Decarbonisation Plan Webinar 4: Appraising options and developing a Decarbonisation Pathway

There will be many different possible outcomes from the options appraisal. What is chosen should reflect the clients aims and objectives, budget and become part of their long-term planning. It doesn’t need to be completed tomorrow!

This is the Q&A session from the session – questions asked by the chairs from questions posted in the question chat and from thoughts arising during the webinar. The answers were provided by the consultants Beatie Blakemore and Elizabeth Flower, who presented the webinar.

Value of thermographic surveys in warm weather

Question: Are thermographic surveys worthwhile if the ambient weather is warm?

Answer: Quantitative thermographic surveys must be carried out during the heating season (winter) to be reliable. The building must be consistently heated, external weather conditions must be stable, and surveys should ideally be conducted after dark and without recent solar gain. While thermal cameras are often used to give anecdotal evidence, robust, quantitative surveys have strict constraints to ensure accurate results.

Use of RAG assessments and weighting of criteria 

Question: Does sequencing affect RAG scores, and are criteria weighted within the RAG assessment?

Answer: Numeric weighting was considered but rejected. Qualitative descriptions were found to be more useful because some criteria are numeric (cost, energy reduction) while others are inherently qualitative (heritage risk, appropriateness). The value lies in the detailed analysis rather than a scored total, and decisions should not be made by counting “green” ratings alone.
Some criteria may carry more importance depending on client priorities. Any weighting is best expressed narratively rather than mathematically.

Integration of maintenance, repair, and strategic goals

Question: How do repair, maintenance, and other non-decarbonisation priorities affect option prioritisation?

Answer: Repair and maintenance are core considerations within the options appraisal. Broader organisational goals—such as accessibility, increased use, and financial resilience—must also be considered. Increased building use may raise energy consumption while still producing positive outcomes through improved sustainability, viability, and public benefit.

Accounting for future building use 

Question: How is future or intensified building use reflected in decarbonisation planning?

Answer: Buildings can be inefficient if underused. Decarbonisation Plans should consider opportunities to increase and diversify use, even if this leads to modest energy increases. Longer-term benefits such as financial resilience and heritage engagement are integral to decision-making.

Embodied carbon in RAG assessments 

Question: When and how should embodied carbon be considered within the RAG assessment?

Answer: Embodied carbon is important but not included as a primary consideration in the Decarbonisation Plan to keep scope, cost, and complexity manageable. Instead, the plan should identify where whole life carbon assessments are needed at the next decision-making stage, particularly when choosing between similar technical options.

Consideration of operational costs and long-term implications 

Question: How are operational costs and long-term implications reflected in the RAG assessment?

Answer: Operational costs can be included as an assessment criterion where they are a key client priority. The criteria set should be flexible and tailored to the building and organisation. Including one criterion may mean excluding others to keep the assessment proportionate.

Risk of delayed decision-making

Question: Is there recognition that lengthy RAG assessments may themselves have negative carbon impacts due to delay?

Answer: Yes. The scope of a Decarbonisation Plan must be proportionate to available resources and decision needs. Regular condition surveys and routine maintenance can enable immediate low carbon improvements without waiting for a full Decarbonisation Plan. The plan should complement, not replace, good building stewardship practices.

Role of the Decarbonisation Plan in building management 

Question: How should a Decarbonisation Plan sit alongside other building management processes?

Answer: A Decarbonisation Plan should form part of a broader framework for managing, maintaining, and caring for a building. It works alongside condition surveys, maintenance planning, and strategic decision making rather than replacing them.

Beatie Blakemore: Associate Director, Project Lead & Architect at Haworth Tompkins

Elizabeth Flower: Associate & Architect at Haworth Tompkins

Dan Miles: Senior Sector Development Adviser, leading the Sector to Net Zero project, supporting heritage organisations on their journey to net zero at Historic England

Dan Miles: Good afternoon everyone!

Hi, my name is Dan Miles. I'm the Senior Sector Development Advisor at Historic England. I'm just going to do a very quick introduction, then I'm going to pass you over to Beatie and Elizabeth.

So just to let you know, this is a co-funded and co-managed project by Arts Council England and Historic England. The co-manager, Feimatta Conteh, is not able to attend today, but she has been co-chairing the previous 3 webinars. So we, both our bodies, commissioned the contractors, or the main contractor, Howarth Tompkins, along with Skelly Cooch, Gardner Theobald, and Connersby, to undertake this project, which you're about to hear the webinar about.

So it was led by Beatie Blakemore and Elizabeth Flower. And we're going to just sort of— I'm going to very quickly recap over the last sort of the main aims of the project. So this is a series of 4 webinars. We're on the 4th webinar, and the main area of the main focus of the project was to demystify the process of commissioning decarbonisation plans, to really help arts and cultural organisations understand the whole process and how everything works. And then it goes through the steps involved in the work, and then the final one is to sort of develop a suite of resources to help the organisations understand and help them move forwards.

