“I almost don’t want to know.”
That’s Hamish at the end of this one, after Cameron Munro spent the better part of an hour explaining what a cheap sensor can tell you about your own house. Once you know what’s floating around in the air when you light the fire or fry the dumplings, it’s hard to go back.
We started our chat talking about monitoring, and it turned into a really good lesson on data. Matt has been putting sensors in the roof of his own house, and he’s got his Claude set up to turn the humidity readings into how many grams of water are in the air. Cameron’s first point is that you shouldn’t start by asking “what sensor should I buy?” Start by asking what you actually want to know. Matt calls it your hypothesis. In plain English, it’s what you think is going on.
Then Cameron shows us the simplest thermal comfort test going. You put a cheap temperature sensor inside a ping-pong ball, spray it matte black, and it tells you how cold the surfaces in the room are. That matters because a lot of the heat leaves your body towards cold walls and windows. A room can be 22 degrees and still feel cold, because the glass is sitting at 15. It’s a great way to show a client why you won’t put single glazing in their house.
Cameron also has a good line on the numbers themselves. Getting data is cheap and easy now. The data isn’t the point. If you’ve got a bunch of numbers and you can’t say what they mean, so what?
We spend a fair bit of time on Matt’s favourite topic, treated pine battens. Matt’s theory is that you don’t need them on Melbourne projects, and he’s putting sensors in a lot of his jobs to find out. Cameron has seen the air in a roof cavity sit at 80% humidity or higher from 6pm until 8 or 9 in the morning, and it can be colder than outside on a clear night. But he’s careful. That shows it’s a harsh spot. It doesn’t prove the batten is going to rot. Hamish shares his gut feeling, which is untreated battens on the walls and treated ones on the roof, especially a flat roof.
Cameron splits monitoring into three things: comfort, air quality and energy use. On energy, he explains why clamping a meter on your heat pump doesn’t tell you how much heating you’re getting. A heat pump moves heat, so every bit of power can give you three to five times as much heat. On air quality, we talk about carbon monoxide alarms (about $20, and you need one if you burn anything), and the time a client sent Cameron a photo of a carbon dioxide sensor and called it a carbon monoxide alarm.
Cameron’s big message on air quality is to measure what matters. He doesn’t think CO2 is the one to worry about. He thinks it’s PM2.5, the tiny particles that get deep into your lungs. About half comes from outside and half from inside. In the western suburbs of Melbourne, around 60% of the winter PM2.5 comes from wood fires, even though only a small number of homes use them. Frying and stir-frying spike it too. Matt admits he should have vented his range hood outside, and Cameron is waiting for the letter that says he was right.
The good news is that these sensors now cost under $100. You don’t need lab-grade accuracy. You just need one with an app that shows green or red and keeps the history, so you can see if you’re getting better or worse. Cameron finishes with what he’d like to see tested next, which is what’s happening inside our wall and roof build-ups, because that’s the stuff you can’t see.
As Hamish put it, you can have a ten-star house with a one-star occupant. Data helps, but only if you use it.
LINKS:
Connect with Cam: https://passiveanalytics.com.au/
Pro Clima - https://mindful-builder.captivate.fm/proclima
Wunderbuild - https://www.wunderbuild.com/
Biz Tech Guru: https://www.biztechguru.com.au/
Connect with us on Instagram:@themindfulbuilderpod
Website: www.yoursanctum.com.au/
Connect with Matt:
Instagram: @carlandconstructions
Website: www.carlandconstructions.com/
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[00:00:00] Matt: ProClima studio again. ProClima, major sponsor of the podcast, if you're tuning in for the first time. I don't know why that's so
[00:00:07] Hamish: funny. I don't know why that's
[00:00:08] Matt: so funny. I know, 'cause we kind of... It's funny, 'cause we actually forget each time to do it, and then we're, and we forget to introduce our guest as well.
[00:00:13] Hamish: Yeah, but we also, we also, like, never know who's gonna, like, start the podcast either. I know. And so it's like, uh, you, we're, like, looking at each other. 'Cause you've actually watched this on YouTube, I'm, like, looking at Matt, and he's like, "Uh..."
[00:00:23] Matt: So ProClima, big sponsor of ours.
[00:00:25] Hamish: Built to last. We've been using ProClima for, since 2018.
[00:00:29] Matt: So actually, on census, we should... This is gonna cover... So we're gonna talk about monitoring- Not
[00:00:33] Hamish: census.
[00:00:33] Matt: It's not... It's the census. 'Cause
[00:00:34] Hamish: did anyone fucking do the census- Yeah. ... two nights ago? What?
[00:00:37] Matt: So I'm gonna... I could get myself in so
[00:00:40] Hamish: much- That, like, that's why I need to go on fucking medication, 'cause I... It took me, like, four hours to do that and- So
[00:00:44] Matt: I, I could get myself into so much trouble here.
[00:00:46] So- And I'm just gonna say it ...
[00:00:47] Cameron: one of the most, single most, uh, important bits of government data collection.
[00:00:50] Matt: Is it actually?
[00:00:51] Cameron: Uh, of super useful in
[00:00:53] Hamish: so many ways. Uh, do you know, as I'm reading- It's actually ... as I'm reading through it, I'm like- Really? ... "Okay, I understand why we're doing this." Like, I get it.
[00:00:58] Absolutely critical. I totally get it.
[00:00:59] Matt: Absolutely. [00:01:00] The... But I had to fill out Noah's. She's 13 months old, and the question I get is what level is the highest level of education. I
[00:01:06] Hamish: got
[00:01:06] Matt: that one too. I was like, "I'm just gonna tick tertiary." Like, I- I hope you didn't. What? I did. But, like, like, it's a stupid thing, but- You have
[00:01:13] Hamish: just skewed all the data,
[00:01:14] Matt: Matthew.
[00:01:15] No, because, like, obviously it, when you do certain people, it filters the different questions. Yeah, it does. Surely as a kid that is 13 months old, they go- Yeah ... "Let's clear that question."
[00:01:23] Cameron: You, you can't, you can't prejudice what the answer's gonna be, though. You've got to let the respondent answer. And then the reason why it takes the better part of a year for the census results to come out is they do a whole lot of cleaning of the data to remove-
[00:01:34] obviously eg- egregious entries, like what you've just done there, Mr. Callan.
[00:01:39] Matt: Well, there's one which is like, "What language does she talk?" I wrote other. I wrote baby talk.
[00:01:42] Hamish: I wrote baby too. I wrote baby too.
[00:01:45] Matt: I wrote baby-
[00:01:45] Cameron: A- and you two- ... you two are why it takes the better part of a year- ... for the census data to come out.
[00:01:52] Matt: I can't believe he wrote that one. I mean, she screenshotted it too.
[00:01:55] Hamish: So we have a kid about the same age. And I wrote, and I wrote, f- "What language?" Other, baby.
[00:01:59] Matt: Baby [00:02:00] talk. That's what I wrote. Look at him.
[00:02:02] Cameron: And so you are delaying the construction of hospitals in new build areas- Oh, I'm not taking responsibility
[00:02:08] the construction of roads- I blame the government for that ...
[00:02:10] Hamish: all sorts of things.
[00:02:10] Matt: Yeah. Well, don't ask stupid questions that you might get stupid answers to.
[00:02:14] Hamish: They- They're very- Yeah ... reasonable questions if you were- Yeah. Do you know what? I, I must admit, I, as I'm reading through it, I'm just like, "Oh yeah, I kinda understand why this is important."
[00:02:22] We do it
[00:02:22] Matt: every two years?
[00:02:23] Hamish: Every five years.
[00:02:24] Matt: Oh, I felt like I did it not long ago. Um, so we're talking monitoring and censoring. Um, I did, I was having a chat with Cam. I don't know if you've seen this ProClima in Denmark the other day. I don't want to get in trouble here. Germany. Germany. They've actually released an, or they're looking at an ADHERO, and it's got sensors built into the ADHERO.
[00:02:43] Hamish: Do we talk to Villy about this for- No ... sensors with water and stuff like
[00:02:48] Matt: that too? Yeah, so apparently they can like, yeah, so if you- Yeah ... so idea, like I was like, I... My brain goes to like you could do a rooftop deck, you put the Adhere on, it's got the sensors all wired into it, so if there's something going wrong, it will l- alert you.
[00:02:58] Hamish: Yeah, I think, I think Villy was [00:03:00] saying, um, they're doing it- It's
[00:03:00] Matt: not here in Australia- It, it- ... and it's being tried and tested overseas. It- So just caveat
[00:03:04] Hamish: on that ... and, and it's for, um, uh, like big commercial buildings, like if there's a leak in the wall. Mass timber and stuff. Mass timber, yeah, yeah, that's right.
[00:03:10] Matt: Like, what a, like, what a great idea if we could make it work. I think there's some issues around the electrical voltage through a membrane, and the standards and codes, and what happens. Yeah. Which is fair enough, but I think that is such a brilliant idea.
