STBA Paper: Moisture Properties of Insulation Materials and Their Applicability to Traditional Construction Webinar

Hannah: Good afternoon, everybody. Thank you for sparing your time for us today. I really appreciate you doing that. My name's Hannah Reynolds. I'm an architect in the Historic Building Climate Change Adaptation Team here at Historic England. I was pleased to have sat on the project board and also peer reviewed the paper which we're discussing today.
So the paper was commissioned and managed by the STBA and it was authored by UCL. It was jointly funded by Historic England, Historic Environment Scotland and Cadw, in partnership with Northern Ireland Department for Communities. So we're joined today by both Michael and Valentina. So Michael is Director at the Sustainable Traditional Building Alliance. He is a built environment professional with a range of experience across the heritage and sustainability sectors, including construction, project management, professional accreditation bodies, research and voluntary organisations.
Valentina is Technical Director at the UK Centre for Moisture in Buildings and a lecturer in building physics at University College London. She's an expert in building physics and moisture in buildings, with a particular focus on internal wall insulation. Her research focuses on the integration of building physics, predictive modelling, and monitoring for the reduction of moisture-related issues in buildings. Once Michael has introduced the project and Valentina has run us through some of the technical details, we will then be joined by the rest of the project panel for a panel discussion. So the project panel included myself, Moses Jenkins of Historic Environment Scotland, Jill Fairweather of Cadw and Nicola Golden of the Department for Communities Northern Ireland.
We will allow some time at the end to answer your questions, if you want to post them in the chat during the presentation. Without further ado, I will hand over to Michael, who will introduce the STBA and the project.
Michael: Thank you, Hannah, for the introduction and for hosting us here today. At the STBA, we are a not-for-profit which aims to increase understanding and uptake of good practice in the sustainable retrofit of traditional buildings, using a collaborative approach between heritage, sustainability and industry perspectives. We engage in a variety of initiatives including events, research, guidance, tool development, policy advocacy and more. So please do consider joining us if your interests align.
The concept for this publication really started early last year when we published a briefing paper on the use of natural insulation materials when retrofitting traditional buildings. That paper made a case that natural materials are ideally suited for retrofitting traditional buildings because of a range of their material properties, including superior moisture management, as well as generally lower embodied energy and carbon. But we noticed there's still much disagreement across the sector, particularly around terminology and approaches. There's confusion around material definitions and properties, and some misuse of concepts, particularly breathability.
Furthermore, new materials and products which have been developed over recent years, particularly natural and biogenic materials, means there are more options than ever when seeking to add insulation to traditional buildings to increase energy efficiency. Thus, the challenge for this publication was to convey to both practitioners as well as owners the basic science of moisture movement in traditional buildings, including terminology and mechanisms, and then to describe the different approaches to insulating, along with the practical challenges of getting it right when designing and installing insulation on traditional buildings.
It needed to be detailed and grounded in the building physics, without being overly specific to particular building typologies or unique context in order to keep it manageable. As Hannah noted earlier, the publication's lead author is the UCL Centre for Moisture in Buildings, and it has been supported by the national heritage bodies, along with wider input from STBA staff, board members and partner organisations. It really shows the strengths of STBA's collaborative effort and we hope it will be as well received, as useful as we think it should be. We envisage this publication as a foundation which we can build on in several ways, including through further materiality research, geographic specific guidance possibly, and the greater development of a key resource within this publication, which is this materials properties table.
Without getting too much into the detail, which Valentina will do shortly, our ambition here is to extend this table into further materials and properties, increasing its usefulness to practitioners and owners alike. We also recognise that to achieve greater impact, we need to engage in a variety of ways. So we're looking to produce videos and short snippets ready-made for social media. We've already found responses on LinkedIn with this table in graphical format, for example, which is great. We'd like to keep this up. So if you'd like to get involved and help support the development of any of these initiatives or others at the STBA, please do let us know. So thank you very much.
And now I'll hand over to Valentina, who will walk us through the publication in greater detail.
Valentina: Thank you, Michael, and thank you, Hannah. I'm very pleased to be introducing the new document that we have written. And really, thanks to the STBA and all the funders and all the support from the panel of experts and other partner organisations. It was such a pleasure to be working on this. But also thanks to Kaat Janssens and Toby Cambray who are my colleagues and, well, they weren't able to join us today, but they've done such great work in this document. And we couldn't do that without them, so I'd like to start by thanking them.