So I think I will now pass over to Beatie.

Beatie Blakemore: Thanks, Dan!

Hello everyone!

So, as Dan has mentioned, this is the fourth of four webinars, which some of you, I believe, have attended before. But for those who haven't, we're going to give you a little very quick recap on what the first 3 webinars included, and if you missed any of them, you can look at them at the Historic England website.

So, webinar 1 was really an introduction to decarbonisation in the built environment and the sort of pressure and need to retrofit our existing buildings in order to achieve our decarbonisation aims as a country.

Webinar 2 was really directed at those who are owning or occupying existing listed buildings, and helping to define the scope of what a decarbonisation plan needs to look like for your specific organisation, the kinds of information that you need to gather to support that exercise, and how to assemble a professional team to support you in undertaking a decarbonisation plan.

Webinar 3 looked at the range of surveys and assessments that you and your professional team would need to undertake as part of a decarbonisation plan, and how that's used to benchmark the performance of your building against others of a similar type, as really providing a kind of baseline from which you can then map out the potential measures that you might undertake to decarbonise your building.

And today, webinar 4 is really looking at what those potential measures might be and how you might critically appraise the options and look to sort of prioritise and implement them over time. So really today we're focusing on what climate change mitigation and adaptation measures are, how to assess and evaluate them in the context of, again, your specific building and project context, how you undertake a process of review and prioritisation, and how this can then underpin a long-term decarbonisation pathway for the building.

And really, this covers the final 3 steps of the decarbonisation plan framework that we've developed as part of this project. And there's a series of resources available on the Historic England website to take you through these steps, the 6-step process that we've undertaken, as well as detailed sort of content guidance for what a final decarbonisation plan might look like. But these last 4 steps are really around appraising options, developing a prioritised list of improvements, and forward planning the process of implementation towards that decarbonisation goal.

So, let's just talk a little bit about what we mean by climate change mitigation and adaptation.

So, really, these are the potential measures that you might undertake to reduce the climatic impact of a building, primarily to lower energy use and direct carbon emissions from the operation of the building. And secondly, the adaptation measures that you would need to do to improve the long-term resilience of the building to climate change and extreme weather events. So this is really thinking about colder, wetter winters and hotter, drier summers, as well as the kind of extreme weather events such as increased risk of flooding and high winds.

And the options appraisal process is used to both identify these range of measures and to appraise and compare them in order to underpin a forward plan. And broadly speaking, these measures can be considered under 3 broad categories.

So firstly, we're thinking about the fabric improvements to the building. So this is really about repair, adaptation, or indeed replacement of fabric to improve its thermal performance. And this is, this is really in order to reduce the risk of heat loss in winter, or indeed heat gain in summer, and to lower the overall energy demand of your building. And you can achieve this through a range of measures that are sort of ranging in complexity, cost, and impact.

And I think it's really important to stress here that the most important thing you need to do is to maintain and repair the fabric of what is there. So this is really, really important first principle. A building that is poorly maintained or in poor condition will lose heat faster than one that is in good condition, and deterioration of the fabric is particularly risky when we're talking about sort of valuable heritage properties as well.

So I think we might have shown this, this image on the right at one of the previous webinars, but what you can quite see quite clearly in this thermographic survey image is that the largest areas of heat loss aren't only from where you might we expect, such as single glazed leaded windows in this case, but also if you can see on the far right, this under item AR7, that perhaps unexpectedly one of the highest parts of heat loss in this building is a, is a crack in the external wall that was barely visible with the human eye, but actually is, is allowing water to penetrate that fabric and increasing heat loss.

So understanding the condition of your building and maintaining it well is a really critical sort of first principle. Once you've done that, the next thing that you can start to look at is insulating the external envelope of the building. So that might include adding insulation to walls and roofs or the ground floor. It might also include addressing the performance of your windows through either replacing or repairing seals to make sure the windows and doors are weather tight and reducing heat loss through lack of airtightness. It might also include replacing or upgrading the glazing, or indeed replacing the whole window unit.

But all of these interventions to the fabric are, I think, what it's really important to say when we're talking about heritage and listed buildings, they all carry particular risks in terms of how they might affect the appearance or the significance of the building, and they need to be undertaken with care and adequate levels of knowledge and understanding about the existing building.

The next category of measure that you could undertake is around the repair, adaptation, replacement of the building service systems that keep the building comfortable and healthy to occupy. So this is really about improving the efficiency of existing services or introducing new, more efficient building services where necessary, and also about introducing a greater level of user control and understanding of how those systems are working. So, as with the fabric, it's really important that you both maintain and repair the existing systems that you have, and also ensure that they are actually working as designed.

So, one of the key problems with— as building service systems become more complex, is that actually a poorly operating service system can both cause unnecessary energy use, but also potentially negatively impact the thermal comfort of the occupants. So, understanding and repairing and maintaining those systems is really critical.