[00:03:21] Cameron: There's no reason why you can't install little water me- uh, moisture sensors in a roof assembly now.
[00:03:27] Like, there's plenty of those things available- Well, just- ... under 20 bucks a pop. You could do the bathroom as well though.
[00:03:32] Matt: Well, that's what I have. Put
[00:03:33] Cameron: them in your bathroom.
[00:03:33] Matt: Yeah, so I've got... What have I got? Well, it's probably similar. The other day we ripped up the roof at my house, and we put the little, um, temperature humidity sensor in there to see, uh, what's actually happening for our moisture, because you can convert, you've taught me, Cameron, and my little Claudis now does, does a conversion, and it converts from absolute, uh, from relative to absolute, so we can see how much grams of water.
[00:03:56] Is that correct?
[00:03:57] Cameron: In, in the air,
[00:03:58] Matt: yeah. Yeah, in the air, in the air. So you can actually [00:04:00] see what, how much moisture is actually in that- depending on that calculation. Yeah, right. So, um, monitoring-
[00:04:05] Hamish: And then, and then why would we do that? What, why would we bother?
[00:04:07] Matt: How much water's sitting in those cavities and-
[00:04:10] Cameron: Mm
[00:04:10] Matt: is it gonna rot out or?
[00:04:12] Cameron: And, and I think Hamish's point is the key whenever you start thinking about monitoring. So whenever I have discussions about this, people seem to wanna jump straight to the, the answer. "What, what should I use?"
[00:04:23] Matt: Just not tread pine.
[00:04:24] Cameron: What... No, no. What, what sort of, what sort of monitor- What sort of monitoring device should I use?
[00:04:31] And the, and the qu- and to me that's a perplexing question because it's like, well, what do you want to know?
[00:04:37] Hamish: Yeah.
[00:04:38] Cameron: Like-
[00:04:38] Matt: What's your hypothesis?
[00:04:39] Hamish: Well, I guess here, here, here's a question. W- what should we be monitoring, and, and what is, what is a valuable thing to monitor? 'Cause we can monitor anything and everything.
[00:04:47] Matt: So I like at my house, so we've got-
[00:04:49] Hamish: I was asking Cam.
[00:04:50] Matt: Yeah, I know, but I've got temperature and, and humidity 'cause I just wanna know-
[00:04:53] Hamish: Yeah ...
[00:04:53] Matt: how we're sitting. It's internal.
[00:04:55] Hamish: Yeah. So that, so that's, that's, that makes sense. But what are some of the other things that we should be monitoring?
[00:04:58] Cameron: Okay. So, so we [00:05:00] could start with the, the thermal performance or comfort of the building.
[00:05:03] Yeah. And obviously ambient temperature is one of those. That's air temperature. Uh, uh, relative humidity is important, obviously for the moisture within the, the buildup, building up within different parts of the building. Um, if you wanna measure thermal comfort more accurately, you wanna be look, looking at things like the black bulb temperature.
[00:05:22] So this is the radiant surface temperatures of within the building, because the way we perceive temperature is not just about the air temperature in the space, it's also the radiation of the sur- Ah, okay ... the surfaces. So about 60% of the heat transfer from us to our environment is from our skin radiating towards cold surfaces.
[00:05:43] And so if you can imagine a building that's 22 degrees air temperature inside in winter, and you've got single glazing, then that glass is probably 15 degrees maybe, the surface temperature. And so your skin is radiating to that surface.
[00:05:57] Matt: And how you- So how are you test- how are you testing radiation?
[00:05:59] Cameron: You...
[00:05:59] This is a [00:06:00] black bulb thermometer. So it's, the simple way to do this is you get a temperature sensor. These cost, like, two bucks. You put them in a, get this, in a- He's getting
[00:06:08] Matt: excited 'cause we've got him on a topic he loves here. I
[00:06:11] Cameron: love it. I love it ... you, you put them in a ping pong ball. And you pr- and you spray that ping pong ball matte black.
[00:06:19] Hamish: So you cut, cut the ping pong ball in half and
[00:06:21] Cameron: then- Or, you know, just cut a little hole, drill a little hole- Put it in there ... in the bottom. Okay. You slot this thing on a wire, the sensor, the thermocouple- Like there's a- ... into this ping pong ball.
[00:06:28] Matt: The black will absorb the heat the most?
[00:06:30] Cameron: Yeah. And it's, and it's a, and it's absorbing the radiation from the environment around it.
[00:06:34] And so the air temperature within that ping pong ball is essentially the radiant temperature.
[00:06:39] Matt: So we're not talking radiation from maybe electrical wires here?
[00:06:42] Cameron: No, no. We're, we're, we're talking-
[00:06:44] Matt: Not EMF stuff ... thermal
[00:06:45] Cameron: radiation.
[00:06:45] Matt: That's another thing we could test that Cam's big on.
[00:06:49] Hamish: Fucking hell, Matt So you broke the bank
[00:06:52] Matt: I know.
[00:06:52] It's gonna get you.
[00:06:53] Hamish: So m- moving on. So what... Okay, so, so I l- I love... I, I, my kids would love this, by the way, like actually [00:07:00] going and doing it. But why would we bother testing that? Well, what's the benefit? What, what, what, what data is that giving us?
[00:07:04] Cameron: So i- if you're trying to make an argument to a client, say for yourselves as builders, that we can't put single glazing in your house because it's gonna condensate and because your thermal comfort's not gonna be very good, you could use that to demonstrate that the overall surface temperatures within this room, if you've got a room that you can use, and there's plenty of buildings around that would be like that, uh, is, is significantly different to the air temperature.
[00:07:30] So that, that, um, uh, radiant surface temperature is much, much lower, and therefore it's not gonna be comfortable for you. A-
[00:07:37] Matt: and this hooks back to your little data hub that you'd make with the Raspberry Pi thing, and
[00:07:42] Cameron: just simply- That, that's the way I do it- Yeah ... but you can buy these things as commercial things.
[00:07:44] Okay. There's a, there's a mob in, um, I think it's Canada or the US that sells a box. I did look at buying one of those, like 600 US bucks or something like that. It's, it's a, it measures to ASHRAE 55, which is the com- thermal comfort standard. Yeah. And so it measures air temperature, relative... [00:08:00] uh, no, not relative humidity, 'cause that's not a, a variable at play.
[00:08:03] This, this whole radiant surface temperatures and stuff, and it gives you that data. It's a very cool little gadget that we've... Well, heaps of fun. Uh-
[00:08:12] Matt: But we don't need it for the way we would build. We kinda know.
[00:08:14] Cameron: No, unless you wanna verify that what you've done is, is, is bee's knees.
[00:08:20] Matt: Yeah.
[00:08:20] Cameron: Um, but, but I suppose this is the other big thing with monitoring, is like it's one thing to get data, which is these days is relatively cheap and easy to do, but the data of itself is not the object.
[00:08:32] I've got a bunch of numbers here. So what?
[00:08:35] Matt: Yeah.
[00:08:35] Cameron: How do I interpret this data? How do I analyze this data in order to obtain information or insights into the problem I, uh, was asking at the outset? So back to Matt's word, you know, hypothesis. That's what scientists like to use. My hypothesis is that, uh, you know, the, um, the, the cavity within this wall is, is [00:09:00] going to have very, uh, extreme...
[00:09:03] you know, is gonna suffer from lots of condensation- Yeah ... or something like that. And, and you might then go and define what you mean by lots of condensation numerically.
[00:09:12] Matt: Yep.
[00:09:12] Cameron: And then you go and design an experiment in order to test that hypothesis. Or you might be at a more sort of, uh, subjective level.
[00:09:22] Uh, as a client, the client has built, you know, commissioned you to build their house, and they're h- hopefully very happy with it subjectively. But hey, I'm numerically oriented. I want to understand more how, how to benchmark the performance of this house.
[00:09:37] Matt: Well, humidity was a, that's what went wrong with my own house, so I thought, well, living quite in a hu- like it was quite humid.
[00:09:42] Cameron: So yeah, perfect example, right? So, you know, the conversation we had last summer was you'd just moved into your house. You said it felt like it was really humid, and we happen to have sensors in your building. Yeah. The temperature and relative humidity sensors, and I could demonstrate to you through that data that in fact the [00:10:00] humidity in your house was well within the boundaries that I would expect it to be.
[00:10:05] Which I think was right b- in the sense that the way we perceive humidity is really
[00:10:13] Matt: Like it's how, like I found, I found it stickier So what, so we don't... So what,
[00:10:15] Hamish: what, yeah, so what was it in
[00:10:17] Matt: your- I just found it a little bit stickier than what I thought so. But as we'd probably, we'd just moved in, there was a lot of water that went into the lime wash paint.
[00:10:23] The slab was probably still somewhat curing. There's a lot of plaster water. Like- Yeah ... there's still water within the building most likely that was still-
[00:10:29] Cameron: But, but you didn't- Yeah ... have excessive humidity.