So many of you might know what UCL is. I'm a lecturer at UCL. But I'm also the Technical Director of the UK Centre for Moisture in Buildings, which I'm not sure many people know about. Our aim, is the development of a moisture-safe, built environment and our approach is to work in a rigorous and transparent manner together with partners from academia, government, industry and the public. And our aim is to improve the way moisture risk is understood and managed in the UK.
So, with this opportunity of the Technical Tuesday, we're here, and also the opportunity of the of the guidance that we have written - we can share and bring this knowledge of moisture further. One of the points of moisture is that the lack of moisture balance can lead to durability and health issues. And I'm sure you're all familiar with these. And just to bring up a couple of points that are always mentioned when we talk about moisture, damp and mould: the Energy Follow Up Survey from reported that overall, % of the households surveyed reported the presence of some damp and mould patches on the walls or ceilings in their home.
And in terms of cost to the health sector, it's costing the NHS around £1.4 billion per year to treat those people affected by housing and this is only the first-year treatment costs and we know it's a long-term issue. So, we really can improve our environment and the health of UK citizens by improving the moisture balance in our homes.
So today I just want to go through a few of the points that we discussed, and we present in in the new document, and particularly starting from what's in the appendix, because I'm not sure - I know some of you have already gone to the appendix - but many people skip the appendix. So just to change it a bit, we start from the appendix. So basically, in the appendix, we have tried to bring together all the moisture transfer and storage mechanisms that are happening in buildings.
So, when we talk about moisture, we talk about, liquid water but also water vapour and ice. And also, we talk about those salts that are dissolved in liquid water. So, it's quite a complex set of properties, and mechanisms happening inside buildings. We can start with vapour transfer, vapour diffusion. Most of us know what it is. But also, air flow and the movement of air of vapour, by the movement of air, that's really important for vapour transfer in buildings, and also liquid water and water transfer. We have capillary flow, and we have gravity flow - they are all very important. And also we know that vapour and liquid are stored in building materials. One way to express how vapour is stored in building materials is vapour sorption.
These are the various mechanisms that we consider in the guide. And one important point is that there is phase change between all the three phases of vapour, liquid and ice. So, we have evaporation, condensation. And as you can see, it can become quite complex and convoluted. So, our challenge was here to really make it easy to understand and easy to act upon. The important point is that these mechanisms do not work in isolation. I just want to give you a brief overview of how the mechanisms interact when - this is an example of a solid wall. It's not as nice as the pictures you have in the report.
But hopefully this conveys the message that we have the interaction of vapour diffusion. We have the airflow that can happen through cracks and gaps, for example, in these, which is a solid wall with internal wall insulation, the reason why I am using solid wall internal insulation here is that it's one of the construction types where we can have all the moisture mechanisms at the same time, which is important to take into account. Then we might have capillary flow from the ground but also from rainwater and on the walls. And then we can have gravity flow if we have, for example, cracks, poor pointing, missing render and so on. So, there can be so many sources interacting.
And one of the examples where we found evidence of this mechanism, where all of these mechanisms work in conjunction is the solar-driven vapour diffusion, which is one of the mechanisms that we cover in the guidance. And the idea there is that we have this reservoir of water and then the sun heats the surface, increases the temperature and leads to evaporation and then from the evaporation, we have vapour diffusion through the fabric. And then we have the drying through vapour diffusion and through airflow. So, a really complex interaction of mechanisms and as you can imagine, it requires an understanding of all the sources and how they work together. So, this was the aim, the aim of the publication. One point here, one important point that I want to mention is that not all of these are all happening at the same time, but we need to be aware, and it's important to know how construction types, what type of mechanisms they allow. And so, these can be quite complicated and quite confusing.
And this is why in the guidance, we try to think about it in a slightly different way. So, we added these boxes where we talk about day-to-day activities and day-to-day, examples of living with moisture. This is just an example about a pair of wet shoes after a rainy, a walk in the rain. If you leave the shoes in a warm room, moisture evaporates and moves into the air. And if we have still air, the evaporation is driven by vapour diffusion, which is the first mechanism that we discussed. If you put them near a fan, we have moving air, which speeds up the drying process and that's driven by what we call convective transport. But then if the shoes are soaked all the way through, water can spread within the material before it evaporates. And that's going through the capillaries of the material and that's similar to capillary action. And if you step on them or just squeeze them, water can squeeze out under pressure. So, pressure really can affect the flow, the flow of moisture.