And the other way you can understand your building better is to introduce metering and sub-metering that will measure the energy use across the building, and that enables you to understand the relative areas of high or low energy use, and you can target your interventions with that knowledge. You might also consider replacing some of the existing systems. For more efficient and lower carbon alternatives. So that could include replacing a gas or oil-fired heating system with an air source heat pump or other heat sources. It may include introducing heat recovery on ventilation systems.

And again, having better control over the heating and ventilation systems that you have will really drive efficiency. And then something that you may all be undertaking already is rolling out replacements of inefficient lighting with high-efficiency LED is another sort of quick win that will actually reduce your consumptions considerably. And then the final category of intervention, which tends to be the most costly, is around generating energy from low and zero-carbon technologies. And this is about reducing both the carbon emissions associated with your building use, but also really importantly reducing demand and pressure on the supply networks.

So this would include heat pumps, as I mentioned, so air, ground, and water source heat pumps that would replace fossil fuel-emitting heat systems that you might have at the moment. It could also include, for larger schemes, heat networks, either at kind of district network heat networks sometimes using waste heat from other activities in an urban site, sometimes across a large estate such as the University Estate, and that can really drive some efficiencies of scale. It might also include generating on-site electricity through solar PV panels or indeed solar thermal.

So at this point, we would like to do a quick poll to understand what types of intervention— if you are a building owner or occupier— what types of intervention you may have already undertaken within your building. And if you are a built environment professional or user of a building, perhaps you can click those that you're familiar with or have been involved with from a professional point of view.

We'll give you a few minutes just to let the numbers come in.

Jess van der Drift: I think it's quite interesting to see that there seems to be a surprisingly even split across the board. Obviously, fabric improvements or adaptations is coming in at almost 46%, which is, I guess, what we expect. But I was expecting there to be more of an extreme split between them and upgrading system services and low and zero-carbon technologies, really. But we'll give you another 10 seconds to cast your votes if you haven't already. Brilliant!

So yeah, it looks like there's 45% of you have looked at fabric improvements or adaptations or undertaken them in your buildings, 30% have undertaken upgrade and service systems. 16% have looked at low and zero carbon technologies, and just 9%, so that's just 4 of the people who voted, have done none of the above.

Beatie Blakemore: That's really interesting, and in some ways it's very encouraging that a lot of people have already undertaken Fabric improvement measures. But I think, as I was stressing before, that can include quite small-scale adaptations to existing fabric as well as replacement or upgrade of thermal performance. So thanks, it's interesting!

Okay, so I think one thing that's really also critical to kind of stress at this point is that energy efficiency measures to existing buildings are really essential in order to meet long-term decarbonisation goals, but there are risks associated with undertaking them. So they can be quite costly and disruptive, but also, if inappropriately designed and detailed, there is a risk of unintended consequences for both the fabric and its occupants. And this is really known as maladaptation, which means where performance and resilience is actually undermined.

So rather than improving the long-term performance and resilience of a building, actually some of those interventions end up causing more harm than good. So this could include moisture accumulation, So inappropriately detailed insulation can contribute to interstitial condensation, leading to mould growth, which both has an adverse impact on occupant health and wellbeing, but also moist fabric, as we've mentioned, can actually increase heat loss from the building and lead to this deterioration of potentially sensitive fabric in the building. So that really is associated with kind of reduced performance and it's really about, or in response to, inappropriate material specification or detailing.

When we're talking about historic and listed buildings, there is also a risk of harm to the significance of the building, either through a loss or change to architectural features or an impact on other broad heritage values.

So I think in the context of listed buildings and historic environments, It's really important that anything that you're proposing to do for energy efficiency is based on a really thorough understanding, both of the history and significance of the site, but also its, its construction type and the specific local climatic risks and, and context that the building is situated in. So that's something we've talked about in the previous webinars in quite a bit of detail.

So the options appraisal process, which Elizabeth is going to take you through in a minute, is really about setting out a structured process through which the various interventions that you might consider can be individually appraised and then considered in the round in a holistic way in order to develop a more appropriate set of interventions to the building. I'm going to hand over at this point to Elizabeth.

Elizabeth Flower: Thanks, Beatie! So once the options for improvement have been scoped out under the 3 kind of categories that Beatie described, they then need to be assessed against an agreed set of building-specific criteria and considerations. So there might be logistical constraints of implementation which could make some interventions more difficult to achieve. So for example, Site access might make it difficult for large pieces of equipment like heat pumps to be installed, or possibly some interventions might require scaffolding, which would cause disruption to day-to-day operations if the building being kept open was a kind of key priority.

Next, the condition of the building fabric should also be considered with regards to the potential improvement option. For example, if a building service is at the end of its life, like gas boilers, or if a building element is in a poor state of repair, like, you know, windows are falling apart, then that could mean that upgrading that element is perhaps more feasible or higher priority.

