#49 | Dew Points, Tropical Climates and Mould with Sonia Holzheimer

Jess Kismet (00:00)
Hello and welcome to the Building Sciology Poddie. My name is Jess Kismet and I am your host.

Today we are joined by Sonia Holzheimer, a mechanical engineer based in Cairns.

Sonia is a leading expert in a field that we don't hear a heck of a lot about in the southern half of the country but understanding this climate is critical to managing indoor air quality on her projects building science in the tropics. Sonia has also been on the technical committee for the AIRAH Indoor Air Quality Conference which is coming up later this year in Cairns and she is going to be a speaker as well which I am really looking forward to.

From cooling coils to dew point and dry bulb temperature, let's get into how Sonia wants to change how we design for tropical climates. Hey Sonia!

Sonia (00:42)
Hello, hello. Thank you so much for having me, Jess.

Jess Kismet (00:46)
It's my absolute pleasure. I am very interested in picking the brains of someone who is a specialist in tropical climates. It's so different to what I do every day.

Sonia (00:55)
Well, a little birdie told me that you might be wanting to know more about tropical climates for another good reason too, because

Jess Kismet (01:02)
in.

Sonia (01:02)
you're going to be moving here maybe. So yeah.

Jess Kismet (01:04)
Maybe, yeah, yeah,

yeah. I bought myself a little townhouse up in Cairns. It's a place that I deeply love. So yeah, very interested, very interested. So let's get into it.

Sonia (01:18)
Excellent.

Jess Kismet (01:19)
So tell me, what is building science literacy like up in Far North Queensland? And how does this impact the success of your work?

Sonia (01:24)
That's a loaded question, Jess, but it's a good one. I'll try not to get myself cancelled locally.

Look, in terms of the architects, the building designers and the tradies, I would say that the building science literacy is patchy. I won't throw everyone under the bus. Those who've been up here for a long time and have worked through the projects, they've built up a real knowledge base and through their experience, they know what works or more importantly, what doesn't work, even if they can't always articulate the building sciences behind it.

Jess Kismet (01:53)
Mm-hmm.

Sonia (01:54)
The bigger problem is that that guidance, like the codes, the standards, and even the product manufacturers documentation is largely written for the southern climates. The Australian Building Code Condensation Handbook is actually a really good example of that.

Jess Kismet (02:10)
Yep.

Sonia (02:11)
And that's not surprising because here's the thing. Forty five percent of Australia's landmass sits above the Tropic of Capricorn and the Tropic of Capricorn runs right through Rockhampton. that's

Jess Kismet (02:23)
Mm-hmm.

Sonia (02:24)
largely half of our continent is above the Tropic of Capricorn. But only five percent of the population lives here. So the

Jess Kismet (02:33)
wow.

Sonia (02:34)
dominant building stock is, course, in the temperate south. And so that's naturally

Jess Kismet (02:38)
Mm-hmm.

Sonia (02:38)
where the

regulatory focus lands. But the numbers tell you just how different these climates are. If you compare the outside outdoor design conditions between say Darwin and Melbourne.

Darwin has almost four times the enthalpy load and that's the total energy in the air and the heat and the moisture combined. Four times. But when you isolate

Jess Kismet (03:02)
a lot.

Sonia (03:03)
just the moisture that needs to be removed, Darwin has almost 80 times the load of Melbourne.

Jess Kismet (03:12)
Wow.

Sonia (03:13)
80 times. So the consequence is that when someone with experience elsewhere, that's a designer, an architect, a builder,

or a contractor comes up here and tries to apply what they know well from down south, they can come unstuck badly. Details

Jess Kismet (03:28)
Mm-hmm.

Sonia (03:29)
that work in Melbourne and Sydney can be genuinely harmful for somewhere like Cairns or Darwin. And there's a compounding issue to that. And that affects even the experienced locals because the practical knowledge that's been built on experience only holds for as long as those conditions stay the same. And the conditions are changing.

Jess Kismet (03:48)
Mm-hmm.

Sonia (03:48)
are being sealed up more tightly. There's more insulation going into the walls. Air conditioning is running for longer, but at lower speeds and at higher efficiency. And the construction methods are evolving. So that experience and knowledge that served the Far North Queensland builders and the like for decades is increasingly being stress-tested by buildings that are behaving entirely differently. In terms of how that impacts the success of my work,

Over the years, I've tried to be really proactive about this, providing support to architects where we can, guiding building design around things like the vapour barrier placement, always on the warm side of the insulation, the

Jess Kismet (04:29)
Mm-hmm.

Sonia (04:30)
importance of sealing roof spaces and why you generally want to avoid at all costs ventilating the roof space in this climate. So when the opportunity is there to advise and pass that on, we do so. The problem is that more often than not, we're

engaged after those decisions have been made.

Jess Kismet (04:48)
Mm-hmm.

Sonia (04:49)
And as a HVAC engineer, you're working downstream of the building science. The building envelope has been designed already. The roof space detail is locked in. And it's virtually impossible for the mechanical system to compensate for that. So the most successful projects are the ones where the building science thinking happened before

Jess Kismet (05:07)
Thank

Sonia (05:07)
the mechanical engineer arrived. And

Jess Kismet (05:09)
Mm-hmm.

Sonia (05:10)
that's when the HVAC system can do its job.

and the mechanical designer can play their part in making sure that the mechanical systems aren't introducing moisture problems and causing issues on their own.

Jess Kismet (05:22)
When you say that air conditioners are running for longer but at lower speeds, what implication does that have?

Sonia (05:29)
Well, what that stems

from is the energy efficiency.

Jess Kismet (05:32)
Mm.

Sonia (05:35)
In the quest to make buildings more energy efficient, includes the mechanical systems. And so

Jess Kismet (05:40)
Mm-hmm.

Sonia (05:40)
more and more they're designed with inverters and variable speeds. And they're only working hard enough so that they're only using just enough energy to maintain the temperature. so they're slowing down and not really working. And unless they're working, they're not removing any of the moisture.

Jess Kismet (05:56)
Right, okay. So this is a whole, when you say inverter and enthalpy, this is all Swahili to me. This is a language I do not understand, so forgive me. when, you're saying, what you're saying is that yet another unintended consequence of more energy efficient buildings is that they are not effectively managing moisture in tropical climates

Sonia (06:16)
you

Jess Kismet (06:16)
as well. Like.

Sonia (06:17)
Absolutely. So in addition to the energy efficiency

efforts that are in place to put all of the insulation into buildings so that they're these super well sealed and incredibly, you know, well isolated boxes that aren't

Jess Kismet (06:31)
Yeah.

Sonia (06:32)
letting in any of the heat and the glazing has been made smaller or maybe it's even double glaze and the like. So none of that heat is going inside the building. And then you've got these air conditioners, which have been

designed to be as energy efficient as possible. So once upon a time before inverters were involved, they would turn on and work really hard and then turn off.

Jess Kismet (06:54)
Mm-hmm.

Sonia (06:55)
now with variable speed drives, instead of doing that, they just run continuously, but just at a much slower speed. And you do get through, you know, through the infinity laws, you get an incredible benefit from efficiency from that. But in order for a cooling coil

to remove moisture, it needs to actually condense that moisture out and to be cold. So if

Jess Kismet (07:17)
Yeah.

Sonia (07:17)
it's not working very hard, it's not removing any moisture. So that wouldn't be so much of a problem. Like if you had this perfectly well sealed box and you had this air conditioner inside it that's not working very hard, that could probably be okay. But the second that you introduce any air and moist air into that, and so

Jess Kismet (07:34)
Yep. Yep.

