The Greener Way to Go: A Conversation with Matthew Cutler-Welsh

Wondering how you can stay ahead in the ever-evolving world of sustainable architecture? Join us as we sit down with Matthew Cutler-Walsh, a leading expert in green building practices, for a deep dive into the rapidly changing landscape of sustainable building in New Zealand. Matthew sheds light on the recent H1 regulation updates, the enthusiastic support from industry professionals like Ben Nansett of MPB Builders, and the tireless advocacy efforts in Parliament. We'll unpack the surging Homestar registrations and the transition towards voluntary schemes, laying down the groundwork for meeting ambitious carbon reduction targets.

Tired of homes that overheat or lack proper ventilation? This episode tackles the critical gaps in New Zealand's Building Code around these pressing issues. Discover how Homestar's guidelines aim to mitigate overheating and improve ventilation through smart design and mechanical systems. Matthew shares personal experiences and expert insights on the benefits and potential challenges of various ventilation systems, underscoring the necessity of adequate home ventilation standards to ensure healthier living spaces.

Curious about the future of high-performance homes in the market? We explore the mounting demand for sustainable design and the hurdles that architects and builders face. Matthew offers practical advice on simplifying building designs for cost-efficiency and sustainability, the power of mid-build open homes as a marketing tool, and the game-changing role of energy modeling tools in achieving stellar Homestar ratings. Tune in to hear about groundbreaking projects, the promising built-to-rent sector, and how Matthew's podcast ventures are steering the industry toward a greener future. Don't miss this insightful discussion that promises to inspire and inform anyone passionate about sustainable architecture.

You can catch more of Matthew's expertise on his other podcast ventures, Homestyle Green (https://homestylegreen.com/) and The Passive House Podcast (https://passivehouseaccelerator.com/podcast)

Chapters:
0:01 - Sustainable Architecture and Green Building Practices
11:07 - Improving Building Code Gaps for Ventilation
24:19 - Market Demand and High Performance Homes
30:05 - Building Code Compliance and Efficiency
41:17 - Effective Design for Efficient Buildings
54:51 - Achieving High Homestar Ratings in Buildings
1:04:11 - Building Industry Podcast Collaboration

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Transcript

Sam Brown: 0:01

Welcome back to the Design Principles podcast For all the registered architect listeners out there. We'll be getting the pot up on the NZRAB CPD portal to lodge for points, so keep an eye out for that pretty exciting stuff. On today's episode, we welcome the man on a mission to help people make a better place to live, matthew Cutler-Walsh. Matthew is a prominent figure in the realm of sustainable architecture and green building practices, serving as a key member of the New Zealand Green Building Council and as a certified Passive House consultant. Matthew is no stranger to the podcast format, being the host of podcasts such as Homestyle Green and the Passive House podcast, where he shares insights on energy efficient design and the importance of environmentally friendly construction. We're stoked to have him on to share his wealth of knowledge and passion for creating a more sustainable future. We hope you enjoy. I think a pretty good place to start Matthew would be. I know personally there's been a bit of movement around with the recent H1 stuff and a bit of advocating to Parliament in the last week. How did that go?

Matthew Cutler-Welsh: 1:28

It's ongoing. It's been quite good from our end that the Minister has been receptive, at least seems to be receptive and is keen to listen to various points of view and is keen to listen to various points of view. There's obviously a lot of support and a whole range of comments, particularly on LinkedIn, which I think was reflective of the initial feedback of H1, was it two or three years ago? Yeah, the consultation was very, very positive and that reflected that sentiment is still there. So at this point I guess we'll see. Yeah, I mean, some of the response has been positive, but the proof will be in action.

Sam Brown: 2:17

Yeah, I know. Oh sorry, Ben, I was just going to say I know that Ben Nanset from MPB Builders who I think I threw in the deep end a little bit to go along and sort of talk from the point of view of you know the builder's point of view.

Matthew Cutler-Welsh: 2:34

No well, andrew Eagles was stoked because he said, oh, this great builder came along and he said well, you know how do you feel about the sustainability thing and like a lot of builders, he's pretty open to not say what he thought. And I love hearing that story of a builder who is initially sceptical of high performance or whether it's passive house, homestar, whatever, and then gets to do a project and then is just all in boots and all yeah, and I think he embodies that quite well. You know, it's really now he's had the opportunity to work on a project like that, can really see the benefits of it. And you know we can talk about it as much as we like, but there's nothing like having a builder say those things.

Sam Brown: 3:20

Yeah, I think that's a pretty good place to kind of start the conversation, both from an architect and a design point of view and then also just a general construction industry point of view. I mean, it's a slowly shifting concept, this green building or sustainable building. I tend to try and stay from the word sustainable because I slandered it in a previous podcast episode, so I've got to check myself a little bit. But yeah, I mean it'd be interesting to know from your point of view, like what is the uptake? How have you seen this sort of area evolve?

Matthew Cutler-Welsh: 3:56

I guess so homestar was launched in 2011 and the first iteration and it sort of ticked along. I was at the green building council at the time and I left just before we reached our 100th project and that was about three years in to homestar and I used to joke when I came back um, nearly three years ago now for my second time around at the green building council. Sometimes we would get 100 registrations in a morning. That's the change that we've seen this sort of exponential growth in interest over that period of time. A lot of that was driven over the last three or four years by kind of order. So last year we did around about 5,000 dwelling registrations just in that year and, to put that into context, we got right up to record numbers of overall building consents last year, touching on 50,000 across the whole country.

Matthew Cutler-Welsh: 5:01

Now Shama Bill's done a few really good presentations this year and he points out that not all of those buildings that are consented will end up getting built. So there's a bit of clawback there. But if we assume around about 40,000 homes being built across New Zealand each year, if we're achieving around that sort of 5,000 mark of dwelling registrations, then that's getting up towards a reasonable market penetration and with that comes brand recognition, which is really important because we're still voluntary in New Zealand, we're still other than a lot of what has been kaiing order has had some obligations in place and one or two other small pockets. It's largely voluntary.

