we're sitting here

wanting to talk about

passive house and what

it is, and I guess

try to educate the

listeners a little

bit more about what

it is we're actually

talking about when

we're talking about

passive house.

So just before we get

stuck into Passive

House, I do want to

do a bit of a warning

that hamish and I

swear, so if you do

have kids in the car,

please be cautious.

I've had a few people

reach out to me and,

they weren't expecting

us to swear and I'm

like, well, if you

know us, we do swear.

So, this is your

one and only warning

going forward.

So, anyway, we're

going to talk about

passive health.

I'd like to say

that it's a sign of

intelligence, but

given that we have Cam

sitting in this room

and I don't think I've

ever heard him swear

, I got him swearing

once when he found

out Drew got to go to

building science camp

and he wasn't invited.

So,

It did tell Drew,

and I quote, fuck

off.

All

so

let's not go there.

that's a whole

other podcast topic.

we had to talk about

Passive House today.

And this is what

we do for work.

So, we'd still say

we're early adopters

in this space.

it is a form of

building that we

would refer to as

the gold standard

of construction.

but rather than have

you should I give you

a description of it.

Cameron, what is

Passive House?

right, so I'll give

you something of

a contrarian view.

So this is my view or

interpretation first.

to me, Passive

House is a building

standard based on

metrics for human

comfort and health.

So the underlying

emphasis there

is on a standard.

So it's, there's a

document that you

can download from

the Passive House

Institute website,

which is the Passive

House criteria and

it's some 50 odd pages.

And it lists a set of

metrics or criteria,

quantitative criteria,

so numbers, which you

must achieve in order

to achieve Passive

House certification.

And those numbers are

related to things like

heating energy use

and cooling energy

use in the summer.

And they all come

back to this idea of

what it is that we

need to make a home

comfortable and healthy

for our occupation.

But within that,

there's two

other things.

there's a quality

assurance overlay that

says, right, in order

to know that we're

going to actually

achieve passive

house performance,

we're going to

have this building

independently reviewed.

So that's the role

of a certifier who

sits separately to

the passive house

consultant or designer.

And also a

modeling framework.

So a set of tools,

models, software

tools, which we must

use to demonstrate

compliance with these

set of criteria.

So when we talk

about models, we

have typically in

Australia, we have the

NatHERS model, which

is everyone that's

the star rating.

And with Passive

House, we do a thing

called PHPP, which

is a Passive House

Planning Package.

Do you want to just

give a quick brief

on the difference,

the two of them, so

people can understand

how this differs

from your traditional

star rating?

Yeah.

Okay.

So firstly, I, I've

never actually done

a NADHERS assessment.

I'm not a NADHERS

assessor, so anything

I say there is

largely speculative.

but underlying all

of the software

packages that you

can buy that do NATAS

assessment is that

Cheneth engine, which

is the thermal model

that CSIRO developed.

That just like the

phpp tries to predict

the energy balance

in a building.

It says, right?

Okay, we're going to

try and achieve these

sorts of temperatures

within this building

at this time of year

winter versus summer

being different.

And in the case of

the channel engine,

it makes assumptions

about rooms within

the building, so the

laundry, It can run

cooler than say the,

the living room.

and then it says,

well, what level of

energy do I require

heating and cooling

mechanical loads?

Do I need to put

into that building

to maintain those

temperatures?

And PHPP is

identical in that

high level sense.

it differs in a number

of ways, in the way

at which it implements

that model and runs

those calculations.

and that's where a lot

of the debate starts.

But.

fundamentally, these

models are about

trying to predict

the performance of

a building and more

critically, I think,

and this is the thing

that I keep banging

on about, is using

these modeling tools

as a design tool,

as guidance to the

architect, the building

designer, the client

homeowner, the builder,

to say, well, what if?

Constantly run these

what if scenarios

because you can't

build two buildings

one with I don't know

50 mil of xps under

the slab and another

one with 100 and then

wait five years and

work out which one

performs better the

model allows you to run

those scenarios before

construction so you

can get insight into

how your building is

going to perform and

run those trade offs

Yeah.

How do you know it's

like, when people

say, oh, my house is

high performing and

how do you know it's

like, was it modeled?

No.

how do you know that

you put the right

amount of insulation?

It's also a cost tool.