And then next on the list, heritage and conservation considerations are obviously key when working in a listed building. Some potential interventions might be completely unfeasible in particularly significant spaces, whilst others might have more of a minimal impact on the significance. Capital cost of each intervention should be considered. Obviously costs will vary depending on how the interventions are packaged and how they're delivered, but a quantity surveyor should be able to calculate at least a high-level capital cost for each intervention to allow kind of relative comparison between them.

And then moving on to cost-effectiveness of each option, another important consideration. We've been asked a lot about payback periods through this study. However, the calculation of these can be quite unreliable, especially given the volatility in energy prices, and sometimes misleading results can be generated.

So instead, what we found is that the pound spent per tonne of carbon reduction achieved is a more useful metric when comparing and assessing potential energy-saving interventions against their capital cost. And then, Beatie touched on climate resilience, again another key criteria, depending on the location and site-specific risk of the building.

So, for example, if a building is particularly at risk from flooding or overheating, some interventions may be more beneficial to help address these risks at the same time as reducing energy consumption. So, these criteria are probably applicable to most buildings. But there may be other specific assessment criteria that interventions should be assessed against. So alignment with client strategic priorities or capital projects, or even what the implications are of not doing each intervention.

So to assess each intervention against the list of set criteria, we create a table like this with the criteria shown along the top, and options for intervention on the left-hand side. And each option is then given a red, amber, or green status against each criteria, with more detailed accompanying notes on the option-specific considerations within the table. And as this is, it's quite a nuanced process, so it's not a scored assessment, but the sort of traffic light status just gives a high-level indication of how appropriate each option might be to the building.

So, for example, an option which achieves more green categories, so is easy to implement, is in high need of replacement or repair according to its condition, has a low impact on its heritage significance, a low capital cost, and high reduction in energy and carbon, and then a high efficiency. Would score in the kind of green section and then vice versa. If an intervention was scoring more kind of worse against those criteria, they'd be in more of the red section.

As I said, this is quite a detailed and nuanced process. So in reality, at the end of the assessment, we'll have something like this, which is a very long list of potential interventions, each assessed against these building-specific criteria. And even this table here just shows a snapshot of— this is one of the case study buildings where the full assessment and the long list of options went across several pages like this.

And the text within the table and within the report document then covers the detailed analysis of each improvement option against the criteria. And again, the RAG statusing just provides this kind of high-level visual snapshot of the relative benefits of each option. So, to break this down a bit, I'm going to demonstrate how the options appraisal process might look in reality for one option for intervention using another of the case study buildings that was studied as part of the Decarbonisation Pilot Study.

So, this is the Littonville Library in Newcastle. It's a Grade II* listed building, it's a library and cultural community hub around 2,000 square metres, and they were currently in the early stages of a capital project with aims around improving accessibility, adding in new learning spaces, and expanding their cultural programming. And as part of this capital project, some fabric and fabric repair and refurbishment considerations and services upgrades were going to be implemented, but at the time of the study, it wasn't clear exactly which interventions would be included, so our assessment needed to factor that in.

The interior of the library is shown here, and the most historically significant areas of the building are the front facade and some of the main spaces within the interior. And then on the lower floors, there's a series of more flexible use spaces and an archive store, which are of lesser significance. And then as a whole, it's a fairly low-tech building, heated by gas boilers and radiators, and is entirely naturally ventilated, so no kind of modern MBHR or mechanical extract systems.

So, the option for improvement that we are going to look at is the roof lanterns. So, there were 3 single-glazed metal-framed roof lanterns, which are kind of highlighted on a roof plan here in blue. That sit above more ornate domed glass laylights beneath, which you can sort of see in the section on the right-hand side there. But the lanterns themselves weren't original to the building. The potential measure for improvement is to replace these lanterns but not the laylights below.

So the lanterns could be replaced with double-glazed units, keeping the heritage laylights intact. and this could allow better control of ventilation within the lanterns themselves, perhaps through actuated or automatic openings. So in terms of condition, the kind of influence here was very high priority. The lanterns have various kind of cracked glass panels. You can see in the image the lead flashings and cappings are in very poor condition, and require kind of full and quite urgent replacement. There's also evidence of water ingress and plaster damage in the rooms below, which are of high heritage significance as well.

And then added to this, there's also asbestos rope possibly present within the glazing bars, which could decay and cause a health hazard and is actually very difficult to keep in situ without replacing the lantern entirely itself. And the condition survey recommended that these issues needed to be addressed within a year.

However, obviously this replacement and these lanterns are very large and will be very difficult to implement and quite complex logistically, so the laylights beneath would need to be protected, possibly scaffolded as well, to remain as they are, and then there's also potential structural implications of replacing the lanterns with a double-glazed unit, which could be heavier. In terms of heritage sensitivity, this kind of was found to be kind of medium, in the mid-range of risk. The lanterns aren't visible from the street or from ground level, but obviously they have a significance in their kind of provisional provision of daylight characteristics to the interior of the library.

