Heat Pumps and the Path to Decarbonisation: Understanding Their Environmental Impact

Dan: Good afternoon, everyone, and welcome to our latest webinar, which will look at the environmental impact of heat pump technology. And we will explain why this is important in the wider context of decarbonizing heating. Thank you so much for joining us today, and it's great to see people attending from all over the UK, and from as far afield as Malta. My name's Dan McNaughton, and I'm a building services engineer at Historic England, and I'm delighted to be presenting again today with Sehrish Wakil.
Sehrish: Thanks, Dan. Good afternoon, everyone. I'm Sehrish Wakil, and I'm also a building services engineer here at Historic England. We're glad that you have all tuned in and are with us here today for this webinar. So, without further ado, I'll take you through the agenda for today's webinar. We're going to start off by asking a simple but important question: why are we talking about this? Well, set the scene and talk about the big picture, the climate goals we're aiming for, and where heat pumps fit into that story. Next, we'll take a moment to define what we actually mean when we say decarbonization. It's a word that gets used a lot, and we want to make sure everyone's on the same page about what we mean by this in the context of heating and buildings. Then we'll move on to grid electricity.
Since heat pumps run on electricity, it's important to understand how clean or not that electricity really is, and how it's changing as we move away from fossil fuels. After that, we'll look at environmental product declarations. These help us measure the environmental footprint of a product throughout its whole life. And we'll show you how they apply to heat pumps and what to look out for when reading through one. From there, we'll get into refrigerants, which are key components in heat pumps, and an important topic to cover. Next, we'll bring all those pieces together and take a look into the carbon impact of heat pumps as a whole. We'll talk about operational emissions and run through the predicted cost of them in the following years to come.
We'll also highlight some really useful resources from Historic England for anyone working on heritage or listed buildings, which can help make sure heat pumps are installed in a way that respects the historic fabric while still contributing to carbon reduction. And finally, we'll wrap the session up with the question and answer session, and we'd love to hear your thoughts. So, do stick around for that part. So, let's dive into why we're talking about the environmental impact of heat pumps and their relevance to decarbonization. Well, first of all, the UK government has committed to reaching net zero by the year 2050, as defined in the Climate Change Act passed in 2008. By the year 2050, the UK is legally required to have reduced its greenhouse gas emissions by 100% from its carbon emission levels in the year 1990.
As such, heating our buildings is one of the biggest contributors to the UK's greenhouse gas emissions, accounting for around 25% of the total greenhouse gas emissions, according to the UK's Heat and Buildings strategy. So if we're serious about tackling climate change, we have to rethink how we heat tall buildings, including historic ones. In 2022, The UK government set a bold target of installing 600,000 heat pumps every year by 2028, under the 10-point plan. As such, in the latest published carbon budget, The Climate Change Committee's Balanced Pathway envisions a major shift by 2040. They estimate about half of all UK homes could be heated using heat pumps. And this is a huge leap from just 1% in 2023. We will post links to the publications mentioned here in the chat.
So, back in 2020, when the sixth carbon budget was published, there was still a lot of uncertainty about which low carbon heating technologies would be right for the UK. Heat pumps were rare. Hydrogen was still on the table, and technologies like heat networks and hybrids were being explored. Fast forward to today, and the picture has changed significantly. The Climate Change Committee now advises against using hydrogen boilers in homes. And according to their recent report, it is clear that air source heat pumps will now lead the way towards decarbonizing our heating systems. This graph, developed by NESTA, based on the data provided in the Climate Change Committee's seventh carbon budget, shows that air source heat pumps are projected to be the dominant technology in our homes.
Air source heat pumps account for around 71% of all low carbon heating installed in existing homes by 2040 in the new balanced pathway. Although there is a role for plenty of other technologies, including direct electric heating, which is expected to comprise around 13% of domestic heating in 2040, with heat pumps following on at 9%. Although heat networks are expected to play a big role for non-domestic buildings. Communal heat pumps then are expected to be at 3% of home heating systems, and hybrid heat pumps are at 5%. Ground source heat pumps are expected to play a smaller role in this pathway. Crucially, it's important to mention that all of these technologies use electricity. And once again, we will provide a link to this data in the chart. So, what do we mean by the term decarbonization?
