#19 - From Aerospace to Energy Efficient Homes and Passivhaus with Dr Cameron Munroe

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Hello and welcome to the
Building Psychology Party where

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we talk about better buildings
to live and breathe in.

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My name is Jess Kismet and today
I am joined by Doctor Cameron

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Munroe.
Cameron is a building scientist

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and the founder of Passive
Analytics, which is a

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consultancy based here in
Melbourne where we are currently

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that helps designers, builders
and homeowners understand how

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buildings truly perform.
Cam has a background in

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engineering and a deep passion
for making homes more

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comfortable, durable and energy
efficient.

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He is one of the best minds in
our industry.

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His understanding of building
performance is second to none,

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and he's an incredibly
articulate communicator as well,

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which means we can all easily
benefit from his knowledge.

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And I'm really looking forward
to this chat.

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Cameron was also recently a
guest on the Mindfulbuilder

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podcast and the conversation was
excellent.

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So if you haven't heard these
episodes, I recommend you go

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back and have a listen in
conjunction with this

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conversation.
I'll link them in the show notes

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as well.
Or you can just look up

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Mindfulbuilder on your favorite
podcasting platform.

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I'm going to try and build on
that conversation today.

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So without further ado, I would
like to welcome you to the

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Building Serology Party,
Cameron.

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Thanks very much.
Yes, good to be here.

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Excellent.
So let's get to know you a

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little bit.
Let's get to let's have a little

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bit of a chat about your
professional history and how you

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got to where you are today.
Sure.

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OK.
So I did aerospace engineering

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here in Melbourne as an
undergrad and from there moved

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to Sweden for about 6 odd years
to do my PhD, also in aerospace

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engineering and then over to the
UK for a few years before

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ultimately making my way back to
Australia.

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And we've had a couple of
different careers over that

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time, but all of them have been
about around the idea of

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modeling numerical remodeling of
different things, be that

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aircraft, transport systems and
now and now buildings.

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And so I guess the way I
approach the world is very much

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about following the numbers
rather than guessing.

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And when it comes to buildings,
that's particularly true when

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we're trying to make decisions,
for example, as to how much

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insulation we should have in a
building, whether we should

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double glaze or triple glaze our
windows.

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We can, we can model all of
that.

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We can assign numbers to it and
therefore run trade-offs as to

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what the best combination is
going to be for a particular

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building in a particular point.
It makes sense.

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Do you have much much to say on
the translation of those numbers

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to reality?
Well, yeah, that's always the

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hard bit, isn't it?
So it's trying to communicate to

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clients and to builders and
indeed architects, building

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designers as well, those
trade-offs in a way that

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actually allows them to make
actionable insights.

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And that's often what we talk
about in engineering or

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certainly in modeling because
you don't want to just do the

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modeling as an outcome in
itself.

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It's got to actually provide
insight for, I say the homeowner

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client to actually make an
informed decision as to say,

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aha, OK, if I do that, that's
kind of far more cost

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effectively improve the thermal
performance of my building than

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if I do that over there.
And so to provide some numbers

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around that to allow them to
make informed decisions rather

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than simply relying upon
guesswork or expert judgement,

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as it were, from the builder,
architect or someone else as to

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what they ought to do.
So it's it's about understanding

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and communicating the why behind
how decisions are made.

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Often, yeah.
Yeah, yeah.

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And I understand we are
currently in Cameron's home in,

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in, in Melbourne.
And when we walked in the front

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door, straight away, the house
felt warm.

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It's about 12 degrees 14°
outside.

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That's Melbourne in winter
today, something like that.

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Yeah, it's cloudy outside.
And as soon as we walked in, the

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first thing I said was I didn't
didn't know that there'd been

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renovations done here and I
thought it's warming here.

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So could you tell us a little
bit about what you've done to

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this home to make it so
comfortable?

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Yeah.
OK, So it's a weather board

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home.
So your classic Australian

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weather board.
So it was a leaky sieve.

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It happened out of 1980s
extension on the back that was,

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you know, pretty poorly built,
didn't look great either.

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So the the extension out the
back was completely demoed.

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The weather board at the front.
We're subject to a heritage

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overlay here, which means we
can't destroy or knock down that

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the front of the house, but we
gathered it internally.

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So I took it back to frame
essentially and then reinsulated

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it, added a membrane for air
tightness and vapour control

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internally, put in a HRV for
ventilation.

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So mechanical ventilation and
the level of insulation is

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roughly twice that that would be
required by building code around

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here.
So.

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R4.
In the walls, essentially.

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R4 Yep, the build up's a little
different.

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And then, you know, 6 plus in
the ceiling, I mean, the

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advantages of ceilings,
especially in our case at the

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front, we've got a pitched roof
is you've got buckets of space.

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So you've got insulation
leftover, you throw it up there.

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And we got, we ultimately, I
was, this is about a decade ago

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that we, we did this project.
I was trying to hit

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certification.
So in a fit for Passive House

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aficionados out there and be 1
of what would have then been I

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think the second or third in the
country, 10.

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Years.
Ago but it was hard work and we

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got down to 1.2 ACH on the air
tightness.

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So for Passive House, for NFT,
you've got to hit one.

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ACH, we didn't quite get.
And we did 4 rounds of BLOB at

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all testing.
And at the time I was bitter and

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twisted.
But ultimately you've got to

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move in, yeah.
And you've got to get on with

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your life.
And of course, the reality is

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that the difference in terms of
energy and and comfort between

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1.2 and one is completely
negligible.

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Yeah.
It really doesn't matter.

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So we need to be pragmatic as
well as obsessed, yeah.

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Absolutely under construction
you renovation projects or

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retrofit projects can be really
hard with membranes and just

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upgrading the building fabric in
general.

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So have you got any boundary
walls or issues here with

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membrane install or did you just
do the internal Intelo membrane?

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Yeah.
So in the extension we did in

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the extension, the new
extension, obviously you've got

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a clean slate.
So you can do internal,

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external.
We were debating what to do with

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the front with the weather
boards.

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Yeah.
So we had old hardwood weather

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boards.
They're in, generally speaking,

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and decent, Nick.
Yeah.

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And so, OK, in theory, the best
thing to do is to pop them off

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and put an external membrane and
then a ventilate cavity button

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in.
We just chose not to do that,

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which is, you know, potentially
risky.

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But again, it just came back to
that compromise between cost,

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time and respecting the heritage
of the building.

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And if you've got an old timber
weather board, often replacing

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it with a new softwood
weatherboard, you're really

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gonna get that long term
durability of that.

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But probably the trickiest
detailed in this building was

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the rammed earth wall that's
behind us now.

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Uh huh is actually trying to
tape the internal membrane to

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the top of that rammed earth
because it is inherently quite a

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rough surface.
Yeah.

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And trying to get that adhesion
right with the with the glue and

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also a line of tape in the way
under the ceiling.

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Uh huh.
Was was a challenge.

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Taping the internal membrane
here on just behind us.

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And also at the plane, so I've
got a raft ceiling above it and

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then we've got a suspended
ceiling of course.

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But we're trying to run our
membrane around on the face of

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the intelo and the tape and seal
it.

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So it felt like it was death by.
Is it always the case with air

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tightness?
It's death by 1000 cuts.

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There's never one panacea.
When you go around and find go,

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haha, there's my solution,
That's my money win.

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It's it's, it gets to a point
when you're sort of down in that

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one sort of ACH range that
you've got probably 50 tiny

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little leaks that are very
difficult to find.

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And at some point you just have
to say near enough is good.

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OK, well job well done here
Cameron, because this house is

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incredibly warm and have you got
any active heating and cooling

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on at the moment?
No, not at the moment.

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I think it must be, I feel.
I reckon it's over 20° in here.

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Be 20 easily 2425° in here right
now.

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Would you say it?
Wouldn't be quite that warm, but

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feels.
It to me. 20 to 21 probably

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compared to where we've been
outside, that's that's probably

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the difference.
But we've just got two single

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split ACS, one in the front, one
in the back half of the house.

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Yeah, and, and perhaps there's a
learning there too is when we

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did this, obviously we were
rather early in the passive

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house movement as it is in
Australia.

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We only installed the single AC
in the back half of the house in

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the living room where we are
now, now under the assumption

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that the HRV was gonna move that
heat and cools in the summer

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from the back to the bedrooms at
the front.

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And that's not quite how it
works because the HRV is moving

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there at a relatively low rate
and so it really doesn't act to

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redistribute your heat through
the building.

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So if you are building a high
performance building and you are

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going down the split system
route as many of us would do,

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you really need to consider
having multiple splits through

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your house to try and distribute
that heating and cooling.

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Otherwise what you'll get is a
well conditioned section of the

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house, but the HIV just won't
move that heat to the other

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half.
And having said that, being a

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high performance envelope, it's
only 18° on the cool side in the

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other half of the house.
If you don't have the heating

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on, it's not 10°.
Yeah, as it would have been this

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in this building initially.
But having gone to the effort,

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18° is not going to make the
comfort expectation, certainly

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not ours.
And so we've installed a second

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AC in front of the house later
in order to, to, to get that

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distribution of heating right.
And So what I often do in my

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projects now is I'll usually
install 2 splits, or recommend 2

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splits to be installed and
possibly even rough in for a

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third, and just leave the pipe
work in the wall so that their

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client can come back later and
install one if they still wish.

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That's really interesting.
It's a really interesting point

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because I mean, Passive House
markets itself on, you know, no

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heating and cooling and in some
parts of the year that can be

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true.
But I think that having the

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ability to actively heat and
cool your spaces is still really

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important as.
Yeah, humans and I think we,

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yeah, we have to be really
careful, don't we, in the

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passive, our space.
I think, you know, the phrase

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passive does indeed suggest no
being cool.

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Yeah, but that's not correct.
No, You know, the modelling is

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always about there's a heating
demand and a cooling demand.

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There's an amount of energy
you're going to require to

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maintain a minimum of 20 winter
and a maximum of 25 in summer.

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And so you still need active
heating cooler.

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Yes, we cannot get away from
that.

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And we need to reiterate to our
clients I think to say, look, we

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need that heating cooling
system.

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You are going to need to operate
it in the middle of winter.

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So now, mid June in a dreary,
cold, miserable Melbourne, if

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you're in a passive house, you
will need to turn your heating

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on.
Yeah, that doesn't mean there's

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a problem in your building, no,
it's just that's how it's

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designed.
But that system is then going to

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run at a relatively low load, so
you'll need very significantly

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less energy to maintain that to
three degrees than you would

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otherwise have done.
But it's not 0.

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No, it's not 0 and equally in
summer there's with highly

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insulated airtight buildings.
There's overheating issues in

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Australia.
So you know, if you have a, a

229
00:11:11,480 --> 00:11:14,840
room on the West facade, for
example, that has no active

230
00:11:15,080 --> 00:11:17,880
cooling in it, that room could
overheat if it's not shaded

231
00:11:17,880 --> 00:11:20,680
correctly or adequately, et
cetera, et cetera.

232
00:11:20,680 --> 00:11:24,440
So there's definitely still
elements of a of a passive house

233
00:11:24,440 --> 00:11:28,520
building that need to be
actively heated and cooled and

234
00:11:28,520 --> 00:11:30,240
controlled.
Yeah, that's true.

235
00:11:30,480 --> 00:11:34,880
I would sort of be cautious
about a correlation between a

236
00:11:34,920 --> 00:11:37,600
high performance building
envelope and increasing the

237
00:11:37,600 --> 00:11:41,520
overheating risk because
insulation of course works just

238
00:11:41,520 --> 00:11:45,400
as well whether it's hot inside
and cold outside or hot outside

239
00:11:45,400 --> 00:11:48,000
and cold inside and reducing the
thermal transmits.