Another important point - so this is just an example, there are several throughout the guide which I recommend having a look at. And the other point is that moisture doesn't just appear and disappear, it just moves. It moves and it gets stored in different materials and systems. And that depends on the environment, the indoor and outdoor environment, as it does in buildings. We have also a focus, particularly where in the appendix you'll see - we have a focus on three of the material properties, three of the mechanisms that are affecting insulation materials and materials - that effect that can happen through insulation materials and other building materials.
The first one is vapour diffusion, and the idea is that, well, we wanted to provide the common quantities that can be very helpful to compare different systems. So, for example, we can quantify how easily water vapour can go through a material in many ways. You might have seen some different data sheets. They have more than one quantity that all go back to vapour diffusion and, the ability for materials to resist or not to vapour diffusion, vapour permeability and so on. So, what we wanted to focus on in the guide is to use a simple quantity that is used widely and is the µ-value, which is the vapour diffusion resistance coefficient. The beauty of this value is that it compares how much more resistant a material is to vapour diffusion if it compared with air. So, a µ-value that is closer to one, it shows that the material behaves similar to air. A µ-value that is much higher shows that the material is a lot more resistant compared with air. So hopefully again, using a similar language and, and having a common use of terminology will help us, really, managing moisture better.
Another value that we mentioned that is related to vapour diffusion is the Sd-value, which represents the vapour diffusion resistance of a layer. And again, this is expressed in relation to the vapour diffusion resistance of still air, same as the µ-value. The difference here is that this quantity compares materials that have a defined thickness. And, for example, we use that to describe the vapour diffusion resistance of AVCLs - air and vapour control layers - and membranes, because of course, when we specify AVCLs or membranes, we don't really choose the thickness we choose them from for other properties. So having a value which includes that information really helps us comparing these kinds of membranes
So, after having this focus on vapour diffusion, which is a very ever important mechanism, but not the only one, we wanted to have a focus on moisture storage of materials. Building materials can store moisture in both liquid and vapour form. For those materials, that store moisture in vapour form, those materials are called hygroscopic materials where vapour, water vapor, can accumulate, on the surfaces of the internal pores and that's what we call the molecular adsorption. And then if we have higher humidity conditions, some pores begin to fill with liquid water and then we have capillary condensation. And as you can see at higher levels of humidity, we can get closer to a mix between liquid, liquid and vapour.
Hygroscopicity refers to the ability of a material to absorb and release water vapour from the surrounding air. And that contributes to a mechanism that we, some of us are familiar with, which is the hygroscopic of moisture buffering. So, some materials are able to release moisture, to absorb and release moisture depending on the environmental conditions. And so hygroscopicity is a way to, to look at this. Then the last focus, on moisture transfer through materials and moisture storage is the capillary flow. So capillary flow refers to the movement of liquid water through the pore structure of a material. And that is driven by surface tension forces, which are the forces, occurring inside the capillaries. So capillary flow is not easy to fully characterise with simple properties.
And there are more than one approaches to characterise those in a macroscopic, way. But broader, the mechanism shows that in smaller pores water uptake is initially fast due to high capillary forces, while in coarser pores, the uptake is slower. With time, we will have a redistribution of this, of this water towards coarser pores. So, the time of uptake will change depending on the size of the pores. And something that is very important to, to consider is that at higher humidity, we really have a mix between moisture storage in vapour phase and moisture storage in liquid phase. And so, both storage and liquid transfer movement can play a role and can occur at the same time as well as vapour diffusion and other mechanisms. So that makes moisture flow really hard to characterise. So, for this guidance we, we decided to keep it simple and look at the broad properties.
So, one of the main discussions we had is about around breathability. Breathability. We have a UKCMB video that you're welcome to have a look at. Breathability is a term that was, well, was a term that started for a good reason, that buildings need to allow wetting, drying and so on. But now it's becoming, a confusing term. So, what we what we think, at the UK Centre for Moisture in buildings - and colleagues agree - is that we can use, a combination of properties to really understand what the moisture, what are the moisture properties of these building materials. So, for example, in the table, that Michael mentioned before, we have started using more than one value. We've started using the vapour permeability, which is related to the vapour diffusion mechanism that I mentioned before. And we use the capillarity that we have defined as the ability to redistribute moisture in liquid phase.