[00:10:31] Matt: No, no, no. We didn't. So, so I
[00:10:31] Cameron: think that's-
[00:10:32] Hamish: Yeah, that, that's, yeah, 'cause you, you just
[00:10:33] Matt: said- But also compared to outside it was pretty low
[00:10:35] Cameron: I, I, I think what you're experiencing was temperature.
[00:10:37] Yeah, yeah. So o- often in the summer, i- certainly in southern Australia, when we claim it's really humid today, it's often just because it's quite warm-
[00:10:46] Hamish: Yeah, yeah ...
[00:10:47] Cameron: inside.
[00:10:47] Hamish: Was it, was it, was it... Do you also think that maybe in your situation it was just you recalibrating what you- It was
[00:10:52] Matt: expectation probably too
[00:10:53] was normal?
[00:10:53] Hamish: Yeah.
[00:10:54] Matt: So like, uh- Yes. Like- So in summer- Yeah ... I think of what I've learned, you gotta work pretty hard with a energy efficient home to [00:11:00] keep it low because if you just let it go, it will just cost-
[00:11:03] Hamish: Be interesting, be interesting to have this conversation in, you know, April next year to see- Yeah
[00:11:08] what you experience
[00:11:08] Matt: because- Well, I know, I'm kind of learning how to use the house. Yeah. Like I didn't run my ceiling fans. I also don't have the best cross ventilation, but I know now how I could maybe- Yeah ... improve on that.
[00:11:16] Hamish: Yeah. Yeah.
[00:11:16] Matt: Um-
[00:11:17] Cameron: And we did have a conversation- Yeah ... about how, so in the thermal modeling, we make assumptions about how often you open your windows.
[00:11:22] Yeah. Yeah. And being in, in, in a western Melbourne, you weren't opening your windows.
[00:11:25] Hamish: No. Do you know? I was just thinking as we're having this conversation, like, there's so, such great, like, YouTube, like, shorts that we could do out of these conversations. Like, I think there's like actually doing some of these experiments and showing people how easy they are and then putting it into context because maybe I'm just a nerd and I, I, I find this stuff interesting, but, like, this would be cool stuff to actually do at home.
[00:11:46] Mm. Like, if you're thinking about renovating and you're asking, "Why wouldn't I just turn the AC on?" Like, "Why wouldn't I just put the heater on?" And if you can actually do some of these really simple tests at home, you can actually demonstrate the reason why you would do
[00:11:57] Cameron: it. Or, or conversely, why is it [00:12:00] when I do turn the heating on, I'm still cold?
[00:12:02] Matt: Yes.
[00:12:02] Hamish: There you go.
[00:12:03] Cameron: Well- Yeah ... the reason it's cold is because of radiating surface temperatures, and here's the data to demonstrate that. Yeah, yeah.
[00:12:08] Matt: I think the one that we looked at doing in mine, I just ran out of time because Nicole, uh, was due any day at that point. It was the last thing on my mind. We- the question we had was, and I always get this with clients with slabs, is like, "Oh, is it gonna be that warm?
[00:12:19] It's gonna be cold on the slab." Whilst I can tell you definitely not at my house. A temperature probe that we could've had that was hooked up would tell us at all times what the slab was sitting at. Mm. Having said that, I kind of now know with my underfloor heating in my, my bathroom upstairs, if I turn it on, it, it kinda gives me a gauge, a temperature sensor with, like, what it's at, and usually it's at 19.5 or 20.
[00:12:42] I don't know how accurate that is, but that- The
[00:12:44] Cameron: slab is 19.5.
[00:12:45] Matt: Yeah. Roughly. Yeah. Roughly. Yeah. So-
[00:12:47] Cameron: The slab itself is probably higher. Isn't that a thermo- stat in the room itself? So that's measuring air temperature.
[00:12:53] Matt: I, no, well, I don't know. Because it's, it's all hooked up through a wire to the, the coils underneath I've
[00:12:58] Hamish: got a test that you could do to [00:13:00] test the, um-
[00:13:00] Matt: I'll put a spindle- You get a
[00:13:01] Hamish: ping pong ball, you cut it in
[00:13:02] Cameron: half.
[00:13:03] Um- I, I think most of those devices, there'll be a little thermocouple within the controller- Big ... on your wall. Yeah. And so it's measuring air temperature. Yeah.
[00:13:09] Matt: Yeah, okay.
[00:13:10] Cameron: Uh, um-
[00:13:11] Matt: But a good one at the moment we're talking about a lot, and I've been joking for a while, is the n- you don't need treated pine batons.
[00:13:16] We now have sensors going in a lot of our projects, 'cause we've got this hypothesis, and we want to prove within Melbourne all the projects we're working on that, yes, you don't need treated pine. Mm-hmm. And that's my hypothesis.
[00:13:28] Cameron: A- a- and I think, you know, a little, a word of caution that we need to be careful what we mean by proof.
[00:13:33] Like, you know, we've proved beyond reasonable doubt that smoking causes lung cancer and is bad for you. Yeah.
[00:13:39] Hamish: Yeah.
[00:13:39] Cameron: You know? That- Yeah, what
[00:13:40] Hamish: you're doing is probably anecdotal ...
[00:13:41] Cameron: uh, a- a- and there is a-
[00:13:43] Matt: Nice beyond reasonable
[00:13:44] Cameron: doubt. You know, s- s- science is about tr- trying to establish truth, but it is never definitive.
[00:13:50] Yeah. And it can always be questioned. So I might do some research and discover that, in fact, smoking is good for you because of something. Now, clearly the scientific community is gonna have, [00:14:00] you know, raise eyebrows at that. And so your evidence to refute that-
[00:14:04] Matt: Yeah ...
[00:14:05] Cameron: years of experience and knowledge has got to be bloody compelling in order to change everyone's view of the world.
[00:14:11] But that is how science works, is continually doing new research- Yeah ... testing existing hypotheses, trying to find holes in things.
[00:14:19] Matt: Yeah, and I think for us with the, we just want to show that- I, I'm pretty certain we don't need it, and we can have a rough guide that it's, whilst it's not a PhD or a thesis or anything like that, it's gonna be enough information that we feel comfortable that what we're doing is completely
[00:14:33] Hamish: fine I think at the end of the day, that's what it comes down to.
[00:14:35] Like- Yeah ... and, and, okay, this is my opinion, my opinion only. Like, on a wall, on a vertical surface on a wall, I would be like, "Yeah, you know what? I'd probably put non-treated pine battens, uh, hard up against the, um, cladding, and then non-treated battens for the cladding battens." If I go to the roof, I'll probably put treated battens on them, like hard up against the, um...
[00:14:57] But that's just me. Well, that, that's where I've got- And that's where my gut, my gut
[00:14:59] Cameron: feels [00:15:00] And, and, and, and maybe more so on a flat roof than a sloping roof. Exa-
[00:15:02] Matt: exactly. Yeah. 'Cause that's where I've got one of my sensors- Yeah ... on a flat roof that gets- Yeah ... zero sun. Yeah. At all, like zero, it's south. It's like it can't get sun, and it's on a cavity batten, and it's a white roof that's two degrees.
[00:15:13] Mm. With-
[00:15:15] Cameron: A- a- and just back to the monitoring part of that. So what you've got in there at the moment is- Yeah ... a temperature and relative- Yeah, yeah ... humidity sensor that's measuring the conditions in the air- Yeah ... within that cavity. And then the other way we do that for that particular problem is we use those little pin-type moisture meters.
[00:15:31] The
[00:15:31] Matt: pro- protometers, whatever
[00:15:32] Cameron: you call them. Yeah. That, that screw into the, the stud and measure the water moisture content within the timber itself. Is that what you've
[00:15:39] Matt: got at- Pro- pro- protometers ... have you done that at your
[00:15:40] Hamish: place?
[00:15:41] Cameron: S- so- Yeah ... I've got, got a few of those around, and- Yeah ... Sean down in Tassie's got plenty of them.
[00:15:45] I've got, I've
[00:15:45] Matt: got one in one of my projects as well. Yeah. If, if we're just buying them, we're gonna put one on each job.
[00:15:49] Cameron: Yeah. So, so coming back to where we started. What's your question that you wanna find out about? How are we gonna evaluate that question? You know, what are the parameters by which we're gonna measure it?
[00:15:59] [00:16:00] Temperature, water moisture content. And then what are our measures of success? What do we define as acceptable or failure for this particular, uh, question that we're asking ourselves?
[00:16:10] Matt: So what are we doing for the, the treated pine? Like, what would you consider an, an okay amount of absolute moisture within that cavity?
[00:16:18] Cameron: Well, that's, so that's where, you know, when I started off this whole- Yeah ... hornet's nest of of de- debate-
[00:16:24] Matt: Yeah ...