240
00:11:48,800 --> 00:11:52,640
The the issue probably becomes
that if it does cool down

241
00:11:52,640 --> 00:11:56,080
overnight in summer, so say it
was 35 during the day and drops

242
00:11:56,080 --> 00:11:59,320
to 15 overnight.
In a conventional poorly

243
00:11:59,320 --> 00:12:02,800
insulated building, that heat
that's built up within the house

244
00:12:02,880 --> 00:12:05,920
overnight during the day can
then dissipate out at night.

245
00:12:06,120 --> 00:12:08,440
Whereas in a high performance
envelope, that's no longer the

246
00:12:08,440 --> 00:12:12,320
case retaining that heat and so
you need a way of purging it.

247
00:12:12,880 --> 00:12:15,840
And that's where being an active
occupant, opening your windows

248
00:12:15,840 --> 00:12:17,720
when it does cool down makes
sense.

249
00:12:18,440 --> 00:12:22,360
But during the day, the critical
thing is always for glazing to

250
00:12:22,360 --> 00:12:25,360
the summer meeting and it's
always external shading.

251
00:12:25,640 --> 00:12:28,720
And we're talking about high
performance glazing units, an

252
00:12:28,720 --> 00:12:32,000
internal blind with the palmette
and whatever that works for

253
00:12:32,000 --> 00:12:34,800
single glazing that does not
work with your very high

254
00:12:34,800 --> 00:12:37,680
performance glass.
So then you have to push your

255
00:12:37,720 --> 00:12:41,560
shading strategy to the outside,
be that a deep Ave., be that a

256
00:12:41,560 --> 00:12:44,840
blind deciduous fine, any number
of solutions and.

257
00:12:45,320 --> 00:12:47,240
This is where the modelling
comes in to help you make those

258
00:12:47,280 --> 00:12:48,840
decisions.
Absolutely.

259
00:12:48,840 --> 00:12:51,840
And this is what I was certainly
overdoing Every project is I

260
00:12:51,840 --> 00:12:54,880
model each and every window, and
I'll say, what if there's a

261
00:12:54,880 --> 00:12:56,640
blind on this one?
What if there's a blind on that

262
00:12:56,640 --> 00:12:58,520
one?
And then I'll rank them and say,

263
00:12:58,720 --> 00:13:03,640
here's the sequence from one to
10 of all your viewer windows #1

264
00:13:03,640 --> 00:13:06,280
is the window that you need to
put a blind on 1st.

265
00:13:06,280 --> 00:13:09,000
And then you just work your way
down as far as budget and your

266
00:13:09,000 --> 00:13:12,360
comfort expectations match.
You know, so some clients will

267
00:13:12,360 --> 00:13:15,400
say, I never wanted to get above
23 in my house, and some in

268
00:13:15,400 --> 00:13:16,880
which case you need to push for
more blinds.

269
00:13:17,240 --> 00:13:20,000
Others will be quite comfortable
at 27, in which case you might

270
00:13:20,000 --> 00:13:22,720
need fewer blinds.
Yep, Yep.

271
00:13:22,720 --> 00:13:24,080
Interesting, very interesting
point.

272
00:13:25,680 --> 00:13:28,480
So as we're talking about HRV,
let's actually touch on that

273
00:13:28,480 --> 00:13:33,680
before we move on this point at
which mechanical ventilation is

274
00:13:33,680 --> 00:13:35,880
required. 5 ACH is in the
building code.

275
00:13:36,720 --> 00:13:40,840
Please discuss.
So this this this is great.

276
00:13:41,000 --> 00:13:46,360
So, so I think there's a lot of
misunderstanding about HRV and I

277
00:13:46,360 --> 00:13:48,720
think we've got to sort of
split, split it out into its two

278
00:13:48,720 --> 00:13:50,480
components.
So there's AV, there's a

279
00:13:50,480 --> 00:13:55,480
ventilation bit and there's AHR
heat recovery bit or MVHR, same

280
00:13:55,520 --> 00:13:57,160
thing.
The mechanical ventilation and

281
00:13:57,160 --> 00:14:01,000
heat recovery, the primary
purpose why we're doing this is

282
00:14:01,000 --> 00:14:05,000
for ventilation, fresh air into
our building, the V, that's the

283
00:14:05,000 --> 00:14:08,440
bit that's critical.
Each and every building needs

284
00:14:08,440 --> 00:14:10,320
mechanical ventilation.
Full stop.

285
00:14:10,480 --> 00:14:12,480
No argument.
I don't care what the air

286
00:14:12,480 --> 00:14:14,800
tightness is.
Every building needs mechanical

287
00:14:14,800 --> 00:14:17,000
ventilation.
Why is that so?

288
00:14:17,320 --> 00:14:21,000
Because even if you have a very
air leaky house, like the house

289
00:14:21,000 --> 00:14:25,320
that we were in now prior to the
renovation was probably probably

290
00:14:25,320 --> 00:14:27,320
wouldn't have got to 50 pascals
of pressure.

291
00:14:27,320 --> 00:14:30,880
You know, it was well north of
30 ACH, a leaky sieve, a classic

292
00:14:30,880 --> 00:14:33,840
Australian house.
And when it was windy outside,

293
00:14:34,080 --> 00:14:36,880
you would have had heaps of
ventilations with the house, far

294
00:14:36,880 --> 00:14:40,520
more than you would need or want
in terms of maintaining a heat,

295
00:14:40,960 --> 00:14:43,440
a comfortable indoor
environment, but more than

296
00:14:43,440 --> 00:14:45,160
adequate for ventilation
purposes.

297
00:14:45,680 --> 00:14:48,320
But but the majority of the time
it's not that windy, certainly

298
00:14:48,320 --> 00:14:51,320
not here in Melbourne.
And and there there might not be

299
00:14:51,320 --> 00:14:54,960
a big temperature difference in
to out and so you would not have

300
00:14:54,960 --> 00:14:57,920
anywhere near adequate of all
fresh air coming into the

301
00:14:57,920 --> 00:14:59,880
building.
There's simply no control.

302
00:15:00,280 --> 00:15:04,160
You're relying on poor building
practice to provide adequate air

303
00:15:04,160 --> 00:15:07,920
supply or you're relying on the
occupants to open window.

304
00:15:08,200 --> 00:15:11,040
Well, how do you know whether
you've opened the window far

305
00:15:11,040 --> 00:15:12,680
enough?
If you go to bed when it's

306
00:15:12,680 --> 00:15:14,440
windy, you just need to crack
them to open.

307
00:15:14,440 --> 00:15:17,200
If it's the wind dies done
overnight, then you should be

308
00:15:17,200 --> 00:15:19,200
getting up 2:00 AM and opening
it further.

309
00:15:19,360 --> 00:15:22,840
But you have no way of knowing
how much air flow you're getting

310
00:15:22,840 --> 00:15:24,160
in.
Whereas the mechanical

311
00:15:24,160 --> 00:15:27,320
ventilation is providing that
controlled, continuous,

312
00:15:27,320 --> 00:15:31,600
regulated, filtered flow of
fresh air regardless of what the

313
00:15:31,600 --> 00:15:35,480
outdoor environment is doing.
Then you come to the second

314
00:15:35,480 --> 00:15:37,520
point, which is the heat
recovery.

315
00:15:37,960 --> 00:15:40,840
So the easiest way to do
mechanical ventilation, if, I'm

316
00:15:40,840 --> 00:15:43,400
sorry, just step back a second,
is simply to turn on your

317
00:15:43,400 --> 00:15:46,560
bathroom, extract fans and leave
them running 24/7.

318
00:15:47,240 --> 00:15:49,440
That will give you fresh air
into your building.

319
00:15:50,200 --> 00:15:52,960
But of course, that's not going
to work very well for you in the

320
00:15:52,960 --> 00:15:55,120
depths of winter or the height
of summer because you're

321
00:15:55,120 --> 00:15:58,840
dragging in that warm or cold
air from outside, which you

322
00:15:58,840 --> 00:16:00,440
don't want to be doing That's.
Also noisy.

323
00:16:00,880 --> 00:16:03,680
And it's and it's very noisy
overload, yeah.

324
00:16:04,280 --> 00:16:07,040
And it's not actually creating
necessarily ventilating all

325
00:16:07,040 --> 00:16:09,200
rooms in the house depending on
the airflow pathway.

326
00:16:09,200 --> 00:16:11,640
So there's a bunch of other
reasons why that's generally a

327
00:16:11,640 --> 00:16:16,040
bad idea, but it comes to the
point of how you need the heat

328
00:16:16,040 --> 00:16:20,600
recovery because you want to
take out that stale moist air

329
00:16:21,120 --> 00:16:24,520
from the building, but in winter
at least you want to retain the

330
00:16:24,520 --> 00:16:28,040
heat and re inject that into the
incoming air and hence the heat

331
00:16:28,040 --> 00:16:30,080
recovery.
And this is where the

332
00:16:30,080 --> 00:16:33,080
relationship to the building
envelope air tightness comes

333
00:16:33,840 --> 00:16:36,680
because if you want to have a
really high heat recovery

334
00:16:36,680 --> 00:16:40,360
efficiency, it's a function both
of the heat recovery efficiency

335
00:16:40,360 --> 00:16:44,640
within the HRV itself, within
the core of the unit and also of

336
00:16:44,640 --> 00:16:47,560
the building envelope itself.
Because if you're only

337
00:16:47,560 --> 00:16:51,760
extracting 40% of the volume of
air through the HRV and the

338
00:16:51,760 --> 00:16:54,840
other 60% is escaping through
the building envelope, you're

339
00:16:54,840 --> 00:16:56,840
not recovering any heat from
that 60%.

340
00:16:57,680 --> 00:16:59,800
So you want to try and build a
nice tight envelope.

341
00:17:00,040 --> 00:17:03,120
So you're forcing all of that
extracted air through the HRV

342
00:17:03,280 --> 00:17:05,400
such that you've got a chance to
recover the heat.

343
00:17:06,119 --> 00:17:08,359
And that's where the
relationship to airtightness

344
00:17:08,359 --> 00:17:11,079
comes in.
So to make the HRV work most

345
00:17:11,079 --> 00:17:14,040
efficiently, you want to be as
airtight as practicable.

346
00:17:14,880 --> 00:17:19,000
But for ventilation, for fresh
air reasons, the airtightness is

347
00:17:19,000 --> 00:17:21,200
essentially relevant.
Yeah, Yep.

348
00:17:21,599 --> 00:17:28,760
So to repeat back to you what
you said the the HIV is for is

349
00:17:28,760 --> 00:17:33,000
for fresh air regardless of air
tightness score and the heat

350
00:17:33,000 --> 00:17:36,920
recovery is to make the the the
air tightness and heat recovery

351
00:17:36,920 --> 00:17:42,440
portion are to allow that system
to operate at its most efficient

352
00:17:42,440 --> 00:17:43,520
level.
Correct.

353
00:17:43,560 --> 00:17:46,400
Particularly given that your HIV
is going to cost you very

354
00:17:46,400 --> 00:17:49,680
significant more than just
putting a couple of fans in your

355
00:17:49,680 --> 00:17:53,240
wall or your ceiling, you want
to actually utilize that asset

356
00:17:53,240 --> 00:17:56,160
to its best value.
Yeah, which really pushes you

357
00:17:56,160 --> 00:18:00,520
towards going, you know, to a
fairly airtight level.

358
00:18:01,120 --> 00:18:03,760
And if you have a less airtight
building envelope?

359
00:18:03,760 --> 00:18:05,080
This is a question that's
popping into my mind.

360
00:18:05,320 --> 00:18:08,840
If you have a less airtight
envelope, that system has to

361
00:18:08,840 --> 00:18:14,520
work harder in order to move air
or the the same volume of air

362
00:18:14,520 --> 00:18:19,440
through its its system.
Does that mean that the system

363
00:18:19,440 --> 00:18:24,480
is then louder talking about the
noise of an HIV shouldn't?

