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Interviews with the leaders, practitioners, and change-makers in the global Passive House movement. A production of Passive House Accelerator.
So New Zealand's H1 is so heavily focused on insulation. It's like a silver bullet for efficiency and comfort.
Speaker 2:Or it's seen that way.
Speaker 1:Yeah, it's seen that way and it's applied that way.
Speaker 2:Welcome to the Passive House Podcast brought to you by Passive House Accelerator, a catalyst for zero carbon building. For news, inspiration and connections from all flavors of Passive House, check out passivehouseaccelerator.com. Sign up to receive regular updates about events, get your questions answered and contribute to the community dialogue. There's loads of free information for experienced professionals and people just starting out on their Passive House journey. We hope to see you at one of our weekly Passive House Accelerator live webinars.
Speaker 2:In the meantime, here's this week's Passive House Podcast.
Speaker 3:Welcome back to the Passive House Podcast. I'm Matthew Cutler coming to you from Auckland in New Zealand.
Speaker 4:And I'm Zach Semke coming to you from Seattle, Washington.
Speaker 3:It's good to have you back safely in Seattle. Zach, you've had a bit of time away?
Speaker 4:Yeah. I was in Mexico, which was wonderful. And on the day that we were flying home from the international terminal, I looked at my iPhone and saw the cartel violence or the action against the cartel there. So I felt happy to be flying back at that moment.
Speaker 2:Yeah. Yeah. Good
Speaker 3:to have you back home safely. Meanwhile, I've been deep diving into the issue of overheating of buildings in my day job. Getting a little bit involved in not directly energy modelling myself, but looking at other people's energy modellings and helping them figure out how to reduce the risk of overheating, which is very topical for today's interview, which is a conversation I had with someone who is from New Zealand, but really valuably has been overseas and experienced building sites in other places around the world. So we'll get into that soon. But before we do, we've got a few people to thank.
Speaker 4:Indeed. So first I want to thank our sponsor of the week, Prosecco, for making everything possible for us at Passive Accelerator, including this Passive House Podcast. Thank you too to our stakeholder partner, NYSERDA, the New York State Energy Research and Development Authority. Thanks to our founding sponsors, four seventy five High Performance Building Supply, Ingui Architecture, Partell, Rockwell North America, and Zola Windows. And thank you to our champion sponsors, Bewizo, Cascadia Windows and Doors, European Architectural Supply, Icon Windows and Doors, Intelligent Membranes, LG Air Conditioning Technologies, Prosico, and Source two thousand fifty.
Speaker 3:Tavis Creswell-Wells is the founder of his own company, which focuses on sustainable building solutions called Ecolution here in New Zealand. He's a building scientist and sustainability specialist. Importantly, after training here in New Zealand, he's been overseas and worked with everything from Bree Am in The UK, Well-Green Star, which is kind of the Australia New Zealand equivalent of LEED, and also things like TM59, which we get into. TM59 is a modelling methodology for addressing the risk of overheating. The other things that we touch on during this episode, because he has come back and is now working here in New Zealand, we have an organisation called BRANS, which is the Building Research Association of New Zealand, and they do a lot of funded research specifically on the building industry.
Speaker 3:He references brands fairly early in this conversation because it definitely informed his career early on, particularly through a project called BEES, which was a building energy end use project. That was one of a number of projects that brands ran to look at the actual end use energy efficiency of some buildings. Then finally Neighbours, which isn't the Australian TV show. It's the National Australian Building Energy Rating Scheme. That's a bit of a handful.
Speaker 3:Neighbours, and that is used for existing buildings. That sounds like a lot, it is a lot, and we touch on that fact in this interview. And when I asked Tavis later on about how all those, or if any of those overlap, particularly when you add into things like Well, which is now getting more established in places like Europe. And then finally, some specific parts of the building code here in New Zealand. Have H1, which is the clause of the building code that deals with energy efficiency.
Speaker 3:And that's most similar equivalent is Part L in The UK, which is their part of their building code and building regulations over there. And we talk a little bit about the differences between those. So a bit of alphabet soup there. So we'll cover that off and let's get into my conversation with Tavis Creswell-Wells.
Speaker 2:I'm joined by Tavis Creswell-Wells, who is a building scientist and sustainability specialist and currently based in Wellington. Thanks for joining us Tavis.
Speaker 1:No worries. Glad to be here.
Speaker 2:Tell us a little bit about how you became a building scientist because it's not that common of a of a thing here in New Zealand.