[00:16:24] Cameron: is I was demonstrating that the relative humidity, or, uh- Yeah ... within that cavity, you know, spends a long period of time, from sort of evening, 6:00 p.m. in the evening, till 8:00 or 9:00 a.m. in the morning- Yeah
[00:16:37] at or above 80% relative humidity in a Victorian climate. And I suggested that to me feels, my hypothesis is, that feels like that's quite a long time to be in that sort of condition in-
[00:16:50] Matt: Yeah ...
[00:16:50] Cameron: admittedly colder conditions. Is there sufficient drying during the subsequent day period- To more than compensate for that [00:17:00] wetting that's occurred overnight And
[00:17:01] Matt: that's probably the time right now we're talking in middle of Aug- or middle of August is this is where it's like the worst drying capacity A-
[00:17:07] Cameron: a- and you're seeing that for your house already.
[00:17:10] Well- You know, the roof is getting high relative humidity
[00:17:12] Matt: But it's, for sometimes it's actually colder in that cavity than it is outside
[00:17:16] Cameron: A- and that was to my point, that it's extreme in both directions. Yeah When the sun is out and striking that- Yeah ... that cladding, the cavity is warmer than outside. Yeah Overnight, especially on a clear night-
[00:17:28] Matt: Yeah
[00:17:28] Cameron: it will be colder than outside.
[00:17:30] Matt: Yeah, I noticed that. I was, I was like, "Oh, it's ac-" and it was, like, two degrees colder in that little cavity Is it night
[00:17:34] Hamish: sky
[00:17:35] Cameron: radiation? Radiation, yeah Correct. But what that doesn't establish is that the batten's gonna rot
[00:17:41] Matt: Yes.
[00:17:42] Cameron: And that's the, that's the, you know, if there's a weakness in my argument, I argue it's that second part of the link.
[00:17:49] The, the first part of my argument that these are extreme environments, I think I can, you know, confidently state. I cannot say that that means your button's gonna rot out.
[00:17:59] Matt: [00:18:00] Well, the best way to do it is in 30 years, take off everyone's bull and roof and go do a massive eye test and see what's happened.
[00:18:06] Cameron: Which is a bit late, of course.
[00:18:07] Matt: Yeah.
[00:18:08] Cameron: Uh,
[00:18:08] Matt: yeah.
[00:18:09] Cameron: Um, but just coming back to the whole monitoring question. So I think we've got, there's probably three classes of monitoring we might wanna do on a building. So we've got thermal comfort, temp- temperature, relative humidity. Let's put that in a, a box.
[00:18:22] Matt: Yep.
[00:18:23] Cameron: The second one is probably related to indoor environment quality or indoor air quality, things like, uh, everyone talks about CO2, carbon dioxide, particulate matter, and so on, which we can come back to in a second.
[00:18:35] And the third one is energy use. So-
[00:18:40] Matt: Oh, yeah ...
[00:18:40] Cameron: part, part of this that always comes up, especially in passive house world, is we've got these particular parameters, you know, our prediction of how much heating energy you're gonna require and how much cooling energy you're going to require. And you might ask a reasonable question.
[00:18:55] Having paid, you know, Carlin Construction or Sanctum Homes X dollars for my house, [00:19:00] how do I know that I'm consuming as much energy as they say I would do?
[00:19:03] Matt: How do you do that? You have to go back to the switchboard on each circuit, put a sensor-
[00:19:06] Cameron: With great difficulty- Just, yeah ... is the short answer. Yeah. So you put a CT clamp, a current transformer- Yeah
[00:19:11] clamp on the, on the heat pump-
[00:19:13] Matt: Yeah ...
[00:19:13] Cameron: circuit. So you've wired up a, an in- a heat pump, you know, an AC inside. You put the CT clamp on it. You can measure the current draw going into that heat pump, how much energy, how many watts or how many watt hours are going into the heat pump. The problem is, that's not how much heating is going into the house or how much cooling is going into the house.
[00:19:36] It
[00:19:36] Matt: gets lost or it might be absorbed by the thermal mass in the house. Is
[00:19:38] Cameron: that what you mean? No, no. It's because of the coefficient of performance- Okay. Yeah ... the function of how the heat pump works. 'Cause it- Yep ... take it another way. It's not a
[00:19:46] Matt: one-to-one ratio. Is that
[00:19:47] Cameron: what you mean? No. Let, let me take it another way.
[00:19:48] So Matt's got, um, a resistive heat, uh, heating in the floor in your bathroom.
[00:19:54] Matt: Yeah. Yeah. Super efficient heating.
[00:19:56] Cameron: No, it's not. So if I, if I [00:20:00] had that CT clamp on a circuit, like I just wired up one dedicated- Yeah ... circuit for that, that- Yeah ... uh, resistive heating element. If I know I've got one kilowatt of draw, or two-- let's go with a more realistic number, 200 watts- Yeah
[00:20:13] going through that circuit into your resistive towel rail, I know that I've got almost exactly 200 watts- Yep ... of heating going into your bathroom.
[00:20:21] Matt: Yep.
[00:20:21] Cameron: One to one, perfect. I've measured how much heating I put in my building. But for the vast majority of us, the most of our heating in the winter is being fed through, met through a heat pump, a reverse cycle AC.
[00:20:34] And so when you put that 200 watts into your Daikin, Mitsubishi, whatever heat pump, you're not actually generating 200 watts of heating.
[00:20:43] Matt: Might be generating 1,000.
[00:20:44] Cameron: You're generating 1,000 because what you're doing is pumping heat energy. Yeah. You're running a compressor that's extracting heat energy from the air around you outside and injecting that inside the building.
[00:20:56] It's not moving air, to be clear, but it's moving the heat energy. [00:21:00]
[00:21:00] Matt: Mm. Mm.
[00:21:00] Cameron: And it's transforming it by a factor of three to five.
[00:21:04] Matt: Yeah, okay. So you'd have to have a... You'd have to know their coefficient performance, then do a calculation and convert that. Which-
[00:21:10] Cameron: At a- Yeah ... at a given temperature, and there's a whole bunch of factors that come into that because that COP is not a constant, and so it would always be an estimate.
[00:21:18] But depending on what you're trying to do, that might be fine. Like, if you're trying to validate your model, knowing that you're within plus or minus, say, 10% is almost certainly good enough. Yeah. You're not gonna try and sue your builder because you're using 10% more heating energy. If you use- Well, who's-
[00:21:36] five times more- Yeah ... then you'd be like, "Hang on a minute. Did you put the insulation in that you said you did?"
[00:21:40] Matt: Or how's this, who's to say they haven't just left a window open the whole time?
[00:21:42] Cameron: And, and there's, and, and, and-
[00:21:44] Matt: It's user error ...
[00:21:45] Cameron: how do you know if in the middle of winter they haven't set their thermostat to 26 degrees?
[00:21:49] Matt: Yeah. So, so, yes.
[00:21:51] Hamish: So, so the, I think Jeremy Spencer says you can have a ten-star house with a one-star occupant. Yeah. Like, you know, it's, it's- That's actually good ... it's brilliant, yeah.
[00:21:58] Cameron: It's, it's spot on,
[00:21:58] Matt: isn't it? So, so let's go back to [00:22:00] the second one when we think about air quality and stuff, because I think let's, let's look at old homes first that aren't even high-performing.
[00:22:07] Carbon monoxide monitoring should be in, uh, anything you're burning anything inside- Yeah ... or gas
[00:22:11] Cameron: appliances. So, so car- carbon monoxide only if you're burning something inside your house. Yeah.
[00:22:15] Matt: Or, or ga- or you got a gas cooktop.
[00:22:18] Cameron: Yeah.
[00:22:18] Matt: Or not
[00:22:19] Cameron: gas top. Well, that's, that's burning something in your house.
[00:22:19] Matt: Yeah, yeah, yeah, okay.
[00:22:20] Yeah, yeah, fair point.
[00:22:21] Cameron: Yeah. Yeah. So, so, you know, don't burn stuff in your house, carbon monoxide problem goes away.
[00:22:26] Matt: Yeah.
[00:22:26] Cameron: So do, too, does nitrogen dioxide, nitrogen- Yeah, yeah ... oxides. Yeah. NOx.
[00:22:30] Matt: Yeah.
[00:22:31] Cameron: Um, so you can do an awful lot for indoor air quality just by not burning stuff.
[00:22:35] Matt: Yeah.
[00:22:36] Cameron: And that includes Hamish's fireplace.
[00:22:39] Um-
[00:22:39] Matt: And, A, can you get those cheap sensors as well, like we got for mine, for those sort of things, or that's a bit different?
[00:22:43] Cameron: Yeah. You can go to Bunnings, they've got a CO2- CO- CO, carbon monoxide- Yeah ... um, alarm.
[00:22:49] Matt: Yeah.