Probably the key benefit of replacing the lanterns themselves was just the energy saving opportunity, which was found to be quite high, and lowering the U-value, so the sort of fabric performance, from 6.5 to 2.1, and that would result in a 13% reduction in heating energy and carbon emissions. Equating to 5.9 tonnes of carbon saved a year. However, back in the red, in terms of capital cost, the replacement of these 3 lanterns would be quite significant, but it's also important to note that some of this cost would need to be spent kind of regardless due to the condition of the lanterns on the essential repair works, so some of that needs to be kind of borne in mind anyway. And then the metric of pounds spent per tonne of carbon saved, as I mentioned before, showing that it's not particularly cost-efficient, but again, assessed against the other criteria, also still quite necessary to happen.

So, all in all, you can see the kind of full assessment summarised along the bottom here. The key considerations being that replacing the lanterns often offers a significant reduction in heat loss and infiltration through the roof glazing, but additional means of ventilation may also be required if the airtightness is improved. So it's— I guess it's also important to note at this point that these other considerations, like the improvements to the ventilation, don't necessarily need to be resolved at this kind of early options appraisal stage, but they do need to be borne in mind during the selection of the preferred options, and they do need to be highlighted for further investigation as well as part of the kind of next steps if this option is selected to be brought forward.

So it's also worth noting that sometimes an improvement option may be chosen to be taken forward simply due to its relationship with other options and kind of interrelationship rather than its own merits. So here we're looking at the insulation of the flat roof areas that are highlighted in yellow on the adjacent roof plan that kind of surround the three glazed roof lanterns. And the energy-saving opportunity is to insulate and recover these areas. And this improvement option was found to be kind of in the mid-range when assessed against the specific criteria.

But in this case, it was kind of considered quite a sensible improvement option to take forward, particularly if the roof lanterns were replaced, and also because some rooftop plant was being considered as part of the capital project. So, it could be done as part of a kind of package of rooftop works, when, you know, work's already been carried out there and some expenses being spent on, you know, contractors and scaffolding setup, etc. It's an interesting example of how an option can kind of be brought forward due to other factors in play.

So next, we're going to look at how proposals are developed following the kind of selection and shortlisting and appraisals process. So following the options appraisal process, and once that's complete and the table I showed earlier is kind of fully populated with each option properly assessed, And the client and consultant team will need to meet to sit down and discuss the findings of the options appraisal exercise and agree the shortlist of achievable preferred measures that they'd like to take forward.

And then the consultant team will undertake some further design assessments to test and illustrate the shortlisted proposed measures in response to spatial heritage and logistical constraints and opportunities. So the scope of this design development will be high level, so we're obviously still at feasibility stage, possibly moving towards kind of outline design, but sufficient to highlight any complexities and risks and key considerations for each potential intervention.

For example, the size, scale, and location, so where does the intervention sit within the building? What's its overall scope, the view from the street, and are there any heritage or planning implications that need to be considered? And then any wider implications and knock-on effects, which could be quite a range of different things, ranging from services upgrades or acoustic upgrades, structural upgrades, or as we saw with the rooflights, an associated requirement improvements to ventilation if airtightness is improved.

And then finally, if we're looking at an intervention that's a low-zero-carbon technology being added to the building, its potential for energy generation could be assessed and sort of calculated at a high level, and also the energy-saving capacity of each intervention could be explored in more detail. And then finally, what further studies, surveys, investigations may be required for each of the potential interventions to be brought forward further.

So at this kind of early stage, design development may include markups of plans and elevations or 3D sketches, such as the kind of elevation diagram below, which shows differing kind of window conditions. Some have secondary glazing, some are still single-glazed. So it's this very kind of high-level scoping out where intervention like upgrading windows kind of would need to be targeted. But also possibly high-level technical estimates.

So, on the right here, you can see a sort of high-level indicative PV panel array, and then below that, the range of kind of estimated outputs that could be possible from including that. And the same can be done for heat pumps as well, that's shown on the right there. So design development then should also assess interrelationships and dependencies between interventions and explore any potential grouping or coordination of works packages.

So I sort of touched on earlier the kind of roof insulation, roof lanterns, solar PVs, and air source heat pumps, all kind of separate interventions and options within that appraisal table, but could all be considered at the same time or could perhaps be phased, but would need to be kind of carefully worked out how those works were done sequentially so as not to have any abortive work. And also, interventions should be kind of assessed with their alignment to any current projects, particularly to help future-proof any ongoing work.

So if there are works going on in the building at the moment, we want to make sure again there's no abortive work or abortive design that's done there that may need to be redone or prohibit certain interventions being incorporated in the future.

So, at the end of this stage, we're looking to have established a shortlist of preferred improvement measures across all of the 3 categories of intervention: new low-zero-carbon technologies, upgrades to service systems, upgrades to building fabric, and then of course maintenance and essential repair works, which kind of feeds into both services and building fabric upgrades. And each measure will have ideally been tested and developed against the site-specific situation, and also have been considered in relation to each other, and whether they can be carried out alone or as a series of kind of packages of work or phases. Which leads on to the next step, so I'll hand over to Beatie.