Speaker 1:Yeah, it's an unusual one. Everyone gets pretty confused, looks on their faces when I tell them what I do. Most seem to think it's some kind of structural engineer for some reason, but not not so much. Yeah, I finished high school and went into university thinking I quite like the idea of becoming an architect, as many do. So went to Victoria in Wellington and did fishy architecture, and I was a little bit surprised what it was what it was all about, but a lot more kind of artistic oriented than I was expecting, which was more of a technical, I guess, approach, coming from an engineering family, especially.
Speaker 1:So after first year, I moved, I looked what else was in the school available and saw this building science thing, which I didn't know anything about. But it seems more up my alley with the more kind of technical and analytical approach. Mhmm. So I tried that out. And yeah, it was a it was a pretty good fit for my nature and still very much obviously building oriented.
Speaker 1:But yeah, just a slightly more technical side of it, which I was I was quite keen to get into more.
Speaker 2:So were you able to transfer from architecture into building science program?
Speaker 1:Yeah. Yeah. At the time, was just like most people did like teaching first year and then kind of split off into different specialisms like landscape architecture and interior as well. Yeah, and second year. Yeah.
Speaker 2:And what did that course include? When you were studying? What what did you what types of subtopics did you cover in building science?
Speaker 1:Undergrad it was it was structures papers, construction, project management, economics, sustainability. That was the my main major was the sustainability elements. So you started to look at things like passive design and environmental science and energy modelling, daylight, natural ventilation, all those kind of things. So it was a pretty broad set of subjects in the undergraduate degree, which gives you a good kind of a nice wide understanding of what's involved in buildings.
Speaker 2:And you you got the chance to be involved with the building energy and use study?
Speaker 1:Yeah, yeah. So at the end of my undergrad degree, that was the B's was in full swing. So I came into that as a research assistant helping a couple of the postgrad students put their their sections together. So that was a good introduction to kind of academia and the research world and what's going on at brands. And yes, I'd feel a little bit more grown up at that point.
Speaker 2:Yeah. For those that haven't heard of the Building Energy and Use study, can you give us an overview?
Speaker 1:Word scraping the memory. I think it was a kind of a deep dive into the types of buildings that we have in the existing building stock in New Zealand, what they're kind of made up of in terms of constructions and some design elements, and figuring out where they sit in terms of efficiency, and ways that we could on a large scale improve the existing building stock. Think it was commercial and residential. But yeah, so that was a while ago now, so yeah, yeah, We
Speaker 2:can come back to that because it I guess there's a question about how much stuff has changed since then, and how much that learning has has been implemented. From there you've done a bit of work on indoor air quality. Where did that interest come from?
Speaker 1:So in postgraduate in the Masters for Building Science, I did my thesis on the rebuild of Christchurch after the earthquakes. This was back in twenty twelve ish. So I started looking I had become interested in passive design and indoor air indoor air quality and all environmental quality, as well as energy efficiency. So started looking at ways to make buildings more efficient while also being comfortable and healthy. And part of that was indoor air quality.
Speaker 1:Yeah. And yeah natural ventilation.
Speaker 2:You've had the opportunity to work overseas. What inspired that and what did you learn?
Speaker 1:Well, so that was my first job out of uni. I got the itchy feet during Masters and really wanted to do my OA, which I'd always planned on doing. So did some travel for a year and then kind of landed in Europe and UK and found this really great job at a place called Kundle. So they're a building services engineers consultancy, get some really good high profile jobs over there and got to learning almost relearning a lot of what I thought I knew in building science. And yeah, they had some amazing projects, really great staff on board.
Speaker 1:Yeah. Top top engineers to learn from and so yeah I got kind of thrown in at the deep end with some really big projects and learning a a whole way a whole range of different types of assessments that we don't really do in New Zealand, I had not not really learned at university. So that was a quite a learning experience.
Speaker 2:Can you give us some examples of of what was different? What did that feel like going from studying building science here, but actually doing stuff in a in a much different building environment?
Speaker 1:Yeah. So one of the first kind of wake up calls I remember was during my masters I was getting quite a lot into daylight analysis and kind of getting to the point that thinking I was a bit of an expert on it. And then very quickly it was brought back down to earth getting over there because pretty much everyone in the team already knew what I was talking about. Right. So I was like, oh, okay, just a just a small fry still.