[00:22:49] Cameron: Because this is such a critical problem. Especially, you know, everyone will have heard those stories about those un-flued gas heaters- Yeah, yeah
[00:22:55] that killed the little old lady because the thing gunked up. And carbon [00:23:00] monoxide is clear, odorous. You just feel a bit drowsy, gonna have a bit of a nap, and you're dead.
[00:23:05] Matt: Yeah. Okay. So, so it's something... Okay, so you can get them from Bunnings. And okay, and they're, where are you in most of those f- is that mainly a gas appliance, or is that, a wood fire's just as highly likely?
[00:23:15] Cameron: Well, a- any of, any incomplete combustion- Yeah ... will generate some CO.
[00:23:20] Matt: Yeah. Okay. Um- Okay. Interesting. That's a very... Okay. And then because you did say that they, and it's from my basic chemi- chemistry knowledge, once you add that extra molecule, it's a whole different calculation.
[00:23:31] Cameron: Yeah. Yeah. So this is, this, this was a, you know, a classic anecdote a few months ago.
[00:23:34] Yeah. A, a passive house project where the client had a fireplace and despite many years of me trying to convince them not to, they did it anyway. Okay, yes, you can certify passive houses with fireplaces. So if you're listening out there and adamant that's what you want to do, okay, I'm gonna try and convince you adamantly that you shouldn't do that.
[00:23:53] But ultimately you can do it. Uh, um, that-
[00:23:58] Matt: So more people do it just to annoy [00:24:00] Cam.
[00:24:00] Cameron: Yeah, possibly. And so in this, a- and, and one- They're fucking expensive
[00:24:03] Matt: as
[00:24:03] Hamish: fireplaces
[00:24:04] Cameron: too ... one, one of the requirements if you do that for a passive house is that you have a carbon monoxide alarm. It's not a, it's not a monitor, it's not recording the carbon monoxide concentration.
[00:24:14] It just triggers and it sets off like a fire alarm, a smoke alarm. It just triggers when it hits the, a threshold to say- Open a window ... "Shit's hit the fan. Get out of your building now."
[00:24:23] Matt: Okay.
[00:24:24] Cameron: You know?
[00:24:24] Hamish: And, and, and, and does it go... At that level, are you moving fast? Like, do you want to get out of the-
[00:24:30] Cameron: Yeah
[00:24:30] 'cause I, I, I don't know what the threshold is, so I'll be- You're not gonna go, "
[00:24:32] Matt: I'll, I'll be a few hours."
[00:24:33] Cameron: No. You're not gonna finish your TV show. I mean, uh, cle- clearly they'd be setting it at a sensitivity way below the level at which- Oh, well, I was just gonna
[00:24:40] Matt: say- But if it w- w- just open all your windows and doors, worst case.
[00:24:42] Cameron: Yeah, and turn off whatever the- Yeah, yeah, yeah ... it is that you're doing.
[00:24:45] Matt: So cut,
[00:24:46] Cameron: so
[00:24:46] Matt: carbon
[00:24:46] Cameron: monoxide. You know, if for argument's sake it is a fireplace, you know, call someone to come and have a look at it- Yeah ... 'cause maybe the flue's blocked up. Yeah, yeah. You know, obvious things like that.
[00:24:54] Matt: Um- Like, they're not, they're $20 on Amazon.
[00:24:55] I'm just looking right now, like, of the alarm. Like, they're not even that expensive.
[00:24:58] Cameron: No, no, uh, to [00:25:00] just like a smoke alarm, right? Um, so I think, you know, i- if you have combustion in your house, you should have that. The, the next one is you, you add an extra mo- oxygen molecule to carbon monoxide- It's CO2 ... you get carbon dioxide, which is a completely different thing.
[00:25:12] And so coming back to my little anecdotal story, in that particular job, the client was adamant they had a carbon monoxide sensor. They sent me a photo of it to send to the certifier for review, and I looked at the photo, and it was an Aranet4, which is a carbon dioxide sensor.
[00:25:27] Matt: Which would've looked very high.
[00:25:29] That's true. You'd be dead.
[00:25:29] Cameron: A- a- and they also had the, the IKEA one that I keep talking about and Hamish about too. Um, but they were measuring carbon dioxide. Completely different- ... compound altogether. Molecule altogether. So what's different between the
[00:25:40] Hamish: two?
[00:25:40] Matt: One's got an extra, two extra oxygen.
[00:25:42] Hamish: So- Okay, okay.
[00:25:43] But what, what's, what's the reality of monoxide and
[00:25:46] Cameron: dioxide? Yeah, so, so carbon dioxide is, again, a combustion byproduct, but is also something we exhale.
[00:25:52] Hamish: Okay.
[00:25:52] Cameron: So in a building- Yeah ... the majority of the carbon dioxide in our environment either comes from outside, because there is, as we know, a [00:26:00] concentration of carbon dioxide outside.
[00:26:01] Yep. About 425 parts per million at the moment, increasing at about two parts per million, contributing significantly to our, our climate crisis. Yep.
[00:26:11] Matt: Okay.
[00:26:11] Cameron: Um, so some of it's coming from outside, but when I'm inside a building, the CO2 concentrations, like in this room that three of us are in a relatively small meeting room now, the CO2 in, in here is probably north of 1,000 parts per million You know, maybe 1,500, something like that Mm.
[00:26:28] So it's, it's a bit, it feels a bit stuffy in here. That's not, I would argue, the CO2 directly that we're experiencing or sensing
[00:26:37] Matt: The nitrous oxide?
[00:26:38] Cameron: No, it's, it's, uh, odors- Okay ... all sorts of other things that you sense that's- Ambience is a bit
[00:26:42] Matt: stinky ...
[00:26:43] Cameron: y- You don't, you don't really sense CO2. You can't, you know, um, sniff your nose and go, "Oh, it's about 900 parts per million in here."
[00:26:53] Matt: What's a, what's a safe- Interesting ... what's
[00:26:54] Cameron: a, what's a safe level? Well-
[00:26:56] Matt: We don't know yet, do we?
[00:26:58] Cameron: Well, I, I think that's a [00:27:00] complicated que- question So, so n- normally you talk about 10,000 parts per million being really problematic, dangerous. I think 5,000 is sort of above that, is starting to get into your orange zone, if you like.
[00:27:13] Hamish: Yeah.
[00:27:14] Cameron: But those levels are never experienced in buildings. At what
[00:27:16] Hamish: point does the canary die?
[00:27:18] Cameron: At the canary, you know, 10,000, nor- well north of 10,000. Okay.
[00:27:22] Hamish: You know,
[00:27:23] Cameron: yeah, well, could be 100,000. I can't even remember that. Two,
[00:27:25] Hamish: and if I ever s- Yeah, but- ... if I ever, like, start, uh, like a sensor, um, company, it's gonna be called Canary, Yellow Canary.
[00:27:32] Cameron: There's actually a sensor out there that actually-
[00:27:34] Hamish: Oh,
[00:27:34] Cameron: really? ... flips upside down when your CO2 goes above whatever the threshold- And, and is, and is it a
[00:27:37] Matt: canary that
[00:27:38] Hamish: just like-
[00:27:38] Cameron: No. I think it's like a canary ... Oh, that's brilliant.
[00:27:40] Hamish: I'm gonna buy one of them just for the sake of it.
[00:27:41] Cameron: Uh, for people who are not numeric, I guess it's kinda handy 'cause you don't have to worry about the number.
[00:27:45] It's canary's happy, canary's dead- ... right? Well, I got a problem. Um, but what I would argue is those very high levels never happen, so the fact that I can't remember what those numbers are hopefully points to you to realize that- Yeah ... they're immaterial. Yeah. What [00:28:00] matters is, you know, those realistic levels that we might experience in buildings.
[00:28:03] An unoccupied building, about 420. Typical building, maybe 600 to 1,000. You know, so it's- What's a
[00:28:10] Matt: passive house sit at?
[00:28:11] Cameron: Well, it, it depends. Fuck me. How many people are in the building?
[00:28:15] Hamish: You just line him up then.
[00:28:15] Cameron: But,
[00:28:16] Matt: uh- No, I thought it was about... I thought it, I said about five, yeah, 500 to 700 ... yeah,
[00:28:18] Cameron: in a bedroom, which is the critical- Yeah
[00:28:20] a master bedroom, where you often have two occupants and a relatively- And a dog ... small volume for eight hours, then it will o- often go to 1,000 or 1,200.
[00:28:27] Matt: Even in a passive house? Mm. And what would a standard house as a comparison be?
[00:28:31] Cameron: North of 2,000.
[00:28:32] Matt: Okay.
[00:28:32] Hamish: And what about, what about a master bedroom with a dog, two adults, and three kids?
[00:28:36] Matt: It depends. What are you doing?
[00:28:37] Cameron: Well, if you got, if, if you got ventilation, you know, it, it, it-
[00:28:40] Hamish: No, it's cold in win- it's cold in Melbourne, so the- all the windows are closed
[00:28:43] Matt: Natural ventilation, isn't it?