Sonia (07:36)
that's where the tropics come in, because here, just like everywhere,

else we're introducing that air because the codes and the standards tell us to but up here it's full of moisture so you're basically taking a hose and you're putting it inside the building and then the air conditioner doesn't see that water it just sees the temperature and it goes nothing to see here I'm perfectly fine you know.

Meanwhile

Jess Kismet (07:57)
Yeah.

Sonia (07:59)
everything is wet so exaggerate to clarify.

Jess Kismet (08:03)
Yeah, no,

that's a funny visual. No, I get it. I get it. That's so interesting. Yet more unintended consequences that I was not aware of.

Sonia (08:10)
Absolutely.

Jess Kismet (08:11)
So this whole air conditioning is a dehumidifier thing. Do people in

Sonia (08:14)
Mmm.

Jess Kismet (08:15)
Far North Queensland rely, they must rely on their air conditioners as dehumidifiers. And you have come out recently in your Hills that Sonia is willing to die on series on LinkedIn, which I thoroughly enjoyed reading.

that an air conditioner is not a dehumidifier and I

Sonia (08:31)
Yeah.

Jess Kismet (08:31)
have had many people say this to me. you

Sonia (08:33)
Yeah.

Jess Kismet (08:34)
know the air conditioner will do that. So let's discuss this why why why not and and what's the best way to do it.

Sonia (08:40)
Look, I love this question so much and this is a hill that I prepared to die on.

Jess Kismet (08:44)
You

Sonia (08:45)
air conditioners are not dehumidifiers and in the far north this misunderstanding causes some real problems. So here's what I think is happening is people turn on their air conditioner and the room feels slightly less sticky. So therefore they believe that the air conditioner is managing humidity and there is like a kernel of truth to that because if you cool air below its dew point the moisture is condensing out of it. That's physics and that's physics

Jess Kismet (09:13)
Mm-hmm.

Sonia (09:14)
that we're relying

on for air conditioning. But here's the distinction that matters. There's a big difference between moisture removal that happens like as a side effect and moisture removal that is purposeful and intentional, measured and controlled. One is incidental. It's a bit like I use the example of when you open the fridge door at night to get a glass of milk, you're using that light to see what you're doing.

you're not using the fridge light to cook dinner with, right? It's incidental right?

Jess Kismet (09:45)
Yeah.

Sonia (09:47)
Whereas the other is intentional. A standard split system or a fan coil unit has got one job, just one job,

Jess Kismet (09:53)
Mm-hmm.

Sonia (09:53)
and that's temperature. And in our efforts, like I was saying before, to reduce the energy consumption, we've engineered these systems within an inch of their lives so that they use the least amount of power possible. And this is a good thing to do.

you know, all for energy efficiency, but in that process, it's not then doing that incidental or even less of the incidental moisture removal. The thing is split systems have been designed for the, like we spoke about how much proportion of the Australian population is in the North. So these systems are designed for all over the world and it's really just

the pinch point, the thin edge of the wedge here because the wettest day of the year is very rarely the hottest day of the year. In fact, it never is. So if a system has been engineered to do exactly what we tell it to do, which is to maintain the temperature on that cold, wet, mild day or night, it's barely working to remove any moisture. It's just circulating, you know, that

moist air through the building and and like I

Jess Kismet (10:59)
Mm-hmm.

Sonia (10:59)
said before you might as well put a sprinkler on. Dehumidifier is a completely different beast. Its objective is moisture removal. It pulls the air across the cooling coil to condense the moisture out just like the air conditioner does except it doesn't stop once it's reached a certain temperature. It keeps on going until it is wrung out the moisture and then it reheats that air before returning it to the space and that reheat

That's the key difference. It decouples the humidity control from temperature entirely. It will keep removing that moisture regardless of the room temperature. In fact, it actually warms up the room slightly, which it sounds strange, but heat is really what we want. The fundamental...

Jess Kismet (11:43)
Does the air

conditioner fight against the dehumidifier then?

Sonia (11:46)
Look, it will do, but it's actually then got a job to do. so it will.

Jess Kismet (11:50)
It's doing its

job. Yeah.

Sonia (11:51)
it will then do its job and in the process

it might even help and remove some more moisture. that's the,

Jess Kismet (11:57)
Yeah, okay.

Sonia (11:58)
you know, that's the part of it. The air conditioner is continuously asking, is the room temperature right? A dehumidifier is asking, is there too much moisture in this air? So they're solving different problems with the same tool, but just with different controls. But expecting one to do the job of the other is where we get into trouble.

Jess Kismet (12:19)
Okay, thank you for clarifying that because that's one that kind of doesn't seem to go away.

Sonia (12:26)
Yeah,

and I think it's been exacerbated because some air conditioners have this dry mode function and

Jess Kismet (12:33)
Yes!

Sonia (12:33)
Yeah, yeah. and you know, finding exactly what that is doing is, is hard to drill down into because, you know, in the manuals, and I have looked, you know, there's very little information on it. What it will be doing is it will be for a period of time. And I can't really find that out easily. But for a period of time, it will be slowing down the airflow, and therefore getting more moisture removal. And it'll, in fact, probably

temperature for a period of time and effectively work like the dehumidifier does in that it will just work as hard as it can and in that sense remove as much moisture as it can but because it doesn't have any heating element afterwards it will sort of make this choice of okay I'm going to do this for 20 minutes and then go back and sort of you know turn on and work hard for a period of time and then probably turn off so it's actually acting

Jess Kismet (13:24)
Mm-hmm.

Sonia (13:26)
in a less efficient way like it did

once before, probably before the inverters were around, but it's not likely to have a humidity sensor. So it's not really doing this with any intent. It's just like, well, we'll do something. So it's better than nothing, but you can't call that a dehumidifier, right? And that's where I think there's a danger though, because

Jess Kismet (13:44)
Mm-hmm. Mm-hmm.

Sonia (13:48)
you can't look at that and go, you know, don't worry, we've got the dry mode. It'll be fine. You know, no, no.

Jess Kismet (13:54)
Mm-hmm. Mm-hmm.

And do you find that you come across buildings that have been operating on, you know, dry mode or, you know, they've been trying to these air conditioning systems have been trying to multitask but there's issues and you can explain why.

Sonia (14:11)
Absolutely.

It is.

a very common

Jess Kismet (14:16)
Mm-mm.

Sonia (14:17)
misconception and you find that things like schools are a classic example where they're like, oh, we'll just turn this on and put it onto dry mode or something. And unfortunately, it can lead into issues. If you are intending to manage the moisture, you need something that was actually designed to do that properly. So you need the dehumidifier. You

Jess Kismet (14:37)
Mm-hmm. Mm-hmm.

Sonia (14:39)
can't employ an air conditioner for really, which is being constructed and designed

for a totally different purpose. You can't use that and rely on it for dehumidification. In the tropics, I'll clarify that. Down south for sure, or somewhere where you're not introducing moisture all the time, but when you've got a system that doesn't know what the moisture is and is not looking for that, so it's obviously,

Jess Kismet (15:02)
Mm-hmm.

Sonia (15:03)
you're only gonna get what you get. And

Jess Kismet (15:05)
Mm-hmm.

Sonia (15:05)
that's not really an engineering approach. That's a,

Jess Kismet (15:08)
Mm.

Sonia (15:09)
I don't know, that's a

in a prayer, right? Not the way I would advocate.

Jess Kismet (15:13)
Do you think the tropics is

kind of, know, I guess for lack of a better kind of description, forgotten about in this HVAC industry? you're saying that 45 % of the landmass is above Rocky but only 5 % of the population. So although it's this extremely difficult climate, not many, not...

it's not the majority of population. So do you get that sense or what's the reason why there's this big gap in understanding and functionality?