Sam Brown: 5:51

So to have that uplift in demand from a voluntary scheme is a really really positive move from our end, sort of saying that there's about 40,000, 50,000 to 40,000 building consents registered last year and of those 5,000 homes are approximately. What's the sort of level of penetration that we need to see? Has the New Zealand Green Building Council done any sort of analysis on the level of penetration that we need to see to really start to see a change in the built environment in New Zealand and things like the demand on power reduce, the overall performance of homes increase, you know, et cetera, et cetera, et cetera.

Matthew Cutler-Welsh: 6:34

So carbon is probably one of the best place contexts for that, because that is becoming, it's going to become more and more of the overarching metric because it incorporates embodied carbon and operational carbon, so carbon equivalents. And we need to go further. We need to go way, way further, because even our really efficient buildings are still not really hitting the targets that some very smart people put together that were the sort of they figured out what a 1.5-degree house would look like. So if we were to achieve our obligations as a country to stay within our emissions budget as a country, to stay within our emissions budget, to stay globally within that 1.5 degree, which we've kind of already exceeded anyway, but we still have some pretty significant financial obligations as a country to minimise our emissions. We're about five times over that target with our standard building practices at the moment.

Matthew Cutler-Welsh: 7:43

So we need to drastically reduce both the embodied carbon and operational carbon of all our houses. So in some ways it's great for me to be positive, as a sort of because it's my job to get out there and sell Homestar and just say you know we're doing a lot and we are achieving a lot, but we need to achieve a lot, lot more. We also have a huge number of existing buildings which can add to that, particularly on the operational side, and some really great work's been done. I don't know if you've seen or taught to Professor Michael Jack down at Otago in Dunedin. Do you know of his work at all?

Sam Brown: 8:26

No.

Matthew Cutler-Welsh: 8:29

He's done some really great modeling work on the New Zealand grid, basically looking at what it would look like if we converted every house in New Zealand to a passive house and how that would reduce the peak demand of the national grid. So as well as reducing our overall energy demand, that's important for emissions, but what's also really important for infrastructure and for minimising those days when we're at risk of not having enough power, that's all about reducing the peak demand. And he's done these curves of sort of varying degrees of going up the scale of Homestar to Homestar 10, ultimately to Passive House, and that's really a great way of reducing those peak demands. So I don't know if there's a I can't really answer your question in terms of a specific number or where we need to be in terms of a tipping point for market uptake for Homestar. I think we're getting close to that from a market awareness point of view, but we need to go much, much further from an overall emissions perspective.

Gerard Dombroski: 9:43

Matthew, for those of us who are unfamiliar with the Green Building Council and what it is that you do, is it essentially, like you guys are, high level, eye on the prize and then helping people have like a baseline or a level to reach in order to achieve some of these bigger goals of reducing carbon?

Matthew Cutler-Welsh: 10:04

Yeah, so that's a good point. I I assume, um, that people know, but but many people don't know. Uh, so we're not a council. That's for the starting point. Even though it's in our name, we're not part of a territorial authority. We are one of about 70 affiliates of the World Green Building Council around the world. We work quite closely with the Green Building Council of Australia, and all of the green building councils around the world are very similar in that they offer tools and also they do a lot of advocacy work and education. But our primary function here in New Zealand is providing mostly voluntary tools for improving the environmental performance of buildings and for people to promote buildings on the basis of that certification. So we provide design tools, but also a pathway and a verification of actual built performance.

Matthew Cutler-Welsh: 11:07

And how I pitch Homestar specifically is to fill in the gaps of the building code, because the way I look at the New Zealand building code right now, there's a whole bunch of just black holes and things like overheating, for example, which is a really important issue issue, and a lot of our houses are now overheating. We're experiencing that more and more and there's absolutely nothing in the New Zealand Building Code to prevent that. So you can have a completely code-compliant house right now, and as long as it has got enough insulation to keep it warm in winter, it's going to be fine and there's nothing to prevent that house from overheating. And that's just one area. There's a bunch of others and that's the reason we exist is to fill in some of those gaps.

Sam Brown: 11:58

That overheating thing is quite interesting and it's a bit of an overheating issue as well as maybe a misunderstanding or an over-insulation response is probably the best way of looking at it. I've heard of situations particularly down in Queenstown with a lot of the new development down in Hanley's Farm there where they've essentially got leaky home 2.0, but nothing's coming from the outside in, it's generating within the wall framing and so they're having these roofs that are like dripping and walls that are dripping but no water is not penetrating, it's just being generated within the home and that's pretty concerning problem down there. I don't know if it's the case anywhere else in the country, but that's you know. That really harkens back to that issue of overheating and therefore high moisture and dew points and things like that.

Matthew Cutler-Welsh: 12:48

It certainly will be, and in some respects Auckland's worse because our relative humidity is higher. So in the recent analysis that Jason Quinn did, using some dynamic modelling of FRSI thermal bridge calculations, it actually flipped some of the assumptions on its head where we used to think of Queenstown being the worst case for internal moisture. But because of that high relative humidity here in Auckland, in some situations it's actually worse, and what that means is you need to have a better ventilation strategy. It all comes back to having much, much better ventilation, and that's another one of those areas. It's not exactly a black hole as I describe it. It's more of a grey area because we do have a clause in the building code for ventilation, but it's woefully inadequate. Basically, everyone complies just by having windows that theoretically can open and you're deemed to comply, and we know that that just doesn't work.

Sam Brown: 13:55

From a design point of view. I know this is a point that Gerard's raised in our conversations before as well. Obviously, if you're looking at passive house these higher levels of homestar projects a lot of the time we're relying on mechanical ventilation, often with heat recovery as well. But is there any design techniques or methods that we can look at that are more passive, to be able to sort of create better airflow and things like that? Or is it just an issue of bringing that cold damp here in?

Matthew Cutler-Welsh: 14:27

There are methods like stack ventilation which work on taller buildings, but generally on anything under three storeys you're not going to get a huge stack effect. So it's kind of like the chimney effect, where you get a big temperature gradient between the, where it's a bit cooler down the bottom and you might have a warm space up the top and it draws the air up through the through the house. That can work quite effectively on on buildings three stories and above, but for most residential dwellings you're not going to get that reliably. So you really, and that's why we have as a requirement in homestar version 5 to have continuous mechanical ventilation, and that that does cause some concern for people to hear that for the first time, because what do you mean you've got to have, we've got to have a fan that runs continuously.