So, we have added a range of values in terms of vapour permeability taken from databases of hygrothermal simulation tools. But we have decided not to add any values. for capillarity because as I mentioned before, the liquid redistribution at high moisture levels can be combined with other mechanisms and therefore characterising, liquid transfer is not always very easy. So, adding a value then wouldn't make much difference. Hopefully this is starting a discussion, is starting a new direction where we can talk about material properties and talk about not just breathability or not, but also how the different properties affect the moisture balance of the material.
So far, I've only talked about materials. So, what is very important for me is that we shouldn't stop, characterising insulation materials on their own, but we really need to move towards systems. So not just insulation systems, but insulation systems working together with the existing fabric of the building. And again, going back to the simple boxes, we thought of an analogy between buildings and a cake. So, a cake isn't just flour, eggs and sugar, it's how these ingredients work together to make it rise, stay moist, or collapse. So having the best material on their own doesn't necessarily lead to success.
And this is the same in buildings, so we can't really judge performance by looking at materials in isolation and all the parts - insulation, structure, membranes, finishes - they need to work as a system with the context. So, with the walls within, within the indoor environment that we have, the outdoor environment that we have and so on. So again, it's a combination, not just individual components that make it robust, durable and fit for purpose.
So again, I would like to thank my, my team, Kaat and Toby. And I would like to thank Michael, and everyone from the, from the funders, Hannah, Jill, Moses, Nicola, and also the partners and everyone who has helped us making it, making it a guidance that many of you can read and I'm happy to answer any questions now.
Hannah: Thank you, Valentina. That was really interesting. If we can put our screens on, we will move to the panel discussion. I'll just put mine on. There we are. If the other panel members could put your videos on, that would be great. Hi, everybody. So, I hope you all kept up with the science bit from Valentina there. We've had some interesting questions, so we'll try and get to those in a moment. So, if we start off, the panel discussion, Jill, I think you were going to start your question first.
Jill: Yes. Thank you. Yes. The paper has a nice, has a really nice diagram on achieving moisture balance. Valentina, can you run through the main sources of moisture, please?
Valentina: Thank you. Yes, I can put, well I put some extra slides here. I don't know if you can see it is a bit small, but. So, the diagram. Well, it's not from us. It's from another really good publication, from the Pebble Trust that I recommend having a look at; when things are good where we need to acknowledge that. And so, I think there are a few points here. So, as you can see, just from a quick glance, there are so many moisture sources which, we need to take into account when we are retrofit, when we assess a building and when we have any interventions.
So, we can start from the indoor environment. We have breathing, sweating, drying clothes - it plays a big role. But also, if we look at the additional moisture sources, we can have plumbing leaks, which is playing an important role. We have gutters leaking or blocked gutters, which means, maybe a lack of maintenance. Another important point is poor pointing, which, which again, takes us to, to the maintenance question. So, there are, from the indoor environment point of view, we do have several moisture sources which are associated to our day-to-day activities, but also we have all these additional moisture sources which are related to the way the building interacts with the outdoor environment, and particularly exacerbated by a lack of maintenance.
So, it's really important to, to ensure that the building is well maintained. And not just the outdoor - the external envelope - is well-maintained, but also, indoors. The services, they can leak, and leaks related to that can lead to, to moisture, hidden or visible moisture and then the risks associated with that.
Hannah: Thank you, Valentina. I think Michael had the next question for you.
Michael: Yeah, thanks. So, I was going to ask again a little bit about breathability. I know you touched on it. But as we're trying to sort of shift away from that, it's, it's a term that's very used right now, materials are labelled 'breathable'. So, I know you touched on it, but what would you or would you recap the key properties that are good to consider, that are sort of a better replacement for 'breathable', so someone who is selecting materials has a, has a sort of better, a better understanding, a better proxy for that.
Valentina: Yeah. That's a good point. So, what we mentioned here is that what we started introducing, the properties of vapour permeability and the properties of, and information about capillarity. And, again, there are some properties we can, we can use, so, like a liquid water absorption coefficient. But what really, what I would like to- so I think there is, there is still a lot more that we can do. So, for example, there are some- for some applications, for example, internal wall insulation, we don't necessarily, we don't use the liquid water absorption as one of the properties
We want to understand how well water can redistribute and get stored in the material before it's too late. So, I just want to - I should have a slide here on internal wall insulation- here. Yeah, so this is just, I have some excerpts from the document, and I think this could give us a bit of information here. So, in terms of what we mean with - what most people mean - with breathability is the ability to allow, drying. I think that's what we need: it's a material, it's a system that allows drying. And we don't necessarily need to have a set of material properties to allow drying.