Sonia (15:41)
Look, I absolutely do think, not so much forgotten about, but the reality is if you've only got five people banging on about it, 5 % of the population banging on about it,

Jess Kismet (15:52)
Yeah.

Sonia (15:53)
you have to sort of put that into perspective. Obviously, there's a greater need for, you know.

with the building stock down south. But the reality is that you get it wrong here. And we're in a situation where we've got so much against us other than the, you know, the ambient conditions. Logistically,

Jess Kismet (16:11)
Mm.

Sonia (16:12)
everything's further away, right?

Jess Kismet (16:14)
Mm-hmm.

Sonia (16:15)
You've got, it takes longer for equipment to get here. It's under a much more onerous environment. So it doesn't last as long. There is all of these things that are,

against us and unfortunately it also tends to not be where necessarily most of the

the guidance and the documentation has been created. I should send it to you afterwards, but even a lot of the original standards and guidance that we have got for Australia was largely based on experience from America. if

Jess Kismet (16:48)
Mm-hmm.

Sonia (16:49)
you reverse the picture and you sit Australia on top of America, most of the northern part actually falls beyond Florida.

So in other words, you know, probably Brisbane is sort of sitting the equivalent of Florida. So, you

Jess Kismet (17:04)
Yep.

Sonia (17:04)
know, we've got our conditions are probably much closer to something like Singapore or

Jess Kismet (17:09)
Mm-hmm.

Sonia (17:10)
like, and we just haven't generally lent into those standards and guidance as much as perhaps what we should have. So.

Jess Kismet (17:19)
So you're saying that Cairns

has got a more extreme climate than Florida. Awesome.

Sonia (17:22)
Yeah, absolutely. Yeah.

Jess Kismet (17:25)
So, okay. These articles that you've written, hills that Sonia is willing to die

Sonia (17:28)
Mm-hmm.

Jess Kismet (17:29)
on, what prompted this creative outburst? I mean, and for those of you who haven't read Sonia's articles, I'm gonna put links in the show notes. You must read them if you are at all interested in HVAC or building science in general and particularly in the tropics. They're great fun to read. You're a good writer.

Sonia (17:44)
Thank you very much. I think creative outburst is a pretty generous way to put it. It was

Jess Kismet (17:50)
I'm like...

Sonia (17:52)
more like this sort of slow build of professional frustration, finally finding an outlet.

Jess Kismet (17:58)
Ha

ha ha!

Sonia (17:58)
Look, I've been in the HVAC industry for a while and there are certain conversations that you just keep on having, know, the same misunderstandings, the same assumptions, the same gaps in what people think is happening in a building and what is actually happening. And for a long time, I would have those conversations one at a time with a client, with a designer at a conference. And then a few moments later, I would watch the same thing happen all over again. So at some point I thought, what if I just write this down?

is a technical paper. That's

Jess Kismet (18:29)
Refer to Article 3. I'm tired.

Sonia (18:34)
right, just point them in, send them my link.

Jess Kismet (18:37)
Yeah.

Sonia (18:40)
just an honest opinion from someone in the industry. And

Jess Kismet (18:42)
Mm-hmm.

Sonia (18:43)
I was hoping it was something that someone might actually read. The hill to die on framing came out of that. because these aren't neutral summaries, they're positions. I tend

Jess Kismet (18:53)
Mmm.

Sonia (18:53)
to feel these days with, you know, everyone speaking, I feel as though people are seeking for you to take a position, right?

Jess Kismet (19:01)
Mm-hmm.

Sonia (19:01)
know, this sort of

mediocrity and you know, meet in the middle, sometimes it's not helpful. So I'm like, no, I'm going to stake a claim here. So saying, you know, this is a hill I'm going to die on this sort of gave me permission to say exactly what I think without sort of wrapping it up in all these qualifications and caveats.

Jess Kismet (19:18)
Mm-hmm.

Sonia (19:18)
The response has seriously surprised me. So I thank you so much that you've read it. And I did expect

Jess Kismet (19:24)
No.

Sonia (19:26)
some pushback because, you know, wasn't sort of written like clickbait.

but I was, like I said,

Jess Kismet (19:31)
Mm.

Sonia (19:31)
know, putting a position out there. But and I wanted people to engage with it rather than just sort of scrolling on and saying, yeah, more of that type thing. But

Jess Kismet (19:38)
Mmm.

Sonia (19:41)
the fact that the response I was getting, it told me that the frustrations weren't just mine. So so that

Jess Kismet (19:45)
Mm-hmm.

Sonia (19:46)
was a good thing.

Jess Kismet (19:46)
All right, my next question. You've argued that regulating dry bulb temperature is useless in the tropics. First of all, what is dry bulb and wet bulb temperature for the listener and for me? And why is this another hill you're willing to die on? The indoor dew point hill. And how does this apply to current building regulations?

Sonia (20:05)
I did go pretty hard with these hills, didn't I? Okay, I'm gonna back this up now. Look, I

Jess Kismet (20:08)
Okay.

Sonia (20:14)
wanna make sure that I'm precise here because this is a really important distinction.

And I'd hate to throw dry bulb temperature entirely under the bus because it does it does have its place. What I'd really argue is that relative humidity is the poor metric and the dew point

Jess Kismet (20:32)
Mm.

Sonia (20:32)
is is what we like need to be or should be or what I would like to see being regulated instead. So let me explain why.

Jess Kismet (20:38)
Mm-hmm.

Sonia (20:39)
Relative humidity is a ratio. It tells you how close the air is to being fully saturated at its current temperature.

temperature. The problem is that the ratio changes every time that the temperature changes, even

Jess Kismet (20:54)
Yeah.

Sonia (20:54)
if the actual moisture content of the air hasn't moved at all. So on a hot afternoon, the relative humidity might be, 60%.

and then the air conditioning kicks in and cools the room down. And like I said before, the hotter the air is, the more moisture it can hold or the colder the air is, the less moisture it can hold. So if that air has been cooled down, it suddenly is going to have a higher humidity, even though the moisture hasn't changed. So that's just the maths. That's just the ratio responding to the temperature change.

And that's why I don't like that. Dewpoint doesn't do that. Dewpoint is a direct measure of the actual moisture content in the air. It doesn't shift when the temperature shifts. If the dewpoint is 20 degrees, it's 20 degrees whether the room is hot or cold. That's why it's

Jess Kismet (21:46)
Mm-hmm.

Sonia (21:47)
such a more useful metric. And that's why...

Jess Kismet (21:50)
Mm-hmm.

Sonia (21:50)
I think we should be designing to that and ultimately regulating to that metric as opposed to relative humidity, which I

Jess Kismet (21:57)
Mm-hmm. Mm-hmm.

Sonia (21:59)
would love to see just thrown out.

Jess Kismet (22:02)
In

passive house it's actually taken into account. So certified passive house we work on the basis of 60 % relative humidity and 20 to 25 degree air and no surface in a passive house is allowed to get below 12.6 degrees because that is the dew point of those conditions which

Sonia (22:18)
Hmm? Hmm? Hmm?

Jess Kismet (22:22)
means that condensation is completely eliminated from a certified passive house building.

Sonia (22:26)
I didn't know that. That is very interesting.

Jess Kismet (22:28)
Hmm

Sonia (22:30)
I wish that in further afield than just Passive House, I wish we had that requirement

Jess Kismet (22:33)
Mmm. Mmm.

Sonia (22:35)
in every other building because that would make the world of difference. Once you've got a regulation in there, it's no longer just good design practice. It's something

Jess Kismet (22:44)
Yeah.

Sonia (22:44)
that we all actually have to derive to. And this is the thing is that in

It's worth mentioning that temperature or humidity in terms of a requirement isn't listed anywhere in the ventilation standards or even in the building code. It

Jess Kismet (23:00)
Mm-hmm.

