Webinar on 'Energy Efficiency: Retrofit in Traditional Buildings Policy and Research Update Part 2'

Energy Efficiency: Retrofit in Traditional Buildings Policy and Research Update – Part 2 

Speakers: Juliet Baillie, Nicholas Heath, Sarah Kahn and Morwenna Slade 

Juliet [00:01] So welcome to this second part of the Energy Efficiency CPD event. I'm Juliet Baillie and I am sector of skills advisor for Historic England. I think most of you who are attending today also attended last week, but I'm aware that there are a few people who maybe didn't. So I just wanted to draw your attention again to the context of this event, which was originally supposed to take place as a face-to-face training opportunity last year as part of a programme of skills and training that we've been delivering at Shrewsbury Flaxmill Maltings, which is Historic England's flagship, major capital project to bring the grade I listed main mill and the grade II listed kiln back into use for a third century. 

The project is supported by the National Lottery Heritage Fund, amongst lots of other generous supporters as well. And the [indistinct] that we're offering are supported by the Andrew Lloyd-Webber Foundation, and we're really grateful for that support today, and it's why we've been able to offer this event free of charge. There will be a survey at the end of the session today, and we'd be really grateful if you could complete that so that we can understand what you get out of the sessions, and also, we've included a question in there, which was to try and get a sense of what you'd like next after this session. So we'd be really grateful if you could take some time to fill that in. 

Today's session will be chaired by Morwenna Slade, who is Historic England's head of Historic Building Climate Change Adaption, and we will have a paper initially from Nick Heath, which will be some case studies, which I think we'll all get lots out of, and then there's some time for a Q&A, followed by a short comfort break. And then we'll have a paper from Sarah Kahn on how we can learn from history for energy efficiency. And then another opportunity to ask some questions, and we'll have a panel Q&A with both the speakers from today and the speakers from the first week's session that you'll be able to ask questions then as well. We just ask that if you are asking a question in the chat, you preface it with a Q just so we can easily spot what is a question in there. That would be really helpful for us. 

I know that, as I said, some people maybe weren't able to come to the last session, so I just wanted to flag, or if anyone wants to kind of revisit it again, it is available online. I think Alice also mentioned that as well, and it's available with a lot of other webinars that have happened in the past that would be really worth looking at, so do take the time to kind of have a look at other recordings. There are some that are also relevant to the subject matter that we're looking at today. 

And before I hand over to Morwenna, I just wanted to flag some other resources that might be useful. I mentioned these last week as well, but just to kind of reiterate that there's Historic England's page about energy efficiency guidance, as well as things like the Sustainable Traditional Buildings Alliance Retrofit Wheel, so please do take a look. But thank you again for joining us, and I'll now hand over to Morwenna. 

Morwenna [03:35] Thank you, Juliet. Hello, everybody. I'm really pleased to welcome you back for our second session. Juliet has summed up everything that we're doing today, so I'm not going to cover too much more ground. I just wanted to say that the sun's popped out, so I'm sitting in a little bit of sunshine while we talk about energy efficiency, which makes February seem a little bit brighter to me. So I hope maybe we can sort of share that around today. 

Like Juliet said, we're going to start with Nick, who's going to do some case studies. Following on from last week, we had lots of really interesting questions, and I am really looking forward to sort of rounding it off with these next two presentations and getting into some chat with everybody, roughly themed based on some of the questions that were raised last week. But I'm really keen to hear sort of what extra questions we get out of the next two presentations. So let's crack straight on, and I'll pass you over to Nick, who's going to take us case studies of traditional and historic building retrofits. 

I can fill ad hoc. So as I mentioned, when we go to the discussion later on, after Nick and Sarah's presentation, I've loosely come up with some themes that I'd like to kind of talk around. And perhaps while we wait for Nick, everyone would like to have a think of these and have a think of the questions. Indeed, if you have questions now that you directly want to ask me about the things Historic England are doing, then do ask them. I'll see if I can answer them sort of very much off the cuff. 

But the loose areas that I was thinking of looking at later on in the discussion were the issue of embodied carbon and energy efficiency measures. I know that many of us are sort of having to balance this decision-making process, and I think that I have some questions that were raised from last week. But how we balance that and the tools that we need, the tools that are currently available and what we might need to do to build new things and to look forwards will be an interesting topic to cover. 

Certainly from my perspective with my work with getting buildings up to EPCE compliance for private rental sector, I've specified heating systems that get us to E, but in knowledge to get to C for 2028, it'll be a totally different heating system, and the one that I'm specifying won't be at the end of its life by any means. So not only is it a sort of practical challenge, it's also a personal challenge for me because you think of what you want to specify, especially in the historic building context, is something that we'll see through its life that will work well until it is required to be changed, or indeed that can just continue to be working perfectly for as long as possible. So this is something that's close to my heart, and I'm super interested to hear people's thoughts around it. 

The second area was very much looking at assessing U-values and absorptivity – now that's a word I struggle to get my mouth round – and how far we take how hard we look at our buildings before we start specifying those measures. And then sort of building on that, once we've assessed the building and we think we know what we want to do, that ongoing maintenance, not only of our historic environment, but also the ongoing maintenance of what we specify and how we want to help our buildings going forward. 

Last week, I highlighted some of the poor decisions that are currently facing our traditional building stock and really thinking about that element of look how they perform now, what are they doing well and then how can we help them do well in the future. As I highlighted last week, really, we need our thinking to be valuing what we have and using that to support it going forwards. Adaptation of our historic environment doesn't necessarily mean new materials new detailing. It sometimes just means helping what we have carry on doing what it does best. 

And then finally, I want to sort of think about, hopefully building on Sarah's presentation – her master's dissertation is a good read – and I really got engaged with this idea of how we can learn from what was happening in the past. So I'm hoping to discuss around the idea of what we can learn from the past and indeed what we should look to in the future: what new materials should we be considering? Where can we be moving from our knowledge of how historic materials work into our production of new sustainable materials? And those that have low embodied carbon, that sequester carbon, indeed, in their production and their use, rather than falling back on the idea of our current modern materials being [indistinct] impermeable. Yeah, we'll take it from here. Thank you. 

Sarah [09:19] No, no, that's absolutely fine. You know, technology gets us all, so what can we do? OK, hi, everyone. I'm Sarah Khan from Roger Mears Architects. I'm a RIBA-accredited specialist conservation architect and a partner at Roger Mears Architects. So for this seminar, I'm here to talk about energy efficiency but from a slightly different perspective. I've carried out some research for Historic England about what we can learn from forgotten energy-efficient historic practices, and perhaps we could use some of these today. 

I'm not going to talk too much about fabric-first retrofit, but I thought I'd touch on it just a little bit before I dive into the research to give a little bit of background. So at Roger Mears Architects, we actually specialise in conservation, so I guess our approach is more conservation first rather than fabric first. But as architects, and I'm sure many surveyors as well, focus does tend to be on fabric first because this is what we do. So this comes first, or this comes more easily, to architects. 

We are more conservation architects, but if you come across a very dilapidated building, then we do strongly recommend going down the fabric-first route, because in some ways, there's more opportunity to do so – the more dilapidation. But then again, while theoretically, there's less conflict between retaining existing elements if there's severe dilapidation, but practically that is not always the case, and you're almost always struggling to try to balance your energy-efficient retrofit with maintaining the significance of the building. 

So in this case, which is Putney Chapel, it was dilapidated for about 40 years, derelict for about 40 years. A lot had disappeared over time, but even if you take one example of putting internal wall insulation, you can't insulate on the outside, clearly. On the inside, you might think there's a lot lost, and yes, you could put very thick insulation, but then there are these lovely beautiful carved-head details on the walls, and you start to lose them. So this was an unlisted building, but even in an unlisted building, you're always constantly struggling and trying to balance the two. 

So, you know, that is our job. So as architects, you come up with innovative techniques, and yes, you achieve a lot in terms of sustainability, but it's never quite as much as maybe you'd hope for. So Morwenna earlier was talking about-- If you're talking trying to do EPC certificates, we might if we work very hard achieve a C, maybe if you're lucky a B, when we're talking about listed buildings. But it feels like still such a consolation prize sometimes. Maybe that's just me. It's very, very hard to achieve higher standards because you will be sacrificing some of the significance of the building, but it does make me think, at least, are we going about it the right way? Is there more we can do? Do we really have to sacrifice energy efficiency in the name of conservation or the other way round? Is there something else that we can do? And that's what led me towards this particular research. 

So some of you may have seen this before on other Historic England talks. So it's the building performance triangle. So the building fabric is one aspect, so we should be looking at the whole building approach, and the three aspects are building fabric, services and the people. So I think a lot of people are aware that you would have to integrate more energy-efficient surfaces, and that makes a lot of difference. And maybe one day, the grid gets decarbonised, and that would make such a huge difference. 

But then there is a third element as well, which is the people, and all three of these interact with each other. They're interlocking variables. I also actually came across older, earlier research by Nick Baker back in the '90s, which talks about the same three variables, but he discusses multiplier effect. So each variable kind of compounds the other, and then if you look at all three variables together, you can get a much better result. Now people are quite aware of the building fabric, and there's a lot that needs to be done still about the services. 

But it's the people element that's actually quite difficult to tackle as well because when dealing with people, you can't quite model it, and it gets a bit harder. But then it is worth understanding and remembering that it is people who use energy, not buildings. So we do have to tackle it, and yes, doing so does require reliance on soft sciences, actually, rather than modelling and building physics, but that's what we have to do. 

So again, just touching on it, but if you are talking about people, then you're actually talking about thermal comfort because the decisions that people make to turn on heating, say example, is actually based on thermal comfort. But I just wanted to highlight that thermal comfort is a person's state of mind, whether they're feeling too hot or too cold, it's actually not measured by room temperature. It's measured by the number of people complaining about it, so it could be 18 degrees inside, but if nobody complains, it's comfortable. So it is harder to numerically catalogue this and get a handle on it. 