We define this as, decarbonization refers to the removal or reduction of GHG, also known as greenhouse gas emissions, with the purpose of reducing the impact of climate change. This includes the reduction of both operational and embodied carbon across the construction, operation, and maintenance life cycle of infrastructure, such as buildings, transportation systems, et cetera, Through a combination of strategies. I will now go on to outline some of the key terms when we refer to carbon emissions. When we talk about carbon emissions in buildings, it's important to understand the two key types: operational carbon and embodied carbon. These are tracked across different lifecycle stages, usually referred to in modules A, B, C and D, as shown in this diagram taken from CIBSE's technical memorandum TM65.
Operational carbon refers to the emissions produced during the building's use phase, mainly from heating, cooling, lighting and appliances. This is covered in module B6, and it's historically been the biggest part of a building's carbon footprint. That's why so much focus has gone into making buildings more energy efficient. Then, we have embodied carbon, which includes all the emissions linked to the materials and construction process of a building. This is captured in modules A1 to A5, raw material extraction, transport, manufacturing, and construction on site. Embodied carbon doesn't stop there. Module B also includes impacts from maintenance, repair and refurbishment over the building's life. Then we have module C, which covers demolition, waste processing, and disposal at the end of life. Finally, Module D captures what we call beyond the life cycle benefits, like recycling materials to avoid future emissions elsewhere. It's often reported separately.
So, when assessing the true environmental impact of a building, especially historic ones we're looking to retrofit, it's not just about cutting operational energy use. We have to look at the full picture across the whole life cycle. That means considering the carbon cost of the materials we use, how long they last, and what happens when the building eventually reaches the end of its life. Now that we've covered operational and embodied carbon, it's important to understand how they come together as what we call whole-life carbon. Whole-life carbon looks at the total carbon emissions associated with the building, from the materials and construction, all the way through to its day-to-day use, maintenance, and even what happens at the end of its life. It gives us the complete picture of the building's climate impact over time.
By assessing whole-life carbon, we can make more informed decisions, not just focusing on energy efficiency, but also on material choices, lifespan and re-use. This graph, produced by the Low Energy Transformation Initiative, who are also known as LETI, in their embodied carbon primer, shows the importance of looking at carbon from a whole-life perspective. This diagram shows the whole-life carbon emissions of a new building, starting with a big spike in its embodied carbon at practical completion, followed by operational emissions across its use, and more embodied impacts from maintenance and end of life. So now, while this is based on a new build, the same principles apply to historic buildings. The difference is, in a historic building that initial embodied carbon was spent long ago.
So, rather than starting up this pink spike, we're entering halfway through the timeline. That means our main opportunity to cut carbon is in the operational phase. What happens from today onward, and this is where heat pumps become so important, by reducing operational carbon emissions significantly over time, they help bring down the total whole-life carbon of the building, including the embodied carbon obtained over time through the maintenance and replacement of the building's heating system. So, even though this diagram shows a new build, the takeaway is just as relevant for heritage buildings. If we want to reduce carbon, we need to look at the whole life: past, present, and future. We will post a link to the LETI Embodied Carbon Primer in the chart.
Dan: Thanks, Sehrish. That was really interesting, and there's clearly a lot of work that goes into producing and understanding an EPD. I'm going to spend a few minutes explaining why grid electricity is important to the environmental performance of heat pumps. So, even though heat pumps are a very efficient type of heating plant, their operational carbon emissions depend on the energy source, and for almost all heat pump installations, this energy source will be grid electricity. You will no doubt have some awareness that in the UK the National Grid is powered by a mixture of renewable energy, nuclear energy, and the combustion of fossil fuels. Electricity generation is a dynamic process.
So, the blend of energy sources used and the carbon intensity of the national grid is constantly changing. Which brings us nicely on to an audience poll. If we could have that, please, Matt. We would like to know: how much do you think that grid electricity in the UK is decarbonized in the 11 years between 2010 and 2021? And you've got four options there, and I see lots of you going for it already, which is great. Your options are a decarbonization of 9%, 29%, 49%, or 69%.