I know Hamish, we use

it all the time to

be like, well, what

amount should we put

on that wall before

it's diminishing

returns or it's just

a waste of money.

Yeah, I was about to

jump in before we use

it as an optimization

tool from when we look

at, you know, to costs,

cost of performance

and cost to budget.

and then we then

basically just provide

that information to the

client to help better

educate them on their

decisions, like super,

super valuable tool.

Okay.

It's great.

And this is where

I think that the

teamwork between say

builder and the passive

house consultant

is critical because

it's the builder.

It's a, you know,

relatively easy.

I think for you guys to

call up your suppliers

and work out how much

it's going to cost for

that extra 50 under

the slab or to go from

90 to 140 wall framing

or whatever it may be.

The cost is relatively

easy to establish.

What is much

more difficult to

establish is what's

the benefit of that?

And so the trade off

that the client needs

make informed decisions

here is to say, well,

that triple glazing

is going to cost me

an extra 15 grand, but

if it only offers me

a 1 percent benefit

in terms of my winter

heating demands, it's

probably not worth it.

So it's a value

for money argument.

Do you, this might be

a tad off topic, but do

you think sometimes it

also focused too much?

Cause when we talk

about comfort,

everyone always

refers to thermal.

There's also things

like sound and odors

and things like that.

Do you also think

that sometimes we

need to consider,

like when people say

triple glazed, that

they might live next

to a train line or a

major road, that we

also need to, like, we

talk about that sort

of level of comfort.

That's not really put

through any sort of

platform at the moment.

Do you think that's

something we also

need to consider?

Yeah.

So there, I mean, there

are acoustic softwares

you can use to try and

estimate things like

the impact of glazing

on sound attenuation.

And I had this on a

project just yesterday

where the client was

asking, well, what's

the benefit of going

for triple glazing.

And for that

particular project

that was very small.

And the cost of triple

glazing was in the

order of an extra 10

grand, and my argument

was, look, it probably

doesn't make sense

for you thermally, but

maybe you would still

like to do it, because

it offers some marginal

acoustic benefit, and

the acoustic benefits,

by the way, are much

more difficult than

just double versus

triple, it's whether

you laminate the

glass, the thickness

of the glass, the

spacing, and so on,

So we pursue the way

in which we perceive

temperature in our

building is both

the air temperature,

but also the mean

radiant temperature.

the radiant surfaces of

the internal surfaces

of our building is what

temperature are they?

The glass, the

internal, you know,

most pain of the glass

will be the warmest

surface in winter, you

know, heating climate

like Melbourne or

Canberra or whatever.

if we go from

High performance

double glazed to

high performance

triple glazed, that

temperature on the

interior surface of

the glass will increase

by about maybe half

a degree, depending

on the temperature

difference in to out.

And so that can offer

a possibly perceptible

improvement in

perceived comfort,

even though it's not

materially changing

the heating demand

in the building.

So there are

some subjective

bits to this.

I know.

one example of this

optimization and

maybe not necessarily

to do with thermal

performance,

was actually on

your brother's

house, Cameron.

Where they chose

to install triple

glazed windows to

the front bedrooms

facing the train line.

But all the other,

windows throughout

the house are all

double glazed.

if my memory serves

me correctly,

that's what we did.

And that was

purely based on,

sound transmission

through the front

bedrooms there.

That's right.

The other thing to

consider, I mean,

if you've got a

real acoustic issue

next to a train line

or something is to

look at lamination

or those really

thicker cavities.

typically in passive

house, you're looking

for a sort of a 16

to 18 mil cavity

between your glass

panes, be that double

or triple glazed.

for acoustics, you're

usually looking for a

thicker glass panes.

Spacer there, so

anything up to 25 30mm.

So that gives you

better acoustic

performance, but at

the trade off of worse

thermal performance.

So there's no free

lunch here, and

you just need to

consider on a case

by case basis.

what are the things

that I think you may

not have touched on

with the when we're

talking about like

passive house at the

beginning was We talked

a lot about modeling,

but we didn't really

touch on the actual

testing side of it

So that's one of the

other major things

With passive house,

which actually doesn't

in most cases occur

with, I guess the star

rating approach is

that it's not tested

during construction.

