Webinar on Energy Assessment: Theory versus Reality

Here you can find a webinar recording on how historic buildings really operate, and the importance of not neglecting the building occupants in the assessment equation. You can also read the content from the Q&A session. The webinar was recorded on 19 July 2022 as part of our 'Technical Tuesdays' webinar series.

Webinar recording

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Matt Faber:

And welcome everybody on this extremely hot day. And thank you all so much for your tips and thoughts on how to stay calm in this. Hey, I'm personally loving sticking my feet in a bowl of cold water. I'm certainly going to try that one moving forward.

Good afternoon, everybody. Welcome. My name is Matt Faber. I am today's technical host, so you'll be glad to hear it's not me giving the presentation because we have our presenters today who are better informed that I am on this subject and you certainly would not want to hear me blathering on for an hour or so.

So, before we start, I should make you aware of a little bit of housekeeping. So it'll take a couple of minutes. So just to let you know that this webinar, as with all Historic England webinars, is being recorded and the recording will be made available for the Historic England website, a link to which I will give you at the end of today's session.

You will notice also an array of icons at the top of your screen. The loudspeaker icon you can adjust volume. So if our presenters are a bit too quiet or a bit too loud you can adjust the volume there. You'll also see a little icon that looks like a handprint or a raised hand. So you can use that to bring something to my attention.

But also that's a really good way of making sure in the first instance that you can all hear us. So before we move forward, please can I ask you to click on that icon and that will tell me that you can all hear me. That's fantastic. That is the Historic England Mexican wave coming in. That's wonderful. Thank you so much.

Brilliant. Okay, let's move forwards. You'll also notice at the top of your screen there's an icon that says CC. If you use the little dropdown arrow to the right of that icon, you'll see that that enables you to use closed captions. All our webinars use closed captions and those closed captions will be also available on the recording. If you enact closed captions, you'll see a black box in front of your screen.

You can adjust the type size if you need a larger typeface, you can do that. You can adjust the size of the text box and you can also adjust the colour of the text as well. As I said before in the recording, closed captions are also available.

We're also happy to provide a transcript if that's something that would be of use to you.

Moving forwards, I can see that a lot of you are using web browsers. I would at this juncture advise not using Internet Explorer. It's not particularly stable with the platform we use, which is Adobe Connect. We would always recommend using Google Chrome or indeed using the Adobe Connect app.

If you'd like a link to the app, I can put that in the chat. So please just say chat that you'd like to link to the app. I know obviously, some of you are working on organizational pieces, but IT might actually not be able to install it for you, in which case the web browser is your go-to option during the webinar.

If you have any comments or questions, please put those in the chat. I can see you. We've all been populating the chats readily already, so any comments you have for questions for our presenters, please put those in the chat. We will respond to your questions either during the session or if not at the end of the presentations during the Q&A session?

That said, it is for me now to make the switch. It's now for me to introduce our chair for today, Robyn Pender, who is the Historic England subject expert for. Well, you tell me, Robyn, what are you the expert in? I mean pretty much everything from what I can see.

Robyn Pender:

Jack of all trades master of none. I’m from the building climate change adaptation team working with Morwenna Hughes and Joanne Williams and we are soon to get more members which is brilliant and I'm doing this today with Katie. Katie over to you to introduce yourself.

Katie Parsons:

Hello. Thank you. I hope you can hear me. I'm one of our historic environment planning advisors.

Our climate change work is something that's taking up most of my time at the moment as it's such a major priority for local authorities and the public generally. So knowing more about the energy assessment of the EPIC program is always, always really crucial for helping us focus our advice in a more practical way. So I hope everyone can take some tips away and some knowledge away from this presentation.

So I'll hand back to Robyn.

Robyn Pender:

So welcome to the third of a three-part series looking at carbon and energy in the built environment. And our first webinar in this series was with my boss Morwenna Slade, and me in conversation with Simon Sturges who wrote the RICS guidance on carbon assessment. And the second was Morwenna and Adala Leeson, now head of socioeconomic analysis and evaluation as the person who brings Heritage Counts reports to life talking about the challenges of carbon assessment with Alice Moncaster of the Open University, I'm delighted to see is in the chat already today too because Alice, of the many things she does, is Freya’s supervisor.

If you missed out on those earlier webinars or would like to watch them again, you can catch up with them on our previous webinars page and Matt is going to post a link for that in the chat. If you'd like to be sure that you find out about all our webinars and about all the other things that technical conservation is up to well in advance you can sign up for our Technical Conservation newsletter just by clicking the button on this poll. Don't worry if you can't remember whether you've already said yes in the previous webinar because our system does cut out the duplicate addresses. And of course, you can unsubscribe at any time just by dropping us a note, but we're hoping you're going to find all of our news is just so enthralling that you're always delighted to see it popping into your inbox.

OK back to carbon and energy. There's just so much of a focus these days on the building fabric, but of course, it's not the building that uses energy, it's the people using the building. And everything we do takes place in or around a building. So understanding that human element is the key to being really sustainable to really deal with changing climate.

But it's been quite shocking how little the way that buildings are used is being taken into account in all the actions that are meant to deal with the climate emergency and really sustainability in general. That's why it gives me the greatest delight to be introducing you to Freya Wise. And if you haven't heard her talk about her research before, then I keep saying it, but it's true, you're in for a real treat. Freya has just completed her PhD viva at the Open University on just this topic. So she's Dr. Wise now in all but final announcement and it really couldn't be better earned. Her research approach was impeccable and the outcomes are super important. Freya is a little bit of an allrounder, that's her painting as well.

And her first degree was in environmental and earth science. But she also has an MLit in war studies from the University of Glasgow. She was led by an interest in history, especially military history, from ancient times through to the 18th century. So for Freya, military history is a product of the society, and that's why she's keen on looking at how social, political, technical history all intersect together.

Her bio at the Open University says she likes to combine the what and how of hard science with some of the why of social science. And I suspect she shares that with quite a bit of our audience today. Freya is going to take us through her amazing PhD research and after that will have time to talk in more general terms about what it all means to getting on the right trajectory towards sustainability.

So don't forget to put your questions in the chat, and if you could remember to prefix the questions with a Q for question that will help us spot them. And so with no further ado and the very greatest pleasure, I'll hand over to Freya. Freya, the space is yours.

Freya Wise:

Thank you, Robyn. And hello, everybody. Hopefully my presentation will magically appear. Yes, it's magically appearing. Excellent. It's lovely. Yes. So as Robyn says, I've just finished my PhD investigating ways to reduce carbon from residential heritage buildings while retaining their heritage values. I've examined technical aspects of retrofit and aspects relating to building residence.

So today I'm going to give you a little bit of background and then a summary of my research drawing out some more details in two areas: energy modeling and window retrofit considerations. I'll then conclude with some implications before opening up to questions.

So it's become very clear that we need to dramatically reduce carbon emissions from built environment as part of wider carbon reduction efforts to prevent devastating climate change. In Europe, the rate of building stock replacement is around 1% per year, so efforts need to focus on massively upscaling and accelerating the energy retrofit of existing buildings.

This includes from older buildings with heritage value, which come in many shapes and sizes and shape the character of our rural and urban areas at both the national and local level. In the UK, around 20 to 30% of homes are likely to have heritage value, although only around 5% are officially designated through listing or conservation areas as official heritage buildings.

And so we have a question for you, I believe that's okay.

So if you'd like to see what you think about that one.