[00:28:44] Cameron: But, but, but whatever it is, I argue that it's not all that important.
[00:28:49] Hamish: Yeah, okay.
[00:28:50] Cameron: It, it's, that, those levels of CO2 are most certainly not gonna kill you.
[00:28:54] Yeah. That's not controversial.
[00:28:55] Hamish: Yeah.
[00:28:56] Cameron: There is some dis- debate or discussion about whether it affects [00:29:00] your temporary cognition, you know, your ability to solve problems. Yeah. And as per a previous conversation we had, I argued, well, if that were true, why is it that submariners- operate in a submarine for north of 2,000 parts per million and are doing pretty damn complicated things.
[00:29:15] Hamish: Yeah.
[00:29:16] Cameron: Um, and the other part is that it might affect your sleep quality and make you a bit grumpy in the morning and so on. So, you know, temporary effects possibly- Kids will do
[00:29:25] Matt: that too, eh?
[00:29:27] Cameron: I- it's a, it's, it... Th- th- these sort of, you know- And yours
[00:29:30] Hamish: haven't even started yet, mate. You're, you're- No. No, she's started
[00:29:32] one, one year old. No.
[00:29:34] Cameron: O- o- or cause you, like, headaches, things like this. I mean, the- You
[00:29:36] Hamish: talking about kids causing headaches or the-
[00:29:38] Cameron: A- and this is, this is the key thing, right? If you're trying to design an experiment to measure the impact of CO2 or, or say your hypothesis is that C- high CO2 concentrations above 1,000 parts per million increase the r- likelihood of having a headache.
[00:29:54] Well, how do you design an experiment for that? What if you've got
[00:29:56] Matt: kids or what if- Because- ... what if you've been up... Yeah. What do you find is good sleep?
[00:29:58] Cameron: People are gonna get headaches [00:30:00] anyway, regardless of- Hmm ... the CO2. Do you take
[00:30:02] Matt: Panadol? Do you not take Panadol?
[00:30:03] Cameron: And so this has always comes down to the quality of the design of experiment to try and separate the impact of CO2 on all the other things that cause headaches or whatever it is that these symptoms you're interested in.
[00:30:15] So I argue, yes, you can monitor CO2, and there are sensors out there that can do that now very cheaply, and they can do it reasonably well with the key caveat that all of them are recalibrating once a week. They have a process called automatic baseline calibration. So they take the past seven days of data in their little circuitry, and they say, "Right, what was the lowest value I measured?"
[00:30:42] And then they re-baseline that to atmospheric. So if we accept that outside is 420 parts, and I've measured that over the past week I got down to 500 parts, then I'm gonna re-baseline. I'm gonna shift all my data now down [00:31:00] 80 parts because I, I have assessed that my sensor has drifted 80 parts away from baseline, and so then I'm gonna re-baseline.
[00:31:10] Now that works if your sensor is exposed to outdoor conditions once a week But in a building that might be occupied 24/7, CO2 might never drop below 600 parts per million over that week.
[00:31:22] Matt: So you kind of need two sensors, one in, one out, that talk to each other.
[00:31:26] Cameron: Conceivably. Um, but again, you know, to my mind, it doesn't much matter-
[00:31:30] Matt: So it's basically gonna get difference in 3%.
[00:31:32] Cameron: A- and these sensors have got a f- you know, a, a, a variability in error accuracy to them anyway, and if you're measuring your CO2 at 1,000 when it's really 1100 or 900, who cares?
[00:31:44] Matt: Yeah.
[00:31:45] Cameron: Especially given that we don't even know that there's a real impact.
[00:31:50] Matt: But something like P 2.5 is probably more important.
[00:31:54] Cameron: And this comes to where I was alluding to the other day when I said measure what matters. Mm. [00:32:00] So if we accept that the debate around CO2 as a pollutant in itself is disputed, then is there some other measure of air quality which does matter? And that, in my view, is fairly clear, and that is fine particular matter, PM 2.5.
[00:32:19] So the 2.5 means microns, so you know, m- uh, 10 to the minus six meters, so tiny little particles of dust, polle- well, pollens are much bigger than this, but thing, things in the air that we breathe in that get past all the hairs and stuff in with our throats and get deep into our lungs, go across the blood barrier, get absorbed into our blood, get into our brains, has been associated with dementia, all sorts of cancers,
[00:32:48] Matt: um- Like definitive like smoking, like we know this?
[00:32:51] Cameron: Yeah. Uh, well, yes. So, well, so the evidence is increasingly clear- Okay ... but we may try and be a little bit-
[00:32:57] Matt: So it's not like PFAS where we still don't know what it does. [00:33:00]
[00:33:00] Cameron: Yeah. Uh, what, what I think, you know, and clearly I'm no air quality expert, but- Pretty good ... what, what, what the, what the, um, air quality community seem to have established over the past 15 or 20 years is that PM 2.5 is increasingly coming up as by far and away the most significant indoor pollutant that affects our health.
[00:33:22] Hamish: So the, what we're talking about now is those items that are burnt
[00:33:28] Cameron: O- oftentimes. There, there, there was also, you know, when you get a windstorm through, it's blowing all sorts of stuff up. I mean, the dust you see is clearly much coarser, much broader than, than this very fine matter. Yep. But there'll be fine matter you can't see that apart from that.
[00:33:41] Yeah, it's like
[00:33:42] Matt: when you fry the dumplings off, that's what spikes mine. It kills Cam's data.
[00:33:46] Cameron: Yeah. A- a- and, and
[00:33:48] Matt: there's- 'Cause it's just frying stuff. Yeah. If you boiled stuff all day, you'd be totally fine.
[00:33:50] Cameron: Okay. So, so where is the PM2.5 in our buildings coming in, in from our houses? Let's concentrate on that.
[00:33:57] Half of it generally is coming from [00:34:00] outside. And so that might be, you know, Matt always tells me how he lives in the western suburbs of- Pressure from into our, our twin,
[00:34:05] Matt: sorry ...
[00:34:06] Cameron: you know, industrial- Yep ... things. You've got trucks, cars. You know, a car, uh, when you've got combustion, you've got stuff coming out of the exhaust.
[00:34:14] Even, like, the brake pads, when the brake pads go on, that generates lots of fine particulate matter. Yeah. The tires, when they're running on the road, they kick up all this fine particles. Other people
[00:34:21] Matt: burning the fire, which makes up, was it 33% of all?
[00:34:24] Cameron: 60, I would say. 60,
[00:34:25] Matt: sorry, yes.
[00:34:26] Cameron: Yeah. So, so t- what Matt was alluding there too is in the western suburbs of Melbourne, where they've done attribution studies to identify where all this PM2.5 is coming from, the typical response is, "Oh, it's all the factories in the west," or, "It's all the trucks."
[00:34:41] Well, no, 60% of it is p- domestic wood fires. Really?
[00:34:46] Matt: Imagine telling people, imagine being that dickhead that says, "Stop your wood fires." Imagine being that person.
[00:34:50] Cameron: Ah. It'd be shocking. You'd break the internet if you suggested that. Um- ... a- and then think of how many people actually have wood fires in, in the western suburbs of Melbourne.
[00:34:59] Can we just get some kind of clickbait [00:35:00] here? Yeah, sorry to, sorry. Like, you know, how many people actually have wood fires in the western suburbs of Melbourne- Probably about- ... and how many are running them on any one night?
[00:35:07] Matt: So probably, like, uh, I'm not... I'm gonna pull a number. Ma- maybe let's call it at a max 5% would have a wood fire, and of that 5%, how many are running it?
[00:35:16] And then-
[00:35:16] Cameron: And, and yet they're contributing 60% of the PM2.5 in the winter season in western
[00:35:22] Matt: suburbs of Melbourne. 'Cause lighting a fire takes effort, and when you come home from work, you go, "Oh, I can't be fucked. Just turn on the electric heater or don't have wood."
[00:35:28] Cameron: That's right. So, so that's my... So half of it's coming from outside.
[00:35:32] Matt: Is it dropping? Because I'm assuming back in the day there would be a lot more wood fires that have been lit.
[00:35:36] Cameron: Well, I, it's probably increasing over recent decades because it's an increasingly popular thing. Certainly in a lot of projects I'm involved in. Yeah. It, it feels like the fancier the house, the more likely there is to be a fireplace.
[00:35:48] Matt: Yeah, I've got to get a particulate sensor back outside, 'cause mine caught fire, ironically.
[00:35:54] Cameron: What? How did that- 'Cause I
[00:35:55] Matt: put it, I, it's not meant to be the rain, I put it in the rain.
[00:35:57] Cameron: Oh, okay. Yeah, okay. So, so half of it's [00:36:00] coming from outside, so how do we manage that? Obviously an airtight building envelope is a great way to start.