Matthew Cutler-Welsh: 15:22

And the answer to that is yes, you do, and that's a good thing, because you, you, you need to have a constant supply of fresh air, because you've got demands, uh, in the home, like people breathing, and you've got sources of moisture which you need to get rid of, um, and you want to have a constant supply of fresh air and and most New Zealanders just don't have that, and also in terms of people get concerned about energy use and reliance on a mechanical system. The fans these days are super, super efficient, so we recommend electrically commuted motors so they're effectively silent. They're super energy efficient and most people wouldn't even notice if you have them sort of dipping down to a fairly low flow rate. It's not like you've got this range hood that's blasting all day long. If it's sized, installed and commissioned properly, it should be able to be designed so that people would not even be aware that it's running either from the sound or from the power bill.

Sam Brown: 16:28

Yeah, I know personally. We've got them in our, we've got a decentralized system in our house and hardware and I think it's the equivalent of basically having a light on during the day from a power usage point of view, and during winter you don't notice that. You don't hear them at all. Summer, often, when it's quite hot, um, or the house is a little bit stuffy, if it's been closed you know been a hot day and the windows and doors haven't been opened at all and it kicks into like summer ventilation mode. It can be loud but it's like 20 minutes of purging and then it's back to sort of normal levels again and uh, doesn't bother me at all, but yeah.

Gerard Dombroski: 17:08

Ben, you have something like that, don't you? The old Alunos? Yeah, yeah, yeah.

Ben Sutherland: 17:12

I've got 11 of them, but I have to say, recently I found myself turning it off at night just because I wake up feeling really, really dry, leaving them on.

Matthew Cutler-Welsh: 17:24

What have you got in your?

Ben Sutherland: 17:24

place. I've got the alunos system, the in wall ones, yeah, but they all just push them, they all talk to each other and push and pull air all around the house, uh. So it works really well and I don't hear it at all. Great, but it does dry the place out.

Gerard Dombroski: 17:43

And which?

Matthew Cutler-Welsh: 17:43

climate. Are you in?

Ben Sutherland: 17:45

Whereabouts this is in.

Matthew Cutler-Welsh: 17:48

Wellington. Yeah right, that's interesting. Well, it's great that they're working effectively. I mean, quite a few people ask about through-wall ventilations like the Lunos because either they're retrofitting or they're trying to squeeze ventilation into a building that doesn't have much of a roof cavity, so they're a really good option.

Ben Sutherland: 18:08

Yes, yes, I don't have much of a roof cavity, and that's exactly why it's just so good. Yeah, easy to install, yeah.

Matthew Cutler-Welsh: 18:16

I mean it's really encouraging seeing more options come onto the market, because prior to well, a few years ago you really had what most people think of when you say heat recovery, ventilation which we don't want to go there and at the other end you had some really flash systems like SteepleElectron or quite amazing machines Zender is the other one. There's sort of really high-end passive house which are fantastic and I highly recommend those, but they're going to be sort of a significant investment for someone. And there are some other options now that are coming to market which are either just continuous extract as opposed to positive pressure, or a ducted extract, which is also a really good option, or even a more simple, more cost-effective system with a little bit of heat recovery in it as well. So it's an emerging market for New Zealand. I mean internationally it's a very mature market but, like a lot of these things, it feels new, because it's new in New Zealand but elsewhere people have been doing this for decades.

Sam Brown: 19:29

I think that's a really good point that you just made about that new New Zealand thing, and it would be interesting to kind of just touch on that a little bit more because I feel like all of this uptake of greener building and focus on embodied carbon and passive house and things like that is very new here but it's well ingrained internationally. I mean, why has the uptake been so? Is there any reason that you can see why the uptake's been so slow in New Zealand in particular? And you know how much are we leaning on international examples to try and sort of like prove our point or make a case here?

Matthew Cutler-Welsh: 20:04

Well, I think we're not leaning on international examples enough, because we're having to go through what I I mean you mentioned leaky buildings 2.0. That's not a new problem either. Germany went through the same thing. A lot of north america went through that two decades ago when they started insulating really well. Uh, you know, going back to the 1970s oil shock, I mean, that's when we started insulating and because of more extreme weather conditions, other parts of the world did that more, and they went through the process of going from cold and drafty to warm and damp, and then coming out the other side and thinking, oh, we need to warm, but we also need to figure out this moisture thing. And so they've already gone through that process. They know how to do it. None of it's. You know, the building science works around the planet. Our physics is no different, so we just need to sort of catch up.

Matthew Cutler-Welsh: 21:03

I think the reason why we have laid behind is because we are a little island down the bottom of the earth and we also have had some monopolies or duopolies who have been quite happy with the way things have been. Yeah, and the reality is it's a relatively small market. You know, there's only 5 million people. We only have to go across the ditch and you've got a five six times bigger market. So if you're an international supplier, you're have to go across the ditch and you've got a five, six times bigger market, um. So if you're an international supplier, you're going to look at new zealand very cautiously with um. You know it's logistically tricky to get to and a limited market on an international scale. So, yeah, I think there's a.

Matthew Cutler-Welsh: 21:46

There's a variety of issues, but I always said a couple of things that I always used to point out is that the people that I met in New Zealand that had the best homes, certainly 10 years ago, were mostly people with accents or Kiwis who had travelled overseas and experienced a house in Toronto or Vancouver or Germany or even the UK and experienced living in constant temperature conditions and inside and come back here and just not accepted what was deemed normal in New Zealand. And I think the other interesting part about the New Zealand psyche is is the concept of innovation, which we really put up on a pedestal and we like to think of ourselves as innovators, and I went on a bit of a an anti-innovation campaign a couple of years ago to say that we in the building industry in New Zealand. We do not need to innovate right now, we just need to catch up.

Ben Sutherland: 22:52

Yeah.

