Webinar on Updates to the Building Regulations Approved Documents Part F and Part L

00:00:00:10 - 00:00:26:07

Speaker 1

Welcome, everybody. And good afternoon. Thank you for joining us. I'm just going to turn my webcam on. There you go. So. Hi, my name's Matt Faber and I'm your technical host for this afternoon, so you'll be glad to hear I'm not giving the presentation because I'm afraid my understanding of building regulatory regulations even is is not as good as it should be.

00:00:26:15 - 00:00:48:08

Speaker 1

And that before we start, we do have a little bit of housekeeping. So first of all, just a little poll to the left of my webcam. Can you hear me okay? I can see clearly some people can't hear me and that's a problem. I will hopefully address that as we as we move forwards, I'll be messaging people to try and offer some support.

00:00:48:08 - 00:01:17:10

Speaker 1

There. So thank you for that. Right. Housekeeping. Just to give you a little heads up on the functionality of the platform, depending whether you're using a browser or the Adobe Connect app, which I know some of you are, there's a little loudspeaker icon at the top of your screen there that'll enable you to adjust volume. So if you can't hear me very well, please feel free to adjust volume.

00:01:17:18 - 00:01:43:18

Speaker 1

Hopefully that'll resolve issues for you. There's a little raised hand icon there to the right as well. If you want to bring something to my attention, please raise your hand and I will. Private message you or message you in the chat room to see if I can offer any support. Also, you'll notice there is a CC or closed captions icon at the top of your screen.

00:01:43:20 - 00:02:12:11

Speaker 1

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00:02:13:07 - 00:02:43:23

Speaker 1

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00:02:44:06 - 00:03:08:17

Speaker 1

If that's not working for you, please use another browser. If you are able to or indeed the Adobe Connect app as well. This session is being recorded as all our webinars are and that recording will be made available to you via the historic England website, a link to which I will provide you with at the end of at the end of this session.

00:03:08:17 - 00:03:32:07

Speaker 1

Okay. Moving on, we have a little polling question for you here. Just to the left, my webcam for anyone who hasn't done all done so already, if you'd like to join the Technical Conservation Newsletter, please just click the yes button and we will add your name to the mailing list and you will start to receive the newsletter from the technical conservation team.

00:03:32:07 - 00:03:54:12

Speaker 1

That's not the webinar newsletter, I should point out. That is for technical conservation and all that activities. That's absolutely marvelous. Thank you very much. Still a few people voting. Fantastic. Thank you for that. Um, uh. Right. Okay. I see someone's in the chat those. Okay. Yeah, fantastic. Laura, well done. Thank you for that. I'm glad you can hear.

00:03:54:12 - 00:04:22:05

Speaker 1

Now, I think maybe you're using Internet Explorer, if that's the case, if the sound drops out, as I mentioned before, please just refresh the page and it'll bring the sound back. If that doesn't work, please mention it in the chat throughout the presentation today. If you have any questions, please put those questions in the chat room. Please prefix them with a capital Q, which enables us to identify the questions more easily.

00:04:23:03 - 00:04:50:12

Speaker 1

Any comments? Please please put those in the chat as well. We will have some of our presenters responding to those comments in the chat as well, but we will also have a Q&A at the end at the end of the session so that we can answer the questions there as well. Okay, that's good. So moving on, I'll introduce you to Joanne Williams, who is the chair for today's session.

00:04:50:19 - 00:04:54:13

Speaker 1

So over to you, Joanne.

00:04:54:13 - 00:05:15:23

Speaker 2

Thanks, Matt. And hello, everyone, joining us today. My name is John Williams. I'm a conservation accredited building fair working in historic England's climate change adaptation team, which sits in the technical conservation team. So today's format is going to be a bit different to normal. If you've been to our previous webinars, instead of taking questions at the end, we're going to split it into two intervals.

00:05:16:08 - 00:05:39:11

Speaker 2

So first, if you have questions relating to part, I'll put those into the chat and at the end of the session we'll start their questions for part F Matt, could I just ask you to introduce the questions before I introduce the others regarding future trading sessions? Brilliant. Thank you. So joining me today is Anna from the HPC, who'll introduce herself shortly and I'll speak to an audit.

00:05:39:15 - 00:06:07:17

Speaker 2

Ian is a building researcher specializing in the field of building performance testing, monitoring and evaluation. He focuses on energy efficiency, indoor environmental quality and occupant comfort. He's routinely involved in field based building research programs, many of which are delivered on behalf of Base and Clark. Among his most significant roles, he is a senior member of the technical team appointed to support the governments of England and Wales in developing their respective revisions to the building regulations.

00:06:08:01 - 00:06:37:17

Speaker 2

Since 2006, Ian has led to the technical changes to the approved document and the building fabric specifications for approved document l, including air tightness standards for the 2021 revisions. He also developed formal guidance for reducing the performance gap, improving levels of compliance, and designing a new process for improving ventilation provision in the retrofitting of existing homes and is also a member of the retrofit Standards Task Group and the steering group for the revisions of past 2030 20:05 30.

00:06:37:20 - 00:07:15:24

Speaker 2

Retrofit an E and specifications is also an accredited retrofit coordinator and over two. Thank you. Hopefully you can hear me. So hello, everyone. And a warm welcome to today's event. I'm Anna Hart and I'm delighted to have the opportunity to introduce myself as the new Education, Training and Application Support Officer with the HPC. So this webinar marks the first of a series of training sessions delivered through a joint initiative between historic England and the BBC.