Each different construction type can allow drying in different ways. So, for example, I'm thinking external wall insulation. You might need, probably you might need to know how vapour permeable the system is to evaluate the level of dry, of drying that it allows. But the reason why I'm bringing internal wall insulation - and also because as Hannah says that's my main interest usually - is that if we look, for example, in internal insulation and we only look at vapour permeability, so that ability to resist vapour diffusion or not, okay, we can say, okay, very, very vapour impermeable layers will block any drying towards the interior.
But we can also say that an overly vapour permeable system can allow excessive vapour diffusion towards the wall insulation interface, which is colder, and then we can have a risk of moisture accumulation and mould growth. So, for this particular case, using just one property like, vapour permeability doesn't tell us the big picture, doesn't tell us how well the system is able to provide drying while reducing the risk associated to wetting. So, as an example, with internal wall insulation, we want to see how well moisture is stored and redistributed in the system before reaching mould growth, excessive moisture accumulation and so on. So, for simpler systems, we can use or material properties for complex systems like internal wall insulation, you might need to start looking at a combination of properties.
And maybe I'm not answering the question, I think. I cannot- we well- we probably haven't decided on what properties are the properties, and this is why next the next step could be agreeing on that and providing more analysis on that. I know, for example, companies like the Fraunhofer Institute of Building Physics, they have developed an additional test called the capi-test [?] to look at capillary redistribution through the system. And that's exactly to look at this kind of, what we call the over-hygroscopic region, which is the region where we have still have vapour, but also we have liquid.
And it's a combination of drying- sorry, it's a combination of moisture transfer mechanisms, which will determine the big wetting and drying picture. So, I hope this answers a bit. I cannot, again, I cannot answer the full picture because every system is different and in terms of liquid in that over- hygroscopic region, we have a lot of complexity.
Hannah: Thanks, Valetina. Yeah, it's obviously a really complex topic that isn't just as simple as only vapour and in vapour diffusion. So, I think that that point is, hopefully getting across to everybody, that we need to consider the wider parameters and implications. So, I had a question for you next on section six of the paper that provides the retrofit design principles, and goes through what people should consider when they're thinking about specifying. I wondered if you could talk a bit more about these, because I find them quite interesting and quite pertinent to what we're doing.
Valentina: Okay, good. Yes, I can definitely. So, in section six, what we've done was taking the principles, the 4 Cs which are, they're coming from the BSI white paper on moisture in buildings, and now they are also in the BSI 5250, the latest version of BSI 5250. So, these four principles are what we call the 4 Cs and we use them at the UKCMB to really guide all our guidance, training and discussing about understanding of moisture throughout the construction, in the construction industry and throughout the process, the construction process.
So, one of the, well, the first one is Context and I'm sure for, heritage, organisations, you are the best to really consider context compared to other industrial, other parts of the construction industry. And one of the points here, so we've tried to identify design considerations, the design considerations that are related to moisture in materials and systems that can, that can fall under that context section. The first bit is a very important point: it's retrofit ready. So being able to prepare the building, assess the building and rectify any issues if there are any, for example, if there is a history of poor maintenance, if there is history of hidden moisture, all these issues have to be rectified before retrofit is happening. So that's an important point. That also can cover inappropriate materials and inappropriate systems that have been placed throughout the years. So that's the first point.
The second point would be minimising and removing sources of excess moisture. As I mentioned before, there are several moisture sources, and we, and of course, some of the moisture sources are inevitable. But of course, reducing, for example, ventilating at source, is a very important point. And providing maintenance regimes where moisture source, additional moisture sources are not occurring within the lifetime of the building, that's also very important. Last point on the context is using the right system, and again, it's considering how the system performs as a whole, but also how the system performs within the context. So different systems might be working well in different conditions. So, again, also because I'm an academic, so I always say, 'it depends', so it was always made difficult for me to you know, to make a recommendation and so on. But it's important to really understand the way our buildings work, the way our fabric works and the context, and then use systems which are appropriate for that.