Speaker 1:So that that was a, yeah, a little formative moment to be going, just getting started. But yeah, in terms of projects, so I think within the first six months of being a graduate, I was given a one of the top banks in Europe, building an HQ in London. So it was, I think it was 60 or 80,000 square meters, Enormous, very, very expensive building. And they they put me on as the modeler. So I had to learn very quickly how to do very complex energy models and also thermal comfort and daylight and all sorts of different energy models.
Speaker 2:And had you done that type of energy modelling prior to that? Like was that part of building science training here?
Speaker 1:Yeah, more so in my masters because of the subjects that I've chosen. You do definitely do some energy modelling in the undergrad building science project, sorry course, but obviously much, much smaller scale, and you kind of really just getting into what it means and what the inputs might be. So it was a huge step up in terms of scale and expectation.
Speaker 2:Yeah. And you mentioned passive solar. When did you first come across Passive House?
Speaker 1:I think I came across it during my thesis, but didn't really get into it too much. I was just looking more at general passive principles like daylighting, window sizes, that kind of thing. But it was over in London because The UK were starting, especially towards the end of my time there, around 2018, that kind of time. Scotland started getting very interested in it to make it part of their building code regulations. We have offices in Scotland, so we were kind of kept up to date with that.
Speaker 1:And certain certain types of projects, so like schools and medium to large scale domestic apartment blocks, they were getting quite interested in in in Passive House to really drive down the energy expenditure and keep their tenants warm.
Speaker 2:Right.
Speaker 1:So it started becoming quite a clear best practice for me. Because it's, it's, yeah, it's really driving down the energy that building needs to begin with before you even start thinking about renewables and technologies to deliver that energy. So it's it seems like an obvious starting point to for for this type of performance.
Speaker 2:Had you done other rating systems or done certifications? Because you you've had experience with with Breem and have you done well and things like Greenstar in your other work?
Speaker 1:Yep. So we learned a little bit about Greenstar back at uni and then over in The UK also suited part L which is the part L's the section of the building code similar to H1 dealing with emissions rather than energy directly. And so that's when you get into the EPC side of that, that's a bit of a rating system. Yes, BREAM, so equivalent to Green Star, similar in a lot of ways, and Well as well. So the company I worked for, they actually did the first well project, the office that we moved into while I was there was the first well project in all of Europe.
Speaker 1:They were the market leaders in that. And then we just really drove that home. So we were getting lots of well projects. And I got to work on or lead one while I was over there, which was a kind of, I think it was a six storey office refurb in the middle of London. Yeah.
Speaker 1:So that was yeah great experience to to kind of be one of the early adopters of that.
Speaker 2:Have you thought much about how all those tools either overlap or contradict each other in any ways or you know how do you think about knowing knowing and having experience with all those? How do you think about all those various certifications and tools now?
Speaker 1:It's a complex one because so, for example, Breanne and Well had a number of the features and credits that overlapped.
Speaker 2:Mhmm.
Speaker 1:So they'll they'll have official crosswalks between the two. So if you're kind of achieving the criteria for well, then you automatically achieve that credit for a brand. Mhmm. So that was quite well set up there. There are other ones that you could potentially push in that direction to to streamline projects and save costs and all that kind of stuff.
Speaker 1:But there's often such nuance in some of the criteria and the standards that each one applies that it can get quite difficult to to make that streamlined. And, yes, sometimes they they really dive into the weeds and get quite complex. So it's yeah. Trying to trying to simplify it to a point where you can apply it to to multiple project types in a way that makes sense is quite difficult.
Speaker 2:How do we make sense of all that in the local context back here in New Zealand? After you've had all that experience, you're seeing kind of where things are heading in different climates. What do you think are some of the the biggest priorities right now in in New Zealand? And and what can we take from that all that breadth of knowledge you've got from those different rating tools and certifications?
Speaker 1:So overheating is a big one. I think we're gonna we're gonna have problems on that coming up in New Zealand. But I guess we'll get into that a bit more conversation later.
Speaker 2:Yeah.
Speaker 1:So I think for me, the one that's really stuck out since coming back is h one. So the equivalent over in The UK Part L is, I would say, a decade or more, like maybe two cycles of of revision ahead. Just as just so much more comprehensive and more easily applied, which I didn't think at the time, but coming back in hindsight, maybe see the kind of the benefit of it. So New Zealand's H1 is is so heavily focused on insulation. It's like a silver bullet for efficiency and comfort.
Speaker 2:Right. Or seen that way.