Sehrish: The results are coming in fast.
Dan: Yeah, that's actually- most people voted actually. So, we've got a bit of a mix. I think most people are going for the middle answers of 29% and 49%, which I can understand. And then we've got broadly similar numbers going for 9% and 69%. So thank you, everyone, for that. But I will reveal that the answer is an impressive 69% reduction in grid electricity, carbon emissions between the years 2010 and 2021. I will say that the data beyond 2021 was impacted by a number of contributory factors. Not surprisingly, the COVID pandemic. During 2021 emissions actually increased by 10%. But overall, the decarbonization picture is a really positive one. And I first started using carbon intensity data in 2001, and one of the more positive changes in the context of climate change is that the carbon intensity of grid electricity is more than half during my engineering career, but of course there's still more that we need to do to realize our net zero ambitions.
And over the past 35 years, you can see the change in trends in the electricity generation mix. It is really pleasing to see the significant drop in the blue line over this period. And that blue line is the use of coal. The other significant observation is that the use of low carbon energy, which is represented by the yellow line, was relatively constant until around 2012. And since then, low carbon energy has grown to become the most significant source of energy generation. This positive trend in the decarbonization of the grid is what makes the operational carbon emissions of heat pumps so appealing when compared with fossil fuel boilers and direct electric heating. So, I've already mentioned that the generation mix that supplies the national grid is dynamic, and you can actually look at the generation mix at any time. This data is updated every half hour.
I've shared an example from early this month just to illustrate what this looks like. And with this example, you can see from the chart on the left that at that particular time, 25% of electricity was generated using solar, and another 25% by gas. That is the yellow and purple sections respectively. And wind, nuclear, biomass and imports all make a significant contribution to the generation mix. But things get really interesting when we look at the chart on the right, which is the carbon output for each energy source. What we can see is that the carbon emissions are dominated by gas, which is the purple section, which represents around 75% of the total carbon emissions, despite gas only providing 25% of the overall power output. This hopefully illustrates how important it is to continue to reduce our dependence on fossil fuels for the purpose of electricity generation.
This is a good point today to show some more positive facts about how grid electricity has decarbonized. So, if we wind our clock back to 1960, coal back then made up 90% of the generation mix, and coal is even higher in carbon emissions than gas. Fast forward to 2020, and the UK grid had its greenest year on record, with almost 68 days of generating electricity without using coal. Again, in 2020, renewable energy accounted for the majority of energy sources to the grid, with 43% of all power coming from wind, solar, bioenergy, and hydroelectric sources. The last fact that I'll share is that on the 21st of December 2023, a record for wind energy generation was observed in the UK, with this accounting for 56% of the electricity generation mix on that date, which is really impressive.
And as a reminder, the reason for talking about grid electricity today is to highlight that the operational carbon emissions of a heat pump will decrease further as the grid decarbonizes. And on this topic, a couple of days ago I heard an academic presenting their work which highlighted that as the operational carbon emissions of a heat pump decrease, then the embodied carbon becomes the most significant environmental impact for a project.
Sehrish: Thanks, Dan. It's really great to see how much the grid is actually decarbonizing and how many renewable sources are actually contributing towards the mix at the moment. So, now we'll go into detail around environmental product declarations, which are also known as EPDs. I'll go into how to read them and what to look out for. An EPD works much like a nutrition label, but it's for a product's environmental impact. It is a document that transparently reports the environmental impact of the product or material based on a product life cycle assessment. For heat pumps, a verified document like an EPD helps provide transparency around how the product affects the environment over its entire lifecycle. Manufacturers, architects, and engineers often need to compare EPDs when selecting suppliers or choosing products with the lowest environmental impact for their projects.
To make an informed decision, it's essential to focus on key factors that reveal the most important details of their environmental performance. These factors help ensure a fair and accurate comparison between iPads and in the next few slides, I'll take you through an example of an EPD for a heat pump. So, I'll start off with, this is the front page of an EPD that we're using in this example, and this is an EPD for a heat pump. The first thing you must ensure is that the EPD is still valid. EPDs are usually valid for around five years before they need to be updated and renewed. You can tell if the EPD is still valid by looking at the date of issue, which is listed here, and it will usually tell you how long the EPD is valid for.