364
00:18:24,480 --> 00:18:26,840
Shouldn't really have to work
any harder because it's still

365
00:18:26,840 --> 00:18:30,880
moving the same volume of air.
So you've you've calibrated,

366
00:18:30,920 --> 00:18:34,760
you've set the system up to
extract say 150 cubic meters of

367
00:18:34,760 --> 00:18:37,400
air an hour.
So the fan is spinning in order

368
00:18:37,400 --> 00:18:40,600
to do that.
So yeah, it shouldn't,

369
00:18:40,600 --> 00:18:43,040
shouldn't, that shouldn't really
play a significant role.

370
00:18:43,400 --> 00:18:46,360
Probably.
The other parts of this equation

371
00:18:46,400 --> 00:18:50,200
though, comes to moisture
management, because what HIV is

372
00:18:50,200 --> 00:18:53,120
also doing, of course, is
continuously extracting moist

373
00:18:53,120 --> 00:18:56,080
air from the wet spaces, which
is absolutely critical in the

374
00:18:56,080 --> 00:19:00,760
first line of control defense to
stop moisture vapor getting into

375
00:19:00,760 --> 00:19:02,640
your wall.
Getting into your ceiling space

376
00:19:02,640 --> 00:19:05,800
and risking getting condensation
is to get rid of it in a

377
00:19:05,800 --> 00:19:09,080
controlled way.
And the HIV is doing that 24/7.

378
00:19:10,680 --> 00:19:13,760
And then in combination, you're
trying to make an airtight

379
00:19:13,760 --> 00:19:17,320
envelope to prevent any of that
vapor that should happen not to

380
00:19:17,320 --> 00:19:21,240
be extracted through the HIV to
get into the wall and thence

381
00:19:21,240 --> 00:19:25,520
condense.
And in terms of extraction fans,

382
00:19:25,520 --> 00:19:29,920
something that I think doesn't
sort of when I learned this, it

383
00:19:29,920 --> 00:19:31,960
surprised me, but of course it
it makes sense.

384
00:19:32,240 --> 00:19:35,120
If you have an airtight building
envelope and only extraction in

385
00:19:35,120 --> 00:19:38,440
your wet areas and no supply
air, then those extraction

386
00:19:38,440 --> 00:19:41,520
spans, depending on the level of
air times that you have

387
00:19:41,520 --> 00:19:44,280
achieved, they don't work as
efficiently because there's no

388
00:19:44,440 --> 00:19:47,440
makeup air, to use an
engineering term, there's no air

389
00:19:47,440 --> 00:19:50,240
coming into the building to
allow air to be extracted from

390
00:19:50,240 --> 00:19:51,320
the building.
Yeah.

391
00:19:51,520 --> 00:19:53,400
So this is a really important
consideration.

392
00:19:53,400 --> 00:19:58,200
I think if you're getting down
to number two or three air

393
00:19:58,200 --> 00:20:01,280
changes an hour and you put in a
standard extraction fan in your

394
00:20:01,280 --> 00:20:05,240
bathrooms, you may find it's not
at all working the way it should

395
00:20:05,240 --> 00:20:07,480
be.
And yeah, and that's right.

396
00:20:07,680 --> 00:20:11,600
And the other other obvious 1 is
a range hood, yes, in your in

397
00:20:11,600 --> 00:20:14,120
your kitchen.
So if you build to a fairly

398
00:20:14,120 --> 00:20:17,080
airtight level, you switch on
the range hood and when you look

399
00:20:17,080 --> 00:20:19,960
at the data sheet for the range
hood, it'll tell you, you know,

400
00:20:19,960 --> 00:20:22,720
600 cubic meters an hour or
something, if that order

401
00:20:22,720 --> 00:20:24,880
perhaps.
And that's often with a certain

402
00:20:24,880 --> 00:20:27,640
duct lengths and you've got an
extract duct with an elbow in it

403
00:20:27,640 --> 00:20:29,640
and might be 5 meters long.
So you've got a state pressure

404
00:20:29,640 --> 00:20:31,560
drop there as well.
So it's a decline.

405
00:20:31,840 --> 00:20:33,840
But yes, the system has got to
be in balance.

406
00:20:34,120 --> 00:20:36,640
If you extract air from the
building, at some point it's

407
00:20:36,640 --> 00:20:39,200
going to depressurize to a level
where the all the walls in the

408
00:20:39,360 --> 00:20:42,000
roof cave.
And that's clearly not going to

409
00:20:42,000 --> 00:20:43,320
happen.
We're not going to create that

410
00:20:43,320 --> 00:20:47,920
level of oppression differential
and instead there will be air

411
00:20:47,920 --> 00:20:50,520
leaking in.
And in a air leaky building, not

412
00:20:50,520 --> 00:20:52,480
a problem.
Air will just leak in everywhere

413
00:20:52,480 --> 00:20:55,760
and everything will operate fine
and dandy as it were.

414
00:20:55,760 --> 00:20:58,360
It affects comfort though of
course, but in an airtight

415
00:20:58,360 --> 00:21:01,240
envelope you need a a make up
air solution.

416
00:21:01,600 --> 00:21:05,480
Now in very airtight buildings
like passive houses, if you've

417
00:21:05,480 --> 00:21:08,480
got a very powerful range hood,
it can often produce enough

418
00:21:08,480 --> 00:21:12,960
static pressure to actually
still extract adequately because

419
00:21:12,960 --> 00:21:18,560
you're never 100% airtight.
But if you have a fairly modest

420
00:21:18,840 --> 00:21:22,320
range, then you might well find
at some point you get to a level

421
00:21:22,320 --> 00:21:25,960
where the fan just spins and not
much air moves, which is

422
00:21:25,960 --> 00:21:28,960
defending the purpose when it's
an extraction fan in a bathroom

423
00:21:28,960 --> 00:21:32,000
or a range of the kitchen.
So you need often you need to

424
00:21:32,000 --> 00:21:34,640
make up air strategy.
And what we've been pointing to

425
00:21:34,920 --> 00:21:38,240
in passive house lately is sort
of things have moved very much I

426
00:21:38,240 --> 00:21:41,040
think now towards externally
venting range hoods.

427
00:21:41,040 --> 00:21:43,920
We used to be on internal
recirculation, carbon

428
00:21:43,920 --> 00:21:46,640
filtration.
I think for air quality it's

429
00:21:46,640 --> 00:21:50,920
right that we should be pushing
to the external solution, but it

430
00:21:50,920 --> 00:21:53,800
is much more difficult because
you've got to make the external

431
00:21:53,800 --> 00:21:56,120
vent airtight.
And then you need to make up air

432
00:21:56,120 --> 00:21:59,240
strategy, which can be done in a
complicated way with another

433
00:21:59,240 --> 00:22:02,800
make up air duct and a fan.
And it can all be electrically

434
00:22:02,800 --> 00:22:05,480
linked or you can simply open
window.

435
00:22:06,920 --> 00:22:10,040
Yeah, crack a window which then
compromises all of your energy

436
00:22:10,040 --> 00:22:12,360
efficiency.
But so do does it make up air

437
00:22:12,360 --> 00:22:15,080
ducts through somewhere else?
I mean the reality is with the

438
00:22:15,080 --> 00:22:18,160
rain should in particular you're
looking at extracting very high

439
00:22:18,160 --> 00:22:22,160
volumes of air, you know 3 or 4
times that of what your HRV is

440
00:22:22,160 --> 00:22:24,960
doing an hour.
And so you're going to need to

441
00:22:24,960 --> 00:22:28,480
provide a supply make up air
solution.

442
00:22:28,760 --> 00:22:31,560
And if you put it relatively,
the sort of the balance you're

443
00:22:31,560 --> 00:22:34,160
trying to achieve is you want to
close enough to the rain should

444
00:22:34,600 --> 00:22:38,720
that it doesn't entrain warm air
from the other end of the house

445
00:22:39,120 --> 00:22:42,240
and create this draft down your
hallway, down to the kitchen and

446
00:22:42,240 --> 00:22:44,160
out.
But you don't want to be so

447
00:22:44,160 --> 00:22:47,440
close to the range hood that you
don't fully capture all of the

448
00:22:47,440 --> 00:22:49,000
pollutants that are coming off
the cook top.

449
00:22:49,640 --> 00:22:52,120
And so you want to be, you know,
for argument's sake, a couple of

450
00:22:52,120 --> 00:22:55,600
meters away to allow that
incoming air from that window or

451
00:22:55,600 --> 00:22:59,160
whatever it may be to come to
entrain all the pollutants

452
00:22:59,160 --> 00:23:02,040
coming up from the cook top and
then out the range hood without

453
00:23:02,040 --> 00:23:07,120
creating too much draft.
And that is why a mechanical HIV

454
00:23:07,120 --> 00:23:11,200
system, the word balanced
mechanical HIV is key because

455
00:23:11,200 --> 00:23:15,040
it's it's an equal supply as
extract and there's no need for

456
00:23:15,040 --> 00:23:17,600
cracking windows or it's extra
vents and things.

457
00:23:17,800 --> 00:23:20,040
And that's a great thing with
HIV, isn't it, That there's

458
00:23:20,040 --> 00:23:22,040
nothing really for the operator
to do.

459
00:23:22,080 --> 00:23:25,360
In fact, time and time again we
get problems with HIV installs

460
00:23:25,360 --> 00:23:27,600
because the client has actually
gone and meddled with it.

461
00:23:29,120 --> 00:23:31,880
And instead the message I think
seems to be should be in our

462
00:23:31,880 --> 00:23:34,560
sort of when we do a hand over
to our clients, don't stuff

463
00:23:34,560 --> 00:23:36,400
around them.
Set and forget.

464
00:23:36,520 --> 00:23:39,320
Set and forget.
Every six months it'll be back

465
00:23:39,320 --> 00:23:41,360
to you and tell you to change
its filters.

466
00:23:41,600 --> 00:23:44,280
That's all you should do.
We've set it up such that it'll

467
00:23:44,280 --> 00:23:47,240
just stick away now for many
years to come, as long as you

468
00:23:47,240 --> 00:23:48,320
don't go fiddling with it.
What?

469
00:23:49,200 --> 00:23:52,440
Do they typically fiddle with?
There's also like, set it on

470
00:23:52,440 --> 00:23:55,360
summer bypass or something that
someone told me this morning.

471
00:23:56,280 --> 00:23:57,840
Yeah, there's all sorts of ways
to it.

472
00:23:57,840 --> 00:24:00,120
I mean, humans are great, aren't
we?

473
00:24:00,120 --> 00:24:02,360
We're very good at taking things
that are working fine and

474
00:24:02,360 --> 00:24:04,600
breaking.
Up indeed, indeed.

475
00:24:05,120 --> 00:24:09,000
All right, so let's move on to
something a little bit different

476
00:24:09,520 --> 00:24:11,480
here.
I'll talk about about moisture

477
00:24:11,480 --> 00:24:15,600
and water ingress.
As as you know, you've taken

478
00:24:15,600 --> 00:24:22,720
your home here from an older,
you know, 30 ACH older home and

479
00:24:22,720 --> 00:24:25,040
you've improved it out of sight
to make it more comfortable.

480
00:24:26,120 --> 00:24:27,000
Not even above the building
code.

481
00:24:27,000 --> 00:24:29,880
But there are also renovations
being done to make homes just

482
00:24:29,880 --> 00:24:32,160
more comfortable in accordance
with the building code.