Matt Faber:

It's always interesting watching the votes coming in, because sometimes it's not always what you're expecting. Yeah, the attendees currently can't see the results, so we'll keep them blind until we've got enough votes in and then we can have a look at them. So yes, they're still coming in thick and fast.

Robyn Pender:

It's interesting. There is still that conception, which I hope we're going to be destroying today.

Matt Faber:

Okay, let's broadcast the results so everyone can see them.

Freya Wise:

OK, so ‘about the same’ and ‘harder’ are winning, ‘harder’ is winning just about. Yeah.

Robyn Pender:

We'll have to ask the same one at the end Freya.

Freya Wise:

Yes. That would be interesting.

Matt Faber:

Okay, let's move that up.

Freya Wise:

Okay. So, yes, the need to conserve important heritage values and the often traditional and regionally specific construction of heritage buildings can present challenges for energy retrofitting. Policy designations are often taken as the arbiter of acceptable changes to heritage buildings and residents' views are often overlooked with little research into the values that they invest in their homes or the barriers that they face in retrofit decision-making.

However, owner-occupied homes make up 63% of UK residential buildings, and in these homes, retrofit is predominantly instigated, managed, and largely funded by residents. If they do not find a retrofit measure acceptable, they will not enact it.

Understanding residents' views and values are therefore important to understand and increase retrofitting rates and to help mitigate climate change. And so my research has investigated technical aspects of buildings through detailed energy simulations and modeling the lifecycle carbon impact of a range of retrofits.

To inform this model and assess the potential for realistic carbon reduction I've also examined aspects relating to the building residents identifying their heritage values, views on carbon reduction and retrofit barriers and energy behaviours and perceptions of comfort.

I created an online survey to provide a broad perspective of residents' views, values and behaviours, and then followed this up with 16 in-depth case studies involving interviews, building tools and technical surveys and participant energy diaries.

I created detailed energy simulation models of the case studies and assessed the embodied, operational and lifecycle carbon impact of a wide range of retrofit measures.

My research focused on the county of Cumbria, which is mainly rural upland region, which also includes the Lake District National Park, which is now a cultural landscape, World Heritage Site. The survey responses and case studies covered a range of building types, ages, mutations, household compositions and energy usage.

Three of the cases were listed, six were in conservation areas and seven were undesignated. Six were within the Lake District National Park and one was in the Yorkshire Dales National Park.

This research has led to a range of interrelated findings in six key areas. We're going to briefly cover findings in the first five areas. Look at energy modelling versus reality in a bit more detail and then use the example of windows to describe some of the complexity around residents' views and values and provide some retrofit modelling results. We’ll then finish off by discussing some of the implications of my findings.

So the heritage values residents invest in their homes are often overlooked in both policy and the academic literature. However, my research has found that residents invest significant values in their heritage buildings, often relating to their sense of connection to location, materials and previous occupants. Residents particularly valued aspects relating to the context, construction, character and connection with their homes.

The majority of residents, in both designated and importantly in undesignated buildings in sorry, Matt, could we have the one before? If I click back, will it mean that we're okay now? It keeps disappearing. Sorry about that. Okay. Anyway, the majority of residents in both designated and designated buildings invested heritage values in their homes. They thought they had heritage value.

And these affected the types of retrofit measures that they considered acceptable, especially in terms of those that have an external visual impact on the building, such as external wall insulation and window replacements.

Residents’ heritage values meant that if they did not find the retrofit measure acceptable, they would not enact it. But they also considered a range of barriers to be important.

So, the slides seem to be doing something a little odd. Apologies about that. So we have another quick question for you I think.

What barriers do you think are most important to residents?

Matt Faber:

We have one or two people saying that they're having issues with sound whilst we're waiting for those votes to come in. Freya, if you're able to increase your microphone volume, that might help. Also for our listeners or attendees if it's very quiet or if Freya’s voice is very quiet, please go to the loudspeaker icon at the top of your screen. Use a little dropdown menu to select adjust, adjust volume and hopefully you'll be able to increase the volume that way as well if that's a problem for you. Also, that might be the case if you're using web browser to press the reload button, or the refresh button to reconnect with this session. So apologies to people who are experiencing sound issues. Okay, so the votes are in. There we go.

Freya Wise:

So cost, cost is winning and then knowledge of options and finding suitable tradespeople.

So very good.

OK, so if we can move on, then you'll see what the residents that I surveyed thought.

Here's a clue for you, they agree with you. Yes. Cost, knowledge of suitable options, heritage values and availability of tradespeople were key barriers for people, particularly finding trustworthy knowledge. Trustworthy information sources was a key problem, and finding tradespeople who could work with all the buildings.

So the International Energy Agency has recently emphasized the behavioural changes across many aspects of life needed for us to reach more carbon goals. However, the diversity of residents’ energy behaviours is often neglected by policymakers in favour of standard assumptions. While behaviours are acknowledged as important, they aren't necessarily well understood in heritage buildings.

The majority of residents in this research, both in the survey and the case studies, already engaged in the range of common positive energy behaviours, including wearing extra layers in cold weather and only heating actively used spaces. Around a third of survey respondents didn't heat their bedrooms and the majority of the case study participants didn't or only minimally heated bedrooms with participants citing an enjoyment of cooler spaces and fresh air, often leaving their windows open.

There was some interest in smart home technology. However, this wasn't something that the majority of residents currently engaged with, and there were suggestions that challenges with rural internet connectivity might be an issue for people.

The average temperatures the survey respondents reported heating their main living space to, in winter of course, was 19 degrees, which is two degrees less than the assumed UK average of 21. And the average from the case study participants was 18 degrees.

So I think we've got another question for you, I'm afraid. Sorry.

About what temperature you heat your main living space too.

Robyn Pender:

Oh, can I try too.

Freya Wise:


Matt Faber:

I should say my father used to keep his temperature throughout his house, all the rooms at 24.

Robyn Pender:

In my grandparents, it is 15 to 16 by preference, wherever they lived.

This set kind of fits with what the residents said too, doesn't it? Yeah. Yeah. Way different to the assumptions.

Freya Wise:

And you had to check your thermometer.

Robyn Pender:

Ah, don’t get me started on thermometers.

Matt Faber:

Excellent. OK

Freya Wise:

Lovely. Interesting.

So residents' behaviours were found to be consistent with adaptive comfort principles, with residents making use of personal and spot heating, including hot water bottles, electric blankets, and the use of various types of stoves and portable room heaters, in preference to higher central heating settings. In the case studies regular use was made of jumpers, slippers, blankets and other traditional thermal comfort mechanisms, with some participants, even mentioning that their cats or dogs were very warming on a cold evening.

So there we are, that's the top tip for keeping warm evidently.

Case study participants also highlighted the benefits of traditional features such as draft lobbies, window shutters and heavy curtains to reduce heat loss and thus energy demand. These types of features can also have the potential to maintain or even enhance the heritage values of the building. These behaviours are very different from standard assumptions more likely to result in lower energy demand.

Improving comfort is often considered a key motivator for retrofitting and heritage buildings are often considered to provide poor comfort for residents.

However, the comfort perceptions of heritage residents in the UK have received very little research attention and those studies that have considered this topic generally focused on low-income households who may be more likely to have poor perception to comfort due to fuel poverty.

The vast majority of survey respondents and all but one of the case study participants were content with overall comfort in their homes.