So, you can see that the validity period here is five years. It's also important to note that the EPD must state that it complies with either EN 15804 or ISO 21930 standards. And over here the EPD states both, which is great. Next, you should also confirm if the EPD covers the exact model you were interested in. The EPD should state whether the product details and the country, where this information is valid, and it should also state the manufacturer's details.
Dan: So, Sehrish, is the reason you need to check the valid country so that you have, I don't know, the correct transportation emission details?
Sehrish: Yeah, it's a really good question, Dan, and you're right in saying so. The location affects the carbon emissions associated with the delivery of materials and the product itself, as well as the carbon emissions associated with the materials used to build the product. You should also check the details of the refrigerant used. Here we can see the lifetime of the refrigerant and its GWP, which stands for Global Warming Potential. This measures the amount of heat a greenhouse gas traps in the atmosphere compared to carbon dioxide over a specified time period. It's a way to quantify and compare the warming potential of different greenhouse gases, and you can also factor this into your whole-life carbon calculation points. What we're seeing here in this EPD is, you should first of all, check the functional unit, which sets the basis for all the environmental data.
This tells you what exactly is being measured. If two EPDs use different units, you can't directly compare them. And the EPD will also provide the reference lifetime of the product and details of its weight, which impacts its embodied carbon values. You'll need to understand the type of information included in each EPD. So, some may cover additional or fewer processes such as transportation, energy use in operation, or end of life disposal. The criteria and period of data used should be consistent to ensure all aspects of the product's lifecycle are accounted for similarly. EPDs can include different lifecycle stages, so there are cradle to gate EPD which cover the extraction of raw materials to manufacturing, as well as cradle to cradle EPDs, which are the same as cradle to gate EPS, but also include information for recycling the product at the end of life.
Then there are cradle to grave EPDs, which are preferable, as they cover the entire lifecycle from extraction to disposal. The EPD should also state which lifecycle stages have been covered. It's also important to ensure that the products being compared use the same lifecycle stages in their EPDs to avoid inconsistencies. It's also important to look out for carbon data. So, as you can see here in the EPD, there is some carbon data listed, and this is the carbon data associated with the maintenance of the heat pump, so that they can be accounted for and factored into whole-life carbon calculations. There will also be a table of various values. The ones that will be of most interest when calculating the embodied carbon of the heat pump will be the GWP total, which are the total carbon emissions from the heat pump.
Then there are GWP fossil, which is related to the fossil fuel specific carbon emissions, and we also have GWP biogenic, which is the carbon emissions from biogenic sources that also contribute to the manufacturing of the heat pump. It is important to compare these values across the stages, especially in the stages A1 to A3, which involves production, and stage B6 during its in-use phase to see where the environmental hotspots are. So, it's also crucial to ensure that both EPDS are verified by an independent third party to ensure the data is credible and consistent with international standards. It's also very important to check that an improved method such as CIBSE TM 65 or One Click LCA has been used during the lifecycle carbon assessment.
EPDs are a great step towards transparency, but when it comes to heat pumps, it's important to understand their limitations too. First off, when it comes to heat pumps, not many EPDs are currently available. While we are finding that more manufacturers are creating them in more recent years, they're still not standard across the board. So, finding a range of data that is comparable can be tricky. Secondly, even when you do find an EPD, the data can be limited. These documents rely on average values, assumptions, and models that might not reflect how a product performs in your specific context. And it's also dependent on what sources of information have been used. And here's a big one: EPDs provide environmental impact numbers, but they're often simplified or generalized, which can lead to under or overestimating the true emissions of your heat pump.