483
00:24:32,800 --> 00:24:35,920
And as you've got an HIV system
in this home, which a lot of

484
00:24:36,160 --> 00:24:38,400
homes who are having
improvements done to them won't

485
00:24:38,400 --> 00:24:43,040
have.
So as we are creating warmer,

486
00:24:43,040 --> 00:24:46,720
more humid environments inside
more airtight environments, we

487
00:24:46,720 --> 00:24:49,400
are creating condensation risk.
And so now we're not only

488
00:24:49,400 --> 00:24:52,360
getting moisture ingress from
driving rain and and cladding

489
00:24:52,360 --> 00:24:54,720
lakes, we're also getting
moisture occurring in our

490
00:24:54,720 --> 00:24:58,360
buildings from inside.
So how can we explain vapour

491
00:24:58,360 --> 00:25:01,840
diffusion and condensation risks
to builders in a way that that

492
00:25:01,840 --> 00:25:05,120
makes sense to them?
OK, so it's a tricky 1, isn't

493
00:25:05,120 --> 00:25:06,400
it?
So I think the first thing to

494
00:25:06,400 --> 00:25:10,240
say is the water vapours all
around us, always wherever we

495
00:25:10,240 --> 00:25:13,760
are in the world, it will vary
the quantity of that water.

496
00:25:14,920 --> 00:25:18,680
And then so you can't escape,
escape the presence of the

497
00:25:18,680 --> 00:25:21,040
vapor.
But what we're wanting to do is

498
00:25:21,040 --> 00:25:23,920
stop condensation.
We're wanting to stop that vapor

499
00:25:23,920 --> 00:25:26,800
from actually condensing.
And so there are two ingredients

500
00:25:26,800 --> 00:25:29,440
to this equation.
There's vapor and a condensing

501
00:25:29,440 --> 00:25:32,680
surface, which is a fancy word
for a cold surface.

502
00:25:33,120 --> 00:25:36,240
And so you get that beer or that
bottle out of the fridge.

503
00:25:37,120 --> 00:25:39,760
Like now I can't see water vapor
in there.

504
00:25:39,760 --> 00:25:43,000
But as soon as I get that bottle
out with the fridge, I know it's

505
00:25:43,000 --> 00:25:44,440
going to get the condensation on
the surface.

506
00:25:44,960 --> 00:25:47,840
What's changed?
I've got a condensing surface, a

507
00:25:47,840 --> 00:25:51,360
cold surface on for which the
vapor can condense onto.

508
00:25:52,200 --> 00:25:54,880
So if you can get rid of the
condensing surface, you don't

509
00:25:54,880 --> 00:25:57,880
have a problem.
If you can reduce the vapor

510
00:25:58,360 --> 00:26:03,280
below the dew point, which is a
fancy term for how much water

511
00:26:03,360 --> 00:26:06,480
can be sustained within an air
mass at a certain temperature,

512
00:26:06,600 --> 00:26:11,040
you don't have a problem.
So heat your heat your air so

513
00:26:11,040 --> 00:26:15,560
that it can it can support more
more vapour, more moisture and

514
00:26:15,560 --> 00:26:19,120
and remove the condensing
surface by insulating or making

515
00:26:19,120 --> 00:26:22,720
sure the layers in your building
envelope are such that you're

516
00:26:22,720 --> 00:26:25,240
not going to get condensation on
those surfaces.

517
00:26:27,200 --> 00:26:29,080
So let's take a steel frame
building for example.

518
00:26:29,200 --> 00:26:33,160
One giant condensing surface in
the wrong conditions.

519
00:26:33,520 --> 00:26:38,880
So how would you, how would you
stop that condensation from

520
00:26:38,880 --> 00:26:40,400
happening on a steel frame
building?

521
00:26:40,560 --> 00:26:43,960
So your classic way of doing the
steel frame stud construction of

522
00:26:43,960 --> 00:26:47,080
course is you insulate between
the studs just as you do within

523
00:26:47,080 --> 00:26:49,520
the frame construction.
And then of course all of your

524
00:26:49,520 --> 00:26:52,480
studs are cold in the winter.
And so on the back face of your

525
00:26:52,480 --> 00:26:54,360
plasterboard, you're just
creating and creating these

526
00:26:54,360 --> 00:26:58,440
lines of condensate of cold
surfaces on which the

527
00:26:58,440 --> 00:27:01,880
condensation can form.
So the only way to solve that

528
00:27:01,880 --> 00:27:06,800
problem is to warm the steel.
And to warm the steel you have

529
00:27:06,800 --> 00:27:09,880
to externally insulate.
So which, and this is where we

530
00:27:09,880 --> 00:27:13,560
get towards this notion of the
perfect wall, is that you have

531
00:27:13,560 --> 00:27:16,400
exterior insulation.
So you separate out your

532
00:27:16,400 --> 00:27:19,760
structural layer, a steel frame
in this case, and you put the

533
00:27:19,760 --> 00:27:23,160
insulation, maybe it's a foam
cladding, whatever it may be on

534
00:27:23,160 --> 00:27:27,000
the outside face of that steel.
So now in winter, and we're

535
00:27:27,000 --> 00:27:29,680
assuming you've like a
Melbourne, Adelaide, Hobart,

536
00:27:29,680 --> 00:27:33,880
whatever type climate that as
you condition the inside of the

537
00:27:33,880 --> 00:27:37,280
house, the steel frame heats up
to exactly the same temperature

538
00:27:37,400 --> 00:27:39,440
as the room temperature.
So say 20°.

539
00:27:39,760 --> 00:27:43,600
And at 20°, you're very unlikely
to get condensation on that

540
00:27:43,640 --> 00:27:47,520
steel unless you have an awful
lot of moisture in your house.

541
00:27:47,560 --> 00:27:49,960
Yeah, yeah.
You made a really good analogy

542
00:27:50,040 --> 00:27:53,240
in the Mindful Build, a podcast
of the conductivity of different

543
00:27:53,240 --> 00:27:54,520
materials.
Could you just repeat that

544
00:27:54,640 --> 00:27:58,080
quickly just so that the
listener can understand how

545
00:27:58,080 --> 00:27:59,600
conductive steel is?
Yeah.

546
00:27:59,600 --> 00:28:02,720
OK, so so you've got three ways
of heat transferring.

547
00:28:03,000 --> 00:28:05,760
You've got conduction,
convection and radiation.

548
00:28:06,160 --> 00:28:08,320
Conduction occurs in solid
materials.

549
00:28:08,320 --> 00:28:10,800
So in a solid, you've got a
bunch of atoms joined in a

550
00:28:10,800 --> 00:28:12,320
lattice.
And what's he?

551
00:28:12,360 --> 00:28:15,600
Heat is energy for kinetic
energy.

552
00:28:15,840 --> 00:28:18,600
And so those atoms vibrate and
they tap into the one next door

553
00:28:19,080 --> 00:28:21,400
and they transfer heat.
That's conduction.

554
00:28:21,680 --> 00:28:24,040
And so conduction occurs in
solar materials.

555
00:28:24,360 --> 00:28:28,160
And so you have very low
conduction in some some

556
00:28:28,160 --> 00:28:31,640
materials like your foams,
plastics and so on, up to very

557
00:28:31,640 --> 00:28:35,080
high conduction, conduction
things like steel and even more

558
00:28:35,080 --> 00:28:37,560
so aluminum.
But you get big differences in

559
00:28:37,640 --> 00:28:40,640
even between metals.
So something like a carbon steel

560
00:28:40,640 --> 00:28:42,760
is about 30 watts per meter
Kelvin.

561
00:28:42,760 --> 00:28:45,560
So this is the measure we use
for thermal conductivity.

562
00:28:45,840 --> 00:28:49,640
A lower number is better.
So just to give that a scale,

563
00:28:49,840 --> 00:28:54,120
your typical glass full
insulation bat is maybe .04.

564
00:28:54,840 --> 00:28:57,240
So you're at 30 with carbon
steel.

565
00:28:57,240 --> 00:28:59,920
So divide those through.
That's many hundreds of times

566
00:29:00,200 --> 00:29:04,160
more conductive then then then
you then you've got other steels

567
00:29:04,160 --> 00:29:06,560
that are up around 50, so you've
got a big difference there.

568
00:29:06,920 --> 00:29:09,360
And then your aluminium is up
around 250.

569
00:29:10,080 --> 00:29:13,760
So what's the worst material we
could use to build our our

570
00:29:13,840 --> 00:29:18,880
window frames from aluminium?
And why do we get condensation

571
00:29:18,880 --> 00:29:20,840
on aluminium window frames in
the winter?

572
00:29:21,680 --> 00:29:23,640
Because they're a condensing
surface.

573
00:29:24,240 --> 00:29:27,200
And so if you want to avoid
condensation, which we all

574
00:29:27,200 --> 00:29:29,960
should, we should not be
accepting this idea, this

575
00:29:29,960 --> 00:29:33,520
culturally embedded idea in
Australia that oh, it's winter,

576
00:29:33,520 --> 00:29:37,040
I get conversation on my window.
No, that is not, that is not

577
00:29:37,040 --> 00:29:40,200
acceptable.
That is not just how it is.

578
00:29:41,240 --> 00:29:44,000
We can do better than that, and
we know exactly why it's

579
00:29:44,000 --> 00:29:45,360
occurring.
And we know how to fix it.

580
00:29:45,600 --> 00:29:48,000
How we know how to fix it?
Indeed.

581
00:29:50,320 --> 00:29:54,600
So what I was, what I was also
getting at was the the analogy

582
00:29:54,600 --> 00:29:57,160
you made between, you know,
you've got a fire and you stick

583
00:29:57,160 --> 00:29:59,480
a piece of timber in it and
always stick a piece of steel

584
00:29:59,480 --> 00:30:02,320
and always stick a piece of
insulation in it.

585
00:30:02,400 --> 00:30:06,920
And how quickly the the end that
you're holding gets hot.

586
00:30:07,360 --> 00:30:11,840
So yeah, I thought that was a
really just a really good visual

587
00:30:11,840 --> 00:30:14,880
or practical example of thermal
conductivity.

588
00:30:14,880 --> 00:30:17,200
Do you know the conductivity of
copper is off the copper in your

589
00:30:17,200 --> 00:30:18,160
head?
No, I don't.

590
00:30:18,760 --> 00:30:22,600
I'm meaning to find out.
It's time for a quick sponsor

591
00:30:22,600 --> 00:30:25,360
shout out.
Today's episode of the Building

592
00:30:25,360 --> 00:30:28,440
Psychology Poddy is proudly
brought to you by our amazing

593
00:30:28,440 --> 00:30:30,320
sponsors, Enduro Builders and
Climate Shore.

594
00:30:30,800 --> 00:30:33,160
A huge thank you to these
incredible businesses for

595
00:30:33,160 --> 00:30:36,160
supporting the podcast and
helping us spread the word about

596
00:30:36,160 --> 00:30:37,640
better buildings to live and
breathe in.

597
00:30:38,080 --> 00:30:40,200
Your support makes this podcast
possible.

598
00:30:40,720 --> 00:30:43,480
Please head over to their
websites and follow their social

599
00:30:43,480 --> 00:30:45,880
pages.
Objective here again is to

600
00:30:45,880 --> 00:30:50,200
eliminate condensing services
and so your primary objective

601
00:30:50,200 --> 00:30:53,400
with any steel in construction
is to keep it on the warm side.

602
00:30:53,560 --> 00:30:56,840
So towards the interior.
So the classic to figure

603
00:30:56,840 --> 00:31:00,280
profile, say you've got a Pfc
lentil above a sliding door

604
00:31:00,280 --> 00:31:03,120
somewhere, might have a 90 mil
deep flange on it.