Speaker 1:Yeah. It's seen that way and it's it's applied that way. The way H1's set up. It's kind of like everything's just about our value.
Speaker 2:So how does Part L work? What makes it different?
Speaker 1:So it's not just heating and cooling demand like H1. It also takes into account your lighting, your hot water and auxiliary, so ventilation and pumps and stuff. Uh-huh. So you're putting you have to put in the systems that you're using, the mechanical MEP systems Yep. As well as the building envelope.
Speaker 1:And you have to put in the efficiency of those systems. And it's not done. It's done at design stage and also at completion of building stage. Because h one is just some at some point during design. So you can make assumptions early on, but you have to then back it up with the documentation that's submitted at the practical completion for what's actually been installed.
Speaker 1:So there's a lot more robustness around the quality of what's been modeled and designed. Yeah. What else? It's it's And
Speaker 2:did that did you did you say that's got a cooling load component as part of it as well as a heating load?
Speaker 1:Yes. Yep. Yeah. So
Speaker 2:cooling Which is quite significant.
Speaker 1:Cooling energy. So in terms of energy, there's also criterion three was looking at exclusively solar gain. So how how so the point of that is to try and limit how much window area was being used on buildings so that you're not just relying on air conditioning or efficient systems to overcome how much heat might be allowed into the building. Yeah. So putting checks and balances through the design process, not just kind of what happens at the end.
Speaker 2:What was your perception when going thinking back to when you were working in The UK and or or, you know, people that you've been in touch with since. What what was your perception of the professionals, how they were adopting that? Because that hasn't always been the case. Right? Like, looking at at things like solar heat gain and and cooling load.
Speaker 2:I I'm that's relatively new in The UK?
Speaker 1:Well, was doing it from day one when I started back in 2015. It was just standard practice. So, yeah, I think it's been going on for a while.
Speaker 2:So it wasn't wasn't seen as problematic by the industry? It was just standard practice?
Speaker 1:It was standard practice. It was the old, you know, client or designer kinda dragging the heels and pulling in a problem.
Speaker 2:Right.
Speaker 1:But really, it was pretty reasonable step. Yeah. If you want a building that performs it doesn't overheat. Yeah. Wasn't it wasn't that difficult to comply with.
Speaker 2:Yeah. And as you say coming back to us here in New Zealand, this is something that you you have you're going to be talking about. You have talked about presenting on. Why is this a big issue for New Zealand? Well, let's start there.
Speaker 2:What why is overheating such
Speaker 3:a big problem for us?
Speaker 1:Basically, because we've got absolutely nothing in place to mitigate it at this point. There's nothing anywhere in building rigs that's set up to control the heating. So any the situation we have where there's not too much of a problem so far is basically just luck.
Speaker 2:Right. Yeah.
Speaker 1:Yeah. And as climate warms, as H1 comes into effect and insulation, well it's been ineffective for a while now, but as the building stock starts to increase with new buildings that have been more insulated. And I think as architectural and real estate's preferences move towards more highly glazed buildings, more compact spaces, there's going to be a lot more solar gain getting in and then not being able to get out because of more insulation. And there's still very little understanding of how windows should be designed, openings should be designed, things that are making them ineffective. Just on that point, I want to make it clear that because there's been quite a bit of talk about the H1 increase in insulation causing overheating.
Speaker 1:Yeah, I
Speaker 4:hear it regularly.
Speaker 1:Yeah, and it's plain and simple, it's not correct. Insulation is just one design component. And it's probably one of the less influential design components compared to things like the amount of glazing you put in on a building or for a space and the amount the ability to ventilate is there far more influential elements to the design than the amount of insulation in the walls or wherever.
Speaker 2:Yeah. Well, so let's dive into that in the solutions space. When you're in energy modelling now here in the New Zealand climate, what do you typically look for to help first identify the risk but then mitigate that risk in a design?
Speaker 1:So back in my previous role which is predominantly commercial, the first thing we'll look for is how much glazing there is because typically there'll be too much glazing on most designs. Yeah. If I had a nickel for every conversation I had with designers about reducing glazed area, you're a wealthy man.
Speaker 2:So that's But I'm guessing as a consultant, you you get to look at a a concept that's already been consented, at least resource consent.
Speaker 1:How much
Speaker 2:sway do you have when the design's already been done?