Although they are good for providing an overview and ballpark figure for whole-life carbon calculations on projects, EPDs can also be made to be cradle to gate, meaning that they only account for the impacts up to the point the product leaves the factory. That leaves out critical carbon data for a heat pump in its whole-life carbon lifecycle. This includes operational emissions which occur during the use phase, the emissions associated with maintaining the equipment, and the carbon associated with decommissioning and replacing the system at its end of life stage. This also makes it challenging to compare EPDs, as a cradle to grave EPD will show different values compared to a cradle to gate EPD. It's always important to ensure you're comparing like for like when looking at EPDs. So, while EPDs can give you an overview, they don't always offer a full picture of your real-world carbon footprint. Bottom line: EPDs are very useful tool, but they are just one piece of the puzzle. Always look beyond the label when making sustainability decisions to ensure you are making correct comparisons when selecting your heating system. Over to you, Dan.
Dan: Thanks, Sehrish. There's certainly a lot to be aware of with EPDs. We're now going to spend a bit of time talking about refrigerants. And to start explaining why they can't be overlooked as part of the wider heat pump environmental considerations- And this may or may not answer the refrigerant question that's appeared in the chat. So, if you attended our recent Heat Pump Technical Tuesday webinar, you may recall that Rossiter prints were defined as the fluid used in heat pumps and other refrigeration plants to efficiently generate heat. I'm not going to go into lots of detail about refrigerants, but I do want to provide an overview, an awareness of the environmental considerations with regards to refrigerants, and we'll touch upon a couple of practical considerations too And- And although we are focusing on heat pumps today, I thought it would be useful to mention where refrigerants are more widely used.
So, most people know that refrigerants are used in domestic refrigeration. Sounds obvious. Your fridge and your freezer, and also in-vehicle air conditioning systems. But what I found interesting was that in 2021, heat pumps only accounted for 6% of total refrigerant emissions in the UK. The chart shows that commercial refrigeration accounts for 26% of the total emissions. But I suspect that the largest proportion of stationary air conditioning at 36% incorporates the large number of air to air heat pumps, which are commonly referred to as air conditioning. Regardless, we can expect to see the proportion of refrigerant emissions associated with heat pumps to increase as this technology is more widely installed.
So, like with anything that we manufacture, there are carbon emissions associated with the production of refrigerants, and there are also significant greenhouse gas emissions when these refrigerants are released into the atmosphere. It is against the law to knowingly release f-gas refrigerants into the atmosphere. Now the f in f-gas refrigerants refer to those which are fluorinated or in more basic terms, refrigerants which contain fluorine. There are ways to recover refrigerants and recycle them. So, you may be wondering why refrigerant released into the atmosphere is still an issue. So, unfortunately refrigerants can be released into the atmosphere unintentionally. These emissions are known as fugitive emissions, and in answer to that question in the chat, these do happen in closed-loop refrigeration systems.
They are caused by leaks, and they can occur during normal operation, during servicing, or from catastrophic leaks. Estimates of the amount of fugitive emissions in systems vary. And really, the most accurate way to determine this is to keep accurate maintenance records, which include details of any refrigerant top ups. So, historically, there's been awareness about the environmental damage of refrigerants through their ozone depletion potential, and I'm sure there will be those among us today that vaguely recall learning about this at school like I did. A significant cause of this was a group of refrigerants known as CFCs, Or if you're a science geek like me, you might know these as chlorofluorocarbons. And CFCs were phased out from 1987 onwards, and as a result of this, scientists predict that the ozone layer will completely regenerate over the next 20 years.
However, this positive development in refrigerants isn't the only environmental concern. Many refrigerants are harmful greenhouse gases which contribute to climate change. We've already mentioned the potential for refrigerants to cause global warming is a key refrigerant property known as GWP, which stands for Global Warming Potential. Sehrish talked about these briefly earlier when she was talking about EPDs. This property measure. This GWP measures. How much a refrigerant contributes to global warming compared to carbon dioxide over a 100-year table. So, from this table, hopefully you can see carbon dioxide there, which is actually the largest contributor to global warming, mainly due to the combustion of fossil fuels. And this has a Global Warming Potential of one.
Now, compare this to refrigerant R410A, which is commonly found in air conditioning systems and heat pumps, and this refrigerant is around 2000 times more harmful in terms of global warming than carbon dioxide. So, hopefully you're starting to understand just how harmful some of these refrigerants can be to the environment.