But there's another kind of important point to note, which is that the focus on indoor temperature actually comes because of air conditioning and because of space conditioning, because if you have central space conditioning, whether heating or cooling, you have to have a set temperature, and then all the studies that happened were to figure out what that set temperature is, where most people would feel comfortable and not complain, basically. But if you don't have that, then people can be comfortable on a much wider range of temperature with a little bit of help from fans, if it's too hot, or radiant panels when it's too cold. So it's much more broad, the temperature range. It's not 21 degrees C or whatever you may think it is. 

And another point that's come up in research is the adaptive opportunities, which is basically things that people can do to make themselves feel more in control and more comfortable. So if you remember again, thermal comfort is more about people complaining about it, and if people have no control over anything, then they complain more. So if they could adjust the room temperatures by opening a window or operating a shading device or something like that, they have more control, and that is one of the reasons why they can be comfortable over a wider range of temperature. 

Now, coming to learning from the past. So we're talking about the people element and how people could be comfortable, but because we're also talking about historic environment-- I mean, these old buildings have been around for a very long time, for hundreds of years, and people have been using them, and somehow, they've been managing to make themselves comfortable. If they had central conditioning, air conditioning, whatever, they probably would've put it in back then, but they didn't have it. 

So what did they do? And also, while we are experiencing global heating now more, but hot summers or exceptionally cold winters especially are not new. For example, Britain was in the grip of a little ice age in the 16th and 17th century, and there have been such cold winters that the River Thames has frozen over, 23 times at least, and at least five times, there's been fairs on the river, so full tents and acrobats and elephants walking across the river and so on and so forth. 

So we've had some pretty cold winters, and also some very hot summers. So the summer of 1858, the Great Stink. Some people know of it. Most people remember it more for London's sewage system because it was three months, June, July and August, where temperature exceeded thirty degrees. The river then dried up, and there was a lot of disease everywhere and a lot of smell, which is why it was Stink. And then one of the things that did emerge was the sewage system, but if you also think that experiencing such extreme heat would've made people think about how to deal with heat in their buildings in terms of comfort as well, and I'll come back to it in some of the later slides as well. 

So how did people manage the buildings to be comfortable in winter? Now, one other thing is I'm going to use a pointer, which is going to look like this arrowhead, to point at certain things in the slides from now on. If this is clear enough, that should be fine. If not, then please do write either in the chat or raise a hand or something, and I can draw on the slide as well, but drawing is a little bit more fiddly. So I'm going to talk about some of the items that could be helpful in winter, but I'll point a bit on this painting as well. So notice wall tapestries, which covers the door. There's obviously the fireplace. The floor here is not carpeted, but in many places, the floors are carpeted, and also notice this little wooden box that we will come to in the next slides as well. 

So wall linings. Everybody knows about tapestries. There used to be tapestries much more famous or more widely used during the medieval time, and we know that it was for decoration but also for comfort, and it was useful because they could be rolled up and taken along during travel as well. They are works of art, and they were meant to be works of art, but they had a practical reason as well, which was to maintain comfort in large buildings, where the heating wasn't so good, and here in Hardwick Hall again you can see that it's also covering the door – door here – so you know it's stopping draft as well. 

Now, wall linings weren't just tapestries. So over time, there were other forms of wall linings. For example, here there's painted cloth. There are embroideries, modern tapestries, and quite often the tapestries were thick wall linings, so would be woollen or have a thick backing. So they were meant for beauty and decoration but also for comfort. And this was also quite interesting, the tent room decoration, where you've got curtains but all over the room, the ceiling, walls, covering windows and doors as well. 

So I think it's not reasonable to dismiss tapestries as a fashion. For one thing, this fashion of wall lining – so if you don't just think of tapestries but other types of wall linings as well – lasted for about 500 years, so it's not really a fashion. It's more like saying that in winter when it's cold, you need a coat, but what that coat looks like will change according to fashion. These wall linings started to disappear and turning into wallpaper more towards Victorian times or end of Georgian times because then you're heating, internal heating, is becoming much better, so you have, perhaps, less need of wall linings. 

So how would wall linings work? They help to manage thermal mass. Now, I'll explain a little bit. Traditional buildings are generally thermally heavyweight. They have thick walls, and what that does it that the thick wall takes a long time to heat up and a long time to cool down, so it causes a little bit of a delay, so if it's very cold outside, it wouldn't be cold automatically inside. So it is a good thing. 

That said, if it's managed poorly, it can become a problem both in summer and winter. So in winter, for example, if you're trying to heat up an old building, the thermal mass starts to work against you, and it takes a very long time for that cold wall to warm up. And perhaps if you line that wall, you waste less energy trying to heat up the wall, and you heat up the space instead. It does provide a layer of insulation with an air gap behind, not as much as putting insulation on the wall, but there is something. 

But the main way it helps is by decreasing the uncomfortable feeling that you have standing next to a cold wall. A couple of clients have said something like, 'Oh, this wall radiates cold'. There's no such thing. It doesn't radiate cold. It's that standing next to it, you are losing a lot of body heat to a cold surface, and that's what makes you feel uncomfortable. In some ways, if you think about a carpet, that's the way the wall linings work, as well. So if you're on a cold stone floor, that can feel quite uncomfortable. But if you put some nice woollen carpet on it, or rugs on it, you immediately feel a little bit more comfortable, and that's basically what the wall linings are doing, as well. 

Compartmentalisation. Now, that was another way that instead of trying to heat the space, you heat the people. You make the people feel more comfortable. So you could have a space within a space, like a little nook that you could create via panelling or via curtains, for example. Here you see these curtains here, which block off a space, and that's the space with the bed, so you want to be more comfortable that side. The curtain here will also help prevent draft coming from the door. But then you also have bed curtains, so you know, that's where you're sleeping, and when you have the curtains drawn around your bed, you're stopping further drafts into where you're sleeping, and you're creating a little comfortable space where you are, so you're comfortable where you are. 

And then localised heating, so the little wooden box that I pointed to. They're foot warmers, so they're basically boxes containing coal that you could put next to where you are so you are comfortable. And then, of course, the Victorians had their own way of innovation, and I really like this little hand warmer, which is like a hot water flask, but it doubled as a purse, so you could take it while you're travelling or sit in the church holding this and still be warm. There is research from Historic England but also from Historic Scotland on U-values of sash windows and how the U-value can be improved by using curtains or shutters or roller blinds or a combination. So you can have quite a lot of improvement by closing shutters and closing curtains and maybe thick curtains, heavily lined curtains, etc. as well.  

Right, so what we did was that after learning these lessons, there are still quite a lot of questions because there's not that much text, and will that still work? Will anyone like it or not? So we did a little experiment in a grade I listed Georgian terraced house, and we took two rooms, office rooms. They're on the same orientation, same-sized rooms, kind of next to each other, and we decided, OK, let's use some of the lessons that we've learned, put it in practice and see how people react to it and try and see if it works or not. 

So some of the lessons that we learned was tapestries, and yes, this was a very low budget experiment, so please don't laugh at the fleece-lined walls in that little nook. But it was more-- You know, use your imagination. It's doing the job of a tapestry, and let's see how it works. And for local warmers, we used foot warmer and a little kind of heated blanket, which could be put on your seat, so it's like a seat warmer as well, and then trying to use local light sourcing and natural daylighting to use less light maybe. 

And with that, actually came the problem of the windows because in a Georgian building, there's large glass windows that we have, and there was a lot of glare coming on the computer screen, so they had black-out blinds fitted, and the minute you put down the black-out blind, it's dark inside and then you've got to turn on lights, so we thought that we could-- I mean, within the same buildings, we found historic photos on those windows. There used to be translucent curtains, so let's try the translucent curtain and see if that works or not.  

Results at a glance. There was, like, a lot of hatred, I would say, for the 'net' curtains, as they termed it, and everyone was like, 'We hate this and this doesn't work and take this away'. The wall lining was quite strange. I mean, people couldn't understand what it was. OK, you're doing an experiment; let's deal with it. It became a talking point, so they started to warm up to it because everybody would come and say, 'What's going on here?' What we found was that it did act as a layer of removable insulation. There was a slight temperature difference between the surface of the tapestry and the wall behind. And the occupant who had the most cosy nook, with wall linings round her, was the one who was most comfortable, whereas everyone else kind of complained a little bit about feeling cold in the experiment week or afterwards, she would say something like, 'Oh, maybe it was a warm week'. 

And then I'd gone away thinking that the translucent curtains were a complete failure, and then when we looked at the [video one?] monitoring, found that the blinds were coming down on all other windows, but the blind where the translucent curtain was up, it would stay up, so they do work. And then actually I came back to them and showed them the results and showed them that it worked, and they were very surprised and shocked that it does work. 

So in terms of the experiment results, we did do some computer modelling, as well. And then we took the existing case where the heating was on at 23 degrees centigrade, on for a long time during the day, seven days a week, because if they didn't have it on over the weekend, the building would cool down too much and take too long to warm up again on a Monday. Now, there is a little bit of improvement with using tapestries or external shutters or internal shutters, but actually the biggest change is by dropping the temperature from 23 degrees to 21. Now, this is something everyone, I'm sure, have heard that 1 degree C less of temperature saves your bills, energy, by 10% and so on and so forth, except that nobody does it, and that's because lowering the temperature gets equated in everyone's head as being uncomfortable. 

So that's not the case. So we also did some modelling for discomfort hours, or improvement in comfort hours. So the existing case obviously had quite a lot of uncomfortable hours, which is why the heating was on so much. Funnily enough, if we disregarded the heating and just by using tapestry, there is quite a lot of improvement in comfort hours and a little bit by using shutters, as well. So if you combine all the measures, there's quite a significant improvement in comfort, and that is the data that we need to kind of help people understand that you could have a lower temperature, have less heating, because all these other things can help you make comfortable at a lower temperature. 

Now, coming to summer. Again, this is a very cute painting. Shows the idealised English summer that we like, but there is a lot of glass, even on this building, and a lot of sunshine, and too much sunshine can create problems. So in terms of summer, I guess the lessons from the past are even more important because they didn't have air conditioning back then, and even now, there is even less air conditioning, so I think our goal has to be to try and avoid having air conditioning as a standard because the energy used by air conditioning is much more than energy used by heating, and our fight with global warming is going to be completely lost if air conditioning becomes a norm everywhere. 