However, a significant number of survey respondents would like their homes to be warmer in winter, but only 10% identified their homes as currently cold, and while several of the case study participants were aware that their homes might average it when they were nearly all content with this and were comfortable with current conditions.

In summer meanwhile, the vast majority of residents identified excellent performance with their homes keeping comfortably cool.

And I believe we have people in the chat talking about their wonderful traditional buildings earlier.

That's good and this was also emphasized by the case study participants, several of whom compared their heritage buildings performance favourably to more modern buildings that they’d experienced.

This excellence in the performance may be very characteristic in the predicted increase in future temperatures, and extreme heat elements.

For some respondents, damp was a challenge with the case study suggesting that many residents this was the result of previous maladaptions where incompatible materials had been used on their buildings while maintenance has been neglected. This is clearly an issue that needs addressing.

I'm sorry. When I change slides it seems to flip through the first photo. I'm not sure why that's doing.

Apologies, but moving on to ventilation.

And so when thinking about ventilation, although 54% of respondents consider their homes drafty or very drafty, only 21% would actually prefer less drafts.

Whereas as mentioned above, many of the case studies liked cooler bedrooms, open windows. So fresh air is apparently in favour in Cumbria.

Poor housing is a serious issue and support is needed to improve conditions for residents in these circumstances. In general, however, these findings suggest that the majority of heritage residents, in Cumbria at least, may be quite content with their current indoor environments.

This may mean that improving comfort isn't as strong a motivator of retrofit of some heritage residents as may be generally assumed.

Moving on to more technical aspects, embodied carbon is that associated with the manufacture, transport and installation, maintenance and end of life of a retrofit. While the lifecycle carbon includes the embodied carbon cost and hopeful operational savings of a retrofit.

This research emphasized the importance of considering the life cycle rather than just operational carbon of retrofit options, with some retrofit options found to actually increase lifecycle carbon, despite making operational savings.

Embodied carbon also affected the most appropriate retrofit measures with solar thermal panels, for example, being a better option in lifecycle carbon terms compared with solar PV for the majority of case studies.

We’re on to question 4.

So I think we need to move to presentation part two.

Okay. So using data from the case studies, three energy simulation models were assessed and I’ll explore one of them in a bit more detail.

A key policy relating to energy use in buildings is the EU’s Energy Performance of Buildings Directive, which mandates, amongst other things, for the production of energy performance certificates, EPCs, which have been transposed into UK law since Brexit.

You’re likely to be familiar with this, but EPCs list a building’s band of energy efficiency from G to A, with G being the worst and A the best. They also list the carbon emissions of a building and contain recommendations to help owners and occupiers improve the energy efficiency of a building.

For each recommendation, the indicative cost, typical cost savings and performance after improvement are listed.

The aim of EPCs is to make the energy efficiency of buildings transparent when buying or letting property. However, across the UK and Europe, EPCs are also increasingly being used as tools to promote the retrofit of existing buildings through the development of minimum energy efficiency standards or MEES. These currently mean that buildings in the UK cannot be let unless they have a minimum EPC rating of E or above.

And there are plans to increase the minimum rating requirements and extend MEES with targets for all properties to be sold or let to reach band C by 2028.

EPCs are therefore a key policy instrument and have become a de-facto tool to inform retrofit in the UK.

The tool used to produce EPCs for existing buildings is reduced SAP, which is a less detailed version of the full standard assessment procedure model used for new build.

Reduced SAP is relatively simple to use and relies on a number of assumptions to quickly produce energy ratings, although it can only be used by qualified assessors.

Assumptions include standardized behaviours where residents are considered to heat their main living spaces to 21 degrees and the rest of the buildings to 18 for specific periods each day. These assumptions are very different to the behaviours of heritage residences examined earlier.

Assumptions made to enable comparison between different buildings. However, if reduced SAP is to be used as a retrofit tool, then it's critical that it takes account of residents specific behaviours.

Having qualified as an EPA assessor, I followed the official conventions to create EPCs for the 13 case study buildings I was able to visit before the pesky coronavirus pandemic came along and meant that I couldn't anymore.

And as you can see reduced SAP significantly overestimates the heating and hot water demands of the case study buildings, with the average overestimation more than 11,000 kilowatt hours or 57.4%. Only heating and hot water is shown here because reduced SAP doesn't include plug electricity loads, so electricity demand is not comparable.

Reduced SAP particularly overestimates energy demand for CS3 and CS11. CS3’s household is often away for work, so their energy use is less than would be expected. Whereas CS11 is a committed environmentalist who only heats his living room and uses wood burning stove for that heating because he wants to keep his carbon emissions as low as possible.

Two of the case studies where actual modelled energy demand are closer are CS6 and CS12 with CS12 being the only case where demand is in fact slightly underestimated by reduced SAP.

Other research has shown energy demand for modern, supposedly high-performance buildings, is often underestimated by EPC models. Both CS6 and CS12 have large modern extensions, which may therefore contribute to the closer actual reduced SAP figures.

Despite the fact that plug loads are not included in the reduced SAP figures but are included in the case study figures, overall carbon emissions are also significantly overestimated by reduced SAP by an average of 62%.

This overestimation is exacerbated by the fact that reduced SAP uses out-of-date carbon factors, in particular, for electricity. Grid decarbonization means that current emissions from official BEIS data for 2021 are 231 grams of CO2 per kilowatt hour, compared with 519 grams used in reduced SAP.

The UK Committee on Climate Change recommends that all buildings should reach EPC band C by 2028. They've also highlighted the need for EPC reform.

Using reduced SAP I modelled the EPC recommended retrofits to all the case studies to reach band C. I then compared the predicted energy demand at band C with actual current energy demand.

As you can see for six of the 11 case studies after band C retrofit reduced SAP still overestimated predicted energy demand compared to current actual demand by an average of 14.5%. Carbon emissions mean still overestimated after retrofit for band C for ten of the 11 case studies by an average of 30%.

The process to generate EPC ratings is rather opaque and based on energy costs as well as building performance. It was therefore not possible to calculate a more realistic EPC rating based on actual performance.

EPC ratings, however, do not reflect actual case study energy demand. The highest rated cases are in the middle of the range of actual energy demand per metre squared. Meanwhile, the lowest rated buildings have both the highest and lowest actual demand.

These low-rated buildings, CS11, CS1, CS2, and CS7 use wood, oil, electricity and oil respectively, while other case studies use gas. Rankings based on cost, the use of out of date carbon factors therefore don't really provide much of an incentive to reduce the use of fossil fuels.

In addition to not taking account of residents' behaviours reduced SAP also poorly represents the performance of traditional construction. The options for stone walls are sandstone and limestone or granite and whinstone.

For CS1 reduced SAP ticks a U value of 2.34 for the walls, while measured U-value for similar thickness sandstone walls by Historic Scotland suggests the U-value of around 1.4, which, while still a long way from the building regulations value for new walls, is still significantly better than the reduced SAP prediction.

More detailed modelling that I've carried out considering wall compositions and more accurate materials is predicted U-values 23% lower than those predicted by reduced SAP.

Finally, recommendations only consider technical measures commonly suggesting solid walls insulation and window replacements for older buildings, which may have an unacceptable effect on heritage values. It would therefore appear that for heritage buildings reduced SAP is not fit for purpose as a retrofitting tool, as it doesn't reflect the reality of residents or their homes.

So, do these heritage buildings actually have high energy demand?

If we compare heating, hot water and cooking demand with UK averages and taking into account floor area, it would appear that they don't.