And then another point that, we have other principles that are about Coherence, are about looking beyond just moisture properties and, and the interaction with the fabric. It's thinking about continuous thermal insulation layers. So having a thermal envelope that is at the same with the same quality, good quality, looking at the air tightness and ventilation strategy and how they go together, and together with the additional interventions. Balancing thermal performance with moisture risk - we might want to go a bit advanced with the thermal performance, but we need to be aware of the moisture risk and vice versa. So that's another point. But also looking at the multiple roles of insulation. So, in different projects we might have different targets. For example, having a low carbon selection of materials, that could be one way, or indoor comfort in summer, or - I don't know - acoustic performance and different systems will perform differently in terms of acoustic performance, comfort in winter and summer comfort and overall, in terms of greenhouse gas emissions. So, these can all also be included in understanding the system as part of a bigger, the wider context compared to the building.
And then another two points which are I think are very important: Capacity, providing capacity and specifying robust systems that can adapt to future climate stresses. We know that in the future we will have bigger seasonal variations so we will have wetter winters and warmer summers, which means that our wetting and drying cycles will be even more extreme and even more exacerbated. So having that, thinking about that the future and allowing systems to be robust beyond what designed for the current climate is also very important in allowing moisture to dry out, because if we accept that in the future, there will be, I don't know, either events like a storm or maintenance, maintenance issues, a lack of maintenance, we need to allow the system to dry out if we go beyond what was designed.
And last but not least is Caution, which means managing the risk after we have understood the risk. So, we need to design for inspection. We need to design for easy maintenance and for minimising risks of visible and hidden moisture. Hidden moisture also plays a big role in in the overall balance of a building. And also, it's important to prioritise reversible or repairable solutions because we are looking at a long time frame here and we cannot just design retrofit and then expect that it's going to be fine until, for the next or years. And of course, with historic buildings we don't want to, we want to make sure that the fabric is not degrading with time. So really, caution is a very important point that sometimes we overlook. And of course, there's more in the guidance if you want to read. These are just the headings. I just put together the headings to try and capture everything.
Hannah: Thank you, Valentina. That's a really, really comprehensive answer. But there's far more to find if you go and read the document, I think. So, the next question then is from Nicola.
Nicola: Hi, Valentina, can you talk about the tools out there to help us to choose materials correctly and where it's mentioned in the guidance?
Valentina: Yeah. Thank you. Yes. There's another section which I think is, yes, section seven, where we have tried to summarise - we didn't want to go too much into detail because there's a lot also there to discuss - but we've tried to summarise the main points of the existing quantitative tools for assessing moisture risk and the latest developments because there have been lots of developments since. So, I think the tool which is more common are tools based on the Glaser method. But as I mentioned, all the different sources interacting, and moisture mechanisms happening in buildings, the Glaser method excludes mechanisms like rain ingress, capillarity, air movement, hygroscopic buffering. So, if the building fabric, allows these mechanisms, then we need to consider them in our analysis. So, as we know, if at the end, it's rarely appropriate for traditional buildings.
So then we go on to the hygrothermal simulations which are what we call WUFI, WUFI calc or WUFI simulation, because WUFI is a proprietary tool, developed by the Fraunhofer Institute of Building Physics, but that's the most common tool used in the industry. The most common way to run hygrothermal simulation is to run them one-dimensional, and those simulations include most of the moisture transfer mechanisms. But of course, sometimes we need applications where we consider a two-dimensional approach. For example, if we have a very, a very vapour impermeable stone with mortar and then a rubber wall, then of course a one-dimensional approach wouldn't really help. In other cases, a one-dimensional approach could be accepted.
But then there are other tools that can provide more advanced analysis, for example, Delphin, which is developed by the by the Technical University in Dresden, or also WUFI 2D or Delphin can, for example, include additional mechanisms such as airflow that I mentioned before. WUFI 2D allows a two-dimensional analysis so there can be more. Of course, these are specialist tools, and we're not expecting everyone designing a system to, to really run these simulations. However, we need those tools to really help us understand how moisture moves in different, in different systems. So, there is an emerging - how do you say it - simplified tools have been emerging.
So mainly they're supporting early-stage assessment, and they are based on hundreds or thousands of pre-run simulations. So, the legwork has been done. And I, well, I just would like to show you one example if this allows me to do that. So, this comes from one of my, PhD projects, and it's actually Kaat Janssen's project so that's why we, we're happy to include this. So basically, the idea here is that we have, a simplified tool. There are other tools, for example, the Rebuild tool, which has been developed as part of a European, a Horizon Europe project, but didn't include the UK as one of the examples. But this tool just shows how you can have a simplified tool, with different, with simple inputs.