Matthew Cutler-Welsh: 22:54

We like to think of ourselves as this number eight wire and figuring things out, and we shouldn't be doing that in housing. We should be going and seeing what's failed, what is working, and just catch up.

Ben Sutherland: 23:12

Yeah, learn from others' mistakes. Been doing it for long enough, yeah.

Sam Brown: 23:19

Do you think as well, that it's almost a failing looking at it from our lens, because a lot of the time architects are the ones that are driving design decisions or driving specification decisions? Do you think it's a bit of a failing from our education providers, be they AUT, vic, auckland or any of the other ones that are out there, for not looking at this or putting it into the sort of the curriculum at an earlier point as well? I feel like I knew nothing. I mean, I did a sustainability paper at university which I didn't really teach much, but I didn't learn any of this until really only you know, two or three years ago.

Matthew Cutler-Welsh: 24:03

Yeah, I think it is. I mean, it's easy to sort of point and blame and I'm not an architect, I did engineering and I'm not not a builder and often I wish I quite like the look of that, particularly on sunny days, not so much on rainy days. Yeah, I have a lot of respect for, for builders, but I I think architects and builders are trained to do the job that is in the marketplace. That's reality for that profession. So I think it's all well and good to train people and even inspire young architects, but if they go out into the industry and the market just demands glass boxes in the best school zone, then that's what they're going to end up learning how to and being asked to design and build by their more experienced colleagues and also the rest of the market. So it's not going to solve it just through education. It's got to be through, you know, systemic shift as well yeah, I think it makes sense, yeah I guess as well.

Sam Brown: 25:16

Yeah, that I mean the request is always going to come from clients as well. And, speaking from our experience, and maybe it's because we are positioned in that slightly more high performance, um, and green building realm, but so many of our inquiries, even within the last 18 months, have come through that avenue of we're wanting a high performance and green building realm, but so many of our inquiries, even within the last 18 months, have come through that avenue of we're wanting a high performance home or we're wanting, you know, this, that and the next thing, rather than just your architecture, which has been has been quite interesting for us to to experience that change I really like hearing about architecture firms.

Matthew Cutler-Welsh: 25:46

I've interviewed quite a few through homestyle Green and then also on the Passive House podcast, and there seems to be this you've got to sort of take this leap as a small practice of getting your first Passive House project or getting your first high-performance project. Often you'll be able to get an article written up about that or some sort of PR or some sort of PR, and then it kind of it often snowballs from there and it doesn't take too many projects for a small firm to get known as a high-performance designer or a passive house designer or whatever it might be. And then it kind of you see these practices get to a point where they are able to say this is what we do and to start not accepting clients. Basically, it might be a little bit different in 2024, when there's a bit of a slowdown and obviously you've got to take whatever works out there. But that is a familiar journey that I've heard over and over again, where some people just need to put themselves out there for one or two projects and then they make a name for themselves doing that type of work. Now I think the more that happens then, the more consumers get to talk about that amongst themselves and sort of be proud of that home, and then it sort of ripples out from there.

Matthew Cutler-Welsh: 27:13

The other thing that I found really inspiring and very effective are mid-build open homes.

Matthew Cutler-Welsh: 27:23

I love the idea of opening up a home and inviting prospective clients into a build when it's just closed in, when the ventilation system is there and it's visible um, if you're doing air tightness, you know when that has just been completed.

Matthew Cutler-Welsh: 27:41

I mean, the best case scenario is you bring the blower door and you do a blower door test with the clients right there and then and there are so many benefits to doing that but the primary one is they're not distracted by the kitchen and the bathroom because they're not there.

Matthew Cutler-Welsh: 27:56

So all the things that are typically taken photos of to sell a house, they're kind of distractions to the performance and they're not there and people can look at how well the envelope is put together, they can see the insulation, they can see the insulation, they can see the ventilation system and understand how it all works, and see the windows, because they'll be there and they can operate the windows. So all the things that are going to matter for how comfortable and healthy that home is, they're all there and they're fully visible, and I've heard that a number of times that that's a whole marketing strategy for some architects and some builders is they get 20 people along to a mid-build open home and you only need two or three people to convert from that and that's your sort of pipeline of work for the next six months.

Sam Brown: 28:46

Yeah, interestingly though, we've done three or four mid-build uh open homes, now um for our home, star high performance homes, and there's been lots of people through and there's been lots of inquiries but nothing's converted so I think I mean I think that's probably more of a reflection of the current market than anything else, but yeah.

Matthew Cutler-Welsh: 29:12

Good on you for doing that, mate.

Sam Brown: 29:14

I totally agree with it being like a good avenue and a good approach. But yeah, unfortunately the reality of it converting hasn't quite come to pass for us yet. Well, I also.

Matthew Cutler-Welsh: 29:25

I mean, what's the typical lead time for the sale of someone's dream home or their last home? Yeah, it might be 10 years. It might be 10 years before they, you know by the between when they start thinking about it and when they're actually ready to embark on that project is there software that you can use to model the potential performance of these systems?

Ben Sutherland: 29:55

It'd be quite cool to just test some designs to see how they're actually going to perform before you know going out there, so we need to make a real one, yeah exactly. You just get Sam to do it.

Matthew Cutler-Welsh: 30:06

You get Sam to do it for you. Yeah.

Sam Brown: 30:08

I can do it for you oh you can.

Sam Brown: 30:10

So I can answer that question. I mean, like, as a Homestar designer, we have access to the Echo modelling tool, which is pretty good. It's not quite as intense and as powerful as, like, the Passive House planning package or anything like that, but it gives you a pretty good understanding of how the home is going to perform. So if you guys need me to model anything, I can do it for you. Easy, man, yeah. Or alternatively, you can do the HomeStar design, of course, yourselves. But there is, in terms of a Revit plugin. We ran beta testing on a Revit plugin for Echo earlier in the year. I don't know where that's at currently, Matthew, if you've got any updates on that.

Matthew Cutler-Welsh: 30:52

Oh for LiveSync.

Sam Brown: 30:56

Yeah.

Matthew Cutler-Welsh: 30:58

Yeah, just working on the Australian developer of that. It's just working on the final touches, so hopefully we'll have that available for Echo in the next couple of months. Oh cool, it doesn't seem to have slowed it down. Echo the energy model that NZGBC has made available for Homestar V5, it is based on the Passive House Planning Package. The uptake of that has been phenomenal.