Speaker 1:Yep. Yes. So that's why we implore architects or clients to bring us on as early as possible, because then we get a chance to actually guide the design down more effective and cost effective routes. But yeah, as you say often it's it is later on in the process, and we're limited with what we can do. So that point often the only thing we can do is change the glazing specification.
Speaker 1:It says a characteristic of glass called the shading coefficient, which is how much solar heat gain is allowed through the glass. And so you can you can reduce that factor to reduce the amount of solar heat coming through. But that should really be a tweak at the end rather than the whole, like all your overheating control coming through the specification of the glass.
Speaker 2:Right. And so this is and and I always get confused with things like solar heat gain, g values, solar factor. I think that that they all are slightly different, but there's a lot of confusion out there in the marketplace about Yeah. How to specify glass for reducing the amount of heat that's coming through which is also different from the amount of light that comes through.
Speaker 1:Yep. Yep.
Speaker 2:But you're saying that so you do have a lever there but it's perhaps not the the biggest lever that you have or the or the biggest factor that in the design that that could be implemented?
Speaker 1:Yeah. It's it's because it's you can't it's not a lever that you can move without influencing other aspects of the design and the performance. Right. So basically, as you if you need to if there's a fully glazed facade and it's gonna be too too much solar gain and too hot, you would say reduce the shading coefficient, which is very similar to the G value or the solar heat gain coefficient. So same in principle, but some nuances.
Speaker 1:So you would reduce that to reduce the amount of heat coming in. But hand in hand with that is the light transmittance, the VLT value. So that's it's the kind of tied to an extent. If you reduce the shading coefficient, you also have to reduce the VLT. So that means less daylight coming in.
Speaker 1:So there are knock ons and then there's a limit to how much you can do it. So it's the glass starts getting darker and it starts getting more expensive as well. And windows are already more expensive than walls. So we would say try to limit how much glazing you have to start with and more wall section and then you get a bit more room to play with these characteristics of the glass.
Speaker 2:Yep.
Speaker 1:Yeah.
Speaker 2:And what about external shading or or and internal shading as well? Is is that do you come up against architects with not wanting to do external shading?
Speaker 1:Definitely. Yep. Right. Or have ideas of what shading they want and won't budge from that.
Speaker 3:Right.
Speaker 1:Yeah, so generally would like prefer to see more external shading because it is a very good first defense to limiting solo game, but it's only effective in a range of scenarios. So a kind of common misconception is east and west facing windows should be using fins rather than vertical fins rather than horizontal louvers. And that's kind of not necessarily any more effective because the sun angle tends to be lower kind of perpendicular to the glass. So anything sticking out from it isn't necessarily doing much shading at all. So at that point, it can just become an extra cost or and maintenance issue and that kind of stuff.
Speaker 2:Okay. So you're saying that vertical shading on the east west face is not necessarily as effective as horizontal fins?
Speaker 1:Well, kind of the general understanding seems to be if you've got east or west facing windows, then vertical fins will be more effective than horizontal levers. Yeah. Which in some cases will be true, but certainly not all cases. So like what I'm saying is you need to not just use it as a automatic solution, but go through a modeling process for both daylight and solar gain to figure out what angle and what configuration actually improves the performance rather
Speaker 2:than
Speaker 1:just kind of assuming that because they're there then everything will work.
Speaker 2:And how much of that still is guesswork or or has to still be guesswork versus what you can actually do with daylight modeling and and looking at really size specific shading and those sorts of things. Can you actually accurately determine that now? Do we have those tools?
Speaker 1:Yeah, certainly. If you go into dynamic modelling, yeah, you can get very accurate predictions or estimates. Not predictions, let's go estimates of what's yeah, it depends what you're looking at, whether it's watts per meter square of solar gain, for example, or cooling resultant cooling from solar coming through that window. Yeah, you can you can get quite accurate and very useful information to then inform and drive the design forward.
Speaker 2:Yeah. So definitely technically feasible, but it's just a case of being asked and being asked early enough to do that analysis. And then guess someone having the budget to to pay someone to do that analysis early on.
Speaker 1:Yep. Those are key. And what would you'd also do or what we would do as consultants would be to take a step back to begin with and say, hey, look, is this is this window facades site even suitable to the kind of shading that's been proposed, or the amount of glazing that's been proposed. And before getting into modelling, which can get expensive, just look at a fundamental level and say, hey, maybe maybe shading is not a good idea at all here. Or maybe, hey, there's a window around the corner that that's probably the one that needs more attention.