00:07:15:24 - 00:07:48:02

Speaker 2

So this series will look at issues from regulatory changes through to climate change, issues relating to heritage and conservation, and will be led by experts in their field such as Ian today. This series will commence in the New Year with potential alternative streaming events such as podcasts, such as supports historic England and the HPC. With tailoring this series of training sessions, please, could you take a moment to post any suggestions you have for potential topics in the chat or in the Q&A box sets up at the moment.

00:07:49:04 - 00:08:15:17

Speaker 2

But if you would prefer to contact me separately, or if you have any other questions relating to training with the HPC, then please feel free to contact me. My email address is training at ABC dot org dot UK. And also just to let you know the HPC is celebrating its 25 year anniversary so you can find out more about what we're doing to celebrate at HPC dot org dot UK.

00:08:15:17 - 00:08:24:11

Speaker 2

Sorry, forward slash HPC at 2025. Okay, thank you. And over to you, Ian.

00:08:30:08 - 00:08:56:03

Speaker 3

Well, good afternoon, everybody. And firstly, thank you for HBC and Heritage Historic England for inviting me to give this talk today. Thank you also to everyone who's joined in giving up your precious lunch breaks to talk about building regulations. I, on the other hand, seem to have given over half my life to building regulations. And so I guess it's a small sacrifice.

00:08:56:21 - 00:09:37:07

Speaker 3

You've given up your lunch break. But anyway, today I am going to give you an update on the parts F and Parts L of the building regulations which were introduced for England in earlier this year. I won't re-introduce myself because Joanna did that, thank you very much. But what I will say, just in addition, is given my close connection with the governments of England and Wales in developing the regulations, I do have to say that I am here today of my own free will.

00:09:38:03 - 00:10:07:09

Speaker 3

I am not representing either of the governments in any capacity. So that means anything that I do say and the opinions I expressed are not representing government policy. So what I'm going to cover today, I say the updates, the focus is going to be on existing dwellings. I'm going to cover just an overview of the changes to both of those documents.

00:10:07:24 - 00:10:26:22

Speaker 3

I'm not going to go into a lot of the background about what was in the previous one, in previous editions and so on. And I'm also going to assume that there's a degree of working knowledge among delegates. So, you know, I'm not going to be covering climate change policy and background and direction and why we're doing all of this.

00:10:27:12 - 00:10:50:17

Speaker 3

I'm not going to be explaining things like what you've done to us. I'm not commenting. If you do have any questions on those, on anything that I do say that you're not clear on, then obviously, please do proper questioning. I'm going to skip over this slide and come back to it, realize that it is in the order. Just some context, really.

00:10:51:24 - 00:11:24:13

Speaker 3

Some of you may well be aware, many of you may well be aware of the future home standard that was consulted on a couple of years ago. I'm not going to spend too much time on it because it mostly relates to new dwellings. However, there is important context here that that will affect existing homes and the future home standard essentially set out the Government's journey towards the net zero policy.

00:11:24:22 - 00:12:13:03

Speaker 3

But as you know, the reduction of greenhouse gases to be net zero by 2050 and that new homes will built now will exist obviously in 2015, we'd hope. And therefore anything that we build now should at least be on that pathway to meeting the net zero policies without needing major works them. So you don't want to retrofit home being built now such that when we get to 2050 it needs some major work to to to meet that zero carbon standard and that includes the heating systems as well that they should be designed to be using low carbon heating rather than fossil fuel based heating.

00:12:13:03 - 00:12:57:18

Speaker 3

As part of the consultation, the Government set out changes to how and Part F and part No. And I will go back to the previous slide here to show these updates. You've probably been you're familiar with I'm hoping with at least part L and part F to some degree. Part Oh, I'm not going to cover at all of just to introduce its existence because it only applies to new dwellings and non non-domestic residential buildings such as care homes, and that is an overheating standard to ensure buildings do not overheat in.

00:12:58:08 - 00:13:30:08

Speaker 3

As part of our changing climate, Part L, the approved documents for that have been updated. They are now in two volumes rather than in four volumes. So it's condensed it into into two. So volume one is dwellings and that's what we'll be looking at today with a focus on the existing site covers new and existing dwellings. Volume two is for buildings other than dwellings.

00:13:30:08 - 00:14:20:22

Speaker 3

Part F was previously one volume covered dwellings and well covered all buildings. Now it's being split into two volume. So like part a part sorry. So that's dwellings new and existing in volume one and all of the buildings in volume two relating to the future home standard. Again, the few things the future home standard set out in four existing homes and that is the Government have a commitment to phasing out the installation of high carbon fossil fuel based heating systems, both in new and existing homes and starting off with new homes.

00:14:20:22 - 00:15:03:01

Speaker 3

But no doubt existing homes, given this 20 plus million of them, will need to consider how they're going to decarbonize. And it may well be that the future home standard is developed to to incorporate more holistically existing homes on this pathway to net zero for existing homes, specifically not new homes. There is a recognition lot of homes being off gas grid that you that there is a greater allowance to use biofuels such as bio LPG or biomass.

00:15:03:01 - 00:15:32:20

Speaker 3

So some form as part of that decarbonization it doesn't apply to new homes just simply because there's not enough wouldn't be enough biofuels to go around. So that applies to existing homes only because of these changes in fuel switching. So on the new part, L does give a greater amount of guidance on building services that are likely to be installed in in existing dwellings.