So what can we do? So basically, the key thing in summer, overheating, is the sun. It's the sunlight coming through glass, which produces a greenhouse effect inside the buildings. And to stop that, you need some shading, and all shading devices reduce heat gain to some extent, but it's external shading that's almost always better than internal shading. Now, I cannot emphasise that enough because people think that it's interchangeable, curtains would be just as fine as an external shade, where that is not quite true, because the sunlight has already gone through the glass, and it's already turned into infrared into heat, so it’s already inside your building if you're using internal shading devices.  

Now, BRE advises that external blinds and awnings, which are retractable, are the best form of shading in the UK because you can have maximum amount of daylight in winter, and you can have them out only when you need them on a very sunny day in summer. Now, everyone I've spoken to about external shading and listed buildings, just gets completely shocked, and everyone's like, 'Oh, my god. We're talking about a listed building here. You cannot have any external shading.' Well, is that true? No, it isn't, because doing research I've found a lot of different types of shades on windows that were traditionally used, and they start to come in around the Georgian time. 

So the simple hanging blind is more of a Georgian blind because that is when the large panes of glass first start to come in in British architecture. And then by the Victorian times, there were lots of different patents and lots of different styles, and a lot of styles, the Victorian ones, also have fabric on the side, because if you see on the hanging blind, sun can still go in from the side, so you still get some sunshine inside, whereas if there's fabric on the sides as well, it blocks sunshine much better. So these are retractable. You still can get a view. You can still get ventilation, so they work really well. 

I think some of you may have seen them more in Europe, but they've kind of completely disappeared from the UK. A few ones to highlight here is the external Venetian blind, for example. I mean, we always Venetian blinds for internal, but I think the first patent for Venetian blind was for an external Venetian blind. And this one I find extremely curious because it's a travel blind, so it can pack away in a suitcase, and you can take it with you while you're travelling. And I found that very funny, and I think if you think of the summer of the Great Stink, it suddenly makes sense that people are terrified of heat even when they're travelling, so they're going to pack a blind with them to go wherever they're going. But I think this also proves that while the blinds were in use also to protect the furniture and fabrics from fading from direct sunshine, it was also there to basically stop the heat from coming into the windows. 

And here we go. So here we have Buckingham Palace, and you see the Spanish blinds here on the window, and towards the right is the interior view of one of the rooms, and then you see the Spanish blinds drawn on the windows here, as well. So you can see how it looks like from the outside and inside, and somehow it looks right. It looks really nice actually, as well. And you can see from inside that you would still have a view of the garden, and you can still have your window open and feel the breeze if there is a breeze, and it works really well in historic context. 

I've got now loads and loads of picture of the external blinds, and it's just to show you how common they used to be. And this is Trafalgar Square, and just about every window here has some sort of a blind, and other than the Grand Hotel, even on these buildings, if you kind of look closely, there are different types of blinds on the windows. Now, I was trying desperately also to find examples where there's external blinds somewhere, and external blinds are still in use today at Osborne House, which is an English Heritage property, and you can see them here. 

And also in Waddesdon Manor. So here you can see external blinds drawn here, and I was able to actually have a phone call with them, and they actually knew how to use the blinds because this building has always had blinds, and they said pretty clearly to us that they use it to protect their collections from fading, but also if it's a really hot day and if they can drop the blinds very early in the morning, they can have a very comfortable environment inside. They were aware of that just by using it because it was there. 

There are lots of other types of external blinds as well. So I found it quite interesting that Lutyens was one of the architects who actually drew the elevation drawings with shutters, so these were planned shutters, for example, in Great Maythem Hall, and you can see a detail of this type of shutter in the middle. And there are a few other drawings as well as this RIBA collection drawing, which showed purpose-designed shutters by architects. I also found this roller blind, a bamboo roller blind, which was integrated with the sash windows, so the practice started happening more in Victorian times rather than a retrofitted blind outside. The sash box already had a space at the top for an integrated roller blind. And this image is actually the external Venetian blind. It's actually from Sydney from Australia, and I saw it during a holiday, and it makes sense that colonial architecture kept this external blind there because it's just hotter there, so they need it more. But that's probably what a sash window with an external Venetian blind would've looked like here in the UK, as well. 

This is just another quote from Panton's book, where again there's a very clear description that internal blinds are not that useful. When it gets hot, you've got to have an external blind, so they knew what they were doing. Some of the other things. So we have external shutters that could be for storm protection, a winter thing as well, but sometimes you see external shutters with these little cut-outs, like heart-shaped cut-outs here, and this was for night cooling, so this is a problem in summer, how to manage thermal mass, because again we've got thick walls that take a long time to heat up, also take a long time to cool down. 

So during the day, when the sun is beating down on them, you don't get hot immediately in midday. There is a delay and the walls start to heat up towards later in the day, and then at night they actually start to release the heat. But then they're releasing the heat inside the rooms, and if your windows are closed, the walls do not cool down properly. So night cooling is one of the traditional things, and if you have shutters with these cut-outs, and sometimes they are internal shutters with cut-outs as well, you can close the shutters. There is security now, and then you can open your window, and there's the cool night air that can come through inside the rooms and cool down the rooms, and that is a very efficient way of managing your thermal mass and making sure that your building is cool during the day when it's quite hot. 

The middle image with a fireplace with curtains was rather shocking. I mean, who puts curtains on a fireplace in the summer? And then basically, the thought was that the curtains are usually there, not just always as decoration, but to manage drafts. So you have a chimney stack, which is fire is not lit in the summer, and there is ventilation coming through, so you have curtains and there are other mechanisms in different types of grades, which are flaps, etc., which you can use to control the ventilation, and yes, I did have a thought that stack effect ventilation in summer, and you've got chimney stacks, and if the chimney stack could be used for ventilation, then you could have cross-ventilation in every room with the window and the chimney stack, possibly. 

And the image to the right is a colonial image, and the punkah, or a fan. So this little thing that you can see with the wooden beam and fabric attached underneath it is a ceiling fan, and here you can see kind of threads or string attached to it, and they would be in colonial times a poor punkah wallah sitting outside pulling that string, and that would move the wooden beam and the fabric across the room, back and forth, and would create a ceiling fan. And in hot climates, you need a ceiling fan to deal with the heat. 

And then like the window awnings, there were also door awnings, which were quite common, and here again, you can see illustration as well as awnings in use. And I think people would open the front doors to stop the sun coming through the door and have ventilation through the building. And then, obviously, net curtains or translucent curtains aren't the only way to deal with glare. There can be translucent roller blinds, beautiful, decorated. I know there's a cultural issue when people think of net curtains, but there are lots of other ways of doing the same thing. Basically, you need something translucent to stop the glare but let the daylight in. 

And then the summer experiment. So we took the same two buildings in the experiment room and the control room and decided to use some of the lessons we'd learned from history and try and apply it and see what happens. So again, a low budget solution, but to try and use awnings or external blinds, we basically threw out the internal blackout blinds outside the window and tied them to the balcony and turned it into and awning. You can see the picture of it from outside and inside. 

And then ceiling fan as well because, it's hard to explain to people, but a ceiling fan is much more efficient than a desk fan because a desk fan you have it, it's right in your face, it blows away papers and maybe your face is cool but the rest of you is still quite hot and sweaty, whereas a ceiling fan will create air movement throughout the room, and it is much more comfortable. 

And then to try and see if stack effect ventilation would work, we had the chimneys cleared, and they had a little flap here to deal with ventilation. So we had that opened and tried to see how that would work, and then again task lighting to try and see-- because in summer, the natural daylight is stronger, and also, they had some kind of old-school ceiling lights in that room, which were very hot-spot lights, so the minute you turn on the hot-spot lights, the room would heat up a lot, and we were trying to avoid that. 

But again, to use more natural light, we had to come back to the translucent curtains here, but this time because we'd given them feedback from the first experiment to show that it really did work, there was actually a lot more enthusiasm, and different occupants wanted to try the translucent curtains themselves, so the curtains actually moved on different windows throughout the experiment. 

OK, and then just to see external blinds. How do they work? These are some thermal imaging that you see in the control room and experiment room. So in the control room here you see that the blinds are kind of very hot. It's like your personal radiator, whereas when you have the blinds outside, externally of the windows, it cools down. And basically, the hot point is the contact between the window and the blind. 

So results are the glass translucent curtains actually worked really well this time, and people were more enthusiastic, and they kind of were like, 'Can you leave it on for a little bit longer?', which was fun to hear. A chimney stack surprisingly worked quite well, and yes, we are aware that different chimneys in different buildings would behave differently, and some would work better than others, but in this case, the chimneys worked really well, and the occupant next to it said that he could even feel the air movement and it really does work. 

And we did do some temperature monitoring as well, so the night cooling was the most effective because we combined with the stack effect, so we had the chimney stack open and the window left open for a little bit, and on some days there was a temperature difference of up to one and a half degrees C inside the room, and people, occupants, also said that they felt a difference when they came in the mornings instead off-- you know, they would come in the morning and feel really hot and open the window immediately, whereas it felt much more cooler and comfortable when they would come in during the experiment days. 

So for the experiment results, there was no air conditioning, so in some ways there was no energy saved, perhaps other than turning off the lights. But there was much more energy saved in terms of potential air conditioning because there were complaining constantly and wanted a portable air conditioner put in, and what we see here from the modelling and we also saw from our experiment results was that external shading definitely has quite an impact on improving comfort. Internal shading also has an impact but less than external shading. Night cooling has the biggest impact because that manages the thermal mass really well and allows the building to function as it was intended to, basically. And if you combine the stack effect with night cooling, that's even better, and of course, if you do all the measures together, your hours of discomfort are improved by 1/3 almost, so pretty good results, I would say. 

Before I finish, there's also a note about consent, so although some of these things look very normal and very simple, if you're dealing with listed buildings, you would need consent. External blinds definitely would need planning consent if the building is in a conservation area, and listed building consent if it's listed. And internal linings, your tapestries or your wall linings, may also need consent, especially if the interior is of special interest. 