Speaker 1:Something like that. So rather than just kinda diving in and into the the weeds, you kinda you have a look at the the principles of the design and and begin there.
Speaker 2:And I guess all of that within the New Zealand context relies on someone being motivated to get a building that actually performs well because none of that is necessarily required at the moment in in our current code.
Speaker 1:Very much not required. It's really only if a client and design team are going for something like Greenstar or HomeStar maybe well to an extent or Neighbours. So if they really do need to be demonstrating certain levels of energy efficiency or performance for daylight or whatever it is, then yeah, there's there's very little driving this this need for improvement.
Speaker 2:Do you get into we talked a lot about overheating, but also the other issues, moisture control, ventilation. Do do you get into that lot these days as well? Is that is that separate to the energy modeling or included as part of it?
Speaker 1:It's pretty much exclusively separate because it's a risky area to be involved in without the the necessary knowledge.
Speaker 2:Okay.
Speaker 1:So yeah, typically energy modelling would just be the sensible element. So without any moisture considered. And if we could see potential risk in a situation, we would recommend something like WUFI modelling. But that that tended to be outside of our scope as consultants. There's not many people in New Zealand doing WUFI well, as far as I know.
Speaker 1:So, yeah, it's it's something it's it's always been on the radar and it would be nice to do, but there is a large risk associated with it and a lot of a lot of upskilling to to be really secure in delivering that.
Speaker 3:Sure.
Speaker 2:Yeah. So we're talking you're talking mostly there about larger commercial buildings where there'd likely be a mechanical service engineers and facade engineers involved taking care of some of that interstitial moisture and condensation concerns?
Speaker 1:Certainly mechanical engineers for anything commercial. Facade engineers, they'll be the supplier and they'll have their in house expertise but often it wouldn't be they wouldn't be too involved in the actual design of the facade or just be more like guidance along what the what products are suitable.
Speaker 2:Thoughts on the benefits and limitations of natural ventilation, particularly in the residential context is a big point of discussion, you know, because apparently Passive House is a closed box,
Speaker 3:you can't open the windows.
Speaker 2:Yeah. Or so the perception is a lot of people. Do you have professional or personal thoughts on on the the value of natural ventilation in New Zealand's environment?
Speaker 1:Yeah, definitely. I think we should be doing more of it, can be doing more of it. New Zealand's a pretty mild climate. There are there are some climates or subclimates within New Zealand that do get quite warm through periods in summer. Yeah.
Speaker 1:Which are the most challenging. But for the most part, we're not so cold that we can't use openable windows. Yeah. I think that there's a few things that happen in New Zealand that's I mean, people don't trust it quite as much. So, like, the way building codes set up with the 5% area is which has nothing to do with overheating control.
Speaker 1:It's also ventilation for fresh air, but it sometimes gets referenced and used as a starting point for natural ventilation. So that's a really misleading definition because 5%, they've based it on geometric area, which is the kind of elevation. As far as I understand it, it's the elevation of the window. Yeah. It has absolutely nothing to do with the actual opening element.
Speaker 1:No. So you can achieve 5% easily, reasonably easily, but what you've actually got is closer to probably one or less percent, which is completely useless for ventilating to avoid overheating. So people end up, they've got these windows and think they're doing okay, but then there's no airflow through them.
Speaker 2:Yeah.
Speaker 1:So they overheat and people just think, oh, opening windows don't work. But it so that's a kind of it's it's pretty misleading. The only thing that's anything like useful or not useful, but relevant is, yeah, not useful.
Speaker 2:Yeah. Staying on the theme of Overheating, you've talked about the some of the limitations of things like PHPP, what what do you what advice do you give or or or what suggestions do you have about dealing with well, what are some of those limitations and and how do you overcome that for looking at overheating?
Speaker 1:Yeah, so PHPP just has a check as part of the criteria for those who don't know 25 degrees is the threshold and up to 10% of the year. This 10% is first of all quite large compared to other methodologies that are out there. And 25 degrees is based only on air temperature as far as I can tell. So there are some like the mean radiant temperature as in the heat coming off glass and other surfaces also affects the temperature in the space and what we feel. So immediately there's a kind of limitation in just the description of what temperature is in PHPP.
Speaker 1:That's one element. But I think that the bigger concern is that PHPP is a single zone modelling software.
Speaker 2:Yep.