Of the 13 case studies, nine have below average energy demand per meters squared and the case study average is lower than the UK average. This is not to say that it's not critical to reduce carbon and energy demand from these buildings and indeed all buildings.

However, it would appear that heritage buildings may have lower energy demand than often assumed. It may be that this assumption comes from their poor representation in standard models. So perhaps what we need is better models rather than better buildings.

There isn't time to go into detail for all of the retrofit measures that I investigated. But let's take windows as an example as they show many of the issues identified in the research.

Windows are often a focus of retrofit efforts to improve thermal performance and reduce infiltration in older buildings. However, they are also often an important feature of heritage value, and the replacement of original windows is often a contentious issue in planning when dealing with designated buildings.

Research in this area has tended to focus on planning interpretations of acceptable changes, identifying that in different areas, rules are sometimes interpreted in different ways. This can mean identical buildings in different areas can receive different decisions on the same retrofit.

This planning inconsistency is also something that residents in both the survey and case studies identified often over time within areas as well as between them, alongside a lack of enforcement when changes that flouted the rules were made.

This issue can sometimes lead to a rather patchwork effect, even in very small areas or indeed individual buildings. As you can see with this one.

Robyn Pender:

Patchwork, indeed.

Freya Wise:

Absolutely. So all of the case study residents with original windows identify them as features that they valued. This was just as true for residents in buildings that were not officially designated and in a range of building types and ages.

Most of the residents had sash windows. However, there were also a range of other window varieties. Residents invested values in all of their window types, something that was also supported by the survey findings.

In particular, residents liked the age of their windows. Several also emphasized that they appreciated the look and character of the original glass as a result of its traditional manufacturing techniques.

A number of residents also had traditional additions to their windows, such as shutters or thick heavy curtains, when they felt these had significant thermal benefits.

Six of the cases also had at least one set of internal shutters and highlighted their benefits in reducing heat loss in winter and playing an important part in keeping their homes cool in hot weather.

So if any of you have shutters that you're using to keep your house cool, do let us know in the chat.

Participants were asked how acceptable different window alterations would be to their heritage values and it can be seen that the most acceptable changes were additions to existing windows rather than full window replacements.

In particular, modern double glazing with UPVC or aluminum frames were not acceptable to majority of residents in this research, something emphasized by the interview comments. The acceptability of window alterations was very similar across both the designated and undesignated cases.

Interestingly, external shutters were universally considered unacceptable by the case studies when the interviews revealed that this was because they did not think the exterior shutters were culturally appropriate for Cumbria, although they did acknowledge that this would be different in other countries where external shutters will warm.

A few of the participants felt internal shutters would also not match the character of the homes, although most of these houses are likely to originally have had internal shutters.

Participants identified a number of barriers to window retrofits.

Cost was a key barrier, especially if something unusual or specialist was required. Residents appeared to be generally willing to pay significant amounts, running to over £1,000 per window for options that were acceptable to their heritage values.

However, not all of them could afford to do so. In general, if they could not afford a heritage sensitive option, they would rather leave the windows as they were instead of making changes that were unacceptable to their values.

Concern for heritage value was also seen in concerns that participants identified around finding appropriately skilled tradespeople to make and install retrofit measures, especially for things like shutters or the reconditioning and draft proofing of existing windows.

For some designated homes planning was also a concern to residents, especially as they felt that decisions could sometimes be irrational.

Three participants expressed concern around the potential reduction of ventilation that could be caused by secondary glazing, particularly CS14 who had damp issues with their home and managed these with ventilation. CS5 meanwhile, had installed their own thick secondary glazing in the northern facade.

They didn't mind not being able to open these windows as they faced a road, but they were cautious about installing further fixed glazing that would reduce their ability to open other windows.

This highlights the importance of considering individual retrofit, such as window changes as part of a whole house retrofit approach, which includes things like considering ventilation strategies.

Maintenance was also an issue highlighted by many residents. Some of their windows had been allowed to get into a poor state of repair either by themselves or by previous residents, and they were now expensive and challenging to bring back to proper working condition.

In addition to the reduced SAP modelling, I also undertook more detailed energy modelling for a wide range of retrofit measures using the modelling tool design builder to create calibrated models for 13 of the 16 cases.

The results for windows showed operational energy and carbon savings for replacing original windows with double or triple glazing, were between 1 and 7% overall energy and carbon from the building and a very similar level of savings for window additions of between 0.1 and 7%. The level of savings was dependent on the types of windows already present.

In addition to the operational carbon, I also considered the embodied carbon to calculate the retrofit with the greatest lifecycle savings for each case. The addition of either internal shutters or secondary glazing to the existing windows was found to make greater lifecycle carbon savings than replacement with triple glazing for 7 of the 13 cases.

This demonstrates the importance of taking a lifecycle perspective when considering retrofit options, as sometimes more heritage sensitive options are also better in terms of their carbon saving potential.

More heritage sensitive options may therefore also have good potential to reduce lifecycle carbon.

The example of windows has highlighted some of the many issues around the need to consider residents' views and values, to use accurate models and to assess embodied as well as operational carbon as part of a holistic approach to retrofit.

It may not all be about windows, but it would appear that quite a lot of it is.

So let's have a look back at some of the key implications of this research.

Firstly, if the findings about the numbers of residents who invest heritage values in both designated and non-designated older buildings hold true beyond Cumbria. It could mean that just under one in three UK homes may be considered to have heritage value by their residents, which affect the types of retrofit measures that they consider acceptable and would therefore enact.

Many of the residents that I spoke to were keen to reduce carbon from their homes. However, they often felt that there wasn't a valid retrofit offer for them which was compatible with their heritage values as they were only aware of measures such as wall insulation or window replacement, which they were not willing to do.

Improved knowledge of heritage sensitive options is also needed as a key barrier that residents identify is a lack of context specific information from trustworthy sources.

Support with cost and maintenance is also required.

Energy behaviours are incredibly important and we need to stop neglecting residents and their behaviours because after all, it's the residents that use energy, not the buildings. Buildings are really good, very energy friendly.

When you put people in them, that goes wrong.

Much greater awareness of these varied behaviours is needed and simulation models should be tailored to actual behaviours if they are to inform effective retrofit.

More research on the comfort perceptions of residents in older buildings is needed, and we need to find ways to have national conversations about comfort so that while working to improve poor housing and address fuel poverty, it's also politically acceptable to suggest that if we want to save the planet, people should probably be wearing jumpers, although maybe not today.

Comfort perceptions shouldn't equate to walking around in a t-shirt and shorts in mid-winter. We also need to recognize the positive as well as negative features of older buildings, including traditional features like shutters and the fact that many of them can provide excellent summer comfort.

This should be factored into retrofit so that in efforts to reduce winter energy use summer comfort isn't lost, especially given future climate predictions.

The reality of energy demand for older buildings in this research is not reflected in assessments EPCs mirroring findings from other studies. If the building isn't using as much energy as expected because models are not accurate, then retrofit measures won't save as much energy and carbon as predicted because you can't save energy which isn't being used in the first place.

This can jeopardize both financial and environmental targets as lower than predicted energy and carbon savings can lead to longer financial payback times. It can also affect our overall ability to meet carbon targets because limited resources for carbon reduction need to be focused in the most effective ways, which relies on accurate modelling.

Changing might also be made to save carbon negatively affect the building's heritage values.

But if savings are lower because actual energy use is lower, they may not be the best measures to take and could cause needless loss of heritage.