And yes, so all of these-- This is an excerpt of the journey that I've been on over the last couple of years. So the report, which will detail it, is going to be published soon on Historic England's website as well, and in the meantime, if you have any questions, feel free to ask me. Thank you very much. 

Morwenna [46:45] Great. Thank you, Sarah. That's really interesting. Certainly from a perspective of looking at your slides looking at all different treatments in sort of one place, in my experience of working on historic buildings, you always find something new, don't you? 

Sarah [47:04] Yes, I know. It was a-- 

Morwenna [47:10] Yeah, there's always a detail or a thing where you're sat there going, 'Well, I didn't know that. How did they use that, and what does that do?' Specifically, I mean, I was thinking about shopfronts and actually having read your report and knowing that you were going to speak today, I was walking in Bristol the other day, and I noticed this historic shopfront, a sort of arcade, and they all had the mechanism for the awnings but no awnings. Have you noticed more now-- 

Sarah [47:45] I noticed it so many times now. So you know, around Bedford Square, even where we had historic images and where we were doing the experiment, there are a lot of awning boxes over windows and even the door awnings. The historic photo that I showed here was from Bedford Square, and I found at least three doors that still had the door awning with the whole mechanism in place, as well. And I rang the doorbells, and I asked them, 'Does anyone know how to use this?' But the owners kind of came and looked at it as well: 'I don't know what this is. I don't know what to do.' 

So it's quite funny. I mean, even ourselves, I used to wonder before, why are these decorative panels on the windows? What are these decorative blind boxes doing? And it just made a lot of sense. I mean, I was quite shocked. I didn't know what I would find when I started this research. The external awnings definitely was the biggest shock, and once I realised what it was, then the evidence was everywhere, and there were so many photos and images as well. But without knowing what it was, I wasn't, I myself, that aware of it, and I was already a conservation architect. 

And also, another surprise for me was chimney stack and possible use of chimney stack for ventilation. That was quite a bit of a shock, but when you think about it, it does make sense, which is why I was saying, 'Stack effect ventilation, chimney stack'. It's a stack. Why can it not be used? 

Morwenna [49:14] Classic ventilation that's already there in a lot of these buildings. 

Sarah [49:18] Exactly. 

Morwenna [49:18] If only we could up the chimneys and-- 

Sarah [49:22] Chimneys! 

Morwenna [49:22] It's the chimney balloons. It's that removable-- I think it's one of those aspects in the work that I've done for EPCs. You're blocking chimneys, and it feels very wrong to block a chimney, kind of without the ventilation. And then knowing that the dissemination of how you would block it during the winter, open it up during the summer, it isn't necessarily added to the action of closing that chimney stack, and I think you've highlighted how that sort of engagement, the personal engagement and the performance of your building is key to how these buildings work. 

And I think you mentioned the soft sciences... 

Sarah [50:11] Yes. 

Morwenna [50:13] ...and that's exactly true in terms of our thermal comfort. I was reading an interesting blogpost the other day, and it was talking about wearable technology, and I thought, how direct link between your little coal foot warmer through to wearable technology, a blanket that you can turn on and off if you need to or your jacket that automatically slightly warms up if you feel cold or not-- 

Sarah [50:43] Yes. The seat warmer was a bit hit. It was such a huge hit, actually, because initially when I was introducing all of these variables, everyone was like, 'What is going on?' This is a little seat warmer, and I was like, 'Oh, actually, I'm going to turn off your heating as well during the experiment'. There was like a sharp intake of breath, but it was like, there's stuff there. I'm not going make you freeze. If anything happens, call me and you've got your personal little radiators and then the seat warmer. And then there were participants fighting over the seat warmer, basically. We only had one! They all wanted it. 

And they really got engaged in it, and at one point, because I had to go back and do feedback to them – how are you feeling, etc. – then I think it's the social scientist part of me; I had a slip of tongue and I called them experiment subjects, and then one of them was like, 'Excuse me. What did you mean, "We're participants.” We're not subjects!' 

[laughter] I know, and I thought that was very apt because we end up getting too involved in the science side of it. And they're the people. They know the building really well in their bones. They may not be able to communicate it that well to you, and then if you engage them and if you explain to them what you're doing and give them feedback-- I think the feedback was very important. Like with the net curtains, everyone was like, 'This is such a modern building and you're putting net curtains. What are you doing?' And then when I showed them the video monitoring results, there was a lot of surprise, and then they were like, 'OK, I'll try it now with an open mind', and then they tried it. And again, it was the same thing, that everybody then wanted it for their window: 'Put it on my window now. Can you leave it on for a little bit longer?  

[crosstalk] 

Morwenna [52:28] No, sorry. You finish. 

Sarah [52:31] OK. No, I was just saying that because these are all traditional measures and they look and feel really old school, so it's very hard to believe that they would work. And for example, even the participant who had the cosy tapestry nook, she didn't turn on the heating. She was the only one who didn't turn on her personal heating throughout the winter experiment, and then when I asked her, she was like, 'Oh, it was a warm week'. No one else said it was a warm week. So it's so subtle, the difference, but you've got to try it, and you have to go in with an open mind, and it does work-- I mean, it worked for centuries, so it does work. 

Morwenna [53:16] It's true. I mean, it's interesting, isn't it? It feels like-- You've highlighted how engaged people were in the past about their personal comfort, their thermal comfort, that they had all sorts of tools in which to try and make themselves comfortable. I think we went through a phase some time ago – and I think we are still in that – in designing buildings that removed agency. Working in some buildings, modern buildings, for example, Heelis from the National Trust, everything is controlled by the building. You don't control your light. You can't control your window, and it is supposed to totally set everything about you, and you have no control over your personal comfort. And it sometimes works, and more often than not doesn't. 

Sarah [54:11] It doesn't work. Yeah. 

Morwenna [54:12] No, and I think that we're almost coming full circle to that idea that yes, there are really good design techniques, materials, methods of creating a building, a modern building, that performs so that we have to put less energy into thinking about our personal comfort. But given the 25% of our building stock that is traditional, we really need to engage in that more practical engaged thought process of how we make our buildings and ourselves work together. Would you agree? 

Sarah [54:46] I definitely agree because one of the other things is that when people are uncomfortable, they are naturally motivated to do something about it. So, I mean, that's why all these historic techniques are there as well. I think it's too simplistic to assume that they just froze to death back then. It's against human nature. Nobody does that and nobody did that, and even now, if you are feeling too hot or too cold, you'll go and open a window or close a window. You'll do something, whatever it is that you can, and that's why, I think, sometimes a lot of frustration also builds in with these fully automated buildings because you can't open a window. 

And in some buildings, you can't even pull down a shade because the shade will come down automatically, and if the sensor is not quite working that day, which we know even today we're having a technology breakdown. I'm doing my presentation earlier because of that, so technology is amazing, but it can let you down sometimes. And then a lot of frustration builds up because you can't change the temperature, you can't pull down a blind, you can't do anything, and again, thermal comfort comes back to how you are feeling. So if you are feeling frustrated, you are not comfortable. 

And then a lot of these lessons from the past, they're common-sense things, which we haven't done in a long time. The historic blinds disappeared around 50 years ago, somewhere around World War II, and they're just out of everyone's vocabulary, so you don't even know that it was there. And a lot of things, like the chimney, ventilation or night cooling or closing the shutters to enable night cooling to manage the thermal mass, or external shading, these are things that help these buildings work. 

So now it almost feels like you've got half a building there with a lot of the things that made it work lost, and now you're trying to work so hard to go against it, and then you're trying to retrofit in a different way, and it's working but not quite working. So there's a lot of frustration because they're missing items. They're missing things in the building that you need to get back. 

Morwenna [56:52] So true, so true. Let's wrap it up there because I think we were going to give everybody a comfort break and a thought process. I actually wanted to highlight something in the chat, which was someone very correctly picked me up on the fact that chimney sheep are better than chimney balloons. They are indeed. Thank you, Freya, for posting that link. I do love a good chimney sheep. If Nick does come back, then we can go to his presentation in a bit, but we'll have a think. 

So apologies, everybody, for the kind of disruption, but if you have-- This is the discussion part of the presentation today. If you have questions for our speakers, then please do put them in the chat box, and I will do my best to read and talk and balance on my head at the same time. I think it would be great-- 

First of all, thank you, everyone who's spoken. It's such a fascinating range of subjects and a range of case studies. I think it's really interesting when we look at the kind of work that we're doing and involving energy efficiency, which is very much a watchword at the moment through a balancing act with embodied carbon, which I think sometimes we think of as sort of whole lifecycle carbon analysis through to whole lifecycle, and there's so many different parts of this that you can start kind of unpicking, and I don't know about you but I sometimes think that I'm thinking about one aspect of carbon and somebody else is actually thinking of a completely different, and we speak at cross-purposes. 

Interesting question that came up from last week was from Warren Williams, who sort of said that he struggles to balance it all and wondered if balancing embodied carbon with energy efficiency, and wondered if there was sort of clear rules of thumb that anyone has or guidance that you would recommend. So I don't know who to go to first. Does anyone have a burning desire to speak first? No. Ah, go on. Harry, go for it. 

Harry [59:21] Yeah, I'm happy to start. Can everybody hear me OK? Is it clear? 

Morwenna [59:26] You're a little bit quiet, Harry. I don't know if you can turn your sound up. 

Harry [59:28] OK, I can try and turn up a little bit. Is that better? 

Morwenna [59:32] Yeah, that's great. 

Harry [59:32] I'll speak a bit louder. Yeah, so that question from last week, I don't know about you guys, but very often when you answer a question and then it moves on and afterwards you think of a better answer to the question. So it happens quite often. It's really frustrating. 

Morwenna [59:48] Well, this is the great thing about two sessions. 

Harry [59:51] So I think a more holistic, kind of more measured argument for me would be to think about-- I was thinking about this concept of historic significance and carbon significance, and I was thinking that actually sometimes we have to think about how we value historic building [indistinct]. But we also need to value carbon fabric or embodied carbon fabric, so I think my first rule of thumb might be to sort of try and be a little bit less invasive, generally, just as a general approach, and obviously, Sarah's fantastic talk, which I really enjoyed, Sarah. I want to talk to you about it, so that's another conversation. 