00:15:33:03 - 00:16:10:19

Speaker 3

And that's now contained in the new edition. I don't want to spend too much time on this just because it does relate still to new homes. But there was a new energy metric in SAP, so up until now, SAP, which is the national calculation methodology tool for dwellings used to assess compliance for dwellings using carbon dioxide emissions from property.

00:16:10:19 - 00:16:49:09

Speaker 3

For the last 20 years that has been the case. However, as we are now using more sort of green energy going into the grid rather than extracting fuels and converting them into power stations and then feeding into the grid. We are decarbonizing the National Grid infrastructure and as this chart shows, we have in looking at carbon emissions, the changes between the previous cartel and the new cartel.

00:16:49:11 - 00:17:21:09

Speaker 3

So these two stacks here, there's been about 75% reduction in CO2 emissions for electricity generation, whereas for mains gas, this there's not much change at all because the calorific values are pretty much and associated. Carbon emissions are very small. So the point is that it's easier now to pass with using the CO2 metric than it is with gas.

00:17:23:01 - 00:17:52:14

Speaker 3

If you use electricity, it's less emissions when compared to gas. So you're trying to counter that because and to prevent people going straight to direct electric because that's easy and cheap and so on and that would have a great impact on the grid. Might overwhelm the grid. There's a drive towards making low carbon forms of heating using electricity for fuel.

00:17:52:14 - 00:18:33:16

Speaker 3

So for example, heat pumps and the Government have introduced the primary energy factor. P And as you can see that the primary energy factor has a greater rate compared to mains gas. So it's more difficult to comply using direct electric unless you have a greater efficiency in the boiler or heat pump compared to the gas equivalent. And the primary energy factor takes into account all of the conversions of the energy before it's delivered into the home.

00:18:34:17 - 00:19:34:08

Speaker 3

And obviously with the below amount processes are involved, then the the lesser the primary energy factor will be. So again, this mostly affects for existing dwellings, its effects extensions, and it's only extensions where you wish to have greater flexibility. And greater flexibility means that you would use a fewer extension, in which case the primary energy factor is part of the mix, along with the other retained metrics carbon dioxide, the public energy efficiency standard, and the uplift to fabric and services.

00:19:34:08 - 00:20:10:00

Speaker 3

So coming on specifically to what approved Document L, volume one for existing dwellings says, there are, as I said, the fabric and services efficiency updates which all come up and see if buildings are being renovated or extended. There's no changes in England for consequential improvements. So consequential improvements are a term whereby if you are planning to do an extension, for example, that you should be required under the regulations to carry out improvement measures.

00:20:10:00 - 00:20:34:11

Speaker 3

So, for example, an extension being built as part of that work, you might need to improve the loft insulation or cavity wall insulation in or whatever to make sure the existing dwelling is improved. As part of that process, there's no changes in England that still applies only to larger dwellings, so over thousand square meters and a treated floor area.

00:20:34:21 - 00:21:36:13

Speaker 3

So very large dwellings in Wales, the consequential improvements apply to extensions of ten meters squared or greater and there's no change necessarily to the provision for consequential improvements which I think are limited to a loft insulation, top up cavity wall insulation and efficiencies on the hot water cylinder. But now because of issues with rain, with rising penetration into the cavity that is more severe in Wales, then a risk assessment is now required as part of that consequential improvement, one of the main drivers for the revisions to the approved documents has been to simplify the structure.

00:21:36:13 - 00:22:04:12

Speaker 3

This sort of fell out the Hackett review, where there's the recommendation most to simplify the guidance that's published in the approved documents. So that's been the main thrust. And hopefully if you've read through the documents so far, you might find it's a it's a bit of an easier read than than that previous versions. Also in some cases, a picture can tell a thousand words, so to speak.

00:22:04:12 - 00:22:42:12

Speaker 3

So there's a lot more diagrams involved with trying to explain what is meant, because feedback has been over the years that, you know, the there's a need for greater clarity. Things can be misinterpreted. So so that's been a lot of the focus on the on the on the new guidance. Whoops for existing dwellings. Most of the thrust has been on improving the building surfaces.

00:22:42:12 - 00:23:19:04

Speaker 3

So specifically for heat generator spoilers and so on. And now there is a process whereby if you are looking to replace a boiler in an existing dwelling, it should be of the same view as the existing dwelling. So a gas boiler can be replaced with a gas boiler, but now you're unable to switch to a different fuel unless that fuel is it just has a lower CO2 and primary energy content.

00:23:20:20 - 00:23:56:07

Speaker 3

So for example, if you are switching to a heat pump that's got lower carbon emission taxes, lower primary energy factors from a gas boiler that should be fairly straightforward. And. Whereas, if you're switching from a gas boiler to directly metric, that's going to be more problematic because of those changes in the the chart. So I showed you earlier about the carbon emission factors and so on.

00:23:56:07 - 00:24:37:08

Speaker 3

So what that means is you, it's kind of pushing you towards low carbon heating. It's not it's not requiring you to have low carbon heating, but it is not you in that direction. The only exception to a backward stepping in fuel switching is if you're, for example, doing it. And if it's a passive house retrofit where you have a dwelling heat loss of less than 25 kilowatt hours per square meter per year, then in those circumstances, the heating provision may well be a post heater battery in an empty system, for example.