Sehrish: Dan, given that you had a heat pump installed in your home recently, can you specify what refrigerant it uses and what would be your preferable choice?
Dan: Yeah, I certainly can. I won't talk so much about my preferred choice because there's a lot of factors in that. But it's a really good question. My heat pump uses R32, which is just above that there, and that's around three times less harmful to the environment than R410A. But as you can see, R32 with a Global Warming potential of 675 is still not something that you want to be releasing into the atmosphere. The positive news with my heat pump is that it is hermetically sealed during construction so that there is no distribution of refrigerant pipework anywhere and fugitive emissions will be negligible. One other factor to consider with the environmental impact of refrigerants is the refrigerant charge. And that essentially means the amount, the mass of refrigerant that is contained within your heat pump, and in some cases the wider refrigerant distribution pipework and emitters.
There is another environmental consideration, and that's the per and polyfluoroalkyl substances, which I think from now on we'll just refer to as PFAS, which are synthetic substances which don't decompose and can contaminate the environment. Not going to go into detail on these today, but I will revisit this table in a moment. So, going back to those F-gas refrigerants that I mentioned earlier, Some of you may have heard of f-gas regulations. This diagram helps to show that from this year there will be a 69% reduction in f-gas consumption, and new heat pumps will need to use refrigerants with a Global Warming Potential of less than 750, and that 69% reduction is from the baseline measure 10 years ago. This reduction will increase further to 79% in five years time. This strategy commits the UK to meet a target of reducing F-gas consumption by 85% by 2036.
So, things are definitely moving in the right direction. So, revisiting this same table of refrigerants, I want to briefly mentioned some of the other refrigerant properties which don't impact the environment, but they do need to be understood during the design of refrigerant systems. And if we have a look at the highlighted column, the first letter refers to the toxicity of the refrigerant, with A denoting lower toxicity and B meaning that it's a high-toxicity refrigerant. The only one that is considered high-toxicity in this table is ammonia, which is just down here. And that isn't to say that class-A refrigerants are nontoxic, and there's actually an exposure limit which applies to them. And the other thing that I want to mention is the flammability classification of refrigerants, because we always get questions about this, and that ranges from 1 to 3 where 1 is non-flammable, 2 is mildly flammable- 2 is lower flammability, and 3 is highly flammable.
The reason I'm sharing this is that one of the low Global Warming Potential, natural refrigerants we call them, that is now widely available in heat pumps is propane, which is just there. And that only has- propane only has a GWP of three, but it is classified as highly flammable. Now, that's mitigated, the flammability risk of propane heat pumps, and so installers and maintenance contractors need to receive specific training. And I believe that the installers also have to complete a refresher course within five years of this training. And as a designer, we have to consider the location of a propane heat pump because it needs to be at least one and a half meters away from openable windows and the same distance from air bricks and down pipes.
Sehrish: Thanks, Dan. It was really interesting to hear so much around refrigerants, and especially around what's projected with the f-gas regulations. So, now we'll go into having a look into the carbon impact of heat pumps as well as what the costs will be projected to look like in the future. So, this graph developed by the Climate Change Committee in their seventh carbon budget report shows the balance pathway for nonresidential buildings results in the net cost around the year 2040 to the economy compared to the baseline. Net cost, in this context, means the overall cost after accounting for both the initial upfront capital costs of heat pumps and the operational savings of installing low carbon heating systems. The Climate Change Committee predicts that the capital costs will be high up to the year 2032, with the installation of energy efficiency measures and the early part of electrification.
Capital costs are predicted to be more stable after this point, and sustained operating cost savings from energy efficiency are predicted to lead to a roughly cost neutral pathway in later years from the year 2040. The Climate Change Committee projects that investment in energy efficiency and low carbon heating will lead to capital costs which decrease over time. They also say that energy efficiency improvements will provide sustained operational cost savings, as will some of the electrification measures. And in the seventh carbon budgets, a huge player in this prediction has been due to the predicted rapid uptake of heat pumps. And now, moving on to this slide. So, this graph shows a comparison of the annual carbon emissions produced by three common types of home heating systems: air source heat pumps, gas boilers, and oil boilers.