Matthew Cutler-Welsh: 31:26

We've had over 10,000 models created on that software just in the last two and a half years. Some of those will be iterations, so it doesn't necessarily mean 10,000 unique designs, but it means that people are using it over and over again to do exactly what you asked, Ben to try a house out and move things around and see how it performs, and it's a great way of optimising that design for performance. But also then, if you're doing a little bit of QS on top of that, you can really figure out where the best bang for buck is on your performance as well where the best bang for buck is on your performance as well, and on top of all the code compliance requirements, so you can use it for code compliance.

Matthew Cutler-Welsh: 32:23

it also gives you a bit of insight into that overheating risk as well. So it gives you a little percentage prediction of time that the house will be above 25 degrees, and then you can start playing around with your window sizes and things like that to try and reduce that.

Ben Sutherland: 32:37

I think you need to open this up to the market. You might inspire some more people to go home start.

Matthew Cutler-Welsh: 32:45

That I mean. So we've got, if we step up from from the schedule method and going back to the start of the conversation, this is something that we're really pitching to MB and also now directly to the Minister, to say we want more modelling. Modelling should be the default instead of the schedule method when it comes to insulation, because the problems around insulation aren't so much to do with the objectives of H1. It's all about how it's implemented in the real world, which is through the acceptable solution typically, and that's where the problem lies. If you actually use the modelling method using tools like Echo, that's where people are going to end up with a much better result.

Gerard Dombroski: 33:34

Isn't the point of the review of the insulation things just about fundamentally kind of reducing complexity, I guess, protecting the bottom end of the market, making sure the people that can only just afford to build something can still afford, because I guess there's there's still the risk that we use complexity and we're just adding more things to a process, whereas I think being an opt-in sort of thing I think then gives people the choice. But I don't know, I see a bit of a danger of making everyone do more work well.

Matthew Cutler-Welsh: 34:15

So my response to that is to say, when do you want to do the work? Because either you get someone like sam to do the work and model it for a couple of hours, or a builder is going to have to figure out how to do funky hips on their roof truss and how to get this ridiculous amount of insulation up into the roof, and then you're also going to have to figure out how to minimise the condensation risk on the underside of the roof. So some work will have to be done at some point and someone will have to pay for materials. It's just a matter of who's doing that work and what the ultimate outcome is.

Gerard Dombroski: 34:59

Maybe we're talking about separate things here. The review of the insulation where they're talking about backtracking?

Matthew Cutler-Welsh: 35:06

Yeah, no, that's what I'm talking about, because putting R6 in the roof is not simple.

Gerard Dombroski: 35:15

Yeah, but what was it previously? What was it like a year ago?

Matthew Cutler-Welsh: 35:17

R3, which was about half of what the rest of the world is with similar climate zones to us. So tracking back from that would put us way back below similar international standards or places that have a similar climate to us. But my point that I was trying to make was that the cost and complexity is often used as a reason to not do things. It was the same when we introduced double glazing. People said, oh, this is too expensive. Houses are already expensive. Why do we need to go this extra mile? Part of it's just change and we just need to get our heads around it. But the benefit of doing a calculation or modelling is it shows you that in most parts of New Zealand you do not need to be putting R6.6 in the roof.

Sam Brown: 36:18

That's what I was about to get to. That makes more sense.

Gerard Dombroski: 36:22

That's what I was about to get to um that makes more sense.

Sam Brown: 36:23

That's what I was about to get to. Matthew is like. I think that's the issue. Just on the h1. Problem at the moment is so many people you only use the schedule method and they look at it and they go oh, this is gospel, I have to put 6.6 on the roof and I have to put 2.8 in the walls, blah, blah. But ultimately when you do the modeling, you realize that a home doesn't perform element to element, it performs holistically. So you're ideally balancing the insulation across the home. So you might end up only needing a 4.8 or something in the ceiling if your walls are better, et cetera, et cetera. So that's why the modelling method works just far more efficiently. So yeah, yeah, yeah.

Gerard Dombroski: 37:06

My underlying concern that I was just trying to get at was just trying to make building a house semi-affordable for people at the bottom end of the market.

Matthew Cutler-Welsh: 37:16

Yeah.

Gerard Dombroski: 37:20

So what's the most?

Matthew Cutler-Welsh: 37:20

expensive part of building a house Materials at the moment.

Ben Sutherland: 37:27

Yeah, and well, the labour. Yeah, two thirds, one third, two thirds. Two thirds material. I would say oh no, there's, I don't know, 50-50.

Sam Brown: 37:44

It's all expensive.

Matthew Cutler-Welsh: 37:48

Yeah, I mean, I don't want to belittle it. Cost is an issue, definitely, and I know that it's all well and good. I'm very hesitant to use percentages because you know, 1% of $1 million is a lot of money, because 1% of $1 million is a lot of money. So we need to be very, very careful about anything that adds additional thousands of dollars to a build if we're going to be conscious of those people that are yeah, insulation is very small, it's very small.

Matthew Cutler-Welsh: 38:19

in the grand scheme of things, and if people are genuinely concerned about housing affordability, there are probably a whole bunch of other things that they could do to easily take $10,000 to $20,000 out of the house, and we've seen this many, many times. So the first one would be thinking about the window size. Windows are some of the most expensive part of the building envelope. They're typically oversized and they're also often bespoke, so we need to do better standardisation of windows. Does New Zealand offer any off-the-shelf windows? Well, that's something I'm really advocating for and I'm hoping that some I don't know if you know of any suppliers that are doing that. Sam, I've been promoting that idea for a long time and I don't think it's going to be very long before a large, probably offshore supplier just stacks a big warehouse full of windows of four sizes and says here they are. We can make them bespoke, but they'll be twice as much If you want these windows of this size and they're available tomorrow. Here they are.

Sam Brown: 39:26

it's funny because I mean that exists for skylights, right, pretty much skylight, the majority of the sky might skylight market, whether it be adlux or vlux or whatever. They're all you know proprietary sizes. Why not windows?

