Clare Parry, Director of the Australian Passive House Association, explains what it means to work on Passivhaus projects in different climates. What, if anything, changes?
Interview with Clare Parry
Melbourne-based Clare Parry has always been interested in environmental sustainability but started out her career not knowing how to get into it. After falling into building services engineering, over time she worked with a number of inspiring people on interesting projects that naturally pushed her in the right direction.
There is Scepticism around Passivhaus in Australia
Most of the uptake so far has been in the colder areas, like Canberra and Tasmania. Much of Clare’s work is in convincing people that Passivhaus works in warm climates, and particularly well in hot and humid ones.
The physics of Passivhaus does not change, regardless of the climate.
The Indoor / Outdoor Lifestyle Leads Many Australians to Believe They Live Comfortably
The opposite can actually be true, particularly in the northern states where it can get extremely hot, and also in Melbourne and the south where it can get too cold, and where in fact 80% of their heating and cooling energy goes on heating.
Clare quotes many expats from Europe and North America who say that Australian homes are the coldest they’ve ever lived in.
In Temperate Climates Less Insulation is Often Required to Reach Passivhaus Standard
In a climate where there are extremes in temperature the insulation plays a dual role, keeping the heat out in the summer and keeping the heat in during the winter.
While there are extremes of temperature in Australia, the temperature differential is not as great as for other parts of the world, thus making it easier to achieve Passivhaus standard with less insulation.
Passivhaus is Based Around Comfort, Not Temperature Alone
There are more factors to comfort than temperature, such as humidity, air speed and radiant temperature (temperature of the surfaces). Clare cites an example in Jakarta where, despite the temperatures not being excessive, the humidity is very high so the amount of air coming into a building needs to be carefully controlled to avoid condensation.
Passivhaus school in Jakarta
The Cost Impact in Australia is High Because of a Lack of Specialist Manufacturing
Though Clare argues the cost savings are still there. An example she gives is of the specialist glazing they require, which they are only just beginning to find in Australia. This specialism, or having to import it, comes at a cost premium so the benefits are taking longer to repay.
Growing The Industry is Critical to Making it More Affordable
This is in terms of the manufacturing but also having the building industry on board too. Indeed the more people that do a Passivhaus project, the easier and more cost effective it will become for the next ones.
Demand for Passivhaus from individuals is bringing along the architects, design teams, construction industry and ultimately then the demand for the supply chain.
“Your Home Will be Something You Engage With to Make Work”
While an Australian house is generally designed for the summer, it also needs to be designed so that it sees the benefit in winter. Clare doesn’t believe that a Passivhaus can be comfortable and efficient the whole year round without engaging with it in some way, which is probably going to be something which is manually or automatically adjustable to get the level of control.
There Are Occasions Where Passivhaus Will Not be Cost Effective
Clare concedes that there are “sweet spots” in Australia where the indoor/outdoor lifestyle works extremely successfully and where Passivhaus wouldn’t really be required.
In fact the Passive House Institute has identified several spots around the world where they can’t get Passivhaus to work cost effectively.
The beauty of Passivhaus is that the benchmark that has been established for where you do meet Passivhaus is set where the cost effectiveness is best.
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Research into the Airtightness of Homes in Melbourne
Although not strictly on this session's topic, Clare shared some amazing research on a random sample of homes in Australia.
Until recently, the building code in Australia did not even mention airtightness! It therefore is not a great surprise to see how leaky these homes were. The purple line shows the airtightness of a Passivhaus (which you may not have noticed because it's virtually hugging 0 ACH).