If EPCs are going to continue to be an increasingly important policy tool for carbon reduction, then modelling tools to assess these buildings must more accurately reflect their performance if these policies are to result in actual rather than only predicted carbon savings.

Embodied carbon of retrofit measures needs to be assessed to enable a life cycle approach to retrofit to be taken.

This will help inform the most effective retrofit measures and make sure that all measures installed lead to lifecycle, not only operational carbon savings.

There may be some synergies between more heritage sensitive options than those with lower embodied carbon. While some of the retrofit measures residents find acceptable, such as windows shutters, may have a small individual impact, they will still lead to greater carbon reductions than no change at all, which is often what currently happens when residents don't consider any retrofit measures to be acceptable.

And if these types of solutions could be scaled up, they could be:-

  1. quick and easy to install, reducing pressure on the construction industry
  2. reducing costs as they become more mainstream and
  3. lead to significant carbon savings if scaled up.

For example, based on my case studies, if only those measures that residents considered acceptable were made, and if this could be applied to all UK homes built before 1944, that could equate very roughly to around a 10% reduction of all UK residential carbon emissions.

Obviously these case studies are not representative of the whole building stock, but it is still likely that significant savings could made quickly, which, given the urgency of the climate emergency, can't be a bad thing.

Overall, my research has found that significant reasonably realistic carbon savings are possible through retrofit that respects heritage values. But for this to be possible, it emphasized the need for a holistic approach that considers residents' values and behaviours, makes use of better models and assesses embodied carbon, recognizing that residents and their buildings have an interlinked and symbiotic relationship.

Thank you very much for your attention.

If you're interested in more information on my research details are available on my profile.

Robyn Pender:

Oh well, I knew that would be amazing. Thank you so much Freya.

You can see how incredibly important this work is for understanding what we should and shouldn't be doing to our buildings if we are really going to make any sort of success of tackling climate emergency. And, you know, those models there based on some very strange misunderstandings of how people and buildings work.

So they really do need to be picked quite a long way. But when we do it unpicks to the point where you get suddenly a whole lot of very simple solutions to these otherwise really intractable problems, suddenly they become simpler.

Matt, do you want to move on to the question slide set.

Matt Faber:

Yes, indeed.

Robyn Pender:

I've just got a little bit of an intro first.

Okay. So at the moment, the buildings we developed before we started relying on fossil fuels are being called hard to treat or problem buildings. But clearly that's topsy turvydom. But what Freya and others have found is how important the people are in this. And that's not just useful if you happen to live in a lovely old building in Cumbria.

It's also critical if you live in a bog standard 20th-century terrace and equally if we look at the rest of the built environment, including what C Smith calls the energy pigs, we really need to start thinking about the whole issue, not just the buildings, but built environments and not just built environments, but people and the things that people put into their building’s environments under the expectation they'll make things work better for them.

And that's where the energy really is going. And that's what we need to understand if we're going to make a difference, because we have to remember that the amount of energy being used has been skyrocketing since the 1990s. So fabric isn't where it's sitting.

We really shouldn't be talking about fabric first. Even for new build, it's actually people first.

What do they need their buildings to do? As Freya said a building without a person in it. That's fine. It’s just a building and how do they achieve what they need to do without using masses of energy and carbon?

So without more ado I think I'll hand over to Katie to begin our question session.

Katie Parsons:

Hello? Yes, I had a question.

I wonder, Freya could potentially go into a little bit more detail on them. I would be really interested in knowing a bit more about what residents themselves thought about the different types of retrofit measures that end up being suggested through the EPC process. I think it's really helpful for all of us here to know a bit more about how things are playing out on the ground.

And obviously, visual impacts are always a consideration and the sorts of work that we do at Historic England and Conservation Officers have to consider things like that. But it would be interesting to know if it's also a factor in residents' preferences.

Freya Wise:

So what we've got here are the recommendations that the EPC certificates produce for each of the case studies and it's colour coded with how acceptable the measures are to residents.

And so you can see that there's quite a lot of red there. The red is that they wouldn't do these changes. And most of the red ones are around replacing windows with double glazing and around having wall insulation.

So those are big, big no, nos for people and I will just mention that my research was focused on Cumbria and nearly all of the buildings I was looking at had bare stone facades.

So external wall insulation is definitely not something that people would not be keen on. Maybe in areas where there are more rendered buildings, it might be less of a problem.

Robyn Pender:

But that might be something we need to look at because, actually, the best thing you can do for retrofit is maintenance. And the buildings probably were rendered originally and to keep them working a good render is probably a good place to start, especially if they've got damp problems to begin with as they probably do if they haven’t got a render.

So that's something that we were going to have to get our heads around again. The Victorians took them off. We might need to be putting them back.

Freya Wise:

That is absolutely true, but I'm not sure that Cumbria Tourism would allow it. It doesn't look so good with the nice stone cottage if you cover it in render.

Robyn Pender:

Yeah, because there's a clear reluctance. Yeah. As Katie said, there's a reluctance to pick out measures that have a visual external impact. Not interestingly for solar panels.

Freya Wise:

No, indeed. People seemed more relaxed about things on their roofs. So the solar PV panels and to a lesser extent, solar thermal panels. Interestingly, some of the residents thought that solar thermal panels would have a larger visual impact than solar PV, which is a little odd because, you know, solar PV, you'd have to cover a large area of the roof.

I mean, it was quite interesting that. I don't know whether some of the interest in renewables is around showing their green credentials on their sleeves, perhaps. So solar panels is a very obvious, look, yes, I'm doing something really, I am saving the planet.

Robyn Pender:

It’s fine as long as your roof doesn't leak back to the same thing.

Yeah. The condition of the building is another thing that's not considered in EPCs, is it?

Freya Wise:

No. No, indeed. So a number of case studies had severe, damp issues. There was one where they had a stream running through their cellar and poor sandstone walls with impermeable render on the outside.

Robyn Pender:

Ah, lovely.

Freya Wise:

A chimney that had been full of water and acting as a water tank on the side of the building for several years, which they had just got sorted. So that was good.

Robyn Pender:

Is that one of the ones that was performing quite poorly?

Freya Wise:

Yes. So they were struggling quite a lot because they had to have low-level heating all year round just to get rid of some of that damp issue. But they normally managed it with ventilation.

Robyn Pender:

But they'll be happier again when they've got the damp sorted out.

Freya Wise:

They would be. But it was interesting talking to the lady, I was saying, so have you ever asked anyone about the damp, about how to do it? And she said, well, no, not really, because if you get a damp sorting expert in to look at where it's coming from, what you're actually doing is you're buying whatever solution they happen to like.

Robyn Pender:

Oh, I can hear Ian screaming in the chat about this.

Yeah, this is the problem of course if you go to the wrong people, and we really need to, to me I think there's a huge problem sitting with all buildings, not just old buildings, whatever that means, not just modern buildings, whatever that means, but with all buildings, how they function. Even a lot of builders don't understand that anymore.

So the critical thing that we need doing doesn't get done or gets almost done wrongly. Like for instance, putting in cement renders.

Freya Wise:


Robyn Pender:

Yeah. Let me see. We should pick a question from the audience because we could keep questioning you for ages, but that we can do anyway.

So where's a good question.

Do you think the respondents were honest in their answers and what are their sort of ages? Something about the demographic, a few people were asking about the demographic.