[00:36:04] Yeah. Hey look, Passive House. Uh, another part of course is HRV, so you filter any air that you are bringing into the building. Yeah. But do bear in mind that most of the standard grade filters you have in things like HRV are not capturing a, a pa- part of that PM2.5. They're certainly catching some of it, but they don't have, you know, HEPA grade or hospital grade filtration to capture- Mm
[00:36:28] all of the really fine stuff. The other half of the particulates are generating within the building, and so the two obvious sources there are if you have a wood fire, and this is, you know, where I get to my disgruntlement with people with wood fires. Hamish. A- and Hamish will tell me he's got a great wood fireplace with a closed door that he keeps nice and sealed and stuff, and I'm like, "Yeah, but how do you get the wood into that fire?"
[00:36:54] It's Blue Cheese. "Oh, well, I open the door." Blue Cheese wood. That, y- yeah. Of course you're opening the door, and when you open the [00:37:00] door, the room floods with the particulates, which then continue to float around that room thereafter, which you inhale. So that's so-
[00:37:08] Matt: But also on that, you're also... It's a selfish thing because you're actually polluting the air outside to your neighbor.
[00:37:15] Cameron: Uh, ex- well, if,
[00:37:16] Matt: uh, yeah- And who- that's assuming he's burning good stuff too.
[00:37:18] Cameron: Uh, uh, that's, that he's not burning treated pine, for example. Yeah. Yeah. Anything
[00:37:22] Matt: else? But, but we, we shouldn't be having treated pine.
[00:37:26] Cameron: But, but- Have you got any
[00:37:27] Matt: data on that?
[00:37:28] Cameron: In a, in an urban area, that's part of the thing, isn't it?
[00:37:31] Or, or even regional towns. It's
[00:37:32] Matt: burn whatever you can get your
[00:37:33] Cameron: hands on. This, this is what gets me in, like, you know, regional Victoria where, you know, we, we, we all live in, in Victoria. All of these regional towns, great air quality, and then come winter, they're all firing up their wood fires. Often these towns are in little valleys, and all the smoke just sits there.
[00:37:50] Hamish: I mean, I don't know, like I, I, I live, I wander outside on a cold Sunday morning- I love
[00:37:55] Matt: the smell of it ...
[00:37:56] Hamish: and, like, I don't want to hate the smell. I'm not saying you should go and light a fire. [00:38:00] But then where I am, like I kind of, I'm right near the river, so you can kind of see the smoke sort of sitting over the river, and I'm like, "Oh, this co- looks quite nice."
[00:38:07] Matt: Beautiful.
[00:38:08] Hamish: It's like- It's
[00:38:08] Matt: quite aesthetic ...
[00:38:09] Cameron: it looks, a- a- and there's must be some innate genetic thing in us humans, right? We all love the look of the flames and the- Yeah ... randomness of them, and I get that whole cozy thing. That's all beside the way. You know, the, the-
[00:38:22] Matt: Put it on the TV. Just get the fireplace on YouTube and-
[00:38:24] Cameron: The evidence is what it is, that this stuff is not good to be burning.
[00:38:27] No,
[00:38:28] Hamish: I know. And, and I'm not, I'm not sitting here trying to argue against it either. Like, I'm very well aware of it.
[00:38:33] Matt: Yeah, you burned your fireplace on the weekend with your hot tub.
[00:38:36] Cameron: A- a- a- and to-
[00:38:36] Hamish: I'm not gonna stop. I'm not gonna stop. I'm very jealous. I'm not, I'm not gonna stop. I was in that wood fired hot
[00:38:41] Matt: tub.
[00:38:42] I'm so je-... I'm, I'm actually jealous.
[00:38:43] Hamish: In fact, do you know what? It was too hot. We actually had to put more cold water in it, it was that hot on the weekend.
[00:38:50] Cameron: But to be fair- ... we all make risk assessments in our lives, you know. Some of us drink, and alcohol's not good for us either, right? We all know that, but we [00:39:00] choose to take that risk.
[00:39:01] And- Yeah ... you know, driving a car, you might get dead when you jump in the car. It's just a reality of life. So we accept that there are risks. But to Matt's point before, when you do start up that wood fire in a built-up area, you're not just affecting yourself, you're affecting your neighbors. Yeah. So there is a moral question about this.
[00:39:19] Um, but to the point of monitoring- These, these- What
[00:39:23] Matt: was the other part that you were gonna say that makes up in the house? We haven't got to the other
[00:39:26] Cameron: 50% Oh, s- sorry. Yes. Right. So combustion. So first part is combustion. Wood fires are concentrated on. If you've got gas cooktop- Yeah ... obviously that's contributing.
[00:39:33] We know that's bad. So don't burn stuff in buildings. Yeah. The other part is related to burning, which is, uh, cooktops. Whenever you are cooking something, like frying something on a frying pan, you are generating a whole range of gases- Oh, yeah ... and p- and partic- particulate things. To Matt's point, you know, frying dumplings.
[00:39:50] Matt: Dumplings, stir fries, Asian food. You spike the fuck out of it.
[00:39:54] Cameron: Yeah.
[00:39:54] Hamish: I would know. I don't monitor it.
[00:39:56] Matt: Oh, it's... Especially if I joke that, look- See,
[00:39:58] Hamish: no, sometimes [00:40:00] ignorance is bliss. Like, living in a non-passive house- I, I put- ... when you've got the fireplace there and nothing's-
[00:40:04] Matt: Look, I will- ...
[00:40:04] Hamish: beeping at you or anything like that, just is like everything's fine and dandy
[00:40:07] Matt: I put my hand up. I did make a mistake, and I will agree with you, Cam. I should have ducted my range hood outside and not recirculated it after seeing the data.
[00:40:16] Cameron: I, I'm looking forward to the letter that s- says, "Cameron, you were right."
[00:40:19] Matt: You, you are right, but still, I still will argue that I would not do a above cooktop range hood.
[00:40:27] I would still downdraft, even though the physics suggests that it's not right. I know, but I- Well,
[00:40:31] Cameron: I'd, I'd much rather a downdraft that's externally venting-
[00:40:34] Matt: Yeah ... you know, for the amount that's required ... a- and I wish I did that. And I don't think I can retrofit one in the future. I, I probably do hard now. I probably could if I wanted to.
[00:40:45] Cameron: Anything's possible with time and money.
[00:40:47] Matt: Yeah. I,
[00:40:47] Cameron: I- But, but, but I, I think, you know, I've got a recirc in my house-
[00:40:51] Matt: Yeah ...
[00:40:51] Cameron: because at the time I thought that was the-
[00:40:53] Matt: It was fi-
[00:40:54] Cameron: it- ... easiest and best choice. We, you know, this is what we all constantly should be [00:41:00] questioning our assumptions and- What
[00:41:00] Matt: is your particular insight of your 2.5 get up to if you cook, out of interest?
[00:41:04] So have you spotted the highest you've spiked it?
[00:41:05] Cameron: Well, it, it varies wildly depending on what- Yeah ... you're cooking, doesn't it? But-
[00:41:08] Matt: Have you hit the 999? I've done that.
[00:41:10] Cameron: No, I've not. Only if you blow a match right over the-
[00:41:12] Matt: I literally was like, was this, uh- I think I was smoking something, which is
[00:41:18] Cameron: Well, crack?
[00:41:19] Matt: No, no, I was smoking off like a, like a stir fry purposely, and it, yeah, he went- It
[00:41:25] Cameron: went nuts, yeah ... it
[00:41:26] Matt: went.
[00:41:27] Cameron: A- and, and so, so, so the back to the point about monitoring, these th- these things used to be really difficult and expensive to monitor. You need, you know, lab grade stuff- Yeah ... that would cost tens of thousands of dollars.
[00:41:38] That is no longer true. Yeah, just
[00:41:39] Matt: get them from China. Al- AliExpress.
[00:41:41] Cameron: You can go to AliExpress and get this stuff for, like, well under 100 bucks. You can go to, you know, I keep banging on about that one. I can get it. You can get it at IKEA. Now, th- these, these sensors, and we'd need maybe to just talk about the details of how these sensors work for a second, because it is relevant to interpreting the data.
[00:41:58] But these things are now well under [00:42:00] 100 bucks. Um, they are giving you a guide which your nose, eyes, et cetera, have no way of really knowing about. So to Hamish's point about ignorance is bliss- Mm ... you carry on until you get one of these things, and then you observe what it does. And to your point, Matt, you observe it go nuts when you're actually doing the cooking event.
[00:42:21] But moreover, for the next four or five hours The room is still indicating very high particulate levels
[00:42:27] Matt: You've got to be at... Like, so I just open my big sliders and open the windows and foom. Fresh. But I take an energy, I take an energy penalty. But also the flip side, like if you have makeup air now with a thermal box, you're gonna have a makeup, you're gonna have a penalty too.
[00:42:38] Cameron: A- and, and certainly in, you know, passive house where we're very keen on trying to get- Yeah ... that energy right, this is a significant impact. So I don't shy away from the fact- Is it though? ... that it increases complexity.