Whereas with passive

house, there are a

number of different

tests I know that we

do in house and that's

making sure that the

insulation's installed

correctly, getting

a thermal camera.

But obviously the

major one is that,

air tightness testing.

Which happens at a

number of different

points along a project

and, you know, in

my experience that

doesn't seem to happen

that often outside

of the performance

construction.

So this is

huge, isn't it?

This is where Passive

House certification,

as opposed to just

Passive House, I think

offers real benefit.

It's that quality

assurance step,

and it's hugely

time consuming.

As a consultant like

myself, it takes

a long time and

a lot of effort.

To get a project

through the

certification process,

but it's providing the

client that quality,

that value sort of

management or that

quality assurance, that

confidence that they're

getting what they're

paying their money for.

That's missing in so

much of the rest of

the building industry,

but it's no different.

Everything else we do

in our daily lives,

you know, we go and

buy a TV or we buy a

new fridge or we go

to the pharmacy and

we buy some medicines.

Those have all been

tested to a standard.

There'll be an

Australian standard

that requires that

all electrical

appliances be tested

And the factories will

be ISO 9001 tested for

quality assurance to

ensure that there's

a good chance that

that TV, when it

arrives, doesn't

electrocute you.

And we'd all agree

that's a good thing.

You know, we don't want

to get electrocuted

when we buy the new,

mixer or whatever.

and the certification

process is very much

the same sort of thing.

It's just ensuring or

trying to ensure, and

there's never a hundred

percent guarantee,

that what you as the

client are paying for

is what you're getting.

and there's so much

documentation and

measurements that

are required to

support that process.

I'd never thought of

it using the analogy of

buying a blender that's

been tested before.

you just make the

assumption that it's

going to be safe.

And yet the

investments, the

amount of money that

we spend on our homes,

that does not ring

true with that end

product of that home.

If it's not a certified

passive house,

90 percent of your

time, where you,

blowing.

the blenders are a hell

of a lot cheaper than

the, than the house.

So if the blender's

cactus, you throw

it out, you don't

particularly care.

If the house is cactus,

what do you do then?

well, that's

what our industry

does right now.

You just throw it out

and you buy a new,

roll it over and

build a new one.

That's not very

sustainable.

Or, or you live in it

and it makes you sick.

I just want to go

back on principles

because we haven't

touched on the Passive

House Principles and

anyone not listening.

I just want to

get people up

to date on this.

There's the Passive

House Principles and

generally the whole

model of Passive House

is what we follow.

So, I I didn't say

that word, the P word.

it's called five, Bits

of information plus

a little bit more.

and it's not picking

some and then choosing

which ones you want.

you have to include

all five of them.

yeah, and and this

is another great

aspect of Passive

House, isn't it?

it's systematic.

I think the real

contribution to

the way we thinking

about buildings of

the Passive House

Institute have done

here is to provide a

systematic framework

to bring together

the elements of good

building physics.

and the passive

house principles as

they're called, and

I absolutely hate

that phrase, you

know, there's that,

figure that bounces

around everywhere.

Everyone talks about

the passive house

principles, this whole

idea of air tightness,

HRV, windows, thermal

bridging, and lots

of insulation.

In a way, I think

that's almost Simple,

generic, good building

physics principles.

Like that, those

five elements, they

existed before the

Passive House Institute

came into being.

They existed before the

Passive House Standard

was established.

They're not new.

We've known for

decades that steel

running through a

thermal envelope will

conduct lots of heat.

We've known for

decades that windows

were fundamental to

building performance.

What Passive House

has done has brought

these things together

in a systematic way

that allows us to

try and put them

together in a way that

makes the building

work really well.

That's the contribution

of Passive House.

It hasn't invented high

performance windows.

there's always

that debate then

on like, Oh, we

build passive solar.

think passive house

is just passive

solar on steroids.

And I'd say any good

passive house still

requires passive solar.

Yeah, and I was working

on a project yesterday

that's sort of run

off thirty degrees

off north axis, long

axis run north south,

lots of glass running

east west, and guess

what the PHPP says,

it's overheating in

the summer and it's

freezing in the winter.

So, passive solar

is absolutely part

of passive house.

Getting those winter

solar gains in is

critical in the PHPP

to getting those

heating demands down in

your cooler climates.

of the things you just

touched on before,

Cam, about, views and

I guess aspects and,

cause in my opinion,

a good home takes

into consideration.