Speaker 1:So it assumes all spaces are one, obviously isn't reality for buildings. So what it can so it kind of averages out what the temperatures are across the space, whereas it's quite possible that you'll have one or two spaces in a house that are facing either north or west likely that are quite a bit warmer at at least during periods of the day and year. So while the PHPP model and check might be saying it's okay, there might be a space or two that are not getting quite warm. So that's why the software we can model zones individually can be beneficial as
Speaker 3:a
Speaker 1:as an added check. So what generally, what I'll recommend is if there's any hint of overheating issues in PHPP, like over over 5%, then you should also be using something like ten fifty nine, SITC ten fifty nine, which is bespoke residential overheating risk analysis.
Speaker 2:Right. Yeah. Okay. So so PSPP first, if it's if it's more than 5% overheating over 25 degrees, then you say, okay, I think I should check this using TM59 to identify any areas that might be particularly uncomfortable.
Speaker 1:Yeah, roughly speaking, you'd want to take it on a case by case basis and also have a look at looking at the plans and elevations to see which spaces may stick out as overheating risks. Anything kind of north facing that doesn't have much shading or west facing bedrooms are often a danger point because they will overheat as you're going to bed. Yeah. And there's no kind of nuance in PHPP to say what time the overheating is occurring.
Speaker 2:Right.
Speaker 1:And as anyone who's tried to get to sleep on a hot night knows it's very uncomfortable and there's not much you can do to escape it.
Speaker 2:Yeah. The
Speaker 1:fan can only do so much. So those are kind of the situations where issues will arise and most likely to arise.
Speaker 2:Is TM59 hard?
Speaker 1:No. Well, when I was doing it in The UK, it wasn't because we had the software, we had like the knowledge to do it. So you just did it and it it could be quite simple. And as long as consultants, also get to suggest ways to remedy any issues that the assessment finds, then yeah, you can work through it quite well. And if you have a design that's, you know, reasonable to begin with.
Speaker 1:There were some situations so we'd use ten fifty two on skills, so ten fifty two is for non residential and ten fifty nine is for residential, and then nuanced for those building types. So schools was quite difficult just because we've got so many students and internal gains in small spaces. So that means a lot of lot of heat being generated that you have to try and reject from the space through ventilation constantly. But in terms of buildings and residential buildings, the ones that tended to be issues were more higher density accommodation blocks, where you might have an apartment facing west and then they've got carried away with glazing. So there's too much solar gain and the windows are restricted to 100 mills, which is often not the case.
Speaker 1:So there's not enough vent flow out of the building. So those those would be issues, and they could be quite difficult to to fix, especially if client or architect weren't willing to reduce glazing area.
Speaker 2:Yeah. Great to know the the solutions are there. It's technically very feasible. It's just a matter of us getting people like yourself involved in in projects early on. Yeah.
Speaker 2:Definitely. So just wrapping up, Tavis, where is where do you think we are now in terms of building science? You know where where have we come from? Got a bit of bit of work to do. Where would you like to see New Zealand progress now and say the next sort of four or five years?
Speaker 1:Yeah, when I came back to New Zealand during COVID it was going quite well. The sustainable buildings sector was going quite well. It seems like there were a lot of people keen to invest in high performing buildings and improving healthful occupants, it's commercial or domestic. And it was, it was strong, it was going in the right direction. But it's definitely taken a big back step in the last two or three years.
Speaker 1:So I'm hoping as people become more comfortable spending money again and investing in buildings, that sustainability and performance element will pick up again. Uh-huh. I think, I'm brutally honest, I don't think much of H1. I think that's a really important thing that we need to focus on and change change quite drastically. Yeah.
Speaker 1:As I said before, think it's at least two cycles behind, say, The UK. Yeah. So there's a lot that can be done there and either add a mechanism to that for overheating or a regulation, standalone regulation for overheating in itself because I think that's going to become quite a big problem in the next decade or so in New Zealand.
Speaker 2:Awesome. Hey. Well, thank you very much very much, Tavis, for your time today and really appreciate your insights and keep up the good work.
Speaker 3:That was Tavis Creswell-Wells. Really great to catch up with him. I actually first came across Tavis when I saw an ad for a session that he was doing. It was done now a couple of weeks ago as we're recording this, which was specifically on that issue of overheating. Because it is becoming more of an issue, not just in Passive but also across the board.