[00:42:47] Matt: I don't really care. It's kinda nice, like, this sounds so precious, 'cause it's so warm inside.
[00:42:52] Sometimes it is kinda nice to open the big slider when it's a bit cooler. Ooh, it's nice.
[00:42:56] Cameron: So taking the cold
[00:42:57] Matt: line. It's like a bit of a fresh- it's like, it's like a cool breeze that's come past.
[00:42:59] Cameron: A- and [00:43:00] certainly I think we'd all agree on balance, if it's gonna cost you an extra 15 bucks a year to heat your house-
[00:43:06] Matt: Not even that
[00:43:07] Cameron: to, to on the other hand, flush out these, you know- Yeah ... harmful pollutants, then clearly you're gonna choose
[00:43:13] Matt: the former. You'll drop it within three minutes quickly.
[00:43:15] Hamish: We were chatting a couple things and, um,
[00:43:17] Matt: um, to- So just how do you sense it, monitor EMF? We never got to that.
[00:43:20] Hamish: We... I'm just gonna ignore that.
[00:43:22] Um, so it, like, it probably is a conversation we should have again about externally ducted range hoods. 'Cause it is a, I think on 100% of my projects now, it's a topic- Code ... it's a topic of discussion.
[00:43:32] Matt: Well, it's NCC though.
[00:43:33] Hamish: Well, you can get a performance solution.
[00:43:35] Matt: I think y- I thought you need to still-
[00:43:38] Cameron: Yeah, I'm not sure if you can now.
[00:43:39] No, I don't think you can. I, I, I think you can on the basis that it's a moisture issue in the code, so you could get a performance solution that- Yeah ... your research is gonna work with- Yeah ... in correlation with HRV. But I, regardless, I'm arguing it's not a good idea. Externally vent your range hood.
[00:43:53] Hamish: Yeah, okay.
[00:43:53] There you go. Um, so other things we should monitor, um, bedrooms, bathrooms?
[00:43:58] Matt: No, I don't need to monitor... [00:44:00] If you have a... Well-
[00:44:02] Cameron: Yeah. So, so, uh, you know, what are you monitoring- Yeah ... in these spaces? In, in your wet areas, your bathrooms, you're probably the relative humidity in combination with temperature is critical.
[00:44:10] Yep. Emphasis on in combination with temperature, 'cause relative humidity only means something if you know- It's always gonna be humid
[00:44:16] Matt: in there when you've had a shower ...
[00:44:17] Cameron: the temperature as well. Yeah. Uh, a- and you wanna see that diminishing- Yeah ... over the subsequent, you know, hour or so to, to minimize the risk of condensation and, and mold growth- Mm
[00:44:25] forming in those spaces. Um, but just if I can jump back to the sensors just for a second, these things now are extraordinarily cheap And you can get any number of proprietary systems. But I would just emphasize, 'cause everyone goes, "Ooh, what's the most accurate one?" Well, that's not really the point. You know, you're not looking for lab-grade accuracy anyway.
[00:44:44] You're just looking for an indication. Is, you know- Mm ... has my PM gone through the roof 'cause I've been frying dumplings or hasn't it? Uh, so, you know, the precision is not, not so critical. Um, what matters is probably the wrapper around it, particularly if you're not a technically sort [00:45:00] of interested, you just want something plug and play.
[00:45:01] So has it got an app that I can pull up- Mm ... and see what these numbers are, and that tells me green, red, you know, so I can interpret what is good and what is bad? Uh, in the back end, is it logging and recording that data so I can see historically am I better or worse than I was last week? 'Cause you're probably trying to manage your building better.
[00:45:19] Mm. You know, I'm gonna open my sliding door after I do the cooking this week. How have I performed? You know, am I-
[00:45:25] Matt: Yeah ...
[00:45:26] Cameron: is it doing what I, I'm hoping it's going to do?
[00:45:30] Matt: No, like I find it helpful. Like it, it's kind of nice when, again, being precious, like I wake up, I can check the outside temperature, and I'm like, "What do I need to wear today?"
[00:45:39] Mm. 'Cause you do lose the perception of- Mm ... what's comfortable.
[00:45:43] Cameron: A-a-and what I use this sort of data for, uh, from the thermal point of view, but also from the air quality point of view, is trying to benchmark buildings. Like, all of this data is only useful if it's contextual and if it actually provides insight into a problem or- Mm
[00:45:57] a solution. Um, and [00:46:00] if I can establish, say, the temperature, the diurnal temperature range, so the high of the temperature during the day, it drops overnight to a low in the morning. And we know in our classic Aussie rubbish building, it might drop 10 degrees or more overnight. You know, it's 10 degrees inside when you wake up in the morning.
[00:46:15] Probably Hamish's house- Yep ... now.
[00:46:17] Hamish: Definitely.
[00:46:17] Cameron: Um, whereas in Matt's house, without any heating overnight, it's probably only dropping one or two degrees.
[00:46:23] Hamish: Yeah.
[00:46:23] Cameron: And so that's a benchmark of performance. And so I can look at various buildings, you know, which, which I've been involved or others have been, and you can say, "Well, how am I performing relative to the greater cohort of buildings?"
[00:46:36] A-a-and, and maybe that provides you some insight to say, "Well, that building's performing really well because it's done X, Y, and Z."
[00:46:43] Matt: What do you want to test? If you could, if you could go forward, say, five years, and if we had a... Like, what were three things you'd want to test to know the answer to or have good data on right now?
[00:46:54] Cameron: I don't know about three things I can think of off the top of my head. I think we need to know more about cavities and [00:47:00] buildups. Yep. Like, uh, think about our flat roof details. Mm. Um, you know, we all recognize now with flat roofs we're gonna have a substrate on the top- Yeah ... ply OSB or something, and then maybe a peel and stick membrane.
[00:47:12] If we're not having a, a vapor- Insulate ... control or air, uh, vapor control membrane on the inside, how problematic is that likely to be in our particular climates? Like, we can do this hygrothermal wa- modeling using things like Wolfie to try and get an idea on those sort of things, but how... D-does that reflect reality?
[00:47:30] Um, and we're constantly playing with different wall and roof buildups, you know, exterior insulation. I, I'd love to see more monitoring of those buildups, you know, within the assembly itself, not just within the house and outside the house, but at different layers within.
[00:47:44] Matt: So the one
[00:47:45] Hamish: Justin- I think, I think, I reckon that's the most important one, 'cause that, that's the ones that you can't see.
[00:47:48] Matt: Well, that's one like Justin's doing right now- ... where it's the insulation at the top quarter, bottom quarter of a truss roof- Yeah ... and completely wrapping. That to me is really interesting.
[00:47:57] Cameron: A- and I think we'd all agree on that. Yeah. So- It
[00:47:59] Matt: can [00:48:00] change a code.
[00:48:00] Cameron: Y- yeah. A- and we need data- Yeah ... and then to analyze that data, to provide insights- Mm
[00:48:06] to go, "Hey, this actually looks like it's all right. We feel confident now that this could be incorporated, say, into the building code."
[00:48:12] Matt: Yeah. If done this way.
[00:48:14] Hamish: Hey, um, Cam, thanks for coming on today. Like I, I mean, I, I'm sitting here right now thinking I've got so many more questions that I reckon this conversation could keep going.
[00:48:22] Like, I'm
[00:48:23] Matt: buying a CO2, not, no, not a CO2, sorry, a carbon monoxide monitor for my parents' house now for their-
[00:48:28] Hamish: Yeah ...
[00:48:28] Matt: their wood fire. I'm just gonna put it in their house- ... go, go for it.
[00:48:30] Hamish: Yeah. And at, like to what we were talking about before, I almost don't wanna know, but I probably do wanna know. Mm. And yeah, I've got a, I've got a young daughter and two young kids, you know.
[00:48:39] And Junie, like, literally stands behind me while I'm like trying to light the fire, and I'm like, "Hey, babe, you've gotta move out of the way." And I'm just like- Yeah.
[00:48:46] Matt: Thank you, Cameron. Thank
[00:48:46] Hamish: you for your time again. Yeah. Thanks, Cam. And do you know what? I, I've said this once, I'll say it again, like the way that you have y- your ability to actually break down complex pro- like-
[00:48:55] Matt: Yeah, conversations
[00:48:56] Hamish: conversations, so some, an idiot like me can understand. And, [00:49:00] and even to, you know, the reports that you deliver as well, like I can read through it, and it's such an easy read.
[00:49:05] Matt: I joke and I say it takes me 20 minutes to fumble through something. You explain it in three words, and they go, "Yeah. Got it."
[00:49:11] Hamish: Yeah, yeah.
[00:49:12] So- No, so thanks. Thanks for coming on.
[00:49:13] Matt: Thank you.
[00:49:14] Hamish: Appreciate it. No worries. Thank you.