All of that.

it's the performance of

the home, but it's also

that connection with

outside and you might

have this absolute

banging view out to

the sort of Northwest

or even the Northeast

or even the East.

And that's really

critical and important

for the client.

In my opinion.

Going through the

process of PHPP and

really understanding

what putting a big

window out in those

elevations does

to performance is

incredibly valuable,

even if you don't quite

land in that passive

house criteria, it's

the understanding of,

well, maybe we do need

to put some shading

there, or maybe we

do need to increase

our heating and

cooling requirements.

And it's actually

just putting that

information back to

the client and them.

Even if it then falls

out of that passive

house classic criteria.

Because at the end

of the day, sometimes

you need to make some

of these concessions

if it is going to

provide that view in

the morning or that

view in the afternoon

because that to me

also feeds into the

well being of the

occupants of the home.

yeah?

yeah?

Am I getting

that right?

mean I'm no expert

but it's, just makes

a home feel nice.

Feels

like, you're not

going to go buy a

beachfront property.

And then,

close off all the

windows because it's

not high performing.

think sometimes there

are limitations what

you can do, but that's

just, you now need to

be creative, I feel.

Yeah.

Yeah.

And as a thermal

engineer, you

know, I'm not a

building designer.

I'm not an architect

and I shouldn't be

because my narrow role

in the world is to say,

well, here's how the

building can be made

to perform thermally.

But for you, as the

building designer or

architect, I need your

feedback and indeed

the clients as to what

are the reasonable

trade offs we're

willing to make here.

And as that project

that I was working on

yesterday demonstrated

in the chat with the

architect, it's like,

well, you know, we were

talking about, there's

all this glazing

to the southeast,

can it be narrowed?

Can we raise it

off the floor?

Can we bring it 600 off

the floor and therefore

reduce the glazing

areas by a couple

of square meters?

Will that make

a difference?

Well, let's run it

through the model

and work it out.

Because at the moment,

that particular

building is going to

require an inordinate

amount of insulation

in the floor, walls

and roof, in order

to get to Passive

House, and even then

it's struggling.

So we need to look

at some trade offs

to get it there.

And the client

ultimately has to

make the choice.

And all we're doing

as consultants is to

try to provide them

with that information,

yourselves as builders

on the cost side,

me on the thermal

side, to say, well,

here's the trade offs.

If you want that

vast expanse of glass

to the southeast,

great, you're home.

But just understand

that it's going to

require more energy

to heat and cool the

building in the winter.

than the Passive

House Standard

would stipulate.

Um,

arbitrary thresholds.

And a lot of the

thresholds within

Passive House are

entirely arbitrary.

Where did the 0.

6 air change

rate come from?

It was essentially

made up.

You know, it was

a stretch target

in Germany in

the late 80s.

For builders that

were then pumping out

homes that were well

under 5 ACH, compare

that to Australia

in had to say, well,

what could they

conceivably do that

was above and beyond

standard practice but

not so inordinately

difficult that no

one had ever been

able to achieve it.

And so they

came up with 0.

6.

The only real criteria

in the passive power

standard that has

any physical basis

is the heating load

requirement of 10

watts per square meter.

Because that's about

the airflow required

into the building for

ventilation and how

much you can heat that

airflow to provide

the heating load.

Everything else are

all arbitrary and

there's no problem

whatsoever with that.

You go to any standard,

you know, back to

our mixer example,

I know nothing

about certification

of electrical

devices, but take my

aerospace background.

when you design an

aeroplane you design

the structural

load requirement

on those wings

based on a certain

turbulence load.

So flying through

turbulence, obviously

the wings are

flapping up and down.

The last thing

you want is those

wings to fall off.

You design the wings

to accommodate that

critical turbulence

load, and then you

add 30% now where

did that extra 30

percent come from?

That's a safety margin.

Well, it's an aircraft.

We can't give it a

safety margin of two

or three because the

thing will be too

heavy to take off.

But we know we want

something more than

a factor of one, so

let's go with 30%.

It's just a made up

number, and so too are

many of the Passive

House criteria.