00:24:38:02 - 00:25:16:14

Speaker 3

And in that case, when you've got very low heat demand, then it's not a problem to change to electric. One of the other changes that's happened in both approved documents out under is the what we've termed second tier guidance documents. So they would be in this context, the Domestic Building Services Compliance Guide have now been superseded, but the important guidance has been retained and moved into the main body of the approved document.

00:25:16:14 - 00:25:58:17

Speaker 3

So in some ways it limits the need to flip from document to document to get the information you need. Everything is now under one cover and so you'll find there's more system specific guidance for different types of boilers and heating systems in the approved document, I. The new part l also now requires that when you are replacing a heating system in its entirety, so you are replacing the entire distribution system, not just a single radiator, but all radiators and probably of the pipework distribution system.

00:25:59:12 - 00:26:43:09

Speaker 3

Those should now be sized to allow for a low carbon heat source such that they can be operated efficiently at 55 degrees, so that may well mean depending on the fabric efficiency, of course, it may well mean that larger radiators are needed compared to those that exist for properties that have a photovoltaics that already exist. If you are going to replace that array, then the new requirement is that the newer I should have at least the same electrical output as the original installation.

00:26:43:09 - 00:27:36:13

Speaker 3

So you can't put the smaller one on. And so that's a fairly minor change. And this new guidance not that is necessarily new provision, but there's new guidance on when you're renovating thermal elements or creating surfaces penetrations or putting new doors windows in that you that there's reasonable provision that you can a process you can follow to show to your building inspector that you've taken measures to reduce heat loss arising through infiltration and you've put appropriate draft ceiling measures or drought sealing, as I've seen to have said that I would use the same applies now with thermal bridging.

00:27:37:00 - 00:28:11:22

Speaker 3

Again, there was provision in the previous L1 B document, but now that's been expanded just to make it more of a provision for you to consider heat losses through thermal, which is it may mostly apply to extensions rather than conversions of existing thermal elements. But yeah, it's it's something to consider the accredited construction detail scheme which is applicable to new dwellings mostly, but it did apply to extensions.

00:28:11:22 - 00:28:49:06

Speaker 3

It's now been archived and instead there is a references to external sources such as the ABC Construction Details Library or other industry guidance. So these illustrations are from zero carbon hub guidance. As long as you're following a process and you can document and demonstrate that process, that thermal pictures have been included in as part of your your construction.

00:28:49:06 - 00:29:29:03

Speaker 3

If we stick with extensions and consider the changes now for the specific guidance for for the fabric elements, I put this table here which the left hand column covers the previous part. L For England, the middle column is now part L England's 2021 approved document, and the right hand column is for Wales. Wales being slightly different. So the main or most significant change there is for extension moves.

00:29:29:12 - 00:30:19:08

Speaker 3

Previously, the usually limiting u-value was 0.28. This is now improved 2.18, both for England and Wales. So what that means is that a 100 mil standard cavity wall is unlikely to meet those new u-values unless you're using very high efficiency, rigid foam boards, I'll probably need to be fulfilled. So and probably in conjunct with lightweight blocks. So you may well see an increase in cavity thicknesses if that's the approach for the extension.

00:30:19:08 - 00:30:52:18

Speaker 3

Roofs haven't changed that significantly for extensions. What the guidance now has for four weeks previously sorry I should say the guidance was separated depending on whether you're insulating up to joist level or whether you're insulating that rafter level. Whereas now there's this one standard for all waves. And England have gone 2.15 for waves and Wales have gone further with point one.

00:30:52:18 - 00:31:26:20

Speaker 3

Three floors have gone from point 2 to 2.18 in England and further to 0.15 in Wales. Windows have jumped a window energy rating band for both England and Wales. So aware of C down to aware of B and the approximate U-VALUES given at 1.6 to 1.4. There's not a direct correlation, but either those would make the standard 1.6.

00:31:27:00 - 00:32:09:07

Speaker 3

So at 1.4 or worby and Dawes have gone from a Dorset Energy rating of a down to a rating of B or 1.4 U-VALUE Again, if we look at renovated items elements, so this might be when you're carrying out a conversion or if your even if you're looking to repair a thermal element, you might be wondering, you might be re plastering from the inside.

00:32:09:16 - 00:32:45:00

Speaker 3

And if you're doing more than 25% of an element, so more than 50% of an element, individual element or doing 25% of the total thermal envelope, then you would need to improve it to the standards. And there's no real change for this stage. I should also say that part L in this round is an interim step, so we might well find an interim step to the future home standard.

00:32:45:07 - 00:33:55:10

Speaker 3

So we may well find in future that these values improve. So a cavity will have insulation to stay the same, soluble insulation stay the same point five, 5.3 respectively. And the only change really is to two roofs, I reckon previously 0.16 for insulating lofts at joist level, 0.18 insulating at rafter doesn't matter now both types are to achieve u-values .16 And if you look at the Welsh approved document for approved document L Volume one, you'll find that there's a greater amount of guidance for limiting the risks associated with cavity wall insulation and solid wall insulation because of the climate change issues, they have the difference in the climates, particularly with rain.

00:33:57:06 - 00:34:30:05

Speaker 3

And I think the Welsh document references past 2035 as as a sort of a risk assessment process to follow that concept some quarters. I won't spend a lot of time on these because there hasn't been any significant changes. The guidance has been simplified quite significantly. Now in some ways I don't like the terms simplified. It's more the the guidance is clearer, it is greater clarity.

