Jesse Clarke is a building physicist. At our Passive House debate on 26 May, he’ll have a lot to say about the science and the evidence of how to build the best buildings.
To understand Passive House, he says you need to know a bit about its history and about how building codes have developed in Australia.
- Jesse Clarke will be one of the speakers debating at The Fifth Estate’s Passive House debate on 26 May. Secure your spot now!
Clarke, technical lead and R&D manager of Pro Clima says that historically, the building code was introduced to ensure houses were structurally sound and to ensure the health and safety of people. In recent years, many codes have introduced energy efficiency and carbon savings into their books, but it doesn’t change their goals of trying to improve the health and safety of the Australian people.
He points to Europe, which focused on energy savings by developing highly insulated and airtight houses, along with double and triple-glazing. But by making the systems more effective at retaining energy in the house, they trapped moisture in the house, causing the so called European “sick building crisis”.
“You’ll get the wrong answer if you focus on energy efficiency as the starting point,” Clarke says, quoting Dr. Max Sherman, a senior scientist at the Lawrence Berkeley National Laboratory.
“You need to start with health and what makes a healthy home, and also what makes an energy efficient home.”
Meanwhile, the UK took on lessons from Europe by overlaying ventilation, maintaining humidity and ensuring the surface temperature within house don’t have cold spots, which lead to mould.
Australia risks facing the same problem, Clarke says, with the NatHERS system (Nationwide House Energy Rating Scheme) allowing bedrooms to get very cold at night, “which a Passive House would never let you do.”
But temperatures are also complex. People like to sleep at different temperatures, and some people prefer to have cold bedrooms in winter, while some still like to sleep with doonas during the middle of summer, he says.
The discussion then needs to be around what temperatures are considered healthy conditions.
Clarke quotes Sherman’s studies, saying people are easily stressed beyond what’s healthy for them, by temperatures that are too hot or too cold, which can sometimes be caused by cold snaps or heat waves.
Discussions either pit human comfort against energy efficiency or find that there needs to be a delicate balance between the two. He says people are looking at the issue in the wrong way.
“Comfort is actually a metric for health. It’s not your body [trying] to be selfish, it’s your body saying, ‘I’m not stressed. I’m not stressing my immune system; I’m in a healthy zone. You don’t want to stress yourself all the time; you want to stay comfortable.”
The issue with adapting European standards
According to Clarke, Central European standards can’t be taken and dropped into a hot climate like Australia, where houses can collect too much sun, generate too much heat and get too hot.
It’s important to think about the cost of taking Central European standards to modify and adapt for Australia, Clarke said, because it is fuelling naysayers who argue Passive House can overheat.
“That’s absolutely true” he says, but so too for 5 or 6 star house.
For example, the Germans are “habitually very good at opening their windows for five to 10 minutes in the morning to purge the house”, but that culture is missing in Australia.
It was only in the past 20 years that mechanical ventilation heat recovery systems (MVHRS) were introduced, which allowed fresh air in without waiting for heat.
While it’s easy to “set and forget”, these systems also need to be maintained, Clarke says. “They are not going to last forever. They are not going to stay clean forever, so you do have to change filters.”
Jesse Clarke will be one of the speakers debating at The Fifth Estate’s Passive House debate on 26 May. Secure your spot now!