Matthew Cutler-Welsh: 39:40

it's such a good question well, I think we're starting to see that um thinking in modular construction, off-site construction, with with some of these building systems where they've they're having standardized cassette wall, cassette sizes and and you know they've got a finite number of building elements and then you design according to those sizes. So the methodology is certainly there and I know that there's always some there's a tricky section or you've got design panel requirements that mean that you have to have more glazing facing the street and some of these other issues. But in general I think you know looking at standardisation of windows would go a long way to bring those prices down. The other thing we talk about quite a lot is making the envelope much more. I hesitate to use the word simple, but it is about simplifying the form of the building envelope.

Matthew Cutler-Welsh: 40:46

Now that doesn't mean that the building should be boring, but I see a lot of house plans and when I look down at the floor plan there are too many corners.

Matthew Cutler-Welsh: 40:57

There appears often to be lots of ins and outs and little bay window kind of things which are lovely. But every corner that you have is an extra cost. Someone quoted me $2,500 or something for every additional corner on average. Now that doesn't mean you can't have a building that looks interesting. You can create interest from changing the cladding or you know different um colors on the outside and you can still have ins and outs on the the outside of the building. But if you look at the thermal envelope and really think about how can you have as many straight lines on that as possible? That's a really good way of reducing cost and that will likely also simplify the shape of the roof, and I see some ridiculous shaped roofs that just have far too many ridges and valleys in them, and you know so. There are all these areas where you can probably easily find $10,000 to $20,000 on a standard group home builder floor plan, before starting to point the finger at insulation as being the thing that makes it expensive.

Ben Sutherland: 42:14

Yeah yeah, complexity is a huge one.

Sam Brown: 42:18

And I think what we're talking to here is a certain section of the market as well, like, obviously, the New Zealand like, particularly, the residential market is, you know, primarily group home building type offerings, with a very, very small amount of it being bespoke. So I mean that's the area that needs to be targeted in the first instance for us to really see differences in terms of both the performance and affordability of housing at a more entry level. But it'd be interesting, yeah, from an architect's point of view, particularly if we're looking at that bespoke stuff. I think, like you've talked about, matthew, having these sort of preset sizes and these, the more rigorous understanding of design decisions in terms of the way that you are developing a home, although it may seem limiting, it can actually be quite an interesting design challenge, I think, something that architects may, you know, may look to, to sort of uh champion a bit, or, hopefully, yeah, you know it's very easy.

Sam Brown: 43:25

It's very easy. I mean, we had a client in Wanaka. They're a little bit frustrating, to be fair. You know they just wanted the entire facade to be glass and we're like, well, that's fine, but you can also just walk outside and have that exact same view. Is it not more interesting or we thought you know it is more interesting from an architectural point of view, to frame aspects of the view. So if you sit here, you see this point of a mountaintop, you catch a glimpse of the lake here and things like that, and they're like, no, we just want glass, all glass, all view, everything, and like that's not challenging or necessarily interesting from a design perspective.

Sam Brown: 44:00

and so I think that's like you know, there's a good balance to be had with using modular systems or even, like you said, smaller amounts of glazing and things like that yeah, I I have been known to say, um, when I see floor to ceiling glass, that the architect was just lazy.

Matthew Cutler-Welsh: 44:20

But um, I can say I'm not an architect, I'm gonna be, I'm gonna be careful look how nice mine line up though.

Sam Brown: 44:30

So yeah, not too lazy, they do line up nicely, mate.

Ben Sutherland: 44:35

Yeah, I just, want to um go back to the sustainability side of these advancements a little bit, bringing in additional mechanical ventilation, for example, is that in a way just transferring the operational carbon issue with the embodied carbon issue? That make sense.

Matthew Cutler-Welsh: 45:00

So there's obviously a lot more embodied carbon, so you're putting more stuff into the house, yeah, yes, uh, to make it operate more efficiently, efficiently. So the the trick there is to put the right amount of extra stuff and have it in the right place, doing the right thing to dramatically decrease the the lifetime energy use, and with something like ventilation, it's. That's not hard, because the benefits of having drier internal environment going, you're going to get that wind from a pure energy point of view anyway, but you're also going to your your interior is going to be that win from a pure energy point of view anyway, but you're also going to your interior is going to be much more durable. So, even if you just look at it from a purely energy and durability carbon lens, you're going to be winning, but the health benefits are going to be even significant, even more significant than that. So that's I mean there was this concept of efficiency first, which is in relation to instead of trying to throw things like solar panels on a roof and call that sustainable, you try and make your envelope as efficient as possible. You start with the enclosure of the building and focus on reducing demand before you start adding supply of energy.

Matthew Cutler-Welsh: 46:31

I've talked about efficiency second, with effectiveness being first, and I think in some of our like most of our New Zealand housing stock, you could argue that they're not effective because they don't adequately keep people healthy and dry and warm. That's what we need to be focusing on first is what is the purpose of housing and are we even achieving some of those fundamental requirements or the purpose of housing? So it's got to be effective first. You know, a V8 F-150 truck sitting not going anywhere is super energy efficient because it's not using any energy. It's not very effective because it's not going anywhere. But a building, most of our existing homes don't use enough energy because they're dramatically underheated, because people are cold and we have high rates of asthma. So we need to ensure that we're making buildings effective first and we can also do that while making them efficient.

Matthew Cutler-Welsh: 47:53

I've kind of gone off on a bit of a tangent in answer to your question, but yes, we do have to put extra stuff into homes because there are things that haven't been in there. We can't just rely on opening and closing windows for ventilation. So we do have to add a little bit of services and mechanical systems in into that to make it work properly. But that's okay as long as we size it correctly, design it well, commission it and look after it, because if we do that, that system will look after the people inside the building and it will also look after the building for much longer. And a big part of sustainability is also about durability. There's kind of overlap between sustainability and resilience, but the more durable the building is, then you know that's more sustainable as well, because we're not going to have to knock the thing down in 20 years because it's all mouldy and falling apart.