00:34:31:04 - 00:35:06:01

Speaker 3

So there is greater clarity on definitions around porches, even though the provision hasn't changed. So the only real technical change is that there's the uplift of the u-values for the glazed elements. They need to be 1.49, whereas you could use 1.6. But yeah, there's no change to that. And for historic and traditional buildings, again, there hasn't been any change as such since they changed the technical guidance.

00:35:06:22 - 00:35:39:20

Speaker 3

But there has been a reduction in the the classifications of building definitions. So whilst it still lists specifically listed buildings and those in conservation areas, there are other buildings that might be of heritage important that would form part of a local authorities plan. They might be within heritage, parks and gardens and so on. So still have heritage value.

00:35:40:04 - 00:36:18:07

Speaker 3

Those classifications have just been have been removed. It doesn't mean to say they don't exist, but you can't list everything. And if you can't list everything, then sometimes that can lead to interesting conversations with conservation officers and building control about how far should you push a building that is of heritage value. So it's kind of giving a greater degree of flexibility rather than trying to understand what the provision in the approved document says exemptions don't automatically apply, not that they necessarily did previously.

00:36:18:07 - 00:37:03:06

Speaker 3

So exemptions from meeting the energy efficiency requirements. But you do need to demonstrate that any energy efficiency improvement measures do cause long term deterioration to the fabric or surfaces of that building. And of course, it references historic England guidance for applying energy efficiency measures. So not a lot of change to historic and traditional buildings. I think that brings us to the end of this first session, which is covering and I'll look at part s in a moment.

00:37:03:06 - 00:37:05:14

Speaker 3

I think we have some poll questions.

00:37:05:22 - 00:37:27:12

Speaker 2

You do and things and that's great. It's there's so much to think about. Isn't that when we're talking about building regs so well, the poll questions are up. If you guys can just have a look at that and put some things in. I've been cataloging the questions, so I'm trying to correlate them. So in the first question is, under most regulations, a change of use is considered.

00:37:27:12 - 00:37:39:00

Speaker 2

A new dwelling does part only apply to specifically newly constructed buildings and extensions? Part oh parto yeah, yeah.

00:37:39:12 - 00:37:48:12

Speaker 3

Part O is only for new buildings. It doesn't apply to any other, so it doesn't apply to extensions. It's just for new buildings.

00:37:48:12 - 00:37:48:23

Speaker 1

That's good.

00:37:49:20 - 00:38:01:14

Speaker 2

Yeah, that's that's really tough I think on my end as well. So part out, how important or relevant is air tightness for conversions?

00:38:01:14 - 00:38:38:10

Speaker 3

There's not any. Okay, air tightness isn't a there's no requirement to carry out any air permeability testing in approved documentation. There is greater guidance on how to demonstrate that you have reduced leaks and so on by, you know, the thermal measures that you are implementing, whether it's replacement windows and so on. You have to demonstrate that they have, you know, not been left with lots of gaps, but it's much less onerous process.

00:38:38:10 - 00:39:05:20

Speaker 3

Spanish for new dwellings. New dwellings. There's a significant amount of guidance that does form part of reasonable provision, reasonable provision being a means by which you need to demonstrate to building control that you have followed the guidance. It's less onerous for existing dwellings. There is more to come on air tightness in existing dwellings and part F in my next presentation.

00:39:06:10 - 00:39:17:04

Speaker 2

Oh, that's fantastic. So next question is primary energy factor for gas and electric is that also looked at in r d sap as it is the SAP?

00:39:17:04 - 00:39:42:21

Speaker 3

And good question. I'm I don't know for sure if I'm honest. I imagine it would be I can't see that r d sap would use different energy factors or carbon emission factors. They'd be locked into the same. Yeah. The only difference between rb sap is reduced data on on the on the inputs. But those, the inputs are those that are put in by the assessor.

00:39:43:00 - 00:39:49:03

Speaker 3

The algorithm would be the same for SAP 97, but I'm not hundred percent on that now.

00:39:49:03 - 00:40:13:05

Speaker 2

I'm pretty sure that's the understanding I had talking to somebody, SAP and SAP colleagues and say, last question and then I'll let you get on to part F. So in percentage terms, how much of an improvement are the 2021, Part L regs, for example, currently this person has a local planning policy requesting ten 20% energy efficiency above existing building regs.

00:40:14:04 - 00:41:19:07

Speaker 3

Okay. Well, the yeah, the in CO2 emission terms party 2021 is I think it's approximately 30. I'm going to go as far as say I think it's precisely 31% reduction compared to the previous part. L So yeah, it's yes. So it's a 31% improvement. So yeah, yeah, you can, I mean, what I'm finding on projects actually with that is where certainly certain local authorities are looking to provide an improvement over part L is that for developments that are using proposing to use heat pumps that actually you probably find that you do more than meet the 31% quite easily without too much effort but certainly for new dwellings.

00:41:20:03 - 00:41:38:17

Speaker 3

That's where the real test is on, on, on the primary energy factor and the carbon emission factors in SAP. So yeah, I think if you're using low carbon heating in this interim part L you will find it's quite easy to meet, but 31%, if not forever.

00:41:39:15 - 00:41:49:12

Speaker 2

Fantastic, brilliant. That's a couple of questions. The chap I'm going to let you carry on, we're part F because a lot of these are about listed buildings. So I'll start responding to people. Thanks.