Speaker 3:And at least with Passive House, someone's doing PHPP, they can identify that risk of overheating at design stage. But as Tavis mentioned, that only happens if someone is looking at the design, and we have nothing in the building code here in New Zealand to require people to look at that operating temperature throughout the year. There is something in The UK, that Part L, and I've looked at that a few times because I'm very interested in regulations around the world, building codes, building regulations that are starting to require addressing the risk of overheating. And UK is one of those. And so is Australia.
Speaker 3:There is something called Section 44 of the National Construction Code in Australia, which has a winter heating demand requirement, but also a summer cooling load requirements when you apply for permission to build as well. And I'm quite excited about that, and suggesting that places like New Zealand that doesn't have any requirement for looking at overheating could adopt some of that methodology into our building regulations as well, because it's becoming more and more of an issue. What were your thoughts from that, Zach?
Speaker 4:Well, was that Tavis Creswell cut his teeth on some big projects early in his career. Scale of that work was really impressive. Know, mean, overheating is just so important. When it comes to how buildings can help us be more resilient, become more resilient to the changes that are already afoot and are going to worsen, there's nothing more important than figuring out how to deal with the extra heat. And, you know, cities like Seattle, where air conditioning was, you know, just not something on anyone's radar just, you know, a few years ago now, it's routine to have AC here.
Speaker 4:And of course, we had that ridiculous heat dome that kind of blew our minds. So certainly in the Pacific Northwest, it's front of mind. But also, as you and Tavis dove into, we need to be thinking about building as systems as we are building new ones and retrofitting them to ensure that we don't inadvertently make the problem worse. I I really appreciated that he was so clear that it's not the fault of insulation, that that we're we're overheating, that that over glazing, and the way that we're dealing with external shading, and and all of the things that you that you guys got into is what makes the problem happen or exacerbates the problem. And again, it comes back to if we just focus on one element of a building, we're missing the power that we have when we can instead approach buildings with a systems based approach and optimize the different elements in the building to make them livable and make them efficient in the winter and in the summer, because we do need both in many, many parts of the world.
Speaker 3:That issue of getting in early in the project is such a challenge. I don't know how to do that. It's something that I grapple with regularly in my work, my daily work, because I often see designs that are fairly developed and think, Oh gee, if only you'd come to us earlier, we could have given some advice on this window to wall ratio, which is really causing problems. It's often too late if we're doing it right at the end. The other thing that I really like about Tavis' story is, as you mentioned, getting to cut his teeth on some big projects.
Speaker 3:That's kind of a consequence of traveling. The other thing that winds me up is us trying to reinvent the wheel all the time. I think the more that we have people reaching out, but also experiencing work in other regions, and seeing where a lot of this really good work, like Part L in The UK, and Section 44 in Australia, there are already methodologies and policies that are working or have been developed that could be implemented relatively quickly. We don't need to wait and spend lots of time developing new policies. The same with technology.
Speaker 3:Tavis mentioned that this is doable now. We've got the tools, we've got the technology to do daylight analysis and sun path analysis on specific sites with local shading of other buildings and the natural environment that's around that building site. That's all doable now. So there's really not as many excuses these days for getting this stuff done at concept stage.
Speaker 4:Yeah. That's such a good point. And so it's really important for us to be sharing these stories across the oceans. It's definitely we're definitely even like and I think it's helpful to remember that, you know, we have certain regions of the world where building code is further behind than other places. But the advantage that we have now is that so many places in the world have been grappling with these problems already and coming up with solutions.
Speaker 4:So, you're right.
Speaker 3:Well, you mentioned sharing stories, Zach, and that's, of course, a big part of the accelerator. That's right. And also Re imagine. And what have got coming up?
Speaker 4:Well, the big thing we have coming up that I hope that everyone will attend is our online conference on March 12 called Re imagine Buildings Multifamily. So this is four hours of real projects with sharing proven strategies you can use in your work. Brings together practitioners, owners, and researchers who are pushing comfortable, resilient, climate ready housing from vision to reality. And this a lineup of speakers that are luminaries in design and engineering and construction of big Passive House buildings in New York and in The UK, in Boston, in Canada, in Texas. And they're going to be coming together to share what they've learned and ensure that people don't repeat any mistakes that folks have learned from along the way.
Speaker 4:So again, it's on March 12 online conference. If you go to the Passive House Accelerator website, you'll see a nice, beautiful banner with a video on the top there, and you can click on the button there and get more details about it. And we hope you'll enroll.
Speaker 3:Welcome. Well, thank you very much. Thanks to Tavis. Thanks to all wonderful listeners. And we'll be back again next week on Passive House Podcast.