Jenny Edwards of Light House ArchiScience is all about “bang for buck”. Passive House (PH) costs way too much for most people, she says, and you can get great results with the building science she brings to the industry.
There are extremes operating around PH, she says.
One side will tell you, “it’s completely unnecessary, which I don’t agree with”, and the other end will say “this is the only safe and effective way” to build, which I also don’t believe. So, I’m in the middle there.”
Edwards can call on 300 projects she’s done in Canberra through her former design and construction and science business called Jigsaw Housing to make her point.
“I’ve worked with a lot of different builders, and that’s been fascinating, because a lot of those builders have done PH training and have built a Passive House. But [they] also worked for us, and they all reached the conclusion that what we do is by far the most sensible approach, which I love.
“That’s something that you’ll see a lot [that] is happening in Passive House. As people do the training, they go through that zealot phase. Then they go out into the world and apply it, and they do start to realise, oh, there are [things] I can learn from passive house, but it’s not the bee’s knees. It’s not the only thing.”
Edwards has a lot of awards for her work, including for Little Loft House.
Her experience of Passive House goes way back, implementing her first blower door in 2008.
“I’ve been implementing the building science years before Passive House came to town,”
Edwards said she was the first company to start blower door testing and thermal imaging in the residential space. Meanwhile, Passive House didn’t come to town until 2014.
What she loves is that it’s brought rising awareness about air tightness and thermal properties. But I just fundamentally disagree with the extent [to which] they insist.”
The issues with Passive House
The 0.6 air changes at 50 Pascals, which is completely over the top, says Edwards, referring to the pressure difference between inside and outside.
Edwards also disagrees with the two layers of “wrapping” that PH implements.
“In today’s world, where we want to reduce the amount of material and labour to achieve cost effective, healthy housing, so it’s just unnecessary.
“I’ve got 300 projects that demonstrate that, achieving an air tightness of below five is perfectly adequate.”
There is a difference between air tightness and air leakage, she says. The latter relates to random and uncontrolled things that aren’t in the design. “It just happens”.
Ventilation is always designed in, whether it’s passive ventilation through opening doors and windows, turning on exhaust fans or having a fancy heat recovery ventilation system.
“This is where Passive House and I differ. We’ve always been very serious about both, but in terms of air tightness, we are going for a much more cost effective [and] achievable level of air tightness.
“Australian construction is very, very leaky. That’s why I bought a blower door and started doing this work, because I wanted to demonstrate how much energy we were wasting through heat escaping through the cracks and gaps.
“I was able to demonstrate that early on in Canberra, through basic draft sealing with a caulking gun.”
Edwards said weather strips on doors and windows could reduce air leakage rate by 20 to 40 per cent, which is often directly correlated to winter energy use. These measures would cost hundreds of dollars at most and create immediate savings in winter energy consumption.
Edwards got into the concept of designing better performing houses when she went to the US to do her training on air leakage and came back to Australia “super passionate” about PH and with samples of all the different wraps that could be used.
But as she started working with the industry, she started to understand how much better results could be with “just a little bit more attention to detail” rather than a lot of extra materials.
And the result? Significant savings.
And Edwards is convinced that achieving the standard of housing she’s delivered is nothing an average builder can’t do. In fact, she often runs air leakage tests in workshops for the Master Builders Association and the Housing Industry Association, where builders discover how easy it is to fix.
There are cases of PH where the houses that have been built for clients have overheated. While Edwards does not want to identify these for fear of opening up a legal can of worms, she does share that they are embarrassed to have spent “so much money”.