00:41:49:12 - 00:42:26:01

Speaker 1

And before we before we move on, I should actually just point out very quickly that we now have building regulations as part of Historic England's advice pages on our website. So I've put the link in there, but also I noticed that that second pole wasn't working properly. So if people have any any thoughts about any other special measures or specific exemptions, please type them very quickly because we've pushed for time now into that that text box at the bottom of that second pole.

00:42:26:20 - 00:42:42:06

Speaker 1

We currently have about 17 minutes left, so we need to push on. But I don't think anyone's typing into that second pole. So let's push on. Okay. Back to you in.

00:42:42:21 - 00:43:13:23

Speaker 3

Thank you. Okay. So I'm going to talk about approved document F 2021. Key changes, again, focusing on the changes applicable to existing dwellings. Now this has been quite a significant change. L might have been fairly light touch. I saw some of the comments about it not being far enough. And so in terms of changes, part F is a bit more profound.

00:43:15:21 - 00:43:42:09

Speaker 3

And what we've had to there's no change in the legal requirement. So the legal requirement is here that when a building work is is carried out in existing dwellings, that the ventilation should meet the standards and improve documents. So you got to meet the the ventilation provision set out or that it should be no less satisfactory than before the work was carried out.

00:43:43:13 - 00:44:10:23

Speaker 3

The problem with the previous version, the 2010 edition of Part S is it didn't really set out what that second point mean. What what does that mean? But no less satisfactory. There was a process to follow, to demonstrate. So this time round we've done that and we've set a new set of guidance for when a building is having energy efficiency measures, usually as part four retrofit.

00:44:10:23 - 00:44:44:11

Speaker 3

So I'll show you what that means before I get into that. And I should say, you know, the same here almost applies with part L, but we've set out a process in existing homes whereby you can follow the guidance and that's in published in the approved document should you wish to have greater amounts of flexibility because the guidance is might be perhaps too prescriptive, then you can always seek expert advice.

00:44:45:07 - 00:45:17:13

Speaker 3

Now specifically for part F, both for England and Wales, an example has been given here that because often this feedback about what does an expert mean. So in this case for part F, we have set out that an example of that doesn't mean it has to be, but an example would be a retrofit coordinator following past 2035 process and that retrofit coordinator or other retrofit professionals could suggest that an after mobility test is carried out.

00:45:17:22 - 00:45:48:03

Speaker 3

So as part of the reducing the infiltration rates, as part of carrying out the energy efficiency measures, you can either follow the simplified process, which I'm about to go through or speak to an expert. So the simplified method you'll find this table in the new approved document. Table 3.1, and this sets out most common retrofit measures, and not all of them.

00:45:48:04 - 00:46:24:09

Speaker 3

Obviously, it would be a much bigger list. This is the full table. And what we set out to do is to try and assign whether the application of this energy efficiency measure or whether it's the whole building or two parts of the building will reduce the air infiltration in a significant way or a less significant way. So that categorized as minus so less significant leakage reduction or a major measure for more significance.

00:46:24:18 - 00:46:56:17

Speaker 3

So if we look at wall insulation, for example, the application of COVID wall insulation to any external wall, it can be all external walls as well, but that is likely to have a minor reduction on infiltration rates. It will have some impact, but not as significant as if we jump to external or internal wall insulation where you're doing greater than 50% of the external area, that's considered to have a major reduction.

00:46:58:11 - 00:47:44:10

Speaker 3

So quite simply, what you look at is a list, all of the measures that you are going to carry out in a property, count up the number of minus the number of maintenance. The caveat here is that, which is where some of the difficulty might be, but time will tell and interesting views on this in a way, it's not a question of times, but what we've also set out in the process is that you've got to also take into account measures that have taken part in that building since its original construction.

00:47:44:10 - 00:48:13:13

Speaker 3

So given that many doors and windows across our properties across the land are at least on their second generation. Not in every case, of course, but in probably the majority of cases. Then that has to be included in part of this assessment. So it's works measures that have already been implemented and those that are proposed. So anyway, existing or proposed, you count up the number of minus on the number of majors.

00:48:13:13 - 00:48:52:02

Speaker 3

You will then come to this table and you'll see we have the number of minus in the top row and the number of majors. So if you are carrying out a retrofit that involves just one major measure, then you are thrown into a different ventilation category. So even through these categories, we have category A, this is where you are carrying out up to two minor measures.

00:48:52:19 - 00:49:46:21

Speaker 3

So that could be cavity wall insulation, it could be installing replacement windows to less than 50% of the dwelling, in which case there is no requirement to carry out any additional ventilation in the dwelling. The infiltration levels should be such that the air quality in that dwelling isn't significantly impacted. However, if you are carrying out three minor measures or one major measure and everything in between, up to six minor measures and three majors, I won't go through all of the iterations that we're pleased to know, but I think you get the message that you will end up in Category B and Category B essentially says that the infiltration levels with all of the measures that

00:49:46:21 - 00:50:18:12

Speaker 3

you've introduced will be significantly reduced. And now you need to provide either natural ventilation following the guidance for less airtight new homes or mechanical ventilation, again, following the system specific guidance for new homes. If you are going further than Category B and you end up with measures, so you into category C, then mechanical ventilation is the same. It's following the system specific guidance.

00:50:19:10 - 00:50:49:21

Speaker 3

But again, I'll come onto this in a moment. Natural ventilation, we're simply saying don't look to the approved documents. To give you guidance on how to naturally vent an air tight dwelling, you will need expert advice. So there is no guidance for new homes, for more air tight dwellings that are naturally ventilated. And so you'll see with both these we referring to the new homes.