Sonia (23:01)
really doesn't care about comfort in any way, shape or form. It does...

concern itself with contaminants and that's why the ventilation standards are there to either remove or introduce air to dilute the contaminants or to remove them. But in terms of temperature and humidity, that's not a regulatory requirement. It comes in as a design request. You know, we would like to see the space at this temperature and humidity, but

Every specification, except for those that are perhaps for an art gallery or a hospital, every design specification will say a temperature, say 22 or 23 degrees, and the humidity. the humidity will have like an asterisk or brackets beside it, which will say uncontrolled or.

you know, by virtue of the cooling coil, you know, it's basically saying the humidity.

is just like we spoke about before, incidental to the

Jess Kismet (24:03)
Mm-hmm.

Sonia (24:04)
temperature. You will just get what you get. It's not under any regime or requirement and therefore it's not measured and it's not controlled. and that's where everything kind of falls down. If it already wasn't weak enough because it's not the temperature and the comfort isn't a regulatory requirement, the actual humidity aspect of it, the part that is managing the moisture is just a do what you can, do your best, but.

Jess Kismet (24:28)
Mm-hmm. Mm.

Sonia (24:29)
you know, no one's gonna hold you to it. so what do you imagine happens in every single building? Nothing it's not addressed until it becomes a problem, which

Jess Kismet (24:35)
Mm, mm, mm, yeah.

Sonia (24:38)
is largely only a problem in the far north. So that's why you've got us sort of banging on about it going, well, hang on a second. This is,

Jess Kismet (24:45)
Hmm.

Sonia (24:46)
this is the issue, right? This is the thin edge of the wedge.

Jess Kismet (24:47)
Mm-hmm. Mm-hmm.

Mm-hmm. And dry bulb and wet bulb, what are they again?

Sonia (24:53)
sorry. So dry bulb is going to be the that's the temperature that you can actually feel. So that's what the thermometer is telling you is the, you know, that dry bulb. And they call it dry because, know, it's opposite to the wet bulb, which once upon a time, you know, they used to have these like sling hygrometers that they would have the thermometer end in water or in like this sort of wetted wick and through evaporation.

it would always be lower than the dry bulb temperature. And it's the difference between those two which ultimately tells you the humidity and will lead you to at 100 % the dew point. So these are all old terms but I guess everybody has got this sense of a dry bulb temperature but that relative humidity, that's the bit that is...

you know, a bit of a looser term because it's so dependent on the temperature. It's a ratio.

Jess Kismet (25:52)
mmm yep

yep okay so a dry they just dry bulb wet bubble are just two different ways of measuring temperature and

Sonia (26:01)
Mm-hmm.

Jess Kismet (26:01)
the wet bulb is encased in something wet so it's cooler because of evaporation okay

Sonia (26:07)
Yeah, yeah. that's and

these are these are older terms, but that's once upon a time how

Jess Kismet (26:11)
Yeah, see

Sonia (26:12)
they used to do it. They would have two thermometers beside each other and one would be literally sitting in this sort of, you know, muslin type material that you would have to wet. And

Jess Kismet (26:21)
Right, okay.

Sonia (26:22)
and so you would then and you swing this around in sort of it would be it literally would have.

Jess Kismet (26:28)
Eight and a half times or?

Sonia (26:29)
You know what, I don't know if there was any particular science to that, but you swing this around, just to get the evaporation to occur so that then, because

Jess Kismet (26:36)
Yep.

Sonia (26:37)
if you just had it sitting there and there's no air movement, it may not be quite accurate.

Jess Kismet (26:43)
Mm.

Sonia (26:45)
And this is the thing is that in a really, really wet.

state, those two are close to each other and that's at 100 % humidity versus somewhere down south like where you are. That's why evaporative cooling works really well in sort of Adelaide

Jess Kismet (26:56)
Mm-hmm.

Sonia (26:57)
because there's such a difference between the dry bulb and the wet bulb. And when you evaporate, it goes all the way down to a very low condition and you can then supply that air even at such a low temperature. Whereas here, the dry bulb and the wet bulb are always very close to each other and they're very, very high.

So the standard design conditions for Cairns is sort of 33 and 28. Whereas

Jess Kismet (27:20)
Mm-hmm.

Sonia (27:20)
in Adelaide, I actually don't know what it is, but it might be 40 as a design condition and maybe, I don't know, in the teens for the wet bulb.

Jess Kismet (27:30)
Mm-hmm. Yeah.

Sonia (27:32)
that's a big difference. Like we

Jess Kismet (27:35)
Mm-hmm.

Sonia (27:36)
said, 80 times between Darwin and Melbourne, the amount of moisture.

Jess Kismet (27:39)
Yeah,

yeah, that's a crazy metric.

Sonia (27:42)
It's crazy.

Jess Kismet (27:43)
So, I mean, this is not really relevant, but my brain won't be able to let it go. How is dry bulb and wet bulb measured now? Is it all done by like computers?

Sonia (27:52)
no, it would be same thing to be honest. But yeah, I mean,

Jess Kismet (27:54)
Bye.

Sonia (27:54)
we just look on the BOM And that's telling me I don't don't throw around, you know, or or it's got, you know, no, I don't get the sock out and put the tooth

Jess Kismet (27:56)
Yeah okay. Alright let the detail go Jess, let the detail go. You're gonna get your sock out and start whippin'.

Sonia (28:05)
in on it is there.

Jess Kismet (28:07)
Okay

cool. Okay now this humidity thing you have said that

Sonia (28:10)
Mm-hmm.

Jess Kismet (28:11)
humidity should be the driver and temperature should ride shotgun in terms of the priorities for controlling the conditions indoors up in the tropics. So if we flipped the design priority in the tropics to moisture first how would this change the average building? Would

Sonia (28:26)
Mm-hmm.

Jess Kismet (28:27)
the occupants notice?

Sonia (28:28)
Well, you don't get what you don't ask for do you? Right? You got to ask to get it. Look, it's great question. And I think the honest answer is that the building would look quite different from a mechanical plant perspective. But the occupants that are in the building may not notice too much difference. And that's probably the point. They'd probably be slightly more comfortable.

But humans can tolerate reasonably wide range of humidity. So if the humidity was 45 instead of 65, they'll probably slightly notice that. But what I think would be more tangible and the things that they would notice is first of all the smell. Odours are far less pronounced in drier air.

because the same air that feels super heavy and close in a humid building carries smells much more effectively

Jess Kismet (29:18)
Mm-hmm.

Sonia (29:19)
than dry air does. I don't know if you've ever been like walked into a cold room and you really can't smell anything even though there'll be food everywhere.

Jess Kismet (29:26)
Crisp.

Sonia (29:28)
It's sort of not obvious.

Jess Kismet (29:29)
Mmm.

Sonia (29:30)
Whereas I noticed it here as soon as it starts to rain, you know, the building will just start to have a bit of a less pleasant smell about it.

Jess Kismet (29:38)
Yep.

Sonia (29:38)
A properly moisture controlled building just smells cleaner or more to the point, a wet damp building smells bad. like, we'll notice that. The second

Jess Kismet (29:47)
Yep, musty.

Sonia (29:49)
thing that I think people would notice is that the building wouldn't be quietly rotting around them. You know, there wouldn't be

Jess Kismet (29:56)
Yeah.

Sonia (29:56)
the mould on the ceiling tiles, the musty storerooms, the black patches near the ceiling diffusers, because that's where it's wet.

These aren't just cosmetic problems. They're symptoms of

Jess Kismet (30:06)
Hmm.

Sonia (30:06)
building and it's HVAC systems losing the moisture battle, losing the moisture war. If

Jess Kismet (30:13)
Mm-hmm.