605
00:31:03,520 --> 00:31:07,760
So you'll often then have to
push that wall out to 140, say

606
00:31:07,760 --> 00:31:12,720
timber framing to give you 50mm
of space towards the outside

607
00:31:12,720 --> 00:31:15,640
face of that Pfc.
So you would run something like

608
00:31:15,640 --> 00:31:20,240
XPS and polystyrene insulation
to try and keep the steel on the

609
00:31:20,240 --> 00:31:23,320
warm side of the assembly.
And it's something that needs to

610
00:31:23,320 --> 00:31:28,000
be detailed during design and
can't because if you give if you

611
00:31:28,000 --> 00:31:31,200
give a builder a detail with
insulated steel and I've never

612
00:31:31,200 --> 00:31:34,120
seen it before or you surprise
them with it and or, you know,

613
00:31:34,480 --> 00:31:37,000
they'll say, oh, I've never done
this before.

614
00:31:37,000 --> 00:31:39,320
And you know, that's not how we
do it and blah, blah, blah.

615
00:31:39,320 --> 00:31:42,560
So those conversations about
using the XPS or EPS

616
00:31:42,560 --> 00:31:45,920
installation on the outside of a
steel frame, all of that

617
00:31:45,920 --> 00:31:48,680
collaboration and communication
needs to happen very early on.

618
00:31:48,840 --> 00:31:53,000
Yeah, you'd really need to see
that in the section details in

619
00:31:53,000 --> 00:31:55,520
your drawing set.
And then the other tricky bit

620
00:31:55,520 --> 00:31:58,320
that comes in with steel often
is obviously you're often

621
00:31:58,320 --> 00:32:02,360
carrying that load into a column
like a steel SHS column.

622
00:32:02,920 --> 00:32:06,640
So you again, assuming it's 90
mil square, you'd externally

623
00:32:06,640 --> 00:32:08,800
insulate it.
But then it's going to have a

624
00:32:08,800 --> 00:32:12,400
bottom plate, it's going to be
sitting on say a cold slab or if

625
00:32:12,400 --> 00:32:15,360
it's suspended timber floor,
it's going to be penetrating

626
00:32:15,360 --> 00:32:17,600
through the thermal envelope to
the subfloor.

627
00:32:17,840 --> 00:32:20,360
And so you've got to come up
with the detail for that.

628
00:32:20,840 --> 00:32:25,720
And so best practice would be to
with say the slab connection is

629
00:32:25,720 --> 00:32:29,280
to put a structural thermal
brake material underneath.

630
00:32:29,560 --> 00:32:31,440
But of course that's got to be
signed off by the structural

631
00:32:31,440 --> 00:32:33,880
engineer too.
So all of that has to be

632
00:32:33,880 --> 00:32:37,440
detailed prior to construction.
And of course, all these shop

633
00:32:37,440 --> 00:32:39,480
drawings have to be done to
account for those different

634
00:32:39,480 --> 00:32:43,040
dimensions that might change.
Absolutely great advice.

635
00:32:44,920 --> 00:32:49,600
If you're in your experience.
Where do most insulation

636
00:32:49,600 --> 00:32:54,080
installs fall down?
Is it gaps, compression, wrong

637
00:32:54,120 --> 00:32:56,640
product selection or something
else?

638
00:32:57,000 --> 00:32:58,720
I'll probably go with one and
three.

639
00:32:58,720 --> 00:33:02,160
So, so, so get gaps and wrong
products.

640
00:33:02,280 --> 00:33:05,200
Not so much wrong product
selection, but wrong product

641
00:33:05,200 --> 00:33:08,440
sequencing.
So start with the gaps first.

642
00:33:08,440 --> 00:33:13,400
So you only need one 5% gaps,
you know, very tiny gaps.

643
00:33:13,400 --> 00:33:16,200
So imagine you've got a wall and
you put your insulation between

644
00:33:16,200 --> 00:33:19,640
your studs that are fairly nice
and tucked in neatly, and then

645
00:33:19,640 --> 00:33:23,680
it drops down below the noggin.
And maybe you're saving some

646
00:33:23,680 --> 00:33:27,240
money and going for a fairly
lightweight, soft and fluffy

647
00:33:27,280 --> 00:33:29,600
wall bat.
And invariably that's going to

648
00:33:29,600 --> 00:33:32,360
sag over time.
And as soon as it starts to sag,

649
00:33:32,360 --> 00:33:36,680
those tiny little gaps will have
a very disproportionate effect.

650
00:33:37,000 --> 00:33:40,120
And how do we work that out?
Because there's, this is sort of

651
00:33:40,280 --> 00:33:42,400
sorry to interrupt your camera,
but there's, there's a lot of

652
00:33:42,400 --> 00:33:45,120
information, a lot of statements
around how tiny gaps will

653
00:33:45,120 --> 00:33:47,200
decrease your installation
performance by 40%.

654
00:33:47,480 --> 00:33:48,880
Where do those numbers come
from?

655
00:33:48,960 --> 00:33:51,400
So the, the, the best way to do
it is in a hot box.

656
00:33:51,400 --> 00:33:54,920
So you take a sample of the wall
and you heat one side of it and

657
00:33:54,920 --> 00:33:57,320
then you can measure the heat
flow across to the other side.

658
00:33:57,320 --> 00:33:59,800
OK within it.
Like just do it experimentally.

659
00:34:00,000 --> 00:34:03,240
That's one way, but you can also
do it theoretically too.

660
00:34:03,240 --> 00:34:06,160
So you can do it in like in the
thermal bridge calculation.

661
00:34:06,160 --> 00:34:10,040
There's the fancy term is a
finite element analysis.

662
00:34:10,040 --> 00:34:12,280
So you take a detail and you
break it up into a whole lot of

663
00:34:12,280 --> 00:34:16,199
time in the squares and you and
you run a bunch of equations on

664
00:34:16,199 --> 00:34:20,600
that to allow heat flow to move
through that that that build up

665
00:34:20,639 --> 00:34:22,840
that you've got and you can
assess the impact.

666
00:34:23,159 --> 00:34:26,520
But probably the the the more
difficult part of it.

667
00:34:26,520 --> 00:34:29,360
So you've got a conduction
problem, but you've also got a

668
00:34:29,360 --> 00:34:33,960
convection problem because air
will be moving through that gap

669
00:34:33,960 --> 00:34:36,440
too.
And when the air moves, it's

670
00:34:36,440 --> 00:34:39,760
taking heat with it.
And even more problematic, it's

671
00:34:39,760 --> 00:34:42,880
taking vapor with it.
And if it takes vapor with it

672
00:34:42,880 --> 00:34:45,639
and moves from warm to cold,
boom, we've got potential

673
00:34:45,639 --> 00:34:46,840
condensation problems.
Yeah.

674
00:34:47,239 --> 00:34:50,719
And that's the cold spots.
The cold spots equals mild spots

675
00:34:51,280 --> 00:34:54,239
problem when you have and you
have gaps in your insulation.

676
00:34:54,400 --> 00:34:55,440
That's right.
Yeah.

677
00:34:55,440 --> 00:34:58,360
So, so that that's the problem
with with gap.

678
00:34:58,400 --> 00:35:01,120
So gaps, you've just got to be
super diligent about the way in

679
00:35:01,120 --> 00:35:03,480
which you install it.
I'm not so fussed about

680
00:35:03,480 --> 00:35:06,560
compression, mild levels of
compression with your fibrous

681
00:35:06,560 --> 00:35:09,720
insulations like your glass
full, it's not a big deal. 5 to

682
00:35:09,720 --> 00:35:12,880
10%, OK.
You know, obviously if you go to

683
00:35:12,880 --> 00:35:15,720
the other extreme and just
compress a glass full bat that

684
00:35:15,720 --> 00:35:19,240
was supposed to be 90 mil down
to 20 or 30 mil, then you've

685
00:35:19,240 --> 00:35:22,000
lost all your benefit because
the whole reason for that bat's

686
00:35:22,000 --> 00:35:24,800
existence is to create lots and
lots of air pockets.

687
00:35:25,200 --> 00:35:28,160
That's what insulation is, lots
and lots of still air gaps.

688
00:35:28,880 --> 00:35:32,160
If you eliminate those air gaps,
well, you've just got glass now,

689
00:35:33,280 --> 00:35:34,880
which is not gonna get you very
far.

690
00:35:35,440 --> 00:35:39,520
But to your Third Point about
wrong product selection, it's

691
00:35:39,520 --> 00:35:43,080
more about the layering I think.
And this is where you say, for

692
00:35:43,080 --> 00:35:47,520
example, say I've got a 90 mil
timber frame and I put an R 2.5

693
00:35:47,520 --> 00:35:50,600
glass full bat in there, which
is pretty standard in southern

694
00:35:50,600 --> 00:35:52,840
parts of Australia.
And you go, well, I'd really

695
00:35:52,840 --> 00:35:55,880
love some extra insulation here.
I don't know, go and stick a, a,

696
00:35:57,080 --> 00:36:01,480
a foam board on the outside of
my stud frame because then I can

697
00:36:01,480 --> 00:36:06,000
get an extra 1.5 to whatever
thickness I want on that, on

698
00:36:06,000 --> 00:36:09,720
that wall and intuitively go,
yeah, that's easy win.

699
00:36:09,720 --> 00:36:13,880
Let's do that.
And, and yes, from a thermal

700
00:36:13,880 --> 00:36:16,600
conductance point of view,
that's a good solution.

701
00:36:16,920 --> 00:36:20,440
The problem is that you're not
considering the moisture

702
00:36:20,440 --> 00:36:24,960
movement through that assembler
and what risks happening is that

703
00:36:24,960 --> 00:36:29,000
you've moved the dew point in
that wall such that the interior

704
00:36:29,000 --> 00:36:32,120
face of the phone becomes a
condensing service.

705
00:36:32,800 --> 00:36:36,240
And again, vapour heating cold
surfaces problems.

706
00:36:37,120 --> 00:36:39,800
And so if you're going to do
something where you've got a 90

707
00:36:39,800 --> 00:36:43,440
mil frame and when I had some
extra reinsulation, it ideally

708
00:36:43,440 --> 00:36:45,880
should be vapor permeable.
Yeah, because on a heating

709
00:36:45,880 --> 00:36:49,240
dominated climate as you move
out through your assembly, you

710
00:36:49,240 --> 00:36:53,040
want to increasing vapor
permeates, increasing vapor

711
00:36:53,040 --> 00:36:55,560
openness.
And so if you put say a wood

712
00:36:55,560 --> 00:37:00,000
fiber or a mineral wool product
on the outside, the water vapor

713
00:37:00,000 --> 00:37:02,120
can continue to to diffuse out
and.

714
00:37:02,720 --> 00:37:05,320
What if you did?
What if you did EPS on a vented

715
00:37:05,360 --> 00:37:07,560
cavity?
You wouldn't get the same

716
00:37:07,560 --> 00:37:09,960
benefit though then, would you?
No, that, that, that's right.

717
00:37:09,960 --> 00:37:14,640
So you imagine say your EPS
based render board system.

718
00:37:15,440 --> 00:37:19,960
So ideally you wanna have a
baton behind that, that EPS in

719
00:37:19,960 --> 00:37:22,960
order to allow any water that
gets past the cladding, past the

720
00:37:22,960 --> 00:37:25,880
EPS to drain away.
And ideally you want to

721
00:37:25,880 --> 00:37:28,920
ventilate that cavity because
you want any moisture that might

722
00:37:28,920 --> 00:37:32,080
diffuse from the outside, from
the inside towards the outside

723
00:37:32,080 --> 00:37:35,280
to be able to escape.
And the more you ventilate that

724
00:37:35,280 --> 00:37:39,920
cavity, the less that's a still
air gap and therefore the APS

725
00:37:39,920 --> 00:37:42,880
that's sitting out in La La land
effectively is no longer

726
00:37:42,880 --> 00:37:45,400
contributing to the R value to
the thermal performance that

727
00:37:45,480 --> 00:37:47,200
will.
Visual only at that point.