Sam Brown: 48:49

It's interesting because I think we, as designers and professionals, we understand when the principles are explained to us. We understand the benefits and the reasoning, but often what I've come across, the difficulty that we've come across, is being able to adequately communicate that or effectively communicate that to potential clients and builders as well. Like are there, are there any sort of methods or do you have any suggestions in a way that we can? We can sort of do that a little bit more effectively?

Matthew Cutler-Welsh: 49:23

I've thought about this quite a lot In New Zealand because we've got a temperate, a kind of moderate climate. We can't make as strong a case purely on energy savings and cost savings. If we were really really cold like in Canada or northern Europe, you'd be able to do a nice little calculation and show them. You know, if you only spend this much then your energy bills are going to be this high. If we spend a little bit more on your insulation and maybe a central heating system, then your energy bills are going to be much lower, and you know it's a simple cost benefit. We don't. We have that a little bit here in New Zealand and there has been some good research done showing that across all the climate zones in Australia through the Green Building Council there. It's a good paper done by KPMG. I can show you the, I can give you the link to that, and it's quite a good piece of analysis because it's really useful when you're having a conversation with a bank because it justifies getting a slightly higher mortgage at the outset to say, well, look, if you give me $10,000 more or $20,000 or $50,000, I'm going to be a better customer for you because I'm going to be able to pay that back faster because my utility bills over the life of that mortgage are going to be a better customer for you, because I'm going to be able to pay that back faster, because my utility bills over the life of that mortgage are going to be much lower. Therefore, I'll be able to pay that off much, much easier. So that's a nice curve to have from the perspective of getting a mortgage. But I think we need to do more than just talk about dollars and straight payback in New Zealand, because the benefits are much more related to health and I come back to that effectiveness of the building and really what people are hoping for in living in their home.

Matthew Cutler-Welsh: 51:23

What I started playing around with in my communication is pointing out those holes in the building code. So there's this concept in commercial building of a green premium to say, if you build your standard building, if you build it to green, it's going to be slightly more valuable. That's sort of above the line thinking of saying, yeah, I'm going to give you something extra. Stepping back from that. There's another concept of a brown deficit. I can't remember the name of the word, but it's basically a brown deficit. It's basically pointing out that if you just build to the building code, you're actually going to be below the standard of what you probably think is reasonable. So I don't know how effective this is, because I'm not a marketing guy. You're delving into sort of negative marketing instead of positive marketing. But I think we almost have a duty of care to prospective homeowners to point out the deficiencies of the building code.

Matthew Cutler-Welsh: 52:29

To say yes, we can build you a building code compliant, but you're aware that it will probably overheat and it will get condensation on the inside because you won't have adequate ventilation. There's nothing to stop it from overheating and you may have some of these significant issues down the track. And, like I say, I don't know how effective that is. But I think it's really important that we don't, or that we at least acknowledge the assumption that most people quite rightly have that the building code is adequate.

Sam Brown: 53:03

Yeah, and I was also going to say that a lot of people, particularly governance, are pretty protective of the building code as well.

Matthew Cutler-Welsh: 53:10

Yeah, and I go back to my point about the building code that there's nothing wrong with the Building Act and there's nothing wrong with the performance criteria or the objectives of most of the clauses in the building code. But it comes down to the implementation and the acceptable solutions of those clauses. That are the real issue.

Sam Brown: 53:30

And it's also often taken as a target rather than a minimum, which I think is a big issue.

Matthew Cutler-Welsh: 53:36

Well, there are two aspects there. Yes, it's seen as the target, but if you take something like wall insulation, in most instances we're not even hitting that target. So not only are people just designing to that threshold of achieving r 2.8, for example in the walls, but 90 of new builds right now. If you were to actually calculate the r value of a consented wall, it wouldn't be anywhere near 2.8.

Ben Sutherland: 54:07

Interesting Gerard, would you say that your workshop landlords have insulated your walls?

Sam Brown: 54:18

Gerard's sitting at around. What 14 degrees in there, gerard.

Gerard Dombroski: 54:23

Yeah, just under 14.

Ben Sutherland: 54:24

You look nice and cosy.

Gerard Dombroski: 54:27

Actually, I insulated the ceiling myself just like 50 mil, which made a small difference back in the day. The overheating was probably the worst issue. It was hilariously hot, like we'd be sitting here without a top on. It's like splitting. Then in winter you're like freezing your ass off as well.

Sam Brown: 54:51

Matthew, before we sort of wrap up, I'd be interested to kind of hear from you whether you've got any sort of notable projects or key examples, whether they be like buildings that have gone through the Homestar process. One that springs to mind is maybe that new Fletcher Living 10-star home, or maybe even like one of the Green Star projects, potentially like the Scion Centre in Rotorua. Is there any others that you sort of popped to mind or that you want to talk to that architects or listeners could potentially look up and take lessons from?

Matthew Cutler-Welsh: 55:31

Well, yeah, I mean the Loko project from Fletcher Living, very exciting. We pointed a few to a couple of your projects, sam, because I think they're really good examples on a smaller scale, but more.

Matthew Cutler-Welsh: 55:50

I wasn't wishing in some ways more, but it was one of the. Yours was one of the first um v5 and it was such a good summary of some of the key things that we point to to say you know, this is what you need to do to go from either building code or even from a previous version of HomeStart from version 4 to version 5, you know, incorporating things like I think you put Lunos ventilation in that first one use SIP panel wall construction. So it's got a whole bunch of just quite nice, accessible systems for people to look at and it's at a level of the market sort of a budget that I think is much more relatable to people. And in some ways, that's why I'm more excited about the rest of Fletcher Living's offering because, yes, they've got this. It's a bit like when you go to a motor show. You know you go to a car show and they have all these amazing like. It's a bit like when you go to a motor show. You know I go to a car show and they have all these amazing like prototypes of things, that which you know maybe come to fruition, maybe won't, but then it's more about what's their next year's model, what's going to actually be available. And that is really exciting because Fletcher Living are also incorporating some of that learning into their, some of their new developments, and that's when we're going to start to see scale and more traction for the real market. I'd love for every house to be a loco. Um, it's going to take a while to get to that point. So there are lots of other projects that we can see out in the marketplace that are achieving that on the way to getting there.