But I think that highlighted a whole set of potential much lighter weight, much more user-friendly, user-engaging ways of retrofitting a building. So I think the question is about embodied carbon versus energy efficiency, and so the question is about what kind of energy efficiency you're trying to achieve. Are you trying to go for something that's actually a bit lighter touch, or are we quantifying it? So you want to be below 80 kilowatt-hours per metre squared per year for space heat demand, or something like that. 

So I thought, well, if we're going to talk about that, then we should start to talk about chunks of bits of retrofit, and one would be structure. And I think generally, when we’re thinking about structure, we need to be thinking about less concrete and less steel and more timber and that, funnily enough, is probably quite in tune with a lot of historic buildings. I think when we’re thinking about materials, I think just as rules of thumb-- So this is thinking about the question of rules of thumb. 

So there's the ICE database, and it's very easy to get embodied carbon values from the inventory of carbon and energy, which is available free. I think it can just register you in, and you get a copy, and that's updated regularly, so that can give you the-- tell you, well, what is an aerogel blanket? What's the embodied carbon of an aerogel blanket versus Celotex versus wood fibre? You won't be surprised to hear that wood fibre's the lowest. And actually, then you can sort of start going a bit more nuanced. You could start to say, 'Well, actually cork is even lower embodied energy because actually it's an incredibly natural material and just has a very efficient production process'. So you could also use EPDs, environmental product declarations, so sort of get into the practice of asking for those. So that's another sort of way of trying to make a judgement between things. 

And I just sort of made a note of windows because I think this comes to the point about layers of building fabric and the age of bits of building fabric and just recognising that when you go to retrofit a mid-terraced house, let's not all think of the same mid-terraced house, but let's think about a mid-terraced house that's got a brand new roof or a mid-terraced house that's got a 60-year-old slate roof or a mid-terraced house that's been beautifully repointed with just the right NHL [deep-tamped?] pointing. They're all different and it's quite hard, but most of us, probably most people attending, would see UPC windows and say, 'Right, let's get them out'. But actually if they're quite young, just a few years old, and they're actually working – the ironmonger is OK and the seals are OK – well then we really should be thinking about leaving those in. So again this embodied carbon and energy efficiency, well, actually you've got double glazing, you may have [indistinct] broken frames, they're doing alright, so actually your retrofit should actually engage with that and think about it being phased over time. 

So there's a first point. I've thought maybe, Paul, do you want to add anything to that? 

Sarah [01:03:49] I wanted to say something. Maybe I can go first? I think I just wanted to say, following on from Harry, basically just explaining a little bit more on my take on it. So one is that with historic buildings, I mean, the conservation approach is also always to do as little as possible, and I think that works quite well with the carbon approach as well, that you leave what's there unless it needs an intervention, so in our case, even the one example that I showed of the deep retrofit, it needed a retrofit. It was in really poor condition, and when it needs such a huge retrofit, that's when we would go, kind of, all out. OK, do as much as you can in terms of energy as well and improve as much as you can, but if the building's doing OK, then leave it as it is. 

One other point that I wanted to make was that in historic buildings, and again, it doesn't need to be listed. It needs to be traditional construction. The life of the building materials, in terms of embodied carbon, is huge. I mean, even if the windows-- You have original Georgian windows. How many hundreds of years has that been in for? Even the example with [indistinct] stained glass, I mean, there was a little bit left, but it was original stained glass that was made when the chapels were built. And then you try and think as well that actually you can't get that glass anymore. It can't be made anymore, so preserving it is huge in terms of carbon, as well as in terms of conservation. 

And same with the timber, the Georgian timber in the windows, or Victorian timber in those windows, that close-grained timber isn't available anymore, so that timber can last another hundred years, but if you replace that window with a new window, that new window will not last as long, so you've got to have that in mind. And also, even if you've got a roof that's at the end of its life and you're putting in a new roof, if you use the traditional methods, like a lead roof, for example – lead is recyclable anyway, so it's fully recyclable – and the lead roof can last a hundred years if it's properly detailed, a slate roof easily 60/70/80 years if it's properly maintained. So the lifespan of these traditional materials is also very long, and that's something that we should be considering. 

Paul [01:06:12] I think if you are refurbishing, say, with internal insulation, then the danger is using things like Celotex or Kingspan, that even if technically they work OK, then the lifespan of those is actually relatively short, perhaps, compared with other solutions, particularly if they've used their blown with some exotic gas to lower the thermal conductivity, then that will deteriorate over time, whereas even something like mineral wool, that's probably got a very long lifespan. 

So I think care must be taken in choosing retrofit materials so that you can guarantee that they do have a long lifespan, the same as trying to-- You know, if you've got perfectly good windows, then try using other measures to reduce the heat loss, like the work that we did for Historic England and Historic Scotland years ago, looking at shutters and blinds and actually high-quality secondary glazing. 

Morwenna [01:07:52] I think it's a really interesting point, isn't it, about allowing things to come to the end of their lifespan. Don't just assume that you need to take it out and that you need to improve it. I mean, when we think of the fact that 40% of UK landfill waste is from the construction industry, part of this is this decision-making about whether something has come to the end of its lifespan and whether it's performing adequately, and in terms of retrofits that I've seen in my own street, there's a house and it's having internal wall insulation, and they have taken all the timber out – I mean, door lining, skirting boards, everything – and it's fine. It's not damp, it's not rotten, it's not-- It's fine. It didn't need to go, and that's part of that decision-making, so in some respects it's about applying the layering of conservation almost in its best elements. Do we want to keep it? Is it important? All these things that we think of when we're looking at listed buildings can also be implied in a retrofit in an energy efficiency context. 

But I wonder whether it's actually much harder-- It sounds easy to go, 'Well, it's not at the end of its lifespan. What are the other alternatives?' However, often the work that we do is driven by policy and legislation, so it's not a case of saying, 'But it's fine. It's performing fine. It's not performing great, but it's performing fine.' But we know that we'll get a much better EPC value if we go and stick Kingspan in or we use Celotex or we'll use material that only has a 30-year lifespan, having removed something that may be 100/200 years old, which was functioning. 

Sarah, do you have that kind of difficulty when you're approaching a project, that you're trying to meet standards that don't necessarily fit with your conservation principals? 

Sarah [01:10:06] Yes, all the time, which is kind of why I made that jibe saying, 'Then you achieve a B or a C'. 

Morwenna [01:10:16] [indistinct] comparing apples with cars. 

Sarah [01:10:17] That's the point. That's the point. So, I mean, I find that it's so difficult even afterwards to explain the work that we've done is pretty close to exceptional when you've got a C to show for it. Yeah, it's very hard because, I mean even in the research that I did when we were modelling, we knew we had the results because we actually did the experiment first and modelled afterwards, so we knew it worked. It worked really well. People were happy, comfortable, we didn't have any heating on, and then you're trying to model it and we were struggling with the modelling as well because you're back to room temperatures, you're back to U-values and we're trying to figure out the U-value for tapestry, and then [that's?] like, 'Oh, come on! This is not how it works.' I mean, the benefit is not in the U-value, but when you're coming to the modelling softwares, that's the constraint that you have. What else can you put in? You can't put in 'They were very happy, and they turned off the heating.' 

So it's very, very difficult to explain, and I think that is the uphill struggle that we have, because then when you're trying to convince other people, even if it's their house or their building that you're retrofitting, it becomes hard because people don't believe you. I mean, I've had some professionals, even, specialists, planning officers, etc., who just come and say, 'Why do you need external heating? Do you have shutters inside? Curtains work the same.' And then you're trying to explain, 'No curtain doesn't work the same as an external shade'. And they just don't believe you. It's like, there is science behind this. I can send it to you. 

But there's this belief that if it works so well, we would've still had them, why did people stop using it, that kind of thing. I think that's where these kind of talks or also come in handy where we share our experiences and people tend to understand it a little bit more and we disseminate information more because we are comparing apples with pears. It's very complicated, and if we've got actual science, if we've got softwares, and then if we've got the soft sciences of dealing with people and trying to merge it all together isn't that simple. But there are ways forward, and the more success stories that we have and the more we share, the more common it becomes, I think. That's the only thing that I can say. 

Morwenna [01:12:44] Keeping up the pressure. Paul, do you have any thought on this? Because I know that your modelling work is very much sort of focused-- your recent work has been focused on looking at different scenarios in terms of climate change, and I wonder whether you think that sometimes we're modelling with performance and yet we're not doing all the rest of the things that we could be doing. 

Paul [01:13:10] That's maybe true. I mean, I suppose I'm mostly looking at the modelling from the point of view of not necessarily improving thermal performance but looking at long-term risks to the fabric if you do add internal insulation, and actually the results are very disappointing in the sense that nothing's really changing. There's always a risk, potentially, due to moisture. Well, it's certainly-- I suppose it depends what climate scenarios you use, but I'm assuming a sort of 2-degree [warming?], which might be conservative, unfortunately. But it doesn't look as though buildings would change very much. There's still a risk of moisture issues when you internally insulate. 

But again, it very much depends on the original fabric and the properties of the original masonry, for example, and we've looked at, say, reducing the amount of insulation to see whether that has any beneficial effect on reducing moisture risk. But again, it really very much depends on how well the, say-- We're mostly looking at brick and different types of brick and how well they absorb moisture, for example, and release moisture. And I think there's problems with considering moisture buffering of hygroscopic insulation materials like wood fibre, and it's a point that Sarah made about thermal mass. It stores heat and releases it and absorbs it, and it takes a finite time to do that. 

And with moisture buffering of materials, if the material takes time to absorb the moisture, it also takes time to release, and some of the results that you get show that you can get quite high moisture contents in, for example, wood fibre insulation because it absorbs a lot of water, but then it takes a finite time to release it, and does that have any impact on the fabric? And I think then it comes back to, how well can we monitor buildings so that we actually can validate these results properly, because garbage in, garbage out. You can never totally trust modelling, and something like using WUFI, which is a one-dimensional model, then you're very limited in how you set the internal conditions, and we maybe need to up our game and use sort of whole building models but able to put in more detail and have a proper model of the occupants' behaviour – what set points they use, what moisture loading we get – and so that we have much more realistic scenarios when we're looking at future performance. 