Beatie Blakemore: Thank you! So the next step is really about determining the sequence of implementation of these measures, and in principle Historic England recommends that the measures to introduce energy efficiency are undertaken following this key hierarchy.

So firstly, looking at sufficiency, reducing energy consumption in real terms. These tend to be the sort of easy wins that I mentioned earlier in terms of looking after what you have, maintaining the fabric, making sure you understand and are operating the systems as designed and intended. Then looking at efficiency, so minimising unavoidable energy use through introducing new and more efficient service systems, or indeed undertaking holistic and fabric intervention works.

And lastly, looking at renewable energy generation and low and zero-carbon technologies. But in practice, and I think Elizabeth has mentioned this in the last few slides, and we touched on it at previous webinars, in practice, actually, the prioritisation and sequence of measures is more likely to be determined by some very specific factors involved in either your building or the context in which your building is operated.

So this is where you need to really think about the alignment with strategic goals and interrelation with perhaps major capital projects, and that ties quite closely with this question of funding availability and funding opportunities. So, how do you frame potential energy-saving interventions as part of a sort of wider strategic vision and set of goals for your building? You'll need to think very carefully about operational impact, and we've mentioned some of the logistical constraints and issues around site access, but key question around, you know, is the suite of energy-saving interventions that you're talking about going to require a whole building closure, or is this something that you can roll out through a series of smaller works, is a key consideration, and one that is again likely to tie back to the question of funding availability and opportunities.

So once those things have been kind of discussed and assessed within the team, you can start to develop a decarbonisation pathway that sets out and illustrates a phased strategy for progressive reduction in carbon emissions associated with operational use. And it can be illustrated graphically in this sort of way. This is an example for the Lytton Phil Library. And what I think it shows, without going into detail on the table, but what you can see is that these interventions will have quite different levels of impact on carbon reduction.

So I don't know how well you can see the screen, but on the left-hand side of the graph, is the carbon emissions associated with operational energy, and down the bottom is time running to 2050. And you can see quite clearly here that some interventions like installing heat pumps will generate a big drop in carbon emissions, but they may be quite difficult to implement or costly and therefore require potentially several years' worth of fundraising in order to implement them. So this is a way of showing how over time you can begin to decarbonise in a set of structured steps. And part of the thinking around developing the Pathway is also around setting out what the next steps will be for implementation.

So to begin with, and I've hopefully sort of stressed this in the early parts of this webinar, integrating decarbonisation considerations into day-to-day management, maintenance, and repair is your absolute first priority. There are a number of quite easy wins that you can achieve in this way, but also for sort of responsible long-term stewardship of your site, this is, this is an absolutely key consideration. If you're looking at more costly and significant interventions, you may need to start to define a brief budget and programme for a major capital project.

And as Elizabeth mentioned, it may be sensible to group some of those energy saving measures into a series of linked interventions if that's the most convincing way to develop a fundraising strategy. And those are the sorts of— this is the moment to sort of tease out the options for how you might deliver some of these interventions over time. And once you have a clear sense of how those interventions are going to be structured, either as one single capital project, or perhaps a series of phased projects, or indeed a mixture of ongoing maintenance and major works, then you can start to look at procuring a design team for RIBA Stages 2 to 7, and indeed to potentially undertake further building performance evaluation to inform the design.

And I think those of you who've been at all 4 webinars will know that the decarbonisation plan is designed to be high-level because it's intended not to require a client body to invest too much money up front in consultancy. It's really designed to scope out the potential interventions and help with decision-making at the very early stages of your thinking. As a result, there are certain interventions that we've mentioned here today, particularly with regards to the fabric, that may require quite a bit more technical assessment to inform the design development.

So at this point of the process, you should know which elements of the sort of proposed measures may need further investigation and detailed design in order to make the proposal more robust and appropriate for your building. At this stage, you should also know which of those potential measures may carry risks in terms of sort of heritage impact and the kind of interventions that you might need to start consulting with statutory bodies on.

So we've given you a bit of a sort of run-through the decarbonisation process, and hopefully you've come away with it, with a better understanding of what it might look like for you. Before we start the questions, and I can see lots of great questions start coming in, but it would be good if you could all just reflect, those of you who are building owners and operators, on what your current and future plans for the building might be over the next 5, 10, and 20+ years.

Where do you think your immediate priorities might lie? What do you think would be most challenging in terms of decarbonisation? And how do you think a decarbonisation plan, as both a process and a document, could help to guide and support your longer-term strategic goals? And if you can put these thoughts into the chat, that would be great, but if not, it would be useful, I think, for all of you to reflect on this and think about this after the webinar.

Elizabeth Flower: Thank you!

Beatie Blakemore: Over to you, Dan!

