fourteen problems with the standard as determined by PHIUS, or Passive House US. It is a complex and technical issue that I am not yet comfortable tackling, but points include:
- Passive House doesn't work in all climates
- Passive house isn't cost effective
- Passive house has a small house penalty
So imagine my surprise to see a tiny affordable Passivhaus certified in sunny Australia! The owner, Bronwen Machin, tells the local newspaper:
I chose this form of building because I am concerned about climate change and the increasing number and intensity of heatwaves we can expect in the future. .. I have also chosen to build very small (40 square metres, 430 square feet) because as a single person that is all I need.
Not only is it passive, it's prefab, built by Carbonlite Design+Build (great name!). Because of the amount of insulation in passive house designs and the mechanical ventilation systems required to manage air changes, and the lack of the need for solar gain through windows in the Australian climate, they can throw out a lot of those things that I thought were in the sustainable design rule book:
Unlike conventional construction, CARBONlite | design + build homes do not rely on orientation, thermal mass or natural cross flow ventilation to perform energy efficiently. This next generation of sustainable homes allows you to build your dream home in any location that performs at any time of the year without the need for excessive heating or cooling. This construction system has proved its performance for decades in Europe and is perfectly suited for the Australian climate.
I have always liked corrugated steel siding too, shiny and reflective in the sun, and really cheap. It makes the house what Bronwyn Barry calls BBB™ - "boxy but beautiful". Combine it with deep overhangs to shade those windows and they hit the required Passivhaus numbers. There aren't too many passive houses in Australia and if I lived there, I suspect I wouldn't want to be bottled in like this, and prefer Andrew Maynard's approach to green building where you do design for natural ventilation and orientation, and blur the line between inside and outside. But it does show that the standard can be applied just about anywhere and in any size.