Morwenna [01:17:38] I think you make a really good point about monitoring what we do versus modelling what we plan to do. It's a really good point. I don't know, Harry, if you have anything to add. Wave if you do because I thought this sort of segues so nicely into assessing U-values and our materials and that word I can't pronounce – absorptivity. 

Sarah [01:18:06] I just had a quick thing. 

Morwenna [01:18:07] Yeah, go for it. 

Sarah [01:18:09] Yeah, I was just saying what you said about modelling versus monitoring that, I mean, in some cases we're quite lucky because we're dealing with existing buildings that are already here and have been here for a long time, which is why I was doing my past study. It's like monitoring what they did before, the behaviour that they've done before that's worked. But also, that's also why I went to do the experiment and I actually did the modelling after, because I was like, 'Why everyone does modelling? Why doesn't anyone try it out?' It's here. The building's here, and why don't we try it out and see how it works and how people react to it, because then instead of modelling how people would react to something, you can actually see and give them feedback and see how well the feedback works. 

And that's why I think initially I was going to just do the experiment, and then we decided, OK, let's do the modelling as well, and see how it compares, what results we get. It's a harder approach, but maybe that's one thing that we do need to consider – try it out, what you can do because that's the building that you'll be working with. And quite often as architects, there's a long lead-in time before you actually get to site. It can be up to a year, easily, while you're still working out what to do, and that could be the time where you could do some trials, some monitoring, etc. 

Morwenna [01:19:30] It's interesting, isn't it, because I think, sort of, coming from a role as an estate surveyor, you open the door and they say you need to fix it now. You know, it's broken; fix it. And you go, 'Well, yes, but it could take 18 months for me to work exactly how to fix it', and they go, 'No, no, no. Yesterday'. And you go, 'Well, how about we try a solution like this?' and they go, 'No, I want it fixed, and I want it fixed yesterday, and here's your budget.' 

So it's always great when you can have a project where you can get into the detail and you have an engaged client, not that I'm at all jealous of Harry's current client, who's doing all the work themselves and being utterly engaged in the process. But actually, an awful lot of us out there on the ground are trying to deliver things with pressures and clients who aren't engaged and won't engage, and I think I've seen, since moving to Historic England, seen proposals where it's all about do it now, work out whether we've got it wrong later. 

And I think, actually, there is a room for that. There is we must move forward. There's a great-- I was trying to think of the-- I was listening to a podcast the other day, and it was about the fact that we've kind of come through this stage of fear with climate change, that fear that it's going to happen, and now we need to break the paralysis of fear and start acting even though we don't know where we're going to, almost. And I think that that there is a real place for the monitoring as well as the planning and the trying out, and as you said earlier, Sarah, it's all about talking to people all of the time about what's working and so that we use the information again when we have good projects, good clients, kind of enough budget to play. But also, when we go back and we look at projects where we've installed things, not personally maybe, but as professionals constantly going through buildings, we can go, 'Well, ten years ago, they did this', and there's clear single-measure imbalance. 

Somebody mentioned in the chat about the retrofit coordinators’ mantra of ventilation before insulation. So often I've seen that just completely the wrong way round – draft stripping before ventilation, insulation before ventilation – and I think that's a fear that a lot of people have with listed buildings, is 'Oh gosh, how do I put ventilation in'. If putting in an extractor fan will involve a listed building [indistinct], well, I won't do that. But actually, they should do it because the system is there to help, not to hinder, and getting good ventilation in traditional buildings, if you can't sort of reinstall that passive ventilation from the chimney stacks, is really important. 

In terms of that balance of measuring, of modelling, of sort of how far do you go before you start installing, Paul? The project in Bolsover, I think you mentioned during your presentation that you'd installed the two versions of internal [wall?] insulation, but there needed to be some repointing on the outside on the gable wall. I just wondered how much sort of-- Was it in good repair before you started, and how much kind of additional work was needed? And did you feel that it was done the right way round, or do you think that there could've been more analysis of the materials or more sort of better maintenance before starting? 

Paul [01:23:15] Better maintenance before starting. That wasn't Historic England's fault. I think it was the social landlord... 

Morwenna [01:23:25] Oh, good! 

Paul [01:23:26] ...that was supposed to do that, but they didn't, but they have, I think, they have done recently, but that's after we've got seven years of monitored data, unfortunately. And I think-- I'm just preparing a sort of final report now, and it's coming back to haunt me that you look at the results and do some modelling and it's very difficult to sort of put your hand on your heart and say I've got total confidence in the results that we're getting because of the pointing problem and how much the impact is, but hopefully, after Covid and we can restart the monitoring, then we've got a good chance of finding out whether we get some change in the results, which would be great. 

But even with the results we've got, I think it's been a useful exercise, and we've got, sort of, 100% data collection over seven years, which is pretty good. So not too bad really, but I do wish that they would've fixed the pointing because there was definitely historic damp problems, and once that moisture's sort of trapped in the building, it's quite difficult to remove it. The best thing that happened was the-- 

Morwenna [01:25:27] Well, perhaps it's more representative for the lack of maintenance than it would've been if it had been well maintained. It's an ongoing issue, isn't it, that we're all starting on buildings that have had a lack of maintenance or need more than we have the budget to do, and I think when you look at a retrofit project, and you think, well, ideally I would take two years to put it in good repair, give it a year to dry out. Hopefully, it's a nice dry year, and then I'll start on the insulation. But none of our projects are on that timescale, and indeed climate change is not on that timescale either. So in some respects, I think that's a good thing that we have that representative data, and then if we know how it's working not where we would like it to be maintained, we can see then how wrong we can get it, I guess. 

Paul [01:26:30] Yeah, but the best thing that happened was the summer of 2018, which shifted the equilibrium of the building immensely, and everything started to dry out. But then we had to stop monitoring at the end of 2018. 

Morwenna [01:26:50] So you missed that winter of 2019, where it rained for seven months straight. That winter, it was somewhat nail-biting, and I have to say there was water coming in in places that-- You know, I was getting phone calls saying, 'There's water coming through this roof. There's never been water coming through this roof.' It's been raining for six months straight. This is representative of the kind of climate issues that we'll be facing. Yes, interesting. I don't know-- Harry, your tool looked incredibly interesting in terms of your decision-making. How deep did you go before you started deciding what you would do? You seem to have really got into everything and the materials of everything. Do you think there is a limit to how far you can go, and how scalable is what you're doing to when you don't have a particularly, either an engaged client or indeed a timescale that allows for that kind of depth? 

Harry [01:27:59] There are a few questions there, so if I don't get through them all, then remind me at the end. Yeah, so the first part was how deep did we go in terms of understanding the building and kind of upfront thinking, and I just want to make a really interesting point about WUFI and absorptivity, because that was your second topic, wasn't it? U-values and absorptivity. And where we're talking about absorptivity, we're talking about A-value. A-value is one of the inputs to WUFI, which is a hygrothermal modelling software, and people like Ecological Building Systems, who supply wood fibre insulation, they would always do a calculation using WUFI to look at the hygrothermal risk. 

And what we started to do was start to do our own [cast and cup?] absorptivity test on buildings, and then we'd arrive at an A-value, and luckily I managed to get hold of Joseph Little's methodology, so we had a really robust methodology, so we could kind of trust the values we were getting out. But actually, in the end, the thing I got most out of it was getting to know the wall up close and literally just being next to the wall and looking at the bricks and seeing markings or funny things on the bricks and then feeling the pointing, and just spending a couple of hours by some brickwork, you actually learn a lot about it. 

So ironically, the sort of method-- the kind of numerical methodology and modelling, I got a bit out of, but actually what I got most out of was getting to know the wall. And so I thought that was quite an interesting sort of turn-up, and that's really where you realise that in the main it's the pointing that's the biggest part of the risk. So yeah, so say on the Maryvale project that I presented last week, we did do [cast and cup?] testing and we did produce an A-value and we did get some hygrothermal modelling done and it did indicate periods of some risk. And then we have to sort of assess that in a sensible way, and so we're going to repoint the walls. We're going to make sure the client repoints them for as long as they're there. We're going to look after them. We're going to slim down the insulation a bit. We're not going to push it to 100 mil. We're going to put it at 80 mil. so there's a little bit more drying action, a bit more heat pushing through the wall. 

So traditionally we've been doing that, but I think we've reached a point now where we've got quite a good feel for the buildings, so in terms of scaling up, it feels like we can't go on doing this for every project. We give a lot of love for these projects. They're on quite small budgets and obviously fees can't possibly cover this in a repeated way, so we try to sort of make these early small projects, research projects, but in terms of scaling up, if there was a bigger building and a larger set of houses, then I think it is possible to still do this kind of in-depth research, because the [indistinct] fee would be larger, so there would be a way of actually still doing some spot sampling, for example, or some of that. 

But scaling up individual projects across the country, really what we should be doing is sharing research in the way that Paul's shared today, Sarah's shared today and I shared last week. We can all share what we know. Unfortunately, quite often there's-- I mean, let's say with some of Paul's work, there's still quite a lot of question marks. Maybe Sarah's work was perhaps a bit clearer today. She pointed the way forward for at least some approaches. 

So if I can, I'm going to slip into talking about U-values because I wanted to just share something. So ArchiMetrics is a bit of live U-value monitoring and measurement, and we actually worked back to get a lambda value for the brickwork. And of course, when you lambda for the brickwork, you're talking about lambda value for brick and a bit of rubble fill and a bit of mortar and a bit of broken brick and a bit of brick on the inside, so you're talking about that overall build-up with a bit of lime plaster. Well, we ended up with a lambda value of 0.4 watts per metre-Kelvin, which I'm sure Paul will say is quite low, but with a value [of it is?] often used as 1 or 0.8, and then I thought, well, I'll just share with everybody the difference in U-value that you get from if you use a value of 0.4, if you use a value of 1. And so with a 20 mm of aerogel blanket on the wall, which is quite a lot of aerogel, we would go for-- there would be a 20% difference in U-value, so U-value of 20 mm aerogel with brickwork of a lambda of 0.4 gives you 0.4 watts per metre squared Kelvin, and with a U-value of 1, it's 0.5 watts per metre squared Kelvin, so it's a 20% more heat loss, apparently, through that brickwork. 