Dan Miles: Just coming back in. Hi, thank you very much for that. Right, let's have a look at some of the questions. There was the first one was on the thermal surveys right at the beginning. I don't know if someone could just quickly reflect on that one in terms of the— I wondered whether thermal surveys were worthwhile even if ambient weather is warm.

Beatie Blakemore: Yeah, this is an important one and one that we cover in one of the earlier webinars. So it's really important that proper thermographic surveys are undertaken in winter, so during the heating season. Now, thermal imaging cameras are quite easy to get hold of, and lots of building professionals and service engineers will use them to provide anecdotal evidence of potential heat loss through a building. But what we covered in one of the earlier webinars is that if you wish to do a properly sort of quantitative thermographic survey that gives you kind of hard data about where your primary areas of heat loss might occur in a building, then there's quite a lot of setup time required to sort of do that properly.

So for— in the first instance, it needs to happen, as I say, in the heating season. You need to make sure that your building is consistently heated everywhere to the same extent. So that might require sort of planning some, you know, management issues for a few days in the run-up to the survey. The external weather conditions are quite important, and you want to ideally do this sort of after dark, so we haven't got sort of, you know, sunlight distorting the data.

And indeed, it's best if actually the sun hasn't been shining for a few days, because that will— a lot of the fabric will have absorbed heat from the sun in that time, and that can again skew the data. So they're incredibly useful surveys to undertake, but they do have some constraints in terms of when you can do them in order for them to be most useful. I hope that's answered the question for whoever asked it, but put more in the chat if you want to know more.

Dan Miles: Brilliant, thank you! And actually, there's 3 of them the questions here that are all really about that sort of RAG assessment and that sort of prior, the sequence. So the first couple, does the sequence of options have a bearing on the scoring in your RAG assessment? And the second one is, do you have the weighting to the criteria under the RAG assessment? Do you have weighting to the criteria under the RAG assessment? So I don't know if you want to have a think about those two.

Beatie Blakemore: Yeah, I mean, Elizabeth mentioned this a little bit earlier and might want to say more on this, but I think we had lots of discussions within the group leading this study and with Historic England about whether or not to introduce numeric weighting to the red, amber, green, as you might see in, say, a sort of risk assessment.

And in the end, as I think Elizabeth mentioned, we felt that actually the sort of, the qualitative descriptions were more useful than a numeric weighting, partly because it's quite hard to then compare— some of the data in the options appraisal, like the capital cost, the cost-effectiveness, and the energy reduction, are numeric in themselves. Others are much more nuanced and are more qualitative, so it's quite hard to kind of compare those.

And in the end, we felt that actually what was more important was that as a team we were doing the detailed thinking and analysis about what was most appropriate or risky for each intervention in each building, as opposed to giving it a sort of scored rating. And I think what I've also sort of mentioned in how you then move through into the implementation phase is that the options appraisal is principally informative. But it won't be the case that actually you will select your preferred options simply by counting up the greens. It'll end up being a much, much more sort of nuanced and discursive approach to what is possible and what is appropriate in your building.

Dan Miles: Elizabeth, do you have anything to add on that?

Elizabeth Flower: No, I mean, yeah, obviously I definitely agree with Beatie. I think the question of the weighting of the criteria is important though, because some criteria can be kind of more of a driver than others. So there could be some really specific client-led priorities that could also be kind of considered more heavily weighted than, I don't know, say the kind of ease of implementation of options perhaps.

So again, like, there could be a kind of weighting to them, but it would probably be a sort of more narrative weighting and part of that kind of nuanced assessment rather than a kind of mathematical process.

Dan Miles: Thanks! It's just making me think, I'm just going slightly off from one of the questions and I'll come back, but this is, you know, the RAG assessment about the implementation of these interventions to decarbonise, but at the same time, both of you were talking about how we need to think about sequencing work or what other types of work might be being required that might not be— they're not directly associated with decarbonisation. So it could be the fact that the roof needs replacing or there's damage. So actually the prioritisation of this could actually be influenced by other things are happening that the organisation's needing to prioritise in other ways. So repair, maintenance, that type of thing.

Beatie Blakemore: Well, repair and maintenance are very much in the Options Appraisal table as a key consideration. I think it's probably one of the first things that you look at because it's just so important for, sort of say, good stewardship of the site. But there are other considerations, like in all of the buildings that we were looking at, the case studies, to varying degrees there were ambitions and aspirations around, for example, people, improved accessibility, physical accessibility, and intensification of use.

And so one key thing that, again, we may have discussed in previous webinars is that we'd like to see a decarbonisation pathway and an energy use pathway that progressively reduces. But in practice, part of what an organisation might be looking at at the time that they undertake a decarbonisation plan is dramatically increasing the intensity with which the building is being used.

So one of the case studies at Shire Hall, we found that actually it had very low operational energy use for a historic building, surprisingly low, and the reason was twofold. One, that it was too cold, it simply wasn't being heated to keep the occupants comfortable, and secondly that, and partly connected to this was that actually the spaces weren't being used as much as they could have been. So, there was an inefficiency of use that actually is a sort of— a different sort of understanding of inefficiency, but one that we need to bring into the thinking.