And therefore, just

because a building

doesn't quite achieve

the passive house

criteria for, say,

heating demand, because

you want the view

out to the southeast,

doesn't mean it's

necessarily a poly

performing building.

it's probably still

in the top 1 percent

of homes performing in

Australia, wasn't it?

quite possibly.

And and again, I

come back to the idea

of modeling here.

You need to do that

modeling to be able

to grasp that, to have

an understanding that

this is, we're on land.

Without the modeling,

you're just guessing.

You're running blind.

the modeling is really

essential to everything

we do in Passive House.

So, I want to talk

to you on some

misconceptions of

Passive House because

I think there's a lot

of false information

out there and it

can sometimes be

really, really hard

to communicate to

people why Passive

House is important.

We sometimes get

really caught up in the

numbers, the detail,

the nerdy stuff, and

not all clients are

wanting to know that.

They just want

a healthy,

comfortable home.

And I feel a lot of

the time, architects,

builders And building

designers really

struggle to sell

passive house to

people because they

just don't know how

to communicate it.

But these

misconceptions

can really, really

hurt what we do.

Now, I've got

five listed here.

I'm going to throw

these both at you and

Hamish, to sort of see

your thoughts on it.

So the first I want

to start with is

passive houses, they

are too expensive.

I would say that

building in general

in 2024 is expensive.

Just as a broad

comment, I would argue

that if you are a

custom home builder

and you are building a

home from scratch and

it is custom, I would

argue that you could

introduce performance

into a building at

no additional cost

to a custom home.

And I would probably

just add that you're

getting a higher

performing building

and therefore it comes

at a higher cost.

And there's an infinite

amount of debate out

there about how much

of that cost uplift

is because it depends

on your base case.

If your base case is a

custom architecturally

designed home, the

margin is going to

be much smaller than

if your base case

is a project built

smack together job

somewhere, where

the margin is going

to be much higher.

I'm quite comfortable

with the idea that

passive house costs

a bit more because

you're getting a

better product.

point that I guess both

Cameron and I just made

then is, what you're

comparing it to is the

most important thing.

that's exactly what

I was about to say,

like what compared

to what the questions

like, I always say,

well, it's expensive

compared to what?

I had a Build A

Friend reach out

the other day and,

I think his message

was, the penny's

starting to drop.

And I'm like,

okay, go on.

And he goes, I'm

costing a project

at the moment where

there's 45, 000 worth

of hydronic as a

provisional sum item.

And that's cheap,

by the way.

and I'm like, okay,

you could completely

remove that, design

it really well, put a

centralized HRV and a

couple of strategically

placed splits for about

30, 000 to 35, 000.

And you are getting

a much more efficient

system to heat and

cool and provide a

healthy environment.

Now there's also a

whole bunch of other

factors you need to

wrap around that to

make sure that that

will be enough to

make it a comfortable

building envelope.

But if you just look

at those two things in

isolation, when people

are saying well you've

got to put in uh HRV

and you've got to do

this and you've got

to do that, I would

say well you could

probably take this out

and rethink the way

that you're building

is the fabric of that

building, remove the

30, 000 worth of,

stone in there and use

something a little bit

more cost effective.

But, and this for me,

performance has to be

put at the forefront

of all our projects

and thinking about

performance from

the outset and not

just as a bolt on.

Because when you

start thinking of

it as a bolt on, it

probably is going to

be more expensive.

I think the big

one is Windows.

Everyone always

thinks Windows are

more expensive.

And I can tell you

now, and I've run

this, I'm starting

to run this data,

Every time we're the

moment, we're actually

sending off window

quotes to aluminium,

Basic style window

that people would get.

And we're getting a

range of them from

your very cheap to

your probably we'll

say architectural,

we mainly work on

architectural buildings

and they are working

with semi commercial

aluminum windows, I

can tell you on one

project, I've only

done this once the

high performance

windows that we

selected to work with

were the cheapest.

And they're the only

one that came back

to me with what I

asked for from a

glazing perspective,

from a performance

perspective.

Most of them I had

to fight just to get

a double glaze coat.

so I think Windows

is always a big one

like, oh, they're so

much more expensive.

I'm pretty confident

that on architectural

homes, they are

definitely on par,

if not cheaper.

chalk and cheese

though too,

isn't it Matt?

I mean, you compare

it to the bog

standard mass volume

sort of, aluminum

windows that we can

get in Australia.