Freya Wise:

Yeah okay. So the survey we didn't ask people about demographics because in our experience, what turns people off surveys more than anything else is at the end where you go and how old are you? What's your economic status? So we didn't ask that, but the case studies were drawn from participants in the survey and provided a really good range of different people.

So we had a number of retired folk, we had a number of people, young families, we had a number of single people, although they were older. Both of those were single residents. So I think we had participants ranging in age from 7 to 84. So that was a fairly good range.

And then in terms of how honest respondents were, again with the survey, it was an online survey, so we can't really tell.

But the case studies bore out the findings of the survey. They were very similar.

Robyn Pender:

That’s really telling.

Freya Wise:

And the case studies. I didn't just ask them and then take them at their word. I was in their houses, I was looking around, I checked their thermostats to see if that agreed with what they actually said. So we did have a number of checks.

Robyn Pender:

That's what made the research so absolutely stellar to me.

And, you know, I think one of the things that stands out and I know that this is something you talk about a lot, the need for a better range of metrics to assess what we mean by comfort and thinking today, not just comfort in cold, but comfort in hot as well.

What do we actually mean?

Freya Wise:

Absolutely. So I think one of your favourite things, not just about air temperature.

Robyn Pender:

No, air temperature hardly comes into it of course, you know. If we look at what makes people feel thermally uncomfortable. And I can swear to it now because the air temperature in here is quite cool, but the sun's just come in and hit me and I'm now boiling. It's radiant and not so much even the radiant that hits you, but you're the hottest body in a space for radiating out into the spaces. Which is why being in those cold stone buildings is so nice at the moment and why it feels so cold in the winter.

And Matt, do you mind just flipping across to those intro slides again? I put two at the end and I think what people might find really interesting.

So let's bring them up.

I spent many years of my life looking at images like this, as I imagine a lot of you have. Without really seeing them until very recently. And when I saw it, I suddenly got such a shock, because what is in all these images and when you go and look at something like medieval interior, you'll see it everywhere?

It's the hanging from the walls. And of course, that's to cut that radiant loss. And, you know, they made canopies and things, so they didn't radiate upwards and so forth as well. And what I find interesting in a lot of these images is that the windows are wide open.

So the thermal physiologists say that the amount of our heat loss that goes in radiant is 60 to 65%.

It's more if you're not wearing any clothes but 60, 65%. But if you're, if you think of transfer just into the air, it's only a few percent internally. If you're outside and you've just jumped out of a sauna in Sweden into a roaring gale, then you can lose up to 22% of your heat by that.

But inside it's only just a few percent. But so, so when you look at these images with the windows in the background open, you think were they getting enough benefit? This image is clearly in winter, you can see by the hat and the clothing, that they could still have that ventilation even in the middle of winter.

It's an interesting thing. We need to do more work on it. But again, we don't really have ways of assessing this and it certainly doesn't come into anything like an EPC.

Freya Wise:

Indeed. It's also interesting, Alice has just said in the chat around people, perhaps wore more clothes, more layers. Yeah.

Robyn Pender:

Yeah. And you're right about cats and dogs. Gill Fairweather said that's what lapdogs and cats were for. Lapdogs were specifically for that.

Freya Wise:

Absolutely, yes. Shih Tzus were bred in Mongolia as foot warmers.

I can just imagine Genghis Khan with a small fluffy mop dog on his feet. So it’s an interesting range of different, different comfort mechanisms that we don't think about because we're quite keen on technical solutions now. It's like if we can't put in a technical something to fix it, it's not proper, proper science or proper something.

Robyn Pender:

Yeah, I guess it's that marketing too that you buy a product. Whereas a lot of what we really want to do to get those really big changes is not something you buy or sell, it’s something you do.

Freya Wise:


Robyn Pender:

I like these comments about wearing spurs inside the house. I was thinking that with carpet. Walk away, taking the carpet with you.

Katie. What about you?

We seem to have dominated.

Katie Parsons:

No, it’s all really fascinating.

I did have another point I wondered if we could potentially go into.

It sort of comes from one of UNESCO's recommendations and something we've talked about before in previous webinars. I do remember Robyn we did one on flooding before COVID, that covered this sort of thing, but I wondered how it work and you Freya’s work.

So we know that looking at the past and learning from our heritage, and our vernacular buildings and traditionally constructed buildings, these sorts of things can convey a lot of traditional knowledge that we may have potentially lost or potentially we could look at. We could look at buildings that were designed for particular microclimatic conditions and transpose those to places which are changing and now experience similar conditions to try and build some resilience.

Robyn Pender:


Freya Wise:

Yes. Yeah, entirely. So some things that the case study respondents did around using their shutters, the traditional feature again, and also some of them did have wall hangings. Hurray!.

And also just really simple things like one couple, they had a big open plan living room, dining room, kitchen. And in the winter they put a curtain across so that the dining room kitchen was separate from the living space and then they were much more comfortable in there and they ended up being able to turn the central heating down by a couple of degrees and have the same level of comfort just literally by dividing the space, by heating the bit where they were, rather than trying to heat the whole building.

Katie Parsons:

That's really interesting because maybe that comes into sort of behavioural changes. And also what becomes popular in terms of style. You know, we went through a phase of seeing a lot of open plan buildings and open plan interiors being proposed. And that obviously has impacts on listed buildings potentially looking at the climate change benefit, the efficiency benefits, keeping more compartmentalized floor plans might be another consideration.

Freya Wise:

Yeah, entirely. Or at least having the options.

Katie Parsons:

Yeah. Moveable options because then you can get that through flow when it’s hotter.

Robyn Pender:

Yeah. Just in the same way you see in lots of Georgian houses here that they have the folding shutters dividing the big rooms into two or three.

Katie Parsons:

Yeah. Yeah.

Robyn Pender:


People weren't stupid in the past and energy was incredibly expensive, so there's a lot that we can learn again, but we've got new things that we couldn't do before that we can throw in.

It's interesting that people who have the Lucite Perspex secondary glazing, super love it, which always puzzled us a little bit.

But then we found out that it is also a radiant break, like the hangings. It's not like glass. So maybe there's more going on there.

Katie Parsons:

And removable secondary glazing got that heat in the winter and then you can remove it when it becomes warmer.

Robyn Pender:

Yeah, I think you don't want to do things that stop you being able to use your windows.

Matt Faber:

Apologies, everybody. I'm going to have to jump in there. I'm afraid we've arrived at the end point of today’s presentation. We've hit the one-hour mark. Slightly run over. So again, I'm going to draw today's session to a close.

Thank you so much, Freya and Robyn and Katie for today's presentation. Absolutely blistering session and thank you so much for delivering that in such hot circumstances.

I'm very aware that many of you have posted questions in the chat and thank you for that. But I'm aware that we haven't responded to those questions at this juncture. What I will do, however, I will ask Robyn and Freya to address those questions after the session, and we will post their answers to your questions on the Historic England website along with the webinar recording.

Just for your benefit, you will see here a series of links. If you click on the title webinars, a webinar survey, it'll display a URL at the bottom of that window. That URL, you can either direct your browser to or you can cut and paste it and keep it for later. The first one, Webinars, takes you to the Historic England webinar pages, where you will find recordings of today's webinar and of previous webinars.

There's probably now hundreds of webinars recordings to dip into at your leisure. The webinar survey, is your opportunity to tell us what we're doing right and indeed what we're doing wrong.

Robyn Pender:

What you need from us.