So, in all the case studies, we were trying to look at the decarbonisation on its own, but also try to bring in some of these other strategic goals of the organisations and overlay introduction of new activities which might actually need more servicing, that actually use more energy, but do provide a more long-term sustainable business model and enable the building to be used and understood by more people.

So there are other kind of benefits, heritage or otherwise, that need to be considered in the mix. So it's, as I say, it's not always a kind of clean downward trajectory of energy use. Sometimes if you want to use the building more intensively and for different uses, you might end up actually using slightly more energy but get more out of the building.

Dan Miles: Brilliant, thank you! I'm going to take the— jump down to the bottom two questions because potentially they're quite similar, thinking about the considerations again with the RAG ratings. So with the timing of implementation, considered in options appraisals? How/when should the embodied carbon from the change be factored into the RAG?

And then the last one is, how are the ongoing operational costs and the long-term implications considered in the RAG weighting? So one is embodied and then the operational costs and long-term implications.

Beatie Blakemore: Yeah, so that— this is another— let's just look at embodied carbon first. So this is another one that we had quite a lot of debates within the sort of project team around because, you know, in an ideal world embodied carbon absolutely would and should be considered as part of a whole life carbon assessment of impact. So if those processes are measuring whole life carbon, which are becoming more and more commonplace and absolutely important in, you know, building projects, but if those processes were more straightforward and more cost-effective, we would have absolutely recommended that that was a key consideration in a decarbonisation plan. But following lots of debate, we actually decided that in order to keep these decarbonisation plans quite sort of lean in terms of consultancy costs and complexity, that embodied carbon wouldn't be a primary consideration, but it is absolutely one of the next things that you might look at.

So again, to take an example from the case studies, one of the things that we were looking at at the Lytton Phil were different options with regards to upgrading the performance of the windows, and that ranged from secondary glazing to reglazing the existing windows to replacing the windows in their entirety. And all of those options gave broadly similar results in terms of thermal improvement, and interestingly weren't a million miles away from each other in terms of cost.

But in order to move to the next stage of decision-making about which to undertake, you would want to do two things principally. One, to look in more detail at their heritage significance, not only of the windows themselves but the individual components of the window, including the glazing. And the next thing you might want to look at is a whole life carbon assessment of those 3 options on the table. So, and again, the decarbonisation plan can kind of signpost the client team to those next level of sort of investigations that you might need to undertake to guide decision making.

Dan Miles: Brilliant, thank you! And then, so, leading to that one, the last— the question at the bottom there, how are the ongoing are operational costs and their long-term implications considered in the RAG weighting?

Beatie Blakemore: Yeah, Elizabeth, do you want to take this one?

Elizabeth Flower: Yeah, I mean, similarly, embodied carbon calculations, it can be quite a kind of challenging process to really give an accurate operational cost and could be quite kind of intensive for the consultant team to work that out. But I think what's worth pointing out is that really that that kind of set of criteria that you assess your options against is your set of criteria that's specific to your building and your priorities.

So if, for example, if operational costs are, you know, I guess they are for many buildings and building owners, but a real key priority and consideration, then that could certainly be a column within that table. But perhaps that's at the expense of another criteria or something. But yeah, I think it's worth noting that those criteria can be flexible and should be adapted to the building and client-specific priorities.

Dan Miles: Excellent! Okay, and then there's one final one that was in the middle here. So, in heritage buildings where RAG assessments can be lengthy and resource-intensive, is there recognition that delay in decision-making may itself have a negative carbon consequence?

Beatie Blakemore: Yes, yeah, I mean, it's a really good point, and I think we covered in webinar 2 this critical thing about sort of defining the scope— well, firstly the purpose, and then in response, the scope of the decarbonisation plan to your availability of funds and resources and to what your kind of key decisions at the table might be. So it's quite, you know, all these kind of very interesting comments around embodied carbon and operational costs and the process of undertaking the RAG assessment, they are lengthy and resource intensive and they are expensive to undertake. So we have to make sure that we're kind of tailoring that scope to provide the basic information you need to make the next set of decisions.

So I would say that alongside a decarbonisation plan, basic things like regular condition surveys at sort of 5-yearly minimum intervals, but with yearly inspection of certain elements of the fabric, is a really important part of just looking after your building well. And that may flag up all sorts of really quite easy things that you can do around, again, replacing seals on windows, for example, dealing with water ingress issues that you don't need to undertake a whole decarbonisation plan and RAG assessments to know whether or not that's a good thing to do. It is just good practice in terms of looking after your building.

So I think the decarbonisation plan should form part of a whole series of kind of processes and frameworks for how you just look after your building well.

Dan Miles: Yes, that understanding and that sort of looking after the building and doing that, yeah, makes Excellent! Brilliant! I think we've come to the end with time. I just think if Jess has— have you got anything else to just finish off the webinar with?