So, for example, here you can introduce the installation and insulation type and thickness. You can decide to add, to explain what insulation you have. You have the masonry thickness. And then you can have external. So, in this case you can choose, you know what the thickness here of the masonry. You can add the orientation of the façade. We know the orientation is important. So, you can choose, you know, west, south, southwest, the colour of the exterior surface. As you can see, these are, inputs which are, available to everyone. And then you can choose whether, you're using a current climate or future climate. In this case, we are looking at the projections. And then you can, well you can decide, for example, what degradation phenomena you're interested in. So, for example, in this case we are interested in wood rot.
So, what the tool does is as an example, it lists all the possible issues happening in this internally insulated project, this is only for internal wall insulation and it's only for London. And of course it can be extended in many ways. So, you can look at frost risk, mould, wood rot, salt, corrosion and bio decay. So here you have a glance. You see that, for some risks, for some of the issues, moisture risk is medium, for some is high and some is low. In this case we were interested in wood rot so we could go a bit more in detail on how to minimise the risk of wood rot for this specific application.
And for example, there's a decision tree that can be, yeah, so we have, for example, in this case we have rain exposure coefficient which is the main driver of the wood risk. So, for a sheltered location there's less risk. And for a non-sheltered location there's more risk. And then the second point is brick. So, we have for a sheltered location, and we don't care about the brick type, but for an exposed location, bricks become important. So, in an exposed location, specific types of bricks will lead to less risk than others. And then after then, another point is the insulation type. So, for not very exposed, for not very exposed cases, the insulation type is very important. So, this is mid to high exposed cases but not extremely exposed. We can see the capillary active insulation, and this is, again, it's a better version of a tool. But you can see that this type of insulation will lead to less, lower or higher risk for this specific case. So hopefully this gives you a bit of an overview of what tools could do. And this is just an example of what we are developing but there can be more. And the idea is that with these kinds of tools we can provide this information to installers, to designers that are not necessarily experts. And then we leave the hygrothermal simulation to the expert when cases are of, I don't know, higher significance or particularly exposed or of other different concerns that we might have.
Hannah: Thanks, Valentina. That's a really great example. I saw some people asking about the link to that product. I think it's linked in the guidance document. I think the link that was uploaded, thank you, Alex for putting that in there, for some reason, it's not working. So, we'll try and sort that out and get a link to everybody for that. But it's a really interesting project. Thank you. So, I think we've got time for one last question, and then we'll try and cover some of the questions from the audience. I think many of them have been, sort of answered as we've been talking and a few links - thank you, Nick, for putting in various links, and details for some of the questions that are coming up. So, I will hand to Michael, who's got, our final question from the panel.
Michael: Yeah. Thank you. Going back to next steps, which we touched on in the intro, the publication identifies a number of knowledge gaps and suggested next steps. What are the critical ones to address, Valentina, in your view, which would most help enable better practice in the sector?
Valentina: Okay. Thanks. So, there are several points that we that we have identified, and we've been discussing about this point for a while. So, I think one of the points here so well, I've put just as a slide, this is, it was a summary slide of the conclusions of the guidance so you're welcome, everyone is welcome to have a read. But I can tell you what I think is, is really important. So one point is the evaluation of the long-term performance and robustness of insulation systems. And with this I mean using monitoring, and larger examples of case- of real case studies of retrofitted buildings. And to be honest, we have, since I started, I used to in my PhD, I had three case studies, and it was such a work and wiring everywhere, and it wasn't very easy to install monitors but now it's a lot easier.
We can have wireless sensors, sensors that can be buried, so there can be so much we can really do to increase that low-cost monitoring that really helps us understand the building as a whole. It's great to understand individual buildings, but we also want to understand how they perform as a whole. And as we've seen, with the current issue with government-funded projects where I think a very large proportion of these projects, they have very high installation quality issues, very poor quality of insulation leading to mould, leading to other unintended consequences. We can have this, we can understand our buildings before we insulate, and we can also understand how buildings work. We have the theory. We have done a lot of work in chambers, so we know, we know what's the best. But then, the application is not easy. I think that's the next challenge is to really evaluate how they work in real life, how they work in practice, and what are the challenges because if I design a detail, sitting on my- well, I can do the best detail, but then if it doesn't work in terms of sequencing, in terms of material availability, if there are some supply chain issues, that will eventually be seen in the final, actual performance.