Matthew Cutler-Welsh: 57:28

The other really exciting thing well, there's a whole bunch of exciting areas. Built-to-rent is quite an exciting space that we're seeing at the moment because that's shifting the whole paradigm of home ownership building affordability, the ability to have more standardisation, not just in windows but also just build methods and typologies. So that's an exciting space and we've got really good uptake and working closely with Simplicity. New ground, capital and also kiwi property have just opened there, built to rent, in sylvia park, right next to the, the shopping mall here in auburn, which is a fantastic project.

Matthew Cutler-Welsh: 58:14

And the other area of uptake is in the residential um sorry, in the retirement village sector. Now they're a really interesting group because they're similar to Kying Order in that they retain their assets. So they have a vested interest that they can kind of see the benefit of building homes that are going to be healthy because that's really important for their clients but also are going to be relatively easy to maintain and be robust over a long period of time. And the other key reason why most of them are really interested in Homestar is because they have now a legal requirement to report on their greenhouse gas emissions. That's something that's coming into play but it exists already for the largest 197 listed companies in new zealand and a lot of those retirement village operators fall within that. So as of the last financial year they were all required by law to report, along with their financial statements, their scope one and scope two emissions, and so I think doing Homestar is a really useful tool for that.

Ben Sutherland: 59:29

Just curious how hard is it to build a Homestar 10, let's say, in comparison to, say, a five? Is it next level or is it achievable?

Matthew Cutler-Welsh: 59:42

So we've had two. It's always a bittersweet when we launch a new version of the tool and then someone comes and delivers a 10 Homestar straight off the bat. I'm like, oh, maybe we didn't make it home.

Ben Sutherland: 59:57

Go to 11.

Matthew Cutler-Welsh: 59:59

So yeah, we've had two already under version 5. In version 5, there's around 130 points available. So to get 10, you need 100 of those. It's definitely achievable. You do need to be thinking about it from the get-go.

Matthew Cutler-Welsh: 1:00:22

It's going to be very hard to take an existing plan and throw things at it. To collect all those points you have to be really considering your form factor, your size, probably aspects of the location that are going to play a pretty important role. But you really have to be optimising that envelope and then thinking then going to the next level in terms of your products and what materials you're specifying and all those other aspects that are in there doing water efficiency really well. You just have to be taking most. You probably have to be collecting points in all of the credits to get up to that level.

Matthew Cutler-Welsh: 1:01:07

But I think with all these I mean it's similar to Passive House projects it's all about getting the right team on board, getting everyone around the table really early on in the project. That's the way to run a project like that and make it happen smoothly and probably at not too much cost. I mean Nathan's project in Nelson. That wasn't a massively expensive build. He did some of the work himself but it's. You know he certainly didn't blow the budget on his project.

Sam Brown: 1:01:44

Did take him a decade.

Matthew Cutler-Welsh: 1:01:46

Well, there is that. But if you're an, architect. You know, you're just working on your own home, if he was his own client, he probably would have fired himself a long time ago.

Sam Brown: 1:01:57

I think. I mean, I think it's like anything, ben, you know, if you've got the time and the team and the budget, it's pretty affordable. I mean, even the budget's not necessarily the thing, but I think it's a matter of having the you probably want a fee from a design. You know, from an architecture design point of view. You want to have a pretty robust fee in there.

Ben Sutherland: 1:02:17

Yeah.

Sam Brown: 1:02:19

But I think it's also having clients that understand this and are willing to sort of take a punt is going to be probably the biggest hurdle, I imagine.

Ben Sutherland: 1:02:32

Yeah, awesome. Well, where do we go to for those of us who are interested some more information? Where do we go to find out more? Well?

Matthew Cutler-Welsh: 1:02:44

we've just launched our design guide for Homestar, so that's really the best place to start. And if you jump onto NZGPC website it's nzgpcorgnz and just type in Homestar design guide, it is up in the top menu but should be fairly easy to find. Homestead design guide. It is up in the in the top menu but should be fairly easy to find. That's a fairly detailed document and it dives straight into some pretty technical stuff about how to design. It gives you sort of a code six and then an eight and above options for and there's this a few different case studies in there you can have a look through, but it goes right into the details that you need to be thinking of and ventilation systems, all the assemblies and that sort of thing. So if, if you're architecturally inclined, that's definitely a really good place to start. We we had some really good input from Respond Architects put that together and there was also some really good support from NZIA, adnz and Brands.

Sam Brown: 1:03:52

Cool, I think that might be time for us, gerard. Any final questions?

Ben Sutherland: 1:04:01

Gerard's frozen.

Sam Brown: 1:04:09

It's too cold. It's got so cold, we've lost him. We've lost him. Well, gerard jumps back on. Matthew, I was just gonna say do you want to take the opportunity as well? I mean, I know that you've got a couple of other um ventures in the podcast realm in terms of getting the word out there do you want to just give a a quick spiel about those?

Matthew Cutler-Welsh: 1:04:23

Sure, thank you. Yeah, homestyle Green podcast sort of. I've launched it kind of as a second season kicking off with Build Aotearoa, and that's more similar to this sort of format. It's a bit more conversational and the idea of that is to have a bit more of a weekly conversation about issues in the building industry and kind of what's going on, with definitely a lean towards sustainability and higher performance building. And I'm also the co-host of the Passive House podcast, which is produced by the Passive House Accelerator, and that's a great bunch there that promote Passive House and also, increasingly, issues relating to Passive House. So we've done a series on off-site manufacturing. We're doing a series at the moment on keeping cool, so really looking at this increasing issue around the world of making sure buildings don't overheat, and we've done a few other series that are looking not just at Passive House, but you can check that out at Passive House Accelerator Awesome.

Sam Brown: 1:05:48

Cool. Well, thank you very much for your time today, matthew, and yeah, thanks for jumping on the conversation and I mean we'll obviously talk a bit more in the future and I hope that sort of this discussion helps direct, you know, other architects and designers and the general public towards this style of the building industry. And yeah, thank you very much Pleasure. All right, thanks guys. Cheers guys, cheers guys, cheers guys.