Good.

So the high performance

stuff that we use

in high performance

building slash passive

house, that there's

just no comparison.

You know, you just need

to look at them, touch

them, feel them, shake

the thing to realise

this is a different

product entirely.

I actually had someone

come out once, it was

an aluminum window

in West Footscray and

the sales guy from

the window company

came out and he was

showing me their

windows, what they had.

And he's like, this is

our bottom range one.

This is practically, it

just keeps water out.

And he goes,

honestly, it barely

keeps water out.

that was what he

was selling me.

Back then I was a bit

naive and I was like,

Oh, cool, cheap, sweet.

Didn't, we didn't go

with them by the way.

But now I look

back, I'm like.

it's Just, yeah,

frustrating.

if we look at what the

fundamental function of

our buildings are, is

to protect the health

and amenity of humans

within that building.

When you start to think

about that, there are

products out there

that quote unquote,

just keep water out.

It makes me personally

feel sick to my

stomach that these

are still available

on the market.

I love it.

So my brother's

looking at a place at

the moment, a factory

for his office,

he's a plumber.

So you went through

the real estate agent.

I'm not saying all

real estate agents

like this, all my

family are actually

real estate agents.

I have a huge amount

of respect for them.

the guy was telling

him, Oh, there was

mold everywhere where,

where a, water tank had

blown up and there was

mold all over the wall.

He goes, Oh,

don't worry.

If you just paint it,

you'll never know.

And James, my brother,

knowing what I

know, and I'm like,

can I go meet this

real estate agent?

Like that whole

wall and structure

is ruined.

Like it'd be screwed.

So.

I also come back to

the thing there's a

huge education we've

got to make across

not just building, but

real estate, everyone

Can I just come back

to something Amish

was saying before

and touching on the

point about cost too.

It strikes me that,

and I'm going to pluck

a number from the

sky here, 90 to 95

percent of the cost of

a build is established

in that very early

concept design stage.

That when you're

doing that sketch

on the bit of paper

or on the CAD about

what this building

form is going to be.

so much of this comes

back, dare I say, to

the architects and

the building designers

when they do that

initial sketching or

the client of, you

know, is this a really

tight form factor or

is this a sprawling

thing with wings out

this way and that way?

Has it got

heaps of glass?

All of those things,

and forget about the

thermal side for a

moment, all of those

things have massive

cost implications

on the build.

Then when you then

stick on the high

performance slash

passive house layer

on top of that, if

it's a multiplicative

effect, you know it's

taking all of that.

You've wanted lots of

glass classes, always

more expensive than

wool, Now you want high

performance as well.

So now we've got

high performance

glass, lots of it.

And we're trying to

get close to Passive

House, so we're having

to work much harder.

So we're definitely

having to triple glaze

rather than double

and we're going to

have to do all this

extra insulation here,

there and everywhere.

It's going to

cost a bomb.

Now, if as the client

you're saying, well,

I've got the pockets

and I'm willing to

take that, then great,

let's go for it.

But if you have got a

tight budget to start

with, you've got to

keep that in mind

from the very outset.

And then again, I come

back to this model

early, model often

argument to say, do

that quick sketch.

Say, yeah, as a

client, I like this.

I think this is going

to work for us and our

family or whatever.

Let's run it through

the model quickly and

just see where we land.

We're just doing that

initial analysis to

say, okay, this is

going to perform really

well or it's not.

and I modeled hundreds

of buildings now, but

even when I look at a

set of plans, usually

there'll be about 20

percent of them that'll

look at it and go,

yeah, that's definitely

going to be great

because it's a nice

tight, compact form.

We've got lots of

glass to the north,

modest glazing ratio.

Why?

Another 20 percent

I'll look at and

go, Ooh, that's

going to be hard.

And that'll be a

combination of the

geometric form of the

building, the glazing

ratio, the But it's on

top of Mount Dandenong

or the Blue Mountains

or somewhere, or it's

got a forest or a

five story building to

the north next door.

And then there's

another 60 or 70

percent in the

middle there.

You're just

not quite sure.

And that's where

you've got to model it.

You just can't guess.

performance is

not a bolt on.

You need to design

for performance from

the beginning and have

those thoughts rolling

around in your head.