Sonia (30:14)
moisture is taken seriously and the design of the HVAC systems purposefully manages the moisture from the start, those things won't happen. And then the occupants...

Jess Kismet (30:22)
Hmm, they're fairly major things.

Sonia (30:24)
occupants would never know what they've been spared, which would be the best outcome. mean,

Jess Kismet (30:27)
Yeah. Yeah.

Sonia (30:30)
the best HVAC system is the one that nobody notices because it's doing its job perfectly. So yeah,

Jess Kismet (30:36)
Yeah.

Sonia (30:37)
I would love to see that.

Jess Kismet (30:38)
Yeah, that's there's some fairly, you know, they're not the building is not going to change cosmetically, but it's going to not stink and not be covered in black mould. Call that a win.

Sonia (30:48)
Yeah, yeah. I mean, the mechanical

system will look different. It will be more sophisticated and more expensive, but you'll get all of those positive outcomes as a result.

Jess Kismet (30:56)
Yeah, yep.

And on that, you said, you kind of alluded to the fact that if a building is working well, or if it's between 45 and 65 % relative humidity, people don't really notice. And the best outcome is when people aren't noticing the conditions around them. Because if they're noticing bad smells and if they're noticing discomfort, then that's the failure of the system. If they're not noticing those things, then it's working.

Sonia (31:17)
No. No.

Jess Kismet (31:20)
But they don't notice they're not noticing.

Sonia (31:21)
That's right.

Jess Kismet (31:21)
So how

does it, you know, if in your job, if you do your job well, no one kind of notices, right? Is that what you find? how does that feel? Because the only time you know, you're going to get a call is if things are failing.

Sonia (31:35)
Yeah, yeah, look, this is a question that does that does sort of come up.

Jess Kismet (31:42)
do people notice? Because things have been so

tough up there for so long, if a job is done well, people are like, wow, this is different.

Sonia (31:49)
No, the invisibility of success is genuinely one of the strange psychological challenges of this work. Nobody is

Jess Kismet (31:56)
Mm. Mm.

Sonia (31:57)
going to call you to say, guess what? This building's been mould free for five years. none

Jess Kismet (32:02)
Yeah, great HVAC system, Sonia.

Sonia (32:05)
of the occupants have got unexplained respiratory symptoms. There's

Jess Kismet (32:08)
Yeah.

Sonia (32:09)
no feedback loop for when you do it right.

Jess Kismet (32:12)
Yeah.

Sonia (32:12)
I mean, you design the system and you hand it over and you move on hoping that your design moves on, but you're not going to find out if it did only when it didn't.

So you do

Jess Kismet (32:22)
Mm-hmm.

Sonia (32:22)
find out about the failures and those failures

Jess Kismet (32:24)
Hmm.

Sonia (32:25)
aren't just expensive. They're coming up more and more in the public conversation. We're starting to see evidence around what poor indoor quality actually costs us in terms of health outcomes, productivity,

Jess Kismet (32:36)
Yeah.

Sonia (32:37)
sick days, chronic illness, that state of the indoor air report, which I'm.

expecting will be discussed at the indoor air quality conference, it came out in late 2025. And there was a significant moment in Australia in terms of putting that evidence into one place and it made it hard to look away from, right? The honest answer for how I try and manage that and reconcile that in my head is that all I can do is stay focused on what I can control. Unfortunately,

Jess Kismet (33:05)
Mm-hmm.

Sonia (33:05)
I can't force every client to invest in moisture management. can't, you know,

write the building code. What I can

Jess Kismet (33:12)
Mmm.

Sonia (33:12)
do is make the argument clearly and consistently every time that I'm in the room, designed to the best standard that I know and use whatever platform I have, whether it's those LinkedIn articles, or conversations like this one, which I really appreciate, to shift what the industry considers to be normal.

Jess Kismet (33:30)
Mm-hmm.

Sonia (33:31)
That's ultimately what needs to change, not just individual engineers making better decisions, but the collective expectation.

of what building in a tropical climate should deliver. When moisture control is considered as fundamental as the structural integrity, when clients ask

Jess Kismet (33:47)
Mmm.

Sonia (33:48)
about a dew point performance in the same way that they ask about cyclone ratings or in the same way that you do in passive house, that's when the invisibility of success won't be like this sort of burden. It'll be the standard.

Jess Kismet (34:04)
Mmm.

Sonia (34:05)
I don't think we're there yet, but that's keeps me going. I hope that we will.

Jess Kismet (34:09)
That indoor air pattern.

Sonia (34:11)
I hope that we will get there.

Jess Kismet (34:13)
Yeah so do I. The indoor air quality report that you mentioned could you direct me where to find that please because I don't think I've read it.

Sonia (34:19)
that it's sure it's

called the state of the indoor air report. And so I'll send you a link afterwards. And,

Jess Kismet (34:27)
Yeah.

Sonia (34:28)
you know, the universities of Melbourne and thrive through the leadership of Lidia Morowska and also through the efforts of Plum Stone with Safer Air and

Jess Kismet (34:38)
Mm-hmm.

Sonia (34:40)
also a Brownyn King. She's

also an advocate, you know, they've really done a wonderful job at putting a focus on indoor air quality and

Jess Kismet (34:49)
Mm.

Sonia (34:49)
state of the indoor air report was an analysis of kind of a mixed bag of Australian buildings and what the, you know, what the indoor air was.

in those buildings, you know, they've assessed them. I mean, it's got a ways to go from a HVAC practitioners perspective, I would have liked to have seen a bit more detail on whether or not the HVAC systems were compliant, whether or not, you know, they were operating, things like that. That's just my engineering brain sort of to

Jess Kismet (35:19)
Yeah, the variables, yeah.

Sonia (35:22)
work. at the same time, it's at least said, look, we've gone out and we've had a look at these buildings and

not all the results are great, some of it's really bad. And that

Jess Kismet (35:32)
Mm. Mm.

Sonia (35:33)
is just a way that then they can package that up and take it to perhaps politicians or even to the industries like AIRAH and say, you know, for whatever reason, these buildings are not, you know, performing the way that we would hope that they would do. So what

Jess Kismet (35:47)
Mmm.

Sonia (35:47)
do do about it? So I think, you know, that's really important. So now it's a conversation, right? It's about what

Jess Kismet (35:53)
Yeah

Sonia (35:54)
what can happen.

And it needs a bit of, you know, it needs to be interrogated to sort of say, well, you why? But yeah, it's a conversation that can be then had at something like this indoor air quality conference. And, yeah, we can get things moving because obviously the question needs to be asked, is it our regulation and our standards which are falling short? Or is it our designs are not?

being designed appropriately. So these are questions that we don't have the full answer to, but we do know that the indoor air quality isn't great in so many of the buildings. Becoming more visible though, like

Jess Kismet (36:28)
And it's invisible. I'm looking forward to Pardon? Yeah.

Sonia (36:36)
in the discussions.

Jess Kismet (36:37)
Yeah, I'm looking forward to that last couple of days of the IAQ conference. You mentioned that there'll be health professionals there. I'm interested in hearing what they have to say. A couple of years ago at the Passive House Conference, had a, of the, there was a builder there and his wife, I think, worked in the building company, but she was a nurse before she was working in his building company. And she would work in,

I think the respiratory ward or she had a particular patient that had a serious respiratory issue and they moved this woman from a from her where she was living into one of their certified passive houses and all of her health like her health improved remarkably in a short period of time and that was one of the most memorable because she had metrics around the indoor air quality that had they been monitoring the indoor air and could compare and that was one of the more memorable talks at

that I remember listening to. So I'm interested to hear more from the health practitioners at this conference because the alignment between construction and HVAC and health needs to be, like there needs to be a collaboration there, a

Sonia (37:39)
Yeah.