728
00:37:47,200 --> 00:37:49,600
Visual and which is fine, you
know you need something to

729
00:37:49,600 --> 00:37:54,600
attach your render to, but don't
go and then falsely claim that

730
00:37:54,600 --> 00:37:56,280
it's giving you some extra
thermal performance.

731
00:37:56,360 --> 00:37:59,560
If you want, yeah, understood.
The builders are often working

732
00:37:59,560 --> 00:38:03,120
from plans that don't show
enough detail around insulation,

733
00:38:03,120 --> 00:38:05,240
install junctions, moisture
management.

734
00:38:06,680 --> 00:38:08,680
How can we improve that
relationship between design

735
00:38:08,680 --> 00:38:13,760
intent and site execution?
Yeah, it's difficult. 1, I don't

736
00:38:13,760 --> 00:38:16,400
think I have a great answer to
this, probably in different

737
00:38:16,400 --> 00:38:20,320
parts.
But obviously the building

738
00:38:20,320 --> 00:38:23,400
designers, architects that are
more experienced in doing these

739
00:38:23,400 --> 00:38:28,600
sorts of constructions have have
a set of standard details that

740
00:38:28,600 --> 00:38:31,080
they'll provide in in their
document package to the builder

741
00:38:32,200 --> 00:38:35,040
that they can go away with.
And equally, builders who have

742
00:38:35,040 --> 00:38:38,640
done this a few times often
won't need to be or want to be

743
00:38:38,640 --> 00:38:41,040
told exactly how to detail it,
say no.

744
00:38:41,480 --> 00:38:46,080
And given that they're on the
tools on site, ultimately having

745
00:38:46,080 --> 00:38:49,080
them having the engagement and
in their minds, understanding

746
00:38:49,080 --> 00:38:51,720
the 3D of how this is going to
all go together, how they're

747
00:38:51,720 --> 00:38:54,720
going to sequence it is
absolutely critical.

748
00:38:55,120 --> 00:38:58,520
But you've got to get from go to
work.

749
00:38:58,520 --> 00:39:02,400
And and that's, that's tricky,
but we do have to improve our,

750
00:39:02,400 --> 00:39:04,520
our detailing.
I, I think it's great that some

751
00:39:04,520 --> 00:39:07,760
of the product suppliers now are
providing standard details.

752
00:39:08,000 --> 00:39:11,680
So that saves all parties from
having to draw their own details

753
00:39:11,680 --> 00:39:14,520
if they can just essentially
borrow a standard details.

754
00:39:14,520 --> 00:39:16,720
And great from a product
suppliers point of view of

755
00:39:16,720 --> 00:39:19,560
course, because they have a
greater deal of confidence that

756
00:39:19,560 --> 00:39:23,000
their product when installed,
will be installed in accordance

757
00:39:23,000 --> 00:39:27,120
with manufacturers
recommendations and therefore is

758
00:39:27,120 --> 00:39:29,560
more likely to work effectively
or as designed.

759
00:39:31,640 --> 00:39:37,320
So really the only solution to
making, I guess it's that that

760
00:39:37,320 --> 00:39:40,080
what gets designed and what gets
built gap, that performance gap

761
00:39:40,080 --> 00:39:41,560
that we're talking about here
essentially.

762
00:39:41,800 --> 00:39:44,760
And the only way to close that
is upscaling everybody.

763
00:39:45,240 --> 00:39:48,080
I think so, but especially, you
know, to to put the owners back

764
00:39:48,080 --> 00:39:50,320
on the poor builders is like
it's not fair.

765
00:39:50,400 --> 00:39:54,480
Is that it's it's kind of not
fair, but but it it what gets

766
00:39:54,480 --> 00:39:57,720
built is what matters.
What gets drawn is irrelevant.

767
00:39:57,720 --> 00:40:02,240
What people like me model is
irrelevant if it's not related

768
00:40:02,240 --> 00:40:04,680
to what actually happens on the
ground on the site.

769
00:40:05,040 --> 00:40:07,800
And I think this is really
terrific, the way.

770
00:40:08,280 --> 00:40:10,880
The industry, or certainly the
subset of the industry in which

771
00:40:10,880 --> 00:40:15,080
I work is sort of transformed in
the past decade or so, is that

772
00:40:15,080 --> 00:40:18,120
we have some fantastic builders
over where I am, at least in

773
00:40:18,120 --> 00:40:22,120
Victoria, that are super engaged
with this now, increasingly

774
00:40:22,120 --> 00:40:29,040
experienced and can deliver on
this without necessarily having

775
00:40:29,040 --> 00:40:32,200
to have every NTH detail drawn
for them.

776
00:40:32,760 --> 00:40:34,240
And there's always this balance,
isn't it?

777
00:40:34,240 --> 00:40:36,600
You know, you don't want a two
page drawing set, but you don't

778
00:40:36,600 --> 00:40:38,800
really want a 200 page drawing
set either.

779
00:40:39,120 --> 00:40:41,960
And invariably there will be
details that need to be worked

780
00:40:41,960 --> 00:40:46,480
out on site that won't quite
work through in the pre pre

781
00:40:46,480 --> 00:40:47,160
construction.
Phase.

782
00:40:47,160 --> 00:40:49,640
Yeah, I was having a discussion
with the builder last weekend

783
00:40:49,640 --> 00:40:52,400
and yeah, he was just
expressing, expressing his

784
00:40:52,400 --> 00:40:54,920
frustration with the level of
detail that they get on the

785
00:40:54,920 --> 00:40:58,040
plans and, you know, the
communication and collaboration

786
00:40:58,040 --> 00:41:01,200
in the early stages.
Not being there and just having

787
00:41:01,200 --> 00:41:03,920
to make it up on site as they
go.

788
00:41:04,040 --> 00:41:06,560
I can imagine that that would be
tricky.

789
00:41:07,280 --> 00:41:09,080
I think the probably the other
thing there to think of

790
00:41:09,080 --> 00:41:11,960
dimensions too is probably the
idea of earlier contractor

791
00:41:11,960 --> 00:41:16,440
involvement in a design project.
Given where prices are at at the

792
00:41:16,440 --> 00:41:19,760
moment in the construction
industry, the idea of going to

793
00:41:19,760 --> 00:41:23,840
the competitive tender doesn't
seem to me to be a particularly

794
00:41:24,360 --> 00:41:27,960
attractive way of proceeding.
By instead involving a

795
00:41:27,960 --> 00:41:31,080
contractor or builder early on
in the design stage,

796
00:41:31,160 --> 00:41:33,400
particularly when it comes to
that sort of construction

797
00:41:33,400 --> 00:41:36,760
drawings and they can provide
input, particularly on the cost

798
00:41:36,760 --> 00:41:40,840
side, constructability and all
of that, Then it feels like that

799
00:41:40,840 --> 00:41:44,640
creates a more collaborative
universal engagement of all

800
00:41:44,640 --> 00:41:47,760
parties so that you don't get
that tension when the builder

801
00:41:47,760 --> 00:41:50,280
has just received a set of
construction ready drawings.

802
00:41:50,320 --> 00:41:51,520
Here you go.
Go build that.

803
00:41:51,520 --> 00:41:53,840
Yeah, it's not that sense of
ownership involvement.

804
00:41:53,840 --> 00:41:55,960
Whereas of course if the
builders had the opportunity to

805
00:41:56,360 --> 00:41:59,760
influence the design and they
both understand it and they have

806
00:41:59,760 --> 00:42:04,920
that sense of ownership as well,
which hopefully helps on side.

807
00:42:05,000 --> 00:42:06,680
Absolutely.
And I am seeing more of that

808
00:42:06,680 --> 00:42:12,120
happening, but it's, it's still
it's, it's still not happening

809
00:42:12,120 --> 00:42:13,760
enough.
There's still a lot of content

810
00:42:14,000 --> 00:42:18,640
attention and frustration in
that translation period, but

811
00:42:18,720 --> 00:42:20,120
yeah, I am seeing more of it
happens.

812
00:42:20,120 --> 00:42:23,240
So we'll focus on the good.
So roof colour is rather a hot

813
00:42:23,240 --> 00:42:25,160
topic.
It's there for aesthetics, but

814
00:42:25,160 --> 00:42:27,560
it's also there for performance.
And there's this contention

815
00:42:27,560 --> 00:42:30,720
between light roofs and dark
roofs, which one's better, heat

816
00:42:30,720 --> 00:42:32,680
island effect, etcetera,
etcetera.

817
00:42:32,960 --> 00:42:34,920
What are your thoughts on that?
OK.

818
00:42:34,920 --> 00:42:39,600
So it depends obviously on the
climate.

819
00:42:39,600 --> 00:42:46,520
It depends on the building as as
well for obviously for summer

820
00:42:46,640 --> 00:42:52,320
heat removal or minimize the
absorptance of of solar

821
00:42:52,320 --> 00:42:53,680
radiation.
In the summer you want a light

822
00:42:53,680 --> 00:42:55,720
colour like say a surface type
of colour.

823
00:42:56,840 --> 00:43:00,920
But in winter you generally
would prefer to have a dark

824
00:43:00,920 --> 00:43:04,560
colour in a in a southern
Australian type of climate from

825
00:43:04,560 --> 00:43:08,720
a thermal point of view.
However, from a moisture point

826
00:43:08,720 --> 00:43:13,160
of view, you often want a dark
colour year round and and what I

827
00:43:13,160 --> 00:43:17,160
think what matters here is not
so much the color of the

828
00:43:17,160 --> 00:43:19,960
cladding or the roof as much as
what you do immediately

829
00:43:19,960 --> 00:43:23,680
underneath it.
And so in high performance

830
00:43:23,680 --> 00:43:28,440
construction now we tend to have
a batten in the walls for

831
00:43:28,440 --> 00:43:31,880
ventilation and drainage.
And I think many builders would

832
00:43:31,880 --> 00:43:34,880
be, would be doing that even in
conventional construction now

833
00:43:34,880 --> 00:43:39,040
too, absolutely rightly for
compensation management and bulk

834
00:43:39,040 --> 00:43:42,440
water ingress.
But similarly also do the

835
00:43:42,440 --> 00:43:45,240
roofing exactly the same way.
So the roof is just a wall

836
00:43:45,680 --> 00:43:49,760
turned on its on the side.
And, and by creating that

837
00:43:49,760 --> 00:43:53,480
ventilation gap between the roof
sheet and you're sacking or

838
00:43:53,480 --> 00:43:57,120
membrane underneath and allowing
air to move through there, you

839
00:43:57,120 --> 00:43:59,640
allow any water that should
happen to get into that roof to

840
00:43:59,640 --> 00:44:02,960
drain down and away.
You allow any moisture that

841
00:44:02,960 --> 00:44:06,560
should drive up and out into
that cavity to be carried by

842
00:44:06,560 --> 00:44:08,120
that air movement through and
away.

843
00:44:08,520 --> 00:44:12,000
And if you have a dark roof
sheet color like builders this

844
00:44:12,000 --> 00:44:13,440
morning, he's got a night sky
roof.

845
00:44:13,440 --> 00:44:18,640
So super dark, it just creates a
much stronger chimney stack

846
00:44:18,640 --> 00:44:19,720
effect.
And we were talking about the

847
00:44:19,720 --> 00:44:21,160
depth of the bat and the
required.

848
00:44:21,440 --> 00:44:24,120
And if you have a dark roof
sheet color, then you don't

849
00:44:24,120 --> 00:44:27,640
necessarily need a steeper bat
because the dark roof sheet is

850
00:44:27,640 --> 00:44:31,200
creating much more warmer air in
that cavity and therefore

851
00:44:31,200 --> 00:44:33,720
driving stack ventilation just
like a chimney.

852
00:44:34,240 --> 00:44:35,360
And that's what you're trying to
do.