So that's actually quite a big difference, isn't it? 20% is no small sum. So yeah, so I just thought I'd share that about the U-value. So now on projects, we kind of take a view on the brickwork, if it looks like it's sort of really solid engineering brick, we might call it 0.8 or 1. And if it sort of looks quite soft and there are red rubbers, you might think, well maybe it's down at sot of 0.6/0.4. And I think that there's been talk amongst my colleagues for years about forming a brick absorptivity and a brick lambda value database, and there is some of that in WUFI. So WUFI does have some [indistinct] and then it usually gives you different types of brick. But I think, wouldn't it be great if Historic England could produce the list? I'm sure that's something that is available or feasible.  

Morwenna [01:33:51] What we need is a proper brick geek, isn't it? 

Harry [01:33:54] It is. It is. 

Morwenna [01:33:56] I think there is such-- 

Sarah [01:33:57] And a stone geek as well. 

Harry and Morwenna [01:33:59] Yeah! 

Morwenna [01:34:02] It's just one of those traditional materials that-- One of the pleasures of working with brick, and historic brick, is the variance and the textures and the colours and all of the things that make it an enjoyable human experience actually make it very difficult to work out how it will perform. But maybe that makes the challenge all the more better. 

I think I've got a couple of questions from the chat. So Ian's sort of highlighted about the-- I'll read it out. 'I suppose even if the best either most conservation-friendly and sustainable internal wall insulation still causes problems with moisture retention and release. What do we use?' I have my opinions. Who fancies kind of chipping in on-- What do we use? Sarah? 

Sarah [01:34:59] Well, I mean, we use normally the natural ones only. So either wood fibre board, we've used hemp lime plaster, or cork board, or reed boards, that kind of basically natural-- We have used wall insulation as well. So generally a natural material is more breathable, so it just allows the moisture to dry out better. But we often also mostly, due to other heritage reasons, don't use too much thickness of insulation. I mean, usually it is because of carved head details or internal wall panelling or there is something on a traditional building. So we don't go as thick as maybe some others will go, but that also allows more breathability. 

And the other thing is, never ever put the vapour barrier on, because I think there were still some people, even when you're using a wood fibre board, to say, 'No, you need a vapour barrier'. No, you don't. No, you don't. Don't ever use that. 

Paul [01:36:04] Also-- 

Morwenna [01:36:05] It may be good-- Sorry, go, Paul. 

Paul [01:36:08] In New Bolsover, we used – or I didn't – but the build did put a lime parge coat on the brickwork before putting the wood fibre on, and that will certainly act as maybe a fungicide layer and as another buffering layer for moisture. So that's recommended for the type of wood fibre that was used at New Bolsover. 

Morwenna [01:36:42] I suppose, I mean, ultimately there are a range of really good products that perform well in different situations. We know that there are risks. The risks are identified. And that practice detailing, one of the previous questions was about suggestions for construction detailing for internal wall insulation, so if anyone has that, perhaps they could add it to the chat. That would be really useful.  

In terms of membranes, one of the questions that came up last week was around the isolation of the external surface when we're insulating internally. So the question actually was that 'Advice from one of the top experts is to completely avoid non-vapour permeable internal wall insulation with solid brick walls to reduce thermal isolation of the external surface and the risk of delamination due to freeze thaw'. 

I thought this was a really interesting point about isolation of elements of the buildings. I wondered if anybody had any experience of that. Have you inspected buildings where it's clearly happened, or whether you have thought about it in your own decision-making when planning for a project? I don't know if anyone-- 

Paul [01:38:06] Well, after seeing that question, I modelled it and had a look at the temperature gradients, whether you got without any insulation and with insulation either PIR with a vapour barrier or with a wood fibre, and really you don't really affect the outer brick very much at all. So-- 

Morwenna [01:38:38] Ah, that's interesting. 

Paul [01:38:41] I think that the issue might be that if the building gets extremely wet on the outside and there is freezing conditions, then there may be an issue with delamination. And if you just leave a brick outside in the frost, it can delaminate and crack, so I'm not convinced it's a problem unless the adding insulation exacerbates the risk of that at all. 

Morwenna [01:39:16] [indistinct] 

Sarah [01:39:16] I think there's also been monitoring. 

Morwenna [01:39:20] Sorry. Go, Sarah. 

Sarah [01:39:21] Sorry. I know that Harry definitely, on one of his projects, had sensors put in the wall to measure what moisture was happening, and that is a way forward if you are particularly worried, because sometimes it happens only on some particular wall due to a reason that you're worried that there may be more damp penetration, so you can put in those sensors and see what's happening. And so far, at least what I'm aware of from all the studies, if a wall is already wet, it takes a very long time to dry out – years – but if you've got insulation that is breathable, then it does allow it to slowly dry out, and once it's dry and if all the other bits are working fine, the pointing is fine, water's draining away, then it does reach equilibrium. 

Harry [01:40:13] Yeah, I reckon it's really worth pointing people's way to the AECB CarbonLite Retrofit course because they've done some really fantastic work on this and it's really, really invaluable, and there's case studies that go through a lot of this in a lot of detail. And I think one of our projects and the sensors in it have been used as one of the case studies, so we've looking at these profiles through the wall, and I think, I mean, if we go back to that question about the freeze thaw cycles, it doesn't actually freeze that often, at least in the south of England. I'm a bit less aware of, sort of, going further north. I'm sure it is much more frequent, but I haven't personally come across this. 

I'm quite observant on buildings and our buildings and the projects we've done, and what we're talking about is does insulation significantly reduce the temperature of the outer layer of brick by the amount that is going to start to make it be damaged more than it would've been if you hadn't added the insulation. And I think Paul's quite rightly saying, 'Well, actually, it's not that much of a difference'. But having said that, when I was external examiner at Dublin Institute of Technology, I do remember reading a master's paper on the freeze thaw cycle and the potential risks around it, and when you do the modelling, it does show quite a few risks. It's just that we haven't really seen that much of it, and I think it's probably more certain types of buildings, like concrete buildings or other forms of construction where there's a heightened risk. 

Sarah [01:41:40] Yeah, the other bit is the maintenance bit. So maintenance is the most boring bit, and gutters are always blocked or whatever, that kind of thing. So basically, when that is happening, then your brick, if it's being soaked constantly because your gutters are overflowing and things like that and it's already quite wet, then the freeze thaw cycle will affect it more because you've got a brick that's been soaking for a very long time, and it's penetrated through. But if everything is working fine and water is being shed as it is meant to be, then actually, it's very rare to see freeze thaw affect the brick because the water wouldn't have penetrated all the way through the brickwork. 

Harry [01:42:22] And it is worth adding-- 

Morwenna [01:42:25] Sorry. Go on, Harry. 

Harry [01:42:28] So just for our listeners, there's a pause between what we say and what we hear. It's worth adding that, of course, a cement-base pointing is going to lead to much greater damage of brickwork of these conditions, obviously, because the cement is not going anywhere, and the brick is going to expand, and that's going to press against the cement pointing, and that's going to be laminate brick. So obviously when the pointing is the wrong material, it's a heightened risk. 

Morwenna [01:42:59] Absolutely. My point was only to kind of major on that maintenance side of things and I suppose highlight the fact that from my almost gut reaction, not knowing the modelling, which I think is super of you, Paul, to have just gone, 'Yeah, let's model that'. That's great, but it's that element of, like, how far is that risk not a risk compared to the saturation? So as we've come warmer and wetter, we may have less freeze thaw, but we might have bigger freezing events, and the buildings will be wetter because of the sort of continuous saturation, where they're not really drying out. And I think that this is where, in sort of danger to sound like a broken record, if we haven't maintained our buildings, then they are naturally at higher risk. 

So if we, almost as our first action right here, right now, we know that we can all maintain our buildings better. There isn't a building out there that won't benefit from maintenance. And when you look at energy efficiency and embodied carbon and sort of climate change risk and the real pressure to act and act now, there's a kind of-- the terminology is around low regrets. Now, as the action with traditional buildings, the biggest low regret action you can take is maintenance. It will benefit you in terms of energy efficiency, it will benefit you in terms of retrofit measures and it will just generally help all the buildings that we're working on just make them more capable of dealing with the change in weather, whether it's rain today and sun tomorrow, or whether over the next 10/15/20 years that increased rainfall and drought events. 

I think, sort of-- I'm really conscious that we've got only a few minutes, and I was really interested in sort of getting each of your perspectives in terms of the use of traditional materials versus the development of new materials, and I think we've slightly touched on it in terms of insulation materials. A lot of these materials, they're new but they're not new, so we've been using cork and hemp and lime for many years, but the formats in which we are now using them are new. We're thinking about sort of manipulating them in a different way, using them to a different effect sometimes. I wondered whether you have anything that gives you confidence in what you're doing, or is there any joy in terms of where our development with products is going? Harry, do you have any thoughts? 

Harry [01:45:50] Yeah, really happy to start this one off because I'm actually involved in a research project at an Innovate UK-funded project with a young start-up company called [Thermalon?], and they're manufacturing a low-carbon aerogel lime plaster, and we're working with Best of Lime, and yeah, they've got a chemical process that is low carbon, and they're actually researching that now. So we're talking about a lime plaster that has aerogel in it, but it's still going to be vapour permeable but may even just replace lime plaster on historic buildings but have a significantly improved lambda value, so that feels quite exciting. To have a low-carbon version of a traditional lime plaster is really wonderful. It will improve and reduce energy. So yeah, so we're going to be plastering a wall later this year. Watch this space. 