Jess Kismet (37:39)
much stronger collaboration.

Sonia (37:41)
Look, absolutely. it's Plum Stones, I suppose, with the Safer Air and with her, you know, non-for-profit organisation, is she's sort of saying she's making or encouraging us to make air sort of this accessibility issue, meaning that everybody should

Jess Kismet (37:55)
Mmm.

Sonia (37:55)
have the opportunity to have access to clean air that's not doing them any harm, of course, which

Jess Kismet (38:01)
Mmm.

Sonia (38:03)
In reality should be the case anyway. mean, that's what our Australian standards should be ensuring no matter what. the fact is that this is the question she's asking is, you know, is that the case? Because it doesn't seem to be.

Jess Kismet (38:14)
Mm.

Sonia (38:15)
what in addition to giving you a link to that state of the indoor air report, there is another report and I don't want to misquote the name of it. But it was also it was really a report on

the experience of a number of people and the impact and the health impact of air and poor indoor air on them. So

Jess Kismet (38:36)
Mm, mm.

Sonia (38:37)
I think this would sort of be another thing and it sounds like it would be, you know, interesting to you and to your listeners as a link to, you know, another piece of the puzzle and another sort of bit of information about just the situation that we have at hand.

Jess Kismet (38:53)
For sure,

for sure. And I really do hope that this document gets taken up and read and talked about and shared and actually does make a difference. There was a report on the impact of biotoxins on health done in 2018. And I'm not sure. I think that's kind of been put in a draw. So

Sonia (39:10)
that right?

Jess Kismet (39:11)
yeah, don't know if it's had, it was widely read in the building science circles, but

Sonia (39:16)
Mm-hmm.

Jess Kismet (39:18)
I haven't heard anything about it for a while. So I'm hoping that

your report stays in circulation and actually does manage to make a difference.

Sonia (39:25)
I won't claim it. This is largely through Lidia Morowska and Thrive

Jess Kismet (39:30)
yeah.

Sonia (39:31)
and the efforts of Safer Air, but I'm definitely

Jess Kismet (39:34)
Mm.

Sonia (39:34)
doing my bit to try and get it out and to read it

Jess Kismet (39:37)
Mm.

Sonia (39:37)
and to understand it. And then from the HVAC practitioners perspective, because I sort of feel like we're the ones that have got to try and fix it and make it work, right? So

Jess Kismet (39:47)
Mm.

Sonia (39:47)
that's our remit is to design these systems.

And we're just moving towards, you know, the solutions.

Jess Kismet (39:56)
Yep, well, I look forward to reading it and sharing it. So I will

Sonia (39:58)
Mm, cool.

Jess Kismet (39:59)
put that link in the show notes as well.

If you were writing a new building code from scratch, what is the very first indoor air quality or moisture clause you would include?

Sonia (40:07)
This is a great question. it's kind of, it kind of goes back to what we'd actually said before about how you can't get what you don't ask for,

Jess Kismet (40:17)
Mm-hmm.

Sonia (40:18)
So if I had my way.

I would want us to learn from other parts of the world and apply their hard-won experience rather than repeat what they've done from scratch. So in the United

Jess Kismet (40:32)
Mm-hmm.

Sonia (40:32)
States, the mechanical ventilation standard, ASHRAE 62.1, this is the equivalent to our Australian ventilation standard, 1668 part 2.

ASHRAE 62.1 includes an indoor dew point limit that applies to systems where the ambient outdoor dew point exceeds a certain threshold. So what that effectively means is that if you are in a region where the ambient moisture levels are persistently high, like Cairns, like Darwin, and you are introducing that outdoor air into a building for ventilation, which we're supposed to be,

then you are required to design that ventilation system so that the indoor dew point is controlled, just like you mentioned with the passive house.

Jess Kismet (41:18)
Yep.

Sonia (41:19)
You must manage that moisture under all ventilation conditions. So I think that this is brilliant. I think that this single, what this single clause achieves is so enormous because right now in Australia,

Designing for moisture control in a hot humid climate like Cairns and Darwin is really just good design practice. It's what a conscientious, experienced engineer does, but it's not required. It lives entirely in the domain of professional judgment, which means it's only gonna happen when the right engineer

Jess Kismet (41:52)
Mm.

Sonia (41:53)
is in the room on the right project and if the client is willing to invest in it.

Jess Kismet (41:57)
Mm-hmm.

Sonia (41:57)
The moment

you put it into a code though, then it's not going to be optional anymore. because that clause is triggered by the ambient dew point, it's not going to impose new or onerous requirements on Melbourne or Adelaide. It would only apply where it actually matters and needs to apply in

Jess Kismet (42:18)
Mm-hmm.

Sonia (42:19)
the tropical regions where the outdoor moisture levels cross that threshold.

It would remove it from recommended, you know, good design practice and good conscience to regulatory requirement.

Jess Kismet (42:32)
Mm-hmm.

Sonia (42:33)
And then it would only apply where it needs to. So that to me would be the first thing I would ask for if I got to write.

Jess Kismet (42:41)
That's a good one. How does it interact with the building envelope? Because obviously there needs to not be a dew point temperature in the building envelope for that to also work. Is that correct? Like

a cold area of a building is where condensation will appear if that temperature is below the dew point of that surface temperature.

Sonia (43:04)
Mm-hmm. Mm-hmm. Look.

Jess Kismet (43:06)
So does

that mean, is it a collaboration between architects, builders and HVAC in order to make that work?

Sonia (43:11)
Well, yes and no. the moment, dew point temperature, at the moment outside, it is in Cairns or something like that, it is like 25. It's really, really high. When there's a lot of moisture in the air, the dew point is very, very high. So that means that a surface doesn't have to be very cold for it to condense.

Jess Kismet (43:30)
Hmm.

Sonia (43:31)
If you employ an air conditioning system that removes the moisture, the dew point temperature actually comes down and it comes down and we would be trying to get it to be that 12 to 13 degree that you were talking about. That would

Jess Kismet (43:44)
Mm.

Sonia (43:44)
be ideal. I think in 62.1 it's actually up at sort of 15 because there is a point of...

the amount of effort that you go to and at least if you have a system that is forced to look at the moisture, it's then just a question of well how much do we go. I would love to see it go down to that 12 and 13 degrees that you spoke about, but 15 would be a good start. But that's a very low temperature condition in the scheme of things. if...

there's not that many surfaces in a space that are going to be down as low as that, whereas

Jess Kismet (44:14)
Mm.

Sonia (44:14)
a relatively humid indoor temperature, which has probably got a dew point of 18, there's far more surfaces that are going to be at 18. And that's where you lose that moisture and the like.

Jess Kismet (44:24)
Yeah. Yeah.

Sonia (44:26)
But you're right, it absolutely has to all tie in together. And this is what I mentioned at the beginning, where

The experienced builders and architects and everything else know that they've got to seal up the building. then there's our discussion around you've got to vapour seal that roof, not ventilate the roof space and things like that. Because the reality is that...

as you'd be aware, with the vapour pressure difference of that hot moist air outside and the cooler,

Jess Kismet (45:00)
Mm.

Sonia (45:01)
drier air inside, that vapour pressure difference is actually sucking that

Jess Kismet (45:05)
Mm.

Sonia (45:07)
moist air into the space.

the right ventilation and HVAC system is actually introducing some of that air and it's cooling it down and removing the moisture. And it is then working to push that sort of moist ambient air away from the building. So it's

Jess Kismet (45:25)
Mm-hmm.