Matt Faber:

Any suggestions that you have for future topics and things that you'd like us to do differently, please put them in that survey. We do use that survey to design our webinar offer to you for the future and as Robyn mentioned at the beginning of the session where it says Historic England's advice and guidance that will take you to our guidance pages, where guidance and information and advice on many, many topics, including today's topics, will be listed there as well.

So that said, it's for me to say thank you, all of you, for joining us today. I hope you found today's webinar as fascinating and informative as I have. I'm going to run out and buy some shutters now along with the awnings and paddling pools.

So thank you all very much. We'll keep the session open just for a couple of minutes so you can cut and paste the links in that window, at which point we will close the session.

Once again, thank you so much Freya for your amazing presentation. Absolutely fantastic. And I'm sure for all of us who joined you today, there is much food for thought.

That said, I will close my microphone, ask the presenters to do likewise and hopefully we will see you all again very, very soon for another Historic England webinar. Thank you all for your time today and good afternoon to you.

Thank you all. Stay cool.

Q&A session

Specifically for Freya’s research:

  • In the broader survey responses were at the discretion of respondents, however these results were supported by very similar finding in the more detailed case studies. The case studies involved interviews, participant energy diaries, energy measurements and site visits by the researcher allow different sources of evidence to be used which allowed residents’ views to be cross referenced.
  • While we didn’t ask for demographic information from the survey respondents free text comments referred to a range of household compositions and age related concerns, both for older residents and for young families. The case studies had a range participant ages from families with young children under ten, all the way up to retired households over eighty. The one demographic that we were missing was young single households, however this reflects Cumbrian homeownership.

Speaking more broadly, sub-standard housing (too cold in winter, too hot in summer, and with indoor air quality problems such as mould growth is often attributed to ‘fuel poverty’, but it is more truthfully the outcome of poor design and poor maintenance. Moisture problems mean people feel colder when it’s cold, and hotter when it’s hot, and can do less to make conditions mor acceptable. Classic issues include

  • leaks (from rain, but also from plumbing, especially in the case of multitenanted buildings, where the leaks can arise anywhere but spread into a very general problem
  • windows that are difficult or impossible to open
  • solar gain from too much glazing
  • high indoor moisture loads because of a combination of overcrowding in small spaces, lack of access to outdoor facilities to dry clothing, and the use of ‘raincoat’ materials such as plastic paints and wallpapers, and cement renders and plasters.

Even well-educated householders often know too little about how their building works to be able to keep it in prime condition. In the case of people renting flats, they are also at the mercy of landlords who might also not be best placed to understand the root causes of problems, but may also be disinclined to spend the time and money needed to sort them. And infamous example is Grenfell Tower, where the residents raised exactly the concerns about fire risks that lead to the tragic fire, but were comprehensively ignored. A great deal of the answer to dealing with climate change is to empower people: to give them more knowledge about how to ‘sail’ their own buildings, and also the ability to act on that knowledge.

Or was it only owners that you looked at, given that tenants are likely not in a position to make material changes to their homes?

The survey was open to both renters and owner occupiers but only five renters responded and none of the case studies were renters so in practice the research ended up being focussed on owner occupiers. An interesting extension to the research would be to investigate the views of tenants and, indeed, landlords on a similar range of issues.

There is currently a lot of research across Europe into how to deal with split incentives between landlords and tenants relating to retrofit for rented properties although not specifically around heritage buildings. One of the main suggestions at the moment is the use of on bill measures, where landlords get loans to do retrofit. The amount of energy is supposed to reduce after retrofit but tenants bills remain and pre retrofit levels and the difference goes to paying off the retrofit savings. This however requires:

a) retrofits to make actual energy savings, and

b) regulatory changes to enable charging for ‘energy services’ rather than just ‘energy’, so is still very much a work-in-progress.

The upstairs in is the roof and there are 2cm thick sheets of polystyrene between the stone tiles and plasterboard ceiling, as insulation. The internal temperature upstairs is pretty much the same as outside. The landlords are ware of this and it probably applies to the majority of their properties. How do you think we can encourage landlords such as this to improve insulation? They have wangled the energy rating a few years ago to just scrape through without needing to do anything.

The government is currently consulting on increasing the minimum energy efficiency of domestic properties from an E rating to a C rating. It is likely this will come into force and landlords will be expected to improve the energy efficiency of their current and future let properties by 2028 or have an exemption.

In terms of the problem you describe, Caroline: to cope with the overheating, is insulating really what is needed, or is that a retrofit red herring? Temperatures will always be high in a converted roof space  (it’s a combination of heat rising and more sun exposure). Unfortunately that means there is only a minimal amount that can be done about it (in other words, there is a reason roof spaces were originally just attics, used for storage but not for living). If there are windows you will get a good deal of benefit from shading for these, such as awnings (if they are rooflights, shades are available for those too, and the work really well).

Because the space are high (well above the ground), though, even in hot weather it might be possible to entice a cooling breeze through the space from the exterior, as long as you keep the glass shaded. It all depends on the aspect and the exposure… And in winter you’ll of course be able take advantage of the heat.

In hot climates they manage the overheating of upper stories by simply not using the too-hot spaces in summer, or perhaps only at certain hours of the day when they can be cooled by the breeze (for example, roof terraces are often only used at night, but then may be used for sleeping). If it’s possible to work out by a bit of trial and error when and how the space works best – which will differ from season to season –then you can try to adapt your use accordingly. For example, using ventilation to flush out the hot air at night, and then leaving the windows open and using the space in the early morning, leaving when it starts to heat up in the sun.

The answer is that external shading (shutters, awnings) is always more effective, because it stops the window glass from heating. Internal shutters prevent heat loss and cut some but not all of the heat radiated back into the room from the glass.

Currently internal shutters appear to be more acceptable to residents than external ones, perhaps because they are easier to operate. Internal options also have fewer planning implications for buildings in conservation areas, but that may change as the knowledge of lost awnings becomes more mainstream. It is even possible to imagine that we may see external shutters and awnings become sustainability ‘virtue-signallers’, in the same way as solar panels now are!

This can sometimes be an option: it depends what you are trying to achieve, and what it is possible for you to do with your windows. In technical terms, to cut heat transfer through the glass secondary glazing (where the two panes of glass are further apart) is more effective than double-glazing, and has a longer lifespan because it doesn’t depend on a vacuum or a non-transfer gas like argon to prevent heat transferring in the gap. But secondary glazing s sometimes difficult to fit, and you certainly want to avoid if possible systems that make it difficult to open and shut the windows – particularly as we head into a hotter climate. This is especially true of windows on a south-facing façade, where overheating may well be a bigger problem than heat loss, even in winter – the last thing you want to do to your windows is make changes that trap heat.

The other issue to consider is the whole-life carbon cost. The materials and manufacture both make this particularly high for ‘insulated glazing units’ (IGUs – the technical term covering both double and triple glazing), and that’s compounded by their short lifespan – you are asking a lot from the seals, because windows flex as they are used, and as the wind hits them. Solar gain may also be reducing the lifespan of exposed units, because glass and aluminium (the main constituents) expand and contract a lot as the temperature changes. That’s why even the best units last only a few decades at best. In fact it’s been shown for triple glazing that the operational energy saved the unit over its lifetime is not enough to cover the carbon and energy used in its manufacture. Sadly, currently IGUs aren’t repairable when the seals fail or if the glass is cracked. Even worse, the additives in modern window glass means it generally cannot be recycled either. Old IGUs therefore straight into land fill, or at best the glass is broken up to act as aggregate for road surfaces. We are hoping this may change over the next few years: several researchers are looking at ways in which it would be cost-effective to repair double glazing.