00:50:49:21 - 00:51:31:03

Speaker 3

So we're simply saying that existing dwellings, if you're changing the ventilation provision, have to meet the new dwelling standards. There's not a new set of guidance or ventilation standards for existing dwellings. You're simply pushed to follow the new dwelling guidance for ventilation specifications, which means A92 quickly talk you through what the changes are to new dwellings because it affects existing dwellings to so the new guidance for part F and provides a simplified guidance for natural ventilation.

00:51:31:03 - 00:52:02:23

Speaker 3

The guidance is now only applicable for leaky homes. So those with an air permeability, those higher than five design or no greater than three on a test, or if you're an existing dwelling and it falls into category B, so that is the approach is for natural ventilation, for continuous mechanical ventilation, which might be a continuous mechanical extra ventilation system or a mechanical ventilation system with heat recovery.

00:52:04:12 - 00:52:46:08

Speaker 3

There's now a single set of guidance, irrespective of the level of air tightness, natural ventilation. So this is things like ventilators and new windows, new table now gives a specific sizes based upon room and use. So habitable rooms like living rooms for multistory dwellings, houses 8000 square millimeter equivalent area ventilator or if it's a single storey dwelling like a bungalow, then 10,000 square millimeters.

00:52:46:17 - 00:53:20:01

Speaker 3

And so you just look at the rooms that you have in your dwelling and you use the appropriate sized ventilator for that room. There's quite a lot of additional footnotes that are, but there are limited footnotes, but they're important footnotes. I'm conscious of time. I'm not going to run through them. But that's the it's worth having a look at the table in your brief document for mechanical ventilation.

00:53:20:20 - 00:53:51:04

Speaker 3

There's been a bit of change here whereby the new ventilation flight rates are based upon the number of bedrooms and the ventilation flow rates are tabulated here. So the two bedroom dwelling needs type of ventilation flow rates, if it's a mechanical system of 25 liters per second for the entire dwelling, these changed slightly from the previous version. So two bedroom dwelling previously was 17 leaks per second for the entire dwelling.

00:53:51:04 - 00:54:23:23

Speaker 3

So now it's up to a 20. And the reason for that is we've now taken away the assumption that many designers had to make about the level of occupancy in the dwelling, the levels of occupancy are now incorporated within the new table. 1.3 The guidance on extract the extract site hasn't changed for intermittent fans. We've still got the same flow rates in this table here.

00:54:23:23 - 00:54:49:17

Speaker 3

Table 1.1 for extract flow rates using intermittent systems. So that's funds that don't run all the time. The sort of like funds that come on with a light or your kitchen canopy, but extra diagrams have been put in specifically for kitchen extracts because it's being feedback over the years. Bank misunderstanding about when is a recirculate nationhood, an extra device.

00:54:49:17 - 00:55:17:05

Speaker 3

And the answer is it isn't. So if you've got recirculation hood, not that guidance has changed, but it's just been made clearer that if you have a recirculation hook then you do need a separate finding that kitchen extracting to isolate and in which case that needs to be 60 liters per second. Whereas if you've got a kitchen extract hood that does extract direct to outside, then that needs only be 32nd.

00:55:17:05 - 00:55:53:11

Speaker 3

So you doubling the size of the extraction flow rate if you're using the recirculation hood continuous mechanical extract that has a not changed at all in terms of the flow rates. But what has changed now is if you are using a continuous mechanical extracts system, but rather than using the background ventilate sizes in the table, I showed you earlier that you need to put in a small one 4000 mm.

00:55:53:19 - 00:56:32:02

Speaker 3

X 4000 square millimeter in each habitable ring replacement windows. So this is if you're not carrying out a retrofit, you're just simply replacing the windows. The current part acting require sorry, the previous parts didn't require triple ventilators, whereas now the new version does require you to have ventilators whether or not the previous windows had them or not. So if you're replacing the windows, you're not going to have a trickle ventilator unless you are putting.

00:56:32:07 - 00:57:10:23

Speaker 3

And that's got to be 8000 square millimeters for a habitable wing or 4000 for a wet room, unless you are putting in an MEP system a continuous mechanical extract, in which case it's 4000. Mm. In the habitable rooms. And if you're putting in an MVA where of course you are not required to have a ventilator because that system deals with a supplier into, the rooms are the key changes to power s testing and commissioning, particularly for mechanical systems.

00:57:12:00 - 00:57:35:02

Speaker 3

But they need to be tested and commissioned and notice given to the building control body. The exemption only dies for intermittent extractions. If you are putting in any new ventilation system in an existing dwelling, then you need to provide information to the homeowner to ensure they know how to operate the system effectively and know how to maintain the system.

00:57:36:15 - 00:58:11:22

Speaker 3

And the Domestic Ventilation Compliance Guide has now been retired and there's quite a lot of system specific guidance clauses from that document that have been put into the main body of the approved document and I think implementation just very quickly on this and then I'm done. So new part, Eleanor came into force in England on the 15th of June this year in Wales that used to come into force on the 23rd of November.

00:58:11:22 - 00:58:36:22

Speaker 3

So they're not quite there yet. So not a month or so from now for for Wales, for England, the transitional arrangements are such that again and this mostly applies to new dwellings, but if you're planning on an extension, then you would have needed to have got your application in before the 15th of June if you wanted to use the previous part well enough.