These figures have been taken from the renewable energy hub. And as you can see here, air source heat pumps are by far the lowest emitters, producing around 850 kilograms of carbon per year. In comparison, gas boilers produce nearly three times the amount of carbon emissions in the year 2500 kilograms, whilst oil boilers are the worst offenders at 5200 kilograms of carbon annually. Now, while heat pumps do require electricity to operate and are not entirely carbon free as a result, they are still considered a form of low carbon heating. Even though heat pumps use electricity. And not all electricity in the UK comes from renewable sources, their overall carbon footprint remains much lower than traditional gas or oil systems despite this. A further reduction in emissions can also be achieved by partly powering the heat pump with energy produced from solar panels or switching to a 100% renewable energy supplier.
Though, as this graph shows, switching from a gas boiler to a heat pump can cut a typical home's carbon emissions by around 1650 kilograms per year. This is equivalent to driving over 7300 miles in a petrol car, according to the openco2.net database. In summary, switching to a heat pump isn't just about reducing bills. It's one of the biggest steps you can take toward a lower carbon, more sustainable home. Over to you Dan.
Dan: Thank you. So, for more information around heat pumps in historic buildings and some of our guidance around installing heat pumps in historic buildings, please refer to our web pages and guidance notes around these topics. We've also published an investigation looking into the viability of air source heat pumps in older buildings, which looks at ten case studies of both air to air air to water air source heat pumps. And we've got three more investigation reports come in which will get published as soon as we're able to, which look at viability of large- larger air source heat pump installations in historic buildings and separate reports for both ground and water source heat pump installations. So we've tried to cover everything there, and we'll put links to both our web pages and the report into the chat for you.
And also, I want to direct you towards the recordings of our other Technical Tuesdays, which covered different aspects of heat pumps and types of heat pumps in case you have missed any of them and want to catch up. And you'll also- by watching those, you'll get a sneak preview of the findings from those different reports that I've already mentioned as well. We'll put a link to the webinar recordings page in the chat. And as you see, there's a wide variety of content available from Historic England. So, it's not just about heat pumps. You can find all sorts of information. But we do have a separate section dedicated for the heat pump events. And that actually concludes the presentation part of today. And thank you for listening. Feel free to reach out to connect with us on LinkedIn if you'd like to keep up to date with our work, and our email address on the screen if you'd like to get in contact. We've now got time to hear any questions that you may have.
Matt: Thank you, Dan. Thank you, Sehrish. I will actually post the questions that you've already had in a chat, I'll put those in the Q&A box so you've got them in there, but clearly you've answered some, if not all. But for everyone else, If you have any questions for Dan or Sehrish, that window in the middle of your screen there, there's a text- you can type text in at the bottom there, and Dan and Sehrish will try to answer your questions.
Dan: Brilliant. I'll get started. There's a couple that I've noticed. The first question was about the pie chart, and that was to do with the grid electricity mix that I talked about. And the question was, in the pie chart it says what is categorized as import. So, the UK imports quite a lot of electrical energy from countries like France and Norway. And you may or may not be aware, we have quite large underwater cables called interconnectors which actually connect countries, and that allows you to import and export energy, which is very useful in a fluctuating energy- dynamic energy mix. So, hopefully that helps answer that one. And the second one I was going to take, it's interesting because I was talking about this with somebody this morning. It says ground source heat pumps could provide a greater contribution to community heating solutions, and remove the necessity to have an external fan unit.
That's referring to air source pumps in every building. And it says that this could be aesthetically important for historic buildings. So yeah, it's a very good point. What we tend- or what we genuinely find with ground source heat pumps is that they're a bit more expensive to install capital-wise than air source heat pumps. And it's all about weighing up what is best for an individual project. Sometimes it's an air source heat pump. Where ground source gets a bit trickier is where you've got a sensitive historic site, particularly with archeology. And once you get the idea of a community heating solution, so connecting more than one building together, that amount of ground work obviously becomes more extensive.