Sonia (45:25)
got a positively pressurised building. It's also working against to protect that building as another layer to stop that moist air from coming in. So,

Jess Kismet (45:35)
Mm-hmm.

Sonia (45:37)
you know, that would be another

Again, good design practice. It would be something that the designer would have to consider. Okay, if I'm going to keep the indoor dew point above a certain level, yes, I need to provide.

Jess Kismet (45:50)
you know, positive building pressurization to overcome the leakiness of the building.

Jess Kismet (45:55)
Yep.

Jess Kismet (45:56)
and you know, that's where the building designer and the HVAC people have to work together, like you say, because obviously some buildings are more leaky than others.

Jess Kismet (46:04)
Hmm.

Jess Kismet (46:05)
And how much you pressurize the building is going to be a decision that is made on reflection of just how leaky that building is and has

Jess Kismet (46:14)
Another

question that just popped into my head and we've got a couple more questions left to go but I just want another quick one. Do you take into account the breeding envelope air tightness score when you're designing your systems?

Jess Kismet (46:26)
Not so much air tightness score, but when we design systems, we do one of the good design practices for for the the tropics is not just considering how much

fresh air that you need to you know satisfy the building code with respect to indoor amenity, but you're actually

Jess Kismet (46:45)
Mm.

Jess Kismet (46:45)
looking at it to make sure that you are providing positive building pressurization to overcome

Jess Kismet (46:51)
Mm.

Jess Kismet (46:52)
infiltration and leakiness from the outside. So that's like another

Jess Kismet (46:56)
Mm.

Jess Kismet (46:56)
tool in your tool belt. And you might look at the construction and you and go, okay, this is a really sealed

Well type building, I only need it to be half an air change per hour more. and that's gonna be over and that has to be over and above, you know, the air that's being exhausted as well. So you gotta

Jess Kismet (47:15)
Mm-hmm.

Jess Kismet (47:16)
do sort of an air balance. if it's a really leaky building, you might turn around and go, look at that. You know, they're gonna be opening the doors lots. There's there's dozens and dozens of of penetrations here. maybe you might go up at sort of one or two or something, but

that ends up being potentially a whole lot of air, right? And

Jess Kismet (47:34)
Mm.

Jess Kismet (47:35)
y there's no point in doing that unless you're actually removing the moisture from that air. Like you wouldn't just supply all of that wet air in. You you've got to use the pressurization with cool, dry air. And that

That can end up being a very, very energy intensive, you know, amount of effort. So you're constantly gonna

Jess Kismet (47:53)
Mm.

Jess Kismet (47:54)
be looking at all of these, you know, the leakiness in the construction and sort of saying, Okay, hang on a second, we need this to be very well sealed. And if it's a very critical space, you might even take it that into account and say, Okay, we need

like art galleries as an example, you might have this close controlled space internally and it might be surrounded by somewhere that has got less controlled. It's still gonna be conditioned, but it's sort of providing a barrier to them the outside again, right? So

Jess Kismet (48:27)
Mm.

Jess Kismet (48:27)
so you sort of and and they do that with physical containment PC laboratories as well. So you have differential pressures of fifty

Jess Kismet (48:36)
Mmm.

Jess Kismet (48:36)
Pascals here.

thirty, twenty here and then and then it goes out.

Jess Kismet (48:42)
Yep.

Jess Kismet (48:43)
yeah. Have I answered your question? I hope I have.

Jess Kismet (48:45)
I so. think so. I think what I'm wanting to understand, think, is is it possible, like, would you be able to reduce the size of an air conditioning system based on a tighter building envelope?

Jess Kismet (48:56)
Yeah. Well, th the reason that you could reduce it was because you didn't have to you didn't have to design it to cater for all of that building pressurization. So instead

Jess Kismet (49:05)
Yeah.

Jess Kismet (49:06)
of it being one or two air changes, it can be back to that baseline of half an air change.

Jess Kismet (49:11)
And you're talking about

ambient pressure there, aren't you? Not it, not it.

Jess Kismet (49:14)
What

no, what I'm talking about is well, yeah, this is isn't it the units are important, aren't they? When I

Jess Kismet (49:20)
Yeah.

Jess Kismet (49:21)
say an air change, I'm talking about we take the we take the volume inside and and you know, area multiplied by that by the height,

Jess Kismet (49:30)
Yep.

Jess Kismet (49:30)
and we're we're working out that that total air volume per hour.

Jess Kismet (49:35)
and how much air your system has to change. Right, okay. Yeah, okay.

Jess Kismet (49:37)
Exactly. And and how much in addition to that and and how

it that would be a mathematical equation then to say if that

Jess Kismet (49:44)
Yeah.

Jess Kismet (49:44)
equates to fifty Pascals or or whatever, but we usually just make an allowance for you know, the volume and then

Jess Kismet (49:51)
Mm.

Jess Kismet (49:53)
that will be an additional amount over and above the

the plus or minus from the exhaust and the introduction of air that you're

Jess Kismet (50:02)
Yep.

Jess Kismet (50:02)
providing to make sure that this building is pushing out that infiltration. And that can be a significant load on an air conditioner. So if you can have that building super tight, then you only need the small, you know, safety margin. So it would make

Jess Kismet (50:17)
Yep.

Jess Kismet (50:18)
a big difference.

Jess Kismet (50:19)
It is incredible how much effort and work has to go into managing air inside buildings. And

Jess Kismet (50:24)
Absolutely. And

Jess Kismet (50:25)
then you add tropical moisture on top of it. Like it's actually insane.

Jess Kismet (50:30)
It

a lot of effort and the the part that is interesting too though is it's all it's a lot of theory too because

Jess Kismet (50:37)
Mm.

Jess Kismet (50:38)
you're you know, on a on a drawing or whatever it is, you're drawing, you know, arrows, this much is going here and everything else. But air in the end does what it wants, right? So it's all this

Jess Kismet (50:47)
Yeah.

Jess Kismet (50:48)
it's really a lot of theory, but you're you know, you're and and some of it

will never be tested. And that's the vulnerability of it because,

Jess Kismet (50:55)
Yeah. Yeah.

Jess Kismet (50:58)
you know, we we have all these great intentions and we write it down and sometimes we don't explain it as as you know, as clearly as what we perhaps should. In our head it makes sense, but it may not be completely

Jess Kismet (51:07)
Mm.

Jess Kismet (51:08)
obvious on the drawings. And then someone's got to interpret it and then install it. And then they may not be able

Jess Kismet (51:12)
Mm.

Jess Kismet (51:13)
to they might install it as you've said, but is it tested? Is it demonstrated

Jess Kismet (51:17)
Mm.

Jess Kismet (51:17)
to, you know,

There's no floating arrow over there which says that you're gonna have twenty litres a second go through there necessarily. So this is the vulnerability of these systems.

Jess Kismet (51:27)
Didn't you read the plan, air?!

All right, cool. All right, let's talk about cool engineers. Tell us about cool engineers.

Jess Kismet (51:35)
Cool engineers. So cool engineers maybe like maybe like s your podcast.

Jess Kismet (51:40)
Mm-hmm.

Jess Kismet (51:40)
Engineers

is my side hustle. It's my passion project.

Jess Kismet (51:44)
Yep. Yep.

Jess Kismet (51:46)
it was it was born when my kids were were being asked, you know, and to think about what subjects that they want to do and the and the career path that they're doing ahead. And engineering was literally the last profession on this great earth that they were gonna consider. It

Jess Kismet (52:03)
Mmm. Mmm.

Jess Kismet (52:04)
was it was just not for them. And

And even the guidance counsellor was really talking them, actively talking them out of it. And as a proud, you know, woman, engineer and mum, I was

Jess Kismet (52:16)
Mm, mm.

Jess Kismet (52:17)
just I was gutted by this.