Because you're right,

as soon as you start.

Just adding in

performance onto a

building that is going

to naturally perform

poorly, that's where

it's going to be

fucking expensive.

So I did some research

last year, actually

got some projects that

we'd quoted in the

past, say 12 months

or estimated, and this

is nothing scientific.

It was just us throwing

some data around

and actually broke

it down into seven

categories and I put

them in front of me.

It was structure,

foundations, cladding,

performance, services,

site costs, and

finishing items.

So I broke it down as

a percentage across

all projects to make it

completely even, and I

found that performance

was probably

equating to about 16.

1 percent of

the building.

So that's your, your

insulation, your

mechanical ventilation,

your windows, all

these other things.

All right.

I found that

finishing items, was

making up about 25.

percent of the

projects percentages.

All right.

What I ended it

actually had two or

three jobs because

I actually had a

few problems where

projects fell over

because, costing, in

the sense of the budget

didn't match brief.

And what we found

is we actually went

and looked at those

projects and it was

the, finishing itings

and claddings that

went straight through

the roof were the

reasons why the project

didn't get over.

Not because of

the performance.

So I have, I've

realized very quickly,

the cost of the

house comes down to

your, your joinery,

the way the house is

fitting out inside,

the floorboards or the

what type of mixing on

your polished concrete,

you have it, what type

of claddings, is it

a standing seam or

some very expensive

child cladding,

standing seam roofs?

Like, let's be honest,

you're not going

to fly, like, when

you're standing on

the street, you don't

see the standing seam

roof , on the street.

So why waste

your money on it?

And that was the

reason the projects

were falling over.

And I actually think

you were on this

project too, Cameron,

that we know of.

But the cost was

purely because of

the design and what

they'd put inside.

There was nothing to do

with the passive house.

The form was all

over the place.

It was gigantic.

Again, it goes back

to the bigger, better

approach, but I think

just because the

project sometimes

are expensive when we

live in a market, the

building is expensive.

Passive houses is

just the easy cop

out to be like,

it's too expensive.

That was a reason

why the project

never went ahead.

Maybe we convince

ourselves before

we've even done the

numbers that it's too

expensive too, Matt.

Because I've seen

projects come across my

desk where The drawings

have got to the stage

before any modeling is

done where the designer

slash architect has

assumed that they're

going to need 100 mil

of XPS under the slab.

And I just look at it

and go, I'm not sure

about that actually,

because this is quite

a good building, good

form factor, good

orientation and north.

Have you run the

modeling to work

out whether you

really need 100.

And probably in a good

third to 40 percent

of my projects that

have come through

at that stage, I'm

actually de spec

ing the insulation.

I'm actually reducing

the amount of

insulation required to

say, look, you don't

actually need that

to hit passive house.

And so we're saving

the client money.

And so if you can

do that modeling

earlier in the design

process, then you

can save yourself a

bit of time on your

drawings and setting

out all your levels.

we've managed to save

five or 10, 000 on

projects just by going

to a 50 mil insulation

from a hundred to 50.

Like these are all

the little performance

grabs that we

look at when we're

modeling in PHPP.

And they do have a big

impact on the cost you

know, in some cases

we've actually found

in a mild climate, a

90 mil frame can reach

passive house classic.

I've got jobs like

that in Victoria too.

I can do, we can get

to Passive House with

a 90mm wall and then

a 45 services cavity

internally insulated.

And that almost blows

our minds really

because most of us

in Passive House

think in our heating

dominated climates, our

Canberras and Victorias

and certainly our

Tasmanias, we're going

to need to go for 140

framing as a minimum.

Not necessarily.

Can I be devil's

advocate here

for a second?

Sure, Matt.

It's unlike you

to be devil's

advocate, but go for

isn't the climate

data based off like

from the nineties that

we haven't actually

really taken, and this

is Nat Hur's passive

house that we haven't

really taken into

account for future.

A climate you're

referring to

there, Matt?

yeah.

So we're, we're, the

data we're looking

off is, is old and

we know that the, the

things are getting

hotter and colder.

Yeah, so the Passive

House climate

data is an average

from, I think it

was 1990 to 2010.

So it's a

long time ago.

Which is a long time

ago, , a different

climate, almost

entirely, climate data

files are always going

to be backward looking

just because we can't

give forward predict.