But it does happen, and... But certainly from an affordability in terms of capital projects, I think we'll see more resource heat pumps, but of course, all types of heat pumps, we've found that they work very well in historic buildings and they've all got a part to play. So, I totally understand the observation, and yeah, it's a good one. Thank you.
Sehrish: Yeah, we've just had another question come through. So, how does the carbon footprint compare to other boilers when the carbon footprint for manufacturing and shipping disposal, etc. are taken into account? This is a really good question, Craig. So, as time goes on and as the grid decarbonizes further, operational carbon will become less significant, as you know, the main operational carbon coming from your air source heat pump is coming from electricity, and the embodied carbon of the heat pumps will be expected to be more significant as time goes on. And my answer to that is that you're still expecting a payback in your carbon compared to the carbon installing your heat pump into your building as you'll get savings in operational carbon compared to using an oil boiler or using the gas boiler.
So, if we look at the whole life, then you're getting- you're seeing that reduction in comparison. But yes, a really good point. You know, embodied carbon, lifetime carbon will be playing a more significant role. And that's why it's so important to look at EPDs, for example, when choosing what equipment you're selecting and seeing what the carbon impact is of that technology.
Dan: Yeah. And then, just before we move on, Sehrish, just to add to that one, a few years ago I saw a study. and I do have to say from a heat pump manufacturer, so you have to consider impartiality and everything, but it actually looked at exactly that, the embodied carbon and operational carbon of both an air source heat pump and a gas boiler. And in that particular example, you can pay back within 12 months, and you'd never do it, but you could actually replace the heat pump every year and still make overall carbon savings. But I'd always recommend a detailed calculation to verify that.
Sehrish: Yeah, I totally do agree with that. And then another question that's popped up: are EPD is provided by heat pump manufacturers. The answer is yes. Heat pump manufacturers do provide them, but they are limited. It's not considered an industry standard at the moment for a manufacturer to provide an EPD for the heat pump. However, where you find that an EPD doesn't exist, there are tools available such as the CIBSE TM 65 tool which can help you calculate the embodied carbon of your heat pump when you want to take into account your whole life carbon calculations.
Dan: Okay, Quite a few good questions come in actually. Thank you for that, everyone. Two easy ones which I'll take for now. One is: are heat pumps a viable low carbon option for buildings only used once or twice a week, e.g. churches? It becomes more tricky when you've got low-use buildings to justify it from a cost perspective. So, you need to look a bit more carefully at that. I've done a bit of work and I've shared in our Technical Tuesdays, so there's a recording of it which shares the findings of how best to decarbonize a group of churches. And what the findings were broadly, a third of that small sample of churches were best suited to air source heat pumps, but those were churches that were used regularly throughout the week and have more communal use and higher overall energy consumption.
So, hopefully that helps there. And there was another question that said: would heat pumps be an appropriate heating system in large and complicated buildings like a palace, for example? Sounds like you've got something very specific in mind there. I have seen them work extremely well on buildings of that size, but of course, you need to have somebody that knows what they're doing to visit the site to understand any particulars. But I have seen it done on that scale and it's been incredibly successful at that scale. So, thank you.
Sehrish: Thanks, Dan. We've had another question. How important is resiliency With high electrification? There is high dependance on electricity and without backup generation or batteries, there is potential for failure. Yes, this is true. As you electrify systems, you have a greater reliance on electricity. So, it is quite important that if you are designing your systems for buildings that are, let's say, mission critical, or let's say, for example, hospitals or offices that have, let's say, vulnerable people in them, you would like to ensure that you do have some form of resiliency in place, such as backup generation, battery storage, etc.. It's also important to mention as well with that point of resiliency, resiliency on the grid as well. So, it's also about making sure that you are able to support those levels of electricity in your design as well, when you do design for your heat pump.
Dan: Yeah, it's interesting that question of resilience and reliability on electricity, and it comes up quite often. And what people don't realize is that your gas boiler won't work without electricity either. So, sometimes that argument falls over. But also, we're putting more and more strain on the grid with electrification. So, that needs to grow and develop with the decarbonization of heating. We're actually at 2 o'clock, So I'm going to close on questions for now.

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