Jess Kismet (52:19)
Mm.

Jess Kismet (52:20)
So after sitting with that for a while, I realized that I had kind of played a little bit of a part in in their poor perception of engineering because I I I hadn't taken the time to explain to them what I did. Or if I did, I hadn't

I hadn't really spoken about it warmly, right? And

Jess Kismet (52:39)
Mm.

Jess Kismet (52:40)
the more I looked into it, the more I saw that in media, in in movies and in sitcoms, engineers are really rarely portrayed as like the cool hero. And you know. yeah, exactly. And

Jess Kismet (52:50)
Yeah, my dad was a civil engineer so I'm partial to engineers.

Jess Kismet (52:59)
but you know, other than that, what what is it? Wallowitz in

You know, the Big Bang Theory, you know, he's the one that they that they torment, you know.

Jess Kismet (53:02)
yeah, love Big Bang. Yeah.

Jess Kismet (53:07)
I mean, Iron Man is a cool engineer, but he's probably not so much known for the engineer.

Jess Kismet (53:12)
Mm.

Jess Kismet (53:13)
but you know, there's there's very few examples of it, except that I just I am pretty excited about I don't know if you've seen I've seen it a few times on Instagram. I haven't seen the movie, but the Hail Mary movie with I think Ryan Gosling.

The alien that is his friend, Rocky, he's an alien, but he's a mechanical engineer, so I thought that was pretty cool. But anyway,

Jess Kismet (53:34)
Mm-hmm.

Jess Kismet (53:35)
I digress. so so the thing is, engineers are rarely portrayed as as cool. And yet

Jess Kismet (53:39)
Yeah.

Jess Kismet (53:40)
every single facet of people's lives, engineers are involved.

Jess Kismet (53:44)
Yeah,

Jess Kismet (53:45)
And when I

Jess Kismet (53:45)
and you're invisible.

Jess Kismet (53:47)
Well, when

I that's just it. And and when I when I would talk to young people and what they want from the career, they would nearly universally say, I wanna have a career of impact. And the thing

Jess Kismet (53:57)
Mm.

Jess Kismet (53:58)
is, I can't imagine another career w that that has more impact. I mean, a doctor is gonna save hundreds, maybe thousands of lives in their lifetime, but one engineer, one civil engineer or one structural engineer in one, you know, bridge design is gonna impact

thousands of lives, let alone if they, you

Jess Kismet (54:16)
Mmm.

Jess Kismet (54:17)
know, design hundreds of bridges in their in their lifetime. So I

Jess Kismet (54:21)
Mm-hmm.

Jess Kismet (54:21)
I s I see that as such a great impact. And the thing is we need more engineers. the numbers are staying flat. we're importing engineers and and I I I have absolutely no objection to overseas engineers.

Jess Kismet (54:34)
Mm.

Jess Kismet (54:34)
They've got they're exceptionally talented, but I would love to see our own homegrown right engineers.

Jess Kismet (54:39)
Mm-hmm.

Jess Kismet (54:40)
So Cool Engineers is my platform for doing my bit. I I'm trying to demystify engineering by talking about it, raising the

Jess Kismet (54:47)
Mm-hmm.

Jess Kismet (54:47)
profile of what what engineers actually do and encouraging engineers, including myself, to speak about their work with pride. And the other thing

Jess Kismet (54:54)
Mm-hmm.

Jess Kismet (54:54)
is that when I say that I'm a HVAC engineer, I would really like it if people don't immediately think that I am in, you know, I'm a vacuum cleaner salesperson.

Jess Kismet (55:03)
Is that what people think when you say that? you sell Dyson's. that's interesting. No.

Jess Kismet (55:04)
Like HVAC, huh? Vacuums. No. No, so

so you know, this and this is the failure of the industry, right? We've we've got to we've we really need to speak about it a little bit more and and and the like. So so if any of this resonates, if you are an engineer, if you are you know in buildings, involved in buildings, if you if you know a young person and and they are

you know, thinking about what they could do, you know, come and find me. I have a I have a newsletter on LinkedIn, which I publish fortnightly where I just talk about hopefully i interesting things that engineers do.

Jess Kismet (55:42)
Mm-hmm.

Jess Kismet (55:43)
I try not to limit it to HVAC, even though that's obviously what I know most, but but that's not

Jess Kismet (55:47)
Hmm.

Jess Kismet (55:48)
all there is. I have

Instagram, which I need to post more on, but you know, I my intention is just to show what engineers do and the the day to day of it. I'm not selling anything. I it's about service and and it's about

Jess Kismet (55:58)
Mm-hmm. Mm-hmm.

Jess Kismet (56:01)
wanting to get, you know, more engineers in into the industry. And the reality is everyone I speak to love what they do. I love what I do. So I want that gift for for for young people. I want I want people to love what they do. So

That's what it's about.

Jess Kismet (56:17)
All right, hit the show notes people. Go and have a look at cool engineers.

Jess Kismet (56:20)
That's it.

Jess Kismet (56:21)
All right, last question. Question I ask everybody, what is the most important thing that you've learned in your career that you want the listener to know?

Jess Kismet (56:27)
The most important thing mm.

Jess Kismet (56:30)
Is it dew point?

Jess Kismet (56:32)
That's a really good one. This is yeah,

do it do it generally or or yeah. Dew point is community. All right,

Jess Kismet (56:37)
It can be anything. It can be philosophical. It can be life advice. Anything.

Jess Kismet (56:42)
anything. All right, life advice, I would say, 'cause we've been pretty hot and heavy on the on the technical. I would

Jess Kismet (56:48)
Yep.

Jess Kismet (56:49)
say stay curious.

Jess Kismet (56:51)
Mm-hmm.

Jess Kismet (56:53)
walk into every conversation with the understanding that the other person has something

That you don't or know something that you

Jess Kismet (56:59)
Yes.

Jess Kismet (57:00)
don't. And if you can walk in with that open mind, like I've learnt this conversation as well, right? So so every single one, every is an opportunity, every conversation is an opportunity to learn something. And if you keep pursuing that knowledge and understanding, eventually you'll realize, like I do, just how little you know.

Jess Kismet (57:18)
Mmm.

Jess Kismet (57:19)
And that will then

Jess Kismet (57:19)
Mmm.

Jess Kismet (57:20)
be in the fire in your belly to learn as much as you can. There there is

Jess Kismet (57:24)
Yep.

Jess Kismet (57:24)
there is a great quote from Avatar and it's something like, it's hard to fill a cup that's already full. So so, you know, don't walk in

Jess Kismet (57:33)
Mmm.

Jess Kismet (57:34)
with that with that cup full or thinking that your cup is full. be like Jake and say, No, no, my cup's empty. You know, fill me up. So

Jess Kismet (57:41)
That's excellent advice.

Jess Kismet (57:44)
Cool.

Jess Kismet (57:44)
You don't know what you don't know, so stay open.

Jess Kismet (57:46)
That's it.

Don't be like those, what is it, that Diane Kru Dunning Kruger people, you know. Yeah. Yeah. No, see that to me, that's at the point where

Jess Kismet (57:52)
Yeah, yeah, I'm on the uptick of that. Like, I thought I knew stuff, I realise I know nothing. So help me!

Jess Kismet (58:02)
you are actually starting to know something. Once you realize how little you know, you're like you're on the exactly, you're on that uptick. So we're on our way. Yeah.

Jess Kismet (58:05)
Yeah, I'm at the very bottom of the uptick, I think.

Cool. Thank you, Sonia. This has been great.

Jess Kismet (58:15)
This has been such a pleasure, Jess. Thank you so much. No worries.

Jess Kismet (58:18)
Awesome. Awesome. Thank you very much.