00:58:36:22 - 00:58:57:03

Speaker 3

But irrespective of when your application went in, works would have needed to have commenced before June next year to carry on using the House, otherwise you will have to use the new document and I think that brings me to the end. Thank you very much.

00:58:57:03 - 00:59:23:01

Speaker 1

Thank you. In just very quickly, we are going into a Q&A session now. I'm very aware of the time. So for of you who have to leave this, I do apologize if you're not able to stay with us for the Q&A. This webinar is recorded so you can obviously catch up with the Q&A session in the recording. So sorry.

00:59:23:01 - 00:59:28:05

Speaker 1

I'll I'll hand back to John now.

00:59:28:05 - 00:59:47:07

Speaker 2

Thanks, Emma and thanks again. I guess when we talked about doing this webinar, maybe we should just pass because that was a lot to cover, but you did a fantastic job. So I've been twittering in the background, answering a few questions, if I could. I've just got a couple for you, which would get your expertize on that. Great.

00:59:47:22 - 01:00:01:04

Speaker 2

So do you think the ventilation provision needed Category C encourages people to make less upgrades and building improvements to avoid needing to upgrade ventilation?

01:00:01:04 - 01:00:36:12

Speaker 3

Yeah. No, it's a it's a it's a good question. And yeah, I mean, there's plenty of barriers at the moment to people wanting to carry out a deep retrofit on their property at the moment, not least due with lack of funding and so on. So yes, we've been well aware of that introducing a potential barrier, but nonetheless, the technical research heavily supports the need to improve ventilation.

01:00:36:20 - 01:01:21:06

Speaker 3

We have seen far too many retrofits that have simply failed and one of the main causes of failure is not necessarily the technical failures, but it's the detrimental effect on residents health that now in an air tight dwelling with insufficient ventilation and the increase of condensation, damp and mold in those in those retrofits is very significant. So and part F is the legal requirement for PAS to actually really depict the health of the occupants through ensuring minimum ventilation provisions are provided.

01:01:21:18 - 01:01:29:21

Speaker 3

So yeah, it's there's always going to be a conflict as well between people and PAS effort. And we've tried to address that in this in this round.

01:01:29:21 - 01:01:48:06

Speaker 2

Yeah. Because they do work so closely together as well. So going on from the that we've got kind of a two parter, so does the typical Bend requirements still apply to listed buildings? And then in addition to that, could a part open loop lockable handle work instead.

01:01:50:21 - 01:02:20:13

Speaker 3

On the second 1/2 part. But first, no, you can't use a a night latch or a lockable handle as part of your background ventilation, simply because you're reliant very heavily on the residents using that provision. And I know there's always the argument that people can close electrical ventilators, too, and they often do. But a window is more likely to be used more routinely.

01:02:22:08 - 01:02:57:01

Speaker 3

It's not to say that that can be a conversation if necessary, which sort of segways to the listed building part of the question, but particularly if there's a building of historic importance, you know, there might be an argument to say it's inappropriate to fit Chicco ventilators in this type of window, in this type of building, rather. So they may allow a relaxation, which could include using a night lunch or something like that.

01:02:57:01 - 01:03:18:07

Speaker 3

But, you know, background ventilate as people do, often default to the common products that are available on the market, which are usually white plastic things that go in the head of a window frame. They don't have to be that. And the proof document doesn't say there have to be that. It's just industry responses to provide a product that looks like that.

01:03:19:08 - 01:03:44:20

Speaker 3

You know, the I've seen quite creative responses to background ventilation over the years for sash windows and the like. And also it doesn't have to be in the window, it can be in the wall, it can be elsewhere in in the, you know, a wall vent, for example. So, yes, listed buildings. It's going to be a tricky one.

01:03:45:00 - 01:03:47:22

Speaker 3

I speak to the conservation officer. They'll know best.

01:03:49:05 - 01:04:07:17

Speaker 2

And that's the thing I think is the you know, a lot of people forget that the building regulations are the law, but the approved document is just guidance. So, you know, you can find a more superior data. That's the right word way of doing it and that can be justified. Then you can go with that example instead of following the approved documents.

01:04:08:16 - 01:04:24:20

Speaker 2

So that is interesting. So we've got three more questions. We've still got quite a few people on the line, so it's always good. So is conversion from barn to dwelling, for example, considered extensions or renovations to obtain part O compliance? The U-Values.

01:04:25:11 - 01:05:06:03

Speaker 3

Um, neither. I think it's well, actually renovations, but strictly it's a part I didn't cover just because I guess maybe time constraints. But also there's been no change here that it's clusters, material change of use or changes to the energy standard of the building in which case there is a provision in the new part L also in the existing original part L in section 11, if you wish to have a look that basically the processes, if you've got a change of use, material change of use.

01:05:06:03 - 01:05:36:21

Speaker 3

So take an agricultural barn of heritage importance that's going to be converted to a dwelling. Then currently you would convert the thermal elements off, but using a well, I guess it depends whether there's a conservation officer involved, whether this it is considered of significant heritage importance. You wouldn't want to do anything that would damage the fabric or the heritage nature of that building, but it is not exempt.

01:05:37:05 - 01:06:03:01

Speaker 3

So you would need to find some way of meeting the standard and that might be to follow the the renovation standards rather than the new build standard. But the main conversions, material change of use in in in England, not necessarily a barn conversion. It might be a house that's been converted into flats. So in which case that's a change of use.

01:06:03:12 - 01:06:11:01

Speaker 3

But there