Morwenna [01:46:52] Have you ever used Diathonite? It's the one with cork incorporated in it. I don't know if you-- It's something that I keep looking into for a project that I want to do, and I'm just sort of thinking, this looks good, and then I-- With all the materials that you haven't used before, there is the thought process that goes behind it – I don't really want to get involved in this. Have you used that? 

Harry [01:47:17] Yeah, I think Diathonite's a really interesting product. Again, I think it's ecological building systems that supply it. I think they're listening in today. I mean, with all these materials, you need to understand them and understand processes on site, and so Diathonite is a very different proposition to corkboards or wood fibre boards, where they are adhered to a wall, and Diathonite is literally sprayed on. You need a machine. It's a very different process. It also produces very high levels of moisture during construction, so you've got to be very mindful of this. There's a good blog on this by The Green Building Store, when they used it and they experienced extremely high moisture levels. But if they're managed, if that process is managed on site, I think it's a really great material. Have you tested Diathonite at all, Paul? 

Paul [01:48:08] Well, funnily enough, we're monitoring a building in Appleby in Cumbria with Historic England, where the owner is actually a lime plasterer, and he's very keen on trying different combinations of lime and insulation materials, and that's one of them. But we did some in situ U-value measurements last year, but I think the results were very disappointing because I think the building was still drying out, so really, we were hoping to go back, well, now. 

But that's not possible, so post-Covid, hopefully, we can get back and remeasure the U-values, and again we're monitoring the building for humidities and temperatures and timber moisture contents, and it's an interesting case study because it's prone to flooding. The River Eden in Cumbria floods Appleby regularly, so we're looking at the resilience of these materials as well. 

But at the moment, I would say about these kind of mixed materials, can the manufacturers please some decent figures on the performance? Because you look at the data sheets, and you think how on earth could I even calculate a U-value from this information, because it-- I'm surprised they get past building control because they don't really have any proper thermal conductivities or vapour permeabilities or anything like that, so I think that's sadly lacking. 

Morwenna [01:50:33] Sarah, how about you? Do you have a preferred option? 

Sarah [01:50:37] Yeah, I mean, I'm not against using some of these materials because-- It really depends on what the material is and if the manufacturers understand the listed buildings and how to use it. So lots of times, we come across things that are marketed for listed buildings. They say they're breathable, but are they really? Not really. What is the definition of breathable? It's not as what we need. So that is disappointing and frustrating, and it can be difficult for people because unless you understand that product, you could go by the marketing and make a very big mistake. 

On the other hand, there are those natural breathable materials and new ones coming up, as the one Harry mentioned, which definitely sounds very interesting. They are more suitable and they are a godsend. When you're looking for, OK, you do want to put some insulation in. What do you do? And then you find the handful of materials. There really are a few that are suitable. 

So then it is very useful because you have a material that is at least tried and tested that you can use it, but again, when you're dealing with existing buildings, there are so many unknowns and so many new things, and you're dealing with a brick wall. Is it a brick wall? Yes and no because it's got a lot of other things going on with it as well. And we've had buildings where all three walls were different constructions, so you have to have a completely different set of solutions for one wall, and then another for a different, and then you've got to make sure that they overlap properly. 

And you will always end up using something slightly bespoke, something different, and then you're, kind of, heart is in your mouth because there is no one to go to to ask, 'Have you done this before?' And you've got to make a decision, and it's quite tough sometimes, and yes, sometimes it is a mix of your gut feeling and whatever literature you can find and whatever research that you can find, and you've got to go for it and realise that actually you're the one now doing research on it, and you've got to share the findings with everyone else. So yeah, that's how to do it. 

Morwenna [01:52:49] That's really true. So true. Go for it, Harry. 

Harry [01:52:52] So I really share your feeling there, Sarah, about heart in mouth. I've been there quite a few times. Just one little factoid that I thought I'd just share with everybody is that it's worth remembering that generally the drying of the wall, we've found from-- Are you still there, Morwenna? Yeah? We've got some slight delay going on here. As long as everybody can hear me. Can you hear me, Sarah? 

Sarah [01:53:19] Yes, yes, I can. 

Harry [01:53:21] I'm worried that the technical infrastructure's about to collapse. But we did some analysis where we looked at how much drying goes inwards and how much drying goes outwards and very detailed looking at the hygrothermal history of the wall over a year. And we did find that there was about 25% was drying inwards and about 75% was drying outwards, so I just want to reinforce the importance of vapour-open materials all the way through the structure that allow that drying action to take place, and the reason why it drives inwards is this phenomenon called back diffusion, where the sun hits the surface and any vapour or liquid moisture vaporises in that wall, and it just goes pow and it just pushes through the wall back right into the interior. So if you have membranes, you're actually stopping that at probably a very inopportune moment in the wall, so I just wanted to add that general technical feel. 

Morwenna [01:54:29] Fab. Well, I think we're going to-- time to sort of wrap it up, which has been such a fascinating conversation with you all, and I suppose what I want to do is leave it on a kind of slightly cheesy, but let's go and, sort of, what would you say the biggest barrier is, and what are you most optimistic about? Paul, what would you say the biggest barrier is [indistinct]? 

Paul [01:54:56] Not understanding buildings, essentially. That not only goes for traditional buildings but, say, post-war buildings, where I think some terrible mistakes are being made with insulating cavity wall buildings with external insulation, which is completely wrong, and yet it's still going ahead. So I think people really need to be better educated in terms of, well, I would say it, but building physics to some extent, and more monitoring of buildings. That's what I would like to see. 

Morwenna [01:55:53] What are you most optimistic about, Paul? Do you feel like there's something that's been really great in the last couple of years? You are allowed to say no [indistinct]. 

Paul [01:56:09] I would say no, not really then, other than that we just have to plod on, don't we, and do our best, and I think you're always learning, which is great, but it would be good to see it actually be disseminated to people who really should know building control and building standards, organisations, governmental level so that they really have a grasp of what we're trying to do. 

Harry [01:56:57] OK, so barrier, attitudes is my barrier, and I'd like to discuss briefly the word maintenance, and I would like to compare buildings to bodies, and I would like to say that we generally don't maintain our bodies. We generally try to keep fit, so I'd sort of-- There's something about the way we think about things, the way-- I think keeping your building fit is the sort of slightly nicer way, and I pulled this little thing out. I don't know if you can see this. I don't know if you guys know it, but it's such a lovely, lovely little booklet, and it's just love your building. And it's like, love your body, love your building, care for yourself, care for your building. Don't just maintain it, which sounds so boring and dull, so I think generally, my barrier is about attitude and sort of the approach we have towards buildings. 

And then reasons to be optimistic. I mean, there are so many. Biden signing the Paris accord, the C-Change, all local authorities, 90% of them, pledging to go carbon neutral by 2030. I know they don't have a clue about how to actually do it, but they've pledged it and they're trying to find solutions. I think there's a C-Change of attitude going on, and I think it's an incredibly exciting time to be working with buildings and retrofit. 

Morwenna [01:58:30] Fab. Thank you. Sarah. 

Sarah [01:58:35] Just one other comment from what Harry was saying about talking about buildings like people. It's something my sister once said to me. She's like, 'Why do you talk about buildings as if they're people?' Apparently, that's my attitude, like they're living things. But, like, they are living things. They've been there for so long, so I do tend to talk about that like that. 

I think in terms of barriers, my biggest thing is that people still talk about climate change or climate emergency as if it's about to happen, and what I would say is that it's happening right now. There's no more about to happen. That was way back in the 90s when scientists were warning, 'Climate change is coming. It's coming.' It's here right now. Where I sit from my office, I can see water going over the gutter. The rain is falling so hard, that it doesn't even get into the gutters. It's flying off onto the pavement, and that never happened before. So we are where we are, and climate change is now. 

In terms of looking for the future, I am generally a very optimistic person, so optimism will always win. I think people are more aware of it right now, so what we've got to do is that we've got to do whatever we can right now. So this ranges from the big things to the small things as well, and that ties in with my research as well. There's always something that someone can do, and whatever it is that you can do right now, you've got to start doing it right now. And yeah, we can do it. 

Morwenna [02:00:13] Thank you all. It's just fascinating. I mean, well, I'm pleased that other people look at buildings like people as well as just me, because sometimes do feel a little bit like an isolated geek, and I think that you're so right, Harry. It is about changing that language that we're using. It is about engaging ourselves and our built environment in a very different way. You can say love yourself, love your building and love your environment, and it is about being more positive in our language. 

Earlier I mentioned about breaking that stranglehold of fear. We do need to act, and some of the things are going to be wrong, but I think having the confidence in ourselves and in our networks and to share the knowledge that's out there and the things that we're developing is going to be the kind of absolute key as we move forward and we all have to act. And I think often sometimes, professionals in our sector can be very judgemental, but I think there is an increasing awareness of attempting to get it right and accepting that sometimes we're going to get it wrong that's really, really key.  

I wanted to say that I'm sorry that Nick couldn't do his presentation, and this will be shared, hopefully. I've got a little message saying that they're going to try and share the slides. I don't know whether we could record it separately, but I'm really sad that Nick couldn't join us for the discussion as well, but I'm sure that we'll be doing it again. 

I wanted to thank all the people behind this. The tech team have been brilliant, and I know that they've had real trouble today, so thank you for your patience, everyone who's joined us. There is a little form, sort of a survey, to fill in after this, and it would be great if you could do this because all the feedback helps us disseminate better and wider. And personally, I'm very keen to know where we go from here. Energy efficiency has been a watchword for a very long time, and I've been taking part events like this for, sort of, well over ten years, and I'm really keen to know where everybody's interested in going next. So that will be part of the survey, so if you can take your time, you can help shape us with our future events. 

So that leaves me just to say thank you very much to all our speakers. So interesting. I wish we could be there in person and repair to the bar. But we will have to do that in the future. I'm not sure if I'm handing back to Alice or Matt or anyone, if anyone's there. 

Alice [02:03:03] Hi, Morwenna. It's Alice. Alice is back. Hello. Hi. 

Morwenna [02:03:08] Thanks, everybody. Thanks for joining us. 

Alice [02:03:13] Thank you, everybody, for joining us.