From First Fuel: 'Building science, not rocket science' 07 October 2021

Last week, Energy Efficiency Council CEO Luke Menzel sat down with Jenny Edwards from Light House Architecture and Science and John Konstantakopoulos from Efficiency Matrix.

Both Jenny and John are leading experts in the field of air-tight building envelopes and energy performance. Understanding how to manage these key areas are crucial in delivering efficient, comfortable, healthy homes to Aussie families.

This transcript excerpt has been edited for clarity. To hear the entire discussion, listen here, or search for First Fuel wherever you listen to your podcasts.

[Luke Menzel] There has been some pretty odd media coverage over the last few weeks, arguing that there are necessary trade-offs between improvements in air tightness and condensation. Jenny, I know you're very passionate about this topic. So perhaps you could kick us off by explaining why this issue is so important, why we need to get the interaction between insulation, air tightness, ventilation and condensation right in our homes?

[Jenny] I am passionate about it, and it is critical because those four things do interact. Houses are complex things but we tend to think of them as pretty simplistic things. It's not rocket science, it's building science. You have to look at how those four things interact. They are all critical if you want to have an energy efficient, comfy and healthy home, and you can't focus on one and forget about the others. So it is really key that we look at all four of them.

[Luke Menzel] Is the issue that there's a view that this is a zero-sum game? Optimise one and the other categories are going to fall off?

[Jenny] First of all, loads of people confuse air leakage with ventilation. Air leakage is that random weird stuff that's happening through holes and gaps in the building structure that you've got no control. On the other hand, ventilation relates to things you do have control over, like opening windows and doors, or running exhaust fans in those areas where you generate water vapor.

So, they're not the same thing, yet over and over again we see some experts in this area talk about them as if they are the same thing. For people like John and I, who are keen on energy efficiency and air tightness but are also super serious about ventilation, they absolutely go hand in hand. You can't do one without the other.

[Luke Menzel] That distinction is important, between the unintentional leakage of air which can create a whole bunch of problems in and of itself, versus, controlled, planned and well-designed ventilation. It also makes a building function properly, almost like an ecosystem, right? Air is flowing through and creating a comfortable, healthy environment for the occupants. Is that fair?

[Jenny] It is fair. If you design an energy efficient house, they are comfortable. In my own home here in Canberra, where the temperature ranges from -8 degrees to 44, we have windows open almost year-round because the house is comfortable. There's plenty of ventilation happening, we're using exhaust fans properly, we've got the insulation, we've got the airtightness. It's all working together using standard construction, readily available technologies, no fancy extra stuff. But, absolutely thinking of it as an ecosystem is important.

[Luke Menzel] We've catalogued one myth, but I think there might be one or two more on the list.

[Jenny] There is one I would like to cover off: The difference between condensation inside the house, and the condensation that's happening in the walls and the roof space of a home. There are a few experts around at the moment suggesting that if we improve the energy efficiency standards or airtightness, we are going to suddenly create condensation problems. But in Australia, we already have condensation problems and it's because our houses are not airtight.

[Luke Menzel] It's the case that in some ways the mould that you can see is almost the good mould because you can see it and you're likely to do something about it. It's in the mould you can't see that can cause really serious damage, and sometimes you don't find out about it until it's too late right?

[Jenny] I always say that to our clients: The condensation you can see in your bathroom, that's the good stuff. We know how to deal with that.

[John] I also think the mould that we end up growing in our walls can also be a source of where it comes into the house. We've seen on many occasions bathrooms where there's a considerable amount of mould mainly on the internal walls of bathrooms. We strongly recommend that all bathrooms are insulated to keep those services as warm as possible.

You also get some soundproofing in there so that you don't have to hear some horrible singing. We have to treat these rooms like gold because that is where things go wrong.

[Luke Menzel] How about you John? What myths are you seeing out there?

[John] One of the most common myths is that addressing these things is really expensive. People think air tightness, and they think you have to have altered construction or that it needs to be really expensive. But you can achieve a lot with standard construction practices and I've done it many, many times, both for new builds and for retrofits.

Just by focusing on that internal plasterboard lining, minimising the penetrations and holes through it, making sure the plasterers don't leave gaps behind the joinery. You know, in this room, for example, I've got a fan/light combination, that's the only hole through the ceiling and it has a square edge. So nice and airtight. That's standard construction. Nothing unusual about that.

And this is a home from the 1970s that I’ve upgraded. And it's definitely the way to go. Apart from anything else, it makes your home able to deal with all sorts of things that the environment is going to throw at us, especially now with climate change, which is making the environment a lot a lot less predictable.

[Luke] So John what are the big takeouts for policymakers and regulators from all this? How do we get on the right track?

[John] A lot of it is about improving building practices. For example, consistency in the way insulation is installed can be massively improved. I think it's documented quite well, but it can be massively improved in practice. And driving that improvement will require checking it. We need to check how well things have been installed, we need to check how tight an enclosure is. They're not necessarily things that are hard to fix or get on top of, but they're out of sight out of mind and we don't see it. So we need to look, and if we can see it, we can fix it.

[Jenny] Yeah, awareness raising with builders is key. You know, John and I both have experience running workshops for builders, and it's not that builders don't care about this stuff, they just haven't thought about it. And once you take a builder through an air leakage test of a house, you can see them go, ‘oh, wow, I never thought about that. That's really easy to fix. Next time, I'll just do this’.

Again, I want to get through to policymakers that this really is achievable. Builders actually respond very well. Let's raise awareness, educate, and they will get on with it.


Jenny Edwards is a leading expert in both theoretical building-envelope testing using thermal performance simulation software, and physical building-envelope testing for air leakage and insulation integrity, using the fan depressurisation method (blower door) and thermal imaging. Connect with Jenny on LinkedIn here.

John Konstantakopoulous is passionate about the importance of the building envelope and has performed more large-building air infiltration tests in Australia than anyone else in the country. Connect with John on LinkedIn here.

This article was originally published in the October edition of Efficiency Insight.