With windows, as with every aspect of retrofit, you have to look at each case on its own merits. Even on one single building the best choice might depend on which window you are talking about.

One of the most effective ways of using double glazing is actually in secondary glazing (to make what is sometimes called a ‘1 + 2’ window). That allows thicker (more robust and longer-lived) units to be used, and also reduces many of the exterior forces acting on them that make the seals fail or cause the glass to crack.

You probably picked up, as the webinar flowed through, that in fact we consider the best ‘retrofit’ actions to be the simple ones – affordable, certainly, and in many cases free. The issue of the cost of repairs relates back to perverse incentives such as the current VAT regime. The work the Welsh Government has been doing with it’s Optimised Retrofit Programme looks at all the issues around this really broadly and holistically, and is trying to empower local SME builders to help people undertake truly effective repairs and holistic retrofits that also make their building more usable.

Landlords really should be forced to keep buildings in a good state of repair, but it has to be said that in owner-occupied houses, the link between income and undertaking timely maintenance is not very clear! People seem to be willing to spend great sums on decorating, but nothing on clearing the gutters…. Let alone upgrading them so they have cope with heavier rainfall episodes.  

Freya also notes that not all her case studies were high economic status (although that wasn’t something was covered in detail, since the participants were not specifically asked about their financial circumstances except in relation to the affordability of retrofit). Some would definitely be considered low-income households. As a more general point, in rural areas poverty and often look different to in more urban areas. People may have large houses, often inherited but they then suffer from fuel poverty, or they spend all their money on buying the property and then don’t have the money to invest in it. For example one of the case studies would have loved to remove the impervious external render from their home and replace with lime increase breathability but they had received quotes for over £4,000 and simply couldn’t afford to make the change. What tended to happen was that those that couldn’t afford sensitive solutions (i.e. hardwood replica sashes) would not replace glazing with a cheaper but less sensitive option, they would just stick with the current situation and put up with it continuing to deteriorate.

Part L 1B requires savings to be made from all buildings if a certain level of retrofit is undertaken, but there are exemptions from specific requirements for designated heritage buildings and for those with traditional construction if changes would damage their significance. In that case only ‘reasonably practical changes’ are required. There is therefore currently quite a lot of flexibility.

However many of the smallerbut highly effective changes that we discussed – changes in the way people operate their buildings, or set their thermostats, or even many window improvements – would not present significant enough alterations to the building to be subject to Part L. Putting up wall hangings for example, doesn’t come under building regulations!

Absolutely, although it does depend what figures you look at and what they are based on. I (Freya) suspect, although I don’t know without doing checking, that residential emissions are based on bill data from utility companies, this is real, measured data for what people actually use, rather than predictions, and we have quite good data on this, at least on electricity and gas (oil and other heating fuels maybe more challenging).

Some data however is absolutely based on EPCs and therefore suspect! At a building stock level in other countries (Germany, France, Denmark) EPCs have be found to generally underestimate energy demand from buildings with lower efficiency ratings and overestimate energy demand from buildings with higher efficiency ratings. At a stock level this may actually balance out somewhat (although there are more low rated buildings than high rated ones!), but it is once you start disaggregating it that it becomes a lot more problematic.

A rather complex answer; but basically, interrogate what the figures are based on, and if it is EPCs then treat it with extreme caution…

A fair percentage of participants were unsure about the technology, required explanations of how it worked and felt the need for more information before forming and opinion. Those who did understand felt that there were three main barriers.

  1. The very likely need to change heating emitter systems to make heat pumps work effectively. This was concerning to residents in terms of disruption, effect on heritage values and potential space requirements for additional radiators, if they didn’t feel that underfloor heating was possible (several had floors with heritage value).
  2. The cost. The more proactive had often looked into heat pump options but had concluded that they just had to high a capital cost to be feasible for them.
  3. A lack of space for ground source heat pumps and significant scepticism about the efficiency of air source heat pumps and a lack of detailed independent information about how they would work. They didn’t what an air source heat pump person to tell them that it would be ‘just what they needed’ in their home, they wanted to understand more about it from a less ‘biased’ source.

Overall for the survey respondents between a quarter and a third would be willing to consider heat pumps now and around 40% might be willing to consider them in the future, but judging by the case studies a fair percentage aren’t very familiar with the technology and what it might involve.

Some other general questions:

Sadly, the course is very short, and there is no need for specialist (or even rudimentary) knowledge of buildings. It’s more about following a tickbox process, and unfortunately this leads to standardised retrofit proposals. In fact, as we know, the best choises are always specific to the building, how it is being used, and exactly where it is. We at HE are keen that ‘retrofit’ should be defined as broadly as possible, and should not be taken to automatically mean ‘deep’ or other fabric-first actions. Our Energy Efficiency guidance document has a triage table of actions that can be a useful guide to working through making your building as sustainable as possible.

These tend to be very ’standard’ and fabric-based. There are measures that the algorithm does and doesn’t understand, especially around window changes. For example, an EPC assessment will never suggest secondary glazing, because double glazing always come out ‘better’ in the algorithm (and is therefore prioritised). 

Part of the problem is that energy benefits are assessed primarily on their effect on air temperature, because the assumption is that a great deal of energy is being used to heat the air, and to keep it at a steady temperature. Also, air temperature is very easy to measure, unlike ‘comfort’! This means that retrofits which might be very effective for improving the comfort of the occupants, but have little effect on the air temperature, will never be recommended even if they greatly reduce the amount of energy that needs to be expended in heating or cooling the air. There are many examples of this, including wall hangings to cut the 60-65% of body heat that is lost by radiation into the wall surfaces, or the use of fans to keep occupants cool in hot weather.

There are a number of things you need to look at:

  1. The definition of retrofit
    We should be thinking people-first. How far can you get with simple passive measures that are low cost, low risk?
  2. Embodied carbon
    It is critical that the whole-life carbon be considered of everything we do – otherwise we risk maladaptation 
  3. Where is the information coming from? Is it a trusted source, or is it selling a product?
    Freya notes: One of my viva examiners said, 'you’d think that local planners/conservation officers would be well placed to deliver that type of information'; but in fact local planning departments were one of the last places that people would go for information.Planning decisions were perceived as inconsistent at best, and biased at worst. Planners may not have the training or the capacity to currently provide this advice, but should Local Authorities therefore be campaigning for more money from central government to provide reliable retrofit advice services?
  4. Forgetting that the climate is warming.
    We have to be very careful that we are not ‘fighting the last war’, and taking actions to reduce the loss of heated air that actually make our buildings more likely to overheat in future.

I think the main aim/point/message that I’d like people to go away with is that we need to consider the whole building AND ITS RESIDENTS holistically, and while we might be getting (slightly) better and whole house thinking we still aren’t good at extending it to the occupants and indeed in extending our understanding of retrofit from ‘lets put something technical in and you’ll be sorted’ to ‘as well as the technical stuff have you thought about dividing your open plan living space with a curtain on cold winters evenings to create a snuggle space by the stove?’ Which isn’t something that your typical architect/energy consultant/builder is going to say to you. Or even more simply, we need to pay attention to the people as they are the pesky things that are using energy.

In conclusion we need an approach that takes account of residents' views, values and behaviours and considers retrofit from a lifecycle perspective, recognising that residents and their buildings have an interlinked and symbiotic relationship.

Also of interest