But, there is, it's

some in the PHPP, you

can do some different

sensitivity testings

for summer overheating.

But one of the things

we tend to find is

that the loads, so

the capacity of the

cooling system in the

summer , in a climate

change scenario, which

is of course the only

plausible thing to

test, but, you know,

how hot or how quick

are you going to test?

You don't actually need

generally need a lot

more cooling capacity.

It's just going to

be that that cooling

system is going to be

running for longer.

And so in thinking

about designing our

buildings, we're

invariably going

to be adding extra

capacity anyway.

So if the PHPP tells

us we need X, we're

going to add X plus

50 percent because

doing so costs us next

to bugger all when

we build a building.

and there's a

few other reasons

why, , the capacity

estimate from PHPP is

not perfect anyway.

So we have reasonable

confidence in 5, 10, 15

years when we get more

of those 45 degree days

that the systems we've

got the cooling of

us in a building.

I was just wondering,

I've always wondered

like how you think

the future, because

sometimes we, yeah,

it works now, but is

it going to work in

20 years, but that

you can change the

data on the backend.

Thanks

Yeah.

So whenever I model a

building, I always test

a bunch of scenarios

of future climate.

Temperatures for

summer overheating.

It's not for, well,

it also actually has

some, testing for

winter heating demand

reductions, but that's

always beneficial

to us in that sense.

but the cooling is

the critical one and

that comes back to

things like ensuring

you've got a cooling

system that's got

ample excess capacity

to deal with those

extreme temperature

periods and that you've

got that external

shading, right?

So this probably then

leads on to my second

misconception, is

that you don't need

heating and cooling

in a passive house.

Yeah, so the phrase

passive house is really

problematic, isn't it?

Because there's

nothing passive

about it and it's

not just for houses.

So both of the words

are kind of wrong.

comes back to

trying to achieve a

minimum heating and

cooling demands at

a reasonable cost.

So could we design

a building in

Melbourne to require

almost zero heating?

Yeah, probably.

It'd probably look

pretty horrible, and

it'd cost an absolute

bomb, and you still

wouldn't be able to

build it anywhere

in, say, Victoria or

an ACT or whatever.

What we're doing is

setting a threshold,

those criteria around

15 kilowatt hours per

square meter per annum

of heating and cooling

demands of energy

required to keep the

building at 20 degrees

in winter and under

25 degrees in summer.

It's low, but

it's not zero.

So you still need

heating and cooling.

and there is, I think,

a client expectation

management role here.

Okay.

To explain, look,

a passive house,

fantastic, great idea.

let's definitely do

that, but understand

you're going to need

heating and understand

when it's 45 degrees

outside for three

days straight, you're

going to need cooling.

And,

that you don't

need heating.

It's just because

some of my clients

don't turn the heater

on, but everyone

lives at different

temperatures and some

want it warmer, some

want it a bit cooler.

and that's what we find

in trying to, validate.

all of these models,

be they NatHERS

or Passive House.

Even with Passive

House, we Passive

House people say,

look, one of the great

things about it is you

get what it says on

the tin, that the as

modeled performance

equates to the as

built performance.

And a large part

of that is the

verification, the

certification process

that does all the

things Hamish was

talking about before,

things like the blower

door test and making

sure the insulation is

installed right and all

of that sort of stuff.

But even when you do

those post construction

evaluations, and

there's been a few

of these done on

in Australia, to

my knowledge, but

certainly in UK and in

Germany, you get a wide

variation performance.

So if you look at

that heating demand

requirement of 15

kilowatt hours per

square meter per annum,

you get built certified

passive houses in

Germany that we running

seven or eight and

others that will be

running 25 to 30.

Why the variation?

Is it because

the building

envelope is poor?

No, it seems to be

those user preferences

that the people running

it under the predicted

heating demand loads

in winter are quite

happy for their house

to run a bit cooler.

Maybe they're running

it at 19 degrees in

winter rather than 20.

That makes a

big difference.

That reduces your

heating demand, but in

the order of about 20%.

And equally, there will

be those that prefer

their house to be 22

or 23 all year out.

and therefore your

heating demands will be

significantly higher.

So, because we have

humans living in

buildings always

slightly different

preferences, we get

different outcomes.

I am going to send