So, we would be able to pick up a lot of these, a lot of these points that we, that we want to avoid before it's too late. So, I think I'm very, well, having worked on internal wall insulation, I'm very positive that these systems can, in general, insulation systems can work if done properly and if done with a greater understanding of our buildings. But also having this data and having this evidence really gives us, better safety, better peace of mind and also will tell us what works and what doesn't work with a clearer picture. So, the other point is really, really key is developing models for the prediction and assessment of more moisture and mould growth risks. So, we have very, sometimes we have very conservative, approaches that are not necessarily appropriate for traditional buildings. And I think that's, that's something that we need to work on a bit more. And also, prediction of frost damage and salt crystallisation. So many salts and so many conditions for crystallisation and biological growth are the same. So, they are all very complex problems that we need to understand and simplify in terms of our response.
And last but not least, as I mentioned, that advancing risk assessment tools, we can have better tools, we can have easier tools. We have the technology to do that. So, and I think we just need the will to do it and, and to improve the quality of our design and installation.
Hannah: Thank you, Valentina. We are fast running out of time for, any of the audience questions, but we've got two minutes, we may have just a second to get through some of them. I think the sort of main theme of things that are coming up. So, vapour coefficient of gypsum plaster. We haven't covered that on this because we were looking specifically at insulation materials, which gypsum plaster unfortunately isn't one, but I'm sure, as we move to considering kind of these parameters a bit more, we can get to, get to that.
So, we've, there's been a bit about, hygrophobic coatings. And we do cover these in the report. One of the authors Toby Cambray has or is still undertaking a PhD on this and has written an intermediate paper, which I think, Nick, has put in the chat, so hopefully you can find that there. I think the summary is it has applications but very, very, very cautious applications on traditional buildings and only if you've got very robust evidence that it's not going to stop capillary flow and liquid moisture evaporation and things like that. And crystallisation or issues that have become prevalent where it has been used before. So, think and use with caution I think is, is the message there.
Full and partial cavity insulation, I think everybody on this panel, unless you disagree: leave cavities as they are if you can, if you're going to fill it, do not full fill it, otherwise you might risk bridging the cavity. There's lots of nods, excellent. Think very carefully. It's particularly with early cavity walls that are thinner than mm - treat them like solid walls. I think that one's covered quite easily.
Breathability. Somebody answered this on paints, that some of the paint manufacturers do have values for the breathability of their paint, but obviously it's not there completely. So maybe that's one of our next steps to reflect on.
So, we've spoken about external coatings. There was a question here about kind of the type of materials used, the correct approach. I think that was Jo in the chat. I said, read the document, have a look, it should give you a guide, but it definitely seems like you're going in the right direction. But of course, it's horses for courses and where you're using particular applications. That's another hydrophobic one. David Wiggins- sorry, scrolling through as people are putting in comments and David Wiggins' research, I'm glad that people have had a look at that. If you haven't seen it, he's done, a British Lime Forum Baker Memorial Lecture, which is really interesting about capillarity of materials and how it's important as a moisture transport mechanism. I think we sort of covered it in the paper and in this, that that is something that we all need to consider as well.
Is there any other questions with one minute over that everybody thinks we should cover? Any particular things? I think there's a lot, I see, there's a lot of local authority, Conservation Officers and other such on the call. I really appreciate that you have a very hard job to do. I think my, kind of, thoughts are that the design team that's putting in your application, hopefully there has been one and they should be able to give you the thorough, robust information that their proposal isn't harming the significance of the building under the Conservation Act, legislation, but also under building regulations so that it's not causing any detrimental impact to the fabric. So, there's two different mechanisms, sort of, at play there, that we need to consider. One being listed building considerations, one being the technical application. But I yeah, I appreciate it's very hard for you, I know that.
I think we've just about run out of time. So, thank you all very much for your input. And I'm sorry we haven't managed to get to more questions. And hopefully that's answered the majority of them. And thank you very much. There have been a few people like Nick Heath in the chat putting answers in, so I really appreciate that. Nick's also on the STBA Board, everybody, so that's how we know who he is, and he's given some good responses. So, thank you for that. And thank you to the panel too. Has anybody got any closing remarks?
Valentina: Thank you, Hannah.
Hannah: Brilliant. Thank you, Valentina, for all of your hard work explaining this very difficult topic.
Valentina: It was a pleasure. Happy to help anytime and to continue the conversation.