853
00:44:35,360 --> 00:44:38,360
You just think of the building
as a layer where the outside of

854
00:44:38,360 --> 00:44:41,960
your sacking, both a wool
membrane and up onto your roof

855
00:44:42,240 --> 00:44:43,920
is really effectively the
outside of the building.

856
00:44:44,520 --> 00:44:48,840
And then I'm going to stick this
sort of like almost umbrella

857
00:44:48,840 --> 00:44:52,040
around the building.
That's this wall cladding and my

858
00:44:52,040 --> 00:44:54,440
roof sheet.
They're set off from that

859
00:44:54,440 --> 00:44:56,120
sarking.
They're separated from it.

860
00:44:56,120 --> 00:44:59,560
So they provide shading and they
stop the bulk water ingress.

861
00:44:59,720 --> 00:45:02,120
See that sarking layer?
But other than that, they're

862
00:45:02,120 --> 00:45:03,960
essentially a separate cattle
fish altogether.

863
00:45:04,320 --> 00:45:07,080
And as soon as you do that and
you provide lots of ventilation

864
00:45:07,080 --> 00:45:10,280
in that cavity, which you
desirably do or want to do for

865
00:45:10,280 --> 00:45:14,040
both condensation and reduce
some overheating, then the color

866
00:45:14,040 --> 00:45:16,520
of cladding becomes less, much
less important.

867
00:45:16,960 --> 00:45:20,800
And so you can your client can
architect can can choose

868
00:45:20,800 --> 00:45:23,640
whatever cladding color that
works for their aesthetic.

869
00:45:24,400 --> 00:45:26,760
In Queensland, I think that
anything darker than monument is

870
00:45:26,760 --> 00:45:30,360
not allowed under the DTS rules
for overheating purposes.

871
00:45:30,640 --> 00:45:33,720
And in those here, you know,
calling dominated climates, that

872
00:45:33,720 --> 00:45:36,200
starts to conceivably make some
sense.

873
00:45:36,240 --> 00:45:39,760
Yeah, Yeah.
Yeah, it becomes a, as you say,

874
00:45:39,760 --> 00:45:44,120
is a moisture control issue.
A I think if you had to take

875
00:45:44,120 --> 00:45:48,320
your pick between moisture and
heat, I think you'd have to take

876
00:45:48,640 --> 00:45:50,560
moisture as a priority, wouldn't
you?

877
00:45:50,560 --> 00:45:51,840
What?
It kills buildings?

878
00:45:51,840 --> 00:45:54,360
Yeah, yeah, yeah.
If the building's dead, doesn't

879
00:45:54,360 --> 00:45:55,960
matter how energy efficient it
is.

880
00:45:56,160 --> 00:45:58,680
Precisely.
So you've got to deal with that

881
00:45:58,680 --> 00:46:02,800
first, yeah.
OK, a couple of questions.

882
00:46:03,000 --> 00:46:04,840
Windows are the trickiest part
of a building envelope.

883
00:46:04,840 --> 00:46:07,000
So what do you think builders
should know about getting the

884
00:46:07,080 --> 00:46:08,680
best them performance out of the
window?

885
00:46:08,680 --> 00:46:11,800
Because it's not just about the
component itself, the

886
00:46:11,800 --> 00:46:13,600
installation matters a lot as
well.

887
00:46:13,600 --> 00:46:16,560
So what's your?
And the Windows systems or the

888
00:46:16,560 --> 00:46:19,840
Windows system is both glass and
frame.

889
00:46:20,280 --> 00:46:22,240
So you've got to consider both
of those.

890
00:46:22,520 --> 00:46:26,320
To touch on the install, our
classic brick veneer install is

891
00:46:26,320 --> 00:46:29,440
probably the worst way you can
possibly install a window

892
00:46:29,440 --> 00:46:31,920
because we go and stick it out
in that cabinet, a cavity, it's

893
00:46:31,920 --> 00:46:33,520
essentially out there in la, la
land.

894
00:46:33,960 --> 00:46:37,600
And if you want the best thermal
performance for your building,

895
00:46:37,800 --> 00:46:40,280
then you've got to have all of
your insulation layers in the

896
00:46:40,280 --> 00:46:42,040
same plane.
So.

897
00:46:42,560 --> 00:46:45,120
Alignment.
So you all insulation, you start

898
00:46:45,120 --> 00:46:46,760
frame and then you hit the
window.

899
00:46:46,760 --> 00:46:48,480
The window is not sitting out
there.

900
00:46:50,240 --> 00:46:54,760
And this is to digress.
This is why one of the problems

901
00:46:54,760 --> 00:46:58,960
with skylights, if I take my
wall and turn it flat and have a

902
00:46:58,960 --> 00:47:01,800
window which is now called the
skylight, I can't have that

903
00:47:01,800 --> 00:47:04,040
sitting in the thermal envelope.
Yeah, it's gonna be poking.

904
00:47:04,120 --> 00:47:05,320
Up.
It's gotta be poking up the

905
00:47:05,320 --> 00:47:07,200
drainage.
And as soon as I make it poke

906
00:47:07,200 --> 00:47:09,600
up, I've got a problem.
Yeah, because I've got a thermal

907
00:47:09,600 --> 00:47:12,120
bridge all the way around the
perimeter, that skylight.

908
00:47:12,120 --> 00:47:16,880
And so I need to get funky with
some XPS, cut a collar around

909
00:47:16,880 --> 00:47:19,680
it, try and insulate around
that, that skylight, which is a

910
00:47:19,680 --> 00:47:22,760
lot of faffing around.
So you've got to ask, at what

911
00:47:22,760 --> 00:47:24,880
point do I really want this
skylight?

912
00:47:24,880 --> 00:47:26,880
How?
Much is that light worth to me?

913
00:47:27,480 --> 00:47:29,640
Exactly.
And you know, I skylights are

914
00:47:29,640 --> 00:47:33,920
sort of the bane of my life, but
in a wall, that's exactly what

915
00:47:33,920 --> 00:47:36,280
you're doing with a brick
veneer, traditional brick veneer

916
00:47:36,280 --> 00:47:37,840
install.
You're putting the window out my

917
00:47:37,840 --> 00:47:40,360
life just like a skylight.
So we can't be doing that.

918
00:47:40,680 --> 00:47:43,720
And I think we've increasingly,
certainly in my universe

919
00:47:44,240 --> 00:47:46,720
builders get that now and we're
over that.

920
00:47:47,680 --> 00:47:51,000
Where I think things get funky
with windows is probably the

921
00:47:51,000 --> 00:47:52,400
frames.
And I think we get that

922
00:47:52,400 --> 00:47:56,440
aluminium is terrible, certainly
broken aluminium is better, UPVC

923
00:47:56,880 --> 00:48:01,360
are very good, Timber is
obviously very good, but you

924
00:48:01,360 --> 00:48:05,640
know come at a price premium.
And then the other critical

925
00:48:05,640 --> 00:48:08,680
component is glazing
specification and we seem to get

926
00:48:08,680 --> 00:48:12,480
that wrong a lot.
Now we're increasingly and we're

927
00:48:12,480 --> 00:48:15,120
seeing double glazing as
standard, but your cheapest

928
00:48:15,120 --> 00:48:19,040
double glazing might have very
modest gaps and might not be

929
00:48:19,040 --> 00:48:21,280
argon filled.
And the argon helps, but it's

930
00:48:21,280 --> 00:48:23,760
not doing the really heavy
lifting, the really heavy

931
00:48:23,760 --> 00:48:27,680
lifting and a good double glazed
unit is the low E coating.

932
00:48:28,320 --> 00:48:33,840
It's this invisible spluttering
of silver and funky chemicals

933
00:48:34,160 --> 00:48:39,440
inside the pane of inside the
glass IGU and the insulated

934
00:48:39,440 --> 00:48:41,600
glazing unit.
And what that's doing is

935
00:48:41,600 --> 00:48:45,160
changing the radiation, changing
the way the emissivity of that

936
00:48:45,160 --> 00:48:47,800
glass surface works, and that
makes a big difference.

937
00:48:47,800 --> 00:48:49,160
Yeah.
So when you say you've got

938
00:48:49,160 --> 00:48:51,560
double glazing, my first
question is, what sort?

939
00:48:51,680 --> 00:48:55,000
Yeah, because there's a factor
of 2 difference in the thermal

940
00:48:55,000 --> 00:48:58,480
transmittance between rubbish
double glazing and really good

941
00:48:58,480 --> 00:49:01,320
double glazing.
And so you need to consider your

942
00:49:01,320 --> 00:49:02,840
building.
Is it in Adelaide?

943
00:49:02,840 --> 00:49:04,200
Is it Melbourne?
Is it Hobart?

944
00:49:04,200 --> 00:49:07,840
Is it in Cairns?
And then look at exactly the

945
00:49:07,840 --> 00:49:10,320
specification of that low E
coating because it can be

946
00:49:10,320 --> 00:49:12,880
tailored to do different things.
In Cairns you're trying to

947
00:49:12,880 --> 00:49:16,000
tailor it to stop solar
radiation getting in always.

948
00:49:16,520 --> 00:49:22,000
In Melbourne or Tassie, you're
trying to allow usually trying

949
00:49:22,000 --> 00:49:25,240
to allow as much of that solar
radiation to get in in winter as

950
00:49:25,240 --> 00:49:28,160
you possibly can.
And so the composition of that

951
00:49:28,680 --> 00:49:32,720
coating will change.
So that is not something a

952
00:49:32,720 --> 00:49:34,280
builder can control.
They can't.

953
00:49:34,280 --> 00:49:37,280
So that specification comes out
of the modeling, whether it's a

954
00:49:37,280 --> 00:49:39,440
a net host building code
compliance model or whether it's

955
00:49:39,440 --> 00:49:41,440
a PHPP model.
That's where that specification

956
00:49:41,440 --> 00:49:44,360
comes from.
As far as install, what can the

957
00:49:44,360 --> 00:49:47,440
builders do?
Of the window.

958
00:49:47,600 --> 00:49:49,080
Of the window, yes.
Yeah, Yeah.

959
00:49:49,080 --> 00:49:51,200
So I suppose so.
We touched upon the thermal

960
00:49:51,200 --> 00:49:53,880
performance, so make sure it's
in the plane and the insulation.

961
00:49:53,880 --> 00:49:55,000
Yeah.
And the other part of the

962
00:49:55,000 --> 00:49:56,800
installation is probably just
water management.

963
00:49:57,320 --> 00:50:00,080
So where's a bit of wall gonna
leak?

964
00:50:00,080 --> 00:50:02,200
The 1st place it's gonna leak
almost invariably.

965
00:50:02,200 --> 00:50:05,080
Is it the window cells?
And so you've got to consider

966
00:50:05,080 --> 00:50:07,920
how you detail your taping of
your sacking.

967
00:50:07,920 --> 00:50:11,200
So your exterior membrane, which
you know, to take a step back,

968
00:50:11,200 --> 00:50:14,920
what's the role of that exterior
membrane, the sacking as we used

969
00:50:14,920 --> 00:50:17,200
to call it?
Well, first and foremost, the

970
00:50:17,200 --> 00:50:20,360
primary reason for that is, is
your second line of defence for

971
00:50:20,360 --> 00:50:23,520
bulk water.
And bulk water is simply a fancy

972
00:50:23,520 --> 00:50:25,240
term for liquid water.
Rain.

973
00:50:25,880 --> 00:50:27,240
Rain.
That's all it is.

974
00:50:27,600 --> 00:50:30,320
It's just rain.
So the rain, you know, what does

975
00:50:30,360 --> 00:50:32,880
Joe Stybrick always say, you
know, there's claddings that

976
00:50:33,200 --> 00:50:35,320
have leaked and the claddings
that haven't leaked yet.

977
00:50:35,680 --> 00:50:38,640
Now it got to assume you're
cladding's gonna leak, water's

978
00:50:38,640 --> 00:50:41,560
going to get in, I'm just going
to drive onto the stud frame.

979
00:50:41,560 --> 00:50:44,560
And of course, when it hits
timber and glass wool, you're in

980
00:50:44,560 --> 00:50:47,200
a world of pain.
So the Sarkings role is to stop

981
00:50:47,200 --> 00:50:48,720
that liquid water getting any
further.

982
00:50:49,160 --> 00:50:52,680
But then by putting that, that
membrane on the exterior of your

983
00:50:52,680 --> 00:50:54,760
stud frame, you've got to make
sure it's not a condensing

984
00:50:54,760 --> 00:50:56,640
surface.
And so you've got to make it

985
00:50:56,640 --> 00:51:00,160
vapor permeable, which is now
what we do in southern climates

986
00:51:00,160 --> 00:51:03,520
in Australia.
But then you've got to make it

987
00:51:03,520 --> 00:51:06,080
continuous onto your window.
And this is where you've got to

988
00:51:06,080 --> 00:51:11,200
tape that membrane onto the
window to allow any water that

989
00:51:11,200 --> 00:51:14,520
gets in past the flashings to
get down onto the tape, to drip

990
00:51:14,520 --> 00:51:17,880
down onto your whether resist
your barrier or you're sucking,

991
00:51:18,120 --> 00:51:20,600
and to drain away.
And would you say that's a more

992
00:51:20,600 --> 00:51:24,600
important use of product than,
say, expanding foam around a

993
00:51:24,600 --> 00:51:26,760
window installation?
Well, let's say expanding foam

994
00:51:26,760 --> 00:51:28,880
has a different role.
So expanding foam really is

995
00:51:28,880 --> 00:51:31,640
about providing, reducing the
thermal bridge around the rough

996
00:51:31,680 --> 00:51:33,760
opening A10 mil gap that you've
got around.

997
00:51:34,120 --> 00:51:37,720
You want to insulate that always
and that's helping somewhat with

998
00:51:37,720 --> 00:51:41,240
air tightness too, assuming
you're using a low expansion

999
00:51:41,360 --> 00:51:45,640
elastic type type foam, which I
assume everybody is, but it's

1000
00:51:45,640 --> 00:51:48,040
not really going to help a great
deal with water management.

1001
00:51:48,960 --> 00:51:51,800
You've really got to rely upon
the tape and the sacking

1002
00:51:51,800 --> 00:51:55,880
membrane to provide your last
line of defense.

1003
00:51:56,280 --> 00:51:59,360
Well, not necessarily the last
line of defense, but your your

1004
00:52:00,680 --> 00:52:03,760
water protection I.
Think a lot of builders use that

1005
00:52:03,760 --> 00:52:09,120
expanding foam for air tightness
so that it works for that to to

1006
00:52:09,120 --> 00:52:11,000
an extent right?
Because it cracks and things

1007
00:52:11,000 --> 00:52:12,680
over time.
Well, and then this comes down

1008
00:52:12,680 --> 00:52:15,960
to its elasticity properties.
Yeah, the elastic ones will

1009
00:52:15,960 --> 00:52:18,480
help, but of course, if you get
a hairline crack as it

1010
00:52:18,480 --> 00:52:21,800
delaminates off the timber, then
it's no longer airtight.

1011
00:52:22,760 --> 00:52:26,400
But what I would argue is you
need to tape the sacking to the

1012
00:52:26,400 --> 00:52:28,680
frame anyway for water
management.

1013
00:52:28,680 --> 00:52:31,120
Yeah.
And by doing that, there's your

1014
00:52:31,120 --> 00:52:32,320
air tightness.
Yeah, yeah.

1015
00:52:32,760 --> 00:52:35,440
And so whatever you do with your
phone beyond that is an

1016
00:52:35,440 --> 00:52:38,680
additional win I.
Think what you say about the

1017
00:52:38,680 --> 00:52:41,320
claddings too.
It's claddings that have leaked

1018
00:52:41,320 --> 00:52:44,440
or claddings that will leak.
I think it's a it's a, it's a

1019
00:52:44,440 --> 00:52:48,080
mind shift in in industry that
we have to understand.

1020
00:52:48,080 --> 00:52:50,920
We have to remember that
claddings are really aesthetic

1021
00:52:50,920 --> 00:52:53,560
only They're not there for
they're not the water barrier.

1022
00:52:53,880 --> 00:52:57,240
They're not the water barrier
because they they're not,

1023
00:52:57,240 --> 00:52:59,600
they're never gonna be perfect.
They're never gonna be perfect,

1024
00:52:59,600 --> 00:53:01,320
but you're hoping that they're
gonna deal with the vast

1025
00:53:01,320 --> 00:53:03,720
majority of bulk.
Yeah, of bulk water, you know,

1026
00:53:03,720 --> 00:53:05,360
90 plus percent.
Mm Hmm.

1027
00:53:05,360 --> 00:53:06,960
And certainly with your roof
sheet, you're hoping they are,

1028
00:53:06,960 --> 00:53:10,320
because if you wanna get a tiny
percent of that water leaking

1029
00:53:10,320 --> 00:53:12,120
past your roof, you're in a
world of pain.

1030
00:53:12,200 --> 00:53:16,560
So to be fair, no one layer is
ever 100%.

1031
00:53:16,880 --> 00:53:19,680
So even you're sacking, even
though no matter how Dylan you

1032
00:53:19,680 --> 00:53:22,960
do it, it's not a submarine.
You can't take that building and

1033
00:53:22,960 --> 00:53:25,960
throw it in the ocean and expect
it won't spring or leak, because

1034
00:53:25,960 --> 00:53:28,760
of course it will.
In just much the same way that

1035
00:53:28,760 --> 00:53:31,640
your airtightness membrane, be
that the external membrane or

1036
00:53:31,640 --> 00:53:35,200
internal one dedicated to the
purpose, you're never getting 0

1037
00:53:35,480 --> 00:53:38,280
ACH, never have a perfectly
airtight building.

1038
00:53:38,920 --> 00:53:42,680
And so no one layer is 100%
trying to do your best, your

1039
00:53:42,680 --> 00:53:45,720
diligence best to make them so.
But you need redundancy.

1040
00:53:46,400 --> 00:53:48,600
You've got to assume that the
thing's going to fail, the

1041
00:53:48,600 --> 00:53:50,720
cladding's going to fail, you're
going to get water through,

1042
00:53:51,360 --> 00:53:53,160
though we know flashing's going
to fail.

1043
00:53:53,280 --> 00:53:56,440
What happens then?
The question is always how far

1044
00:53:56,440 --> 00:53:58,280
do you go?
Because you can assume the next

1045
00:53:58,600 --> 00:54:00,360
tape it, the tape will
delaminate.

1046
00:54:00,360 --> 00:54:03,560
So you need a like a butyl tape
on the sill as well.

1047
00:54:03,560 --> 00:54:06,400
Then you need a back dam, your
sill pan and you need all sorts

1048
00:54:06,400 --> 00:54:08,320
of things.
At what point do you say, well,

1049
00:54:08,320 --> 00:54:10,560
I'm meteorite money in the
building too, So, you know,

1050
00:54:11,840 --> 00:54:13,480
you're trying to minimize risk.
Yeah.

1051
00:54:13,680 --> 00:54:15,360
You can never eliminate risk.
Understood.

1052
00:54:16,440 --> 00:54:19,640
All right, So last question that
I ask all of my guests is out of

1053
00:54:19,640 --> 00:54:22,080
everything that you've learned
in your career, what is the one

1054
00:54:22,080 --> 00:54:24,320
thing that you want the listener
to know to know?

1055
00:54:26,440 --> 00:54:29,880
It's hard.
We don't know.

1056
00:54:31,280 --> 00:54:34,280
I think we've got to be really
contrite and honest with

1057
00:54:34,280 --> 00:54:36,880
ourselves.
Like sometimes they get a bit

1058
00:54:37,080 --> 00:54:39,600
upset when we say that was
doomed to fail.

1059
00:54:40,080 --> 00:54:43,480
Well, that that will absolutely
succeed, I guarantee it.

1060
00:54:44,120 --> 00:54:48,520
Well, there's no guarantees in
life and all we're trying to do

1061
00:54:48,520 --> 00:54:52,160
is stack the deck in our favor.
We're trying to do everything we

1062
00:54:52,160 --> 00:54:55,800
diligently, prudent whether we
can within a budget, within time

1063
00:54:55,800 --> 00:54:59,240
constraints, within practical
limits that the real world is

1064
00:54:59,240 --> 00:55:01,880
all about to try and minimize
the risk.

1065
00:55:02,840 --> 00:55:05,480
And dare I say beyond that,
we're just hoping and we're

1066
00:55:05,480 --> 00:55:09,760
constantly trying to improve and
learn from our mistakes because

1067
00:55:09,760 --> 00:55:11,920
our building materials are
constantly changing and our

1068
00:55:11,920 --> 00:55:13,440
techniques and the codes
changing.

1069
00:55:13,440 --> 00:55:15,320
The way we have to do things
changes.

1070
00:55:15,960 --> 00:55:19,040
But we can't eliminate the risk.
We're just seeking to to

1071
00:55:19,040 --> 00:55:22,880
minimize the risk and we should.
And we should be talking about

1072
00:55:22,880 --> 00:55:26,200
probabilities and relative risk.
I think this is less risky than

1073
00:55:26,200 --> 00:55:28,080
that.
Therefore, we should do that.

1074
00:55:28,560 --> 00:55:30,880
Not that one's gonna work and
that one's going to fail.

1075
00:55:30,880 --> 00:55:34,360
Very good.
Thank you, Cameron.

1076
00:55:34,640 --> 00:55:35,080
Thank you.
Thank.

1077
00:55:35,280 --> 00:55:39,720
You for your time.
That is all for today.

1078
00:55:39,720 --> 00:55:42,800
Thanks so much for tuning in.
There will be another episode on

1079
00:55:42,800 --> 00:55:45,320
a fortnight, so if you would
like to listen into the types of

1080
00:55:45,320 --> 00:55:48,280
conversations that I have all
the time, please subscribe on

1081
00:55:48,280 --> 00:55:51,120
your chosen platform.
Write the show, leave a comment,

1082
00:55:51,120 --> 00:55:53,240
whatever you like, share with
your friends and family.

1083
00:55:53,480 --> 00:55:55,560
I'd love for you to spread the
word about the building

1084
00:55:55,560 --> 00:55:58,320
psychology potty.
There's a link in the episode

1085
00:55:58,320 --> 00:56:01,080
description where you can head
to a landing page and there are

1086
00:56:01,080 --> 00:56:03,600
some show notes there with
relevant links and a full

1087
00:56:03,600 --> 00:56:06,920
transcript of the show as well,
and also links to my socials.

1088
00:56:07,200 --> 00:56:09,480
So if you're not already, I'd
love for you to follow along

1089
00:56:09,480 --> 00:56:12,040
there too as I share lots of
building science and building

1090
00:56:12,040 --> 00:56:14,640
biology tips.
There's also a contact page

1091
00:56:14,640 --> 00:56:17,280
where you can send me an e-mail
or even a voice message.

1092
00:56:17,520 --> 00:56:20,640
So if you've got questions or
suggestions or guest ideas, I'd

1093
00:56:20,640 --> 00:56:23,400
love to hear from you.
I want to know what you wanna

1094
00:56:23,400 --> 00:56:25,080
know, so please get in touch
with me.

1095
00:56:25,520 --> 00:56:27,720
Thanks again.
I'll be back in two weeks, so

1096
00:56:27,760 --> 00:56:29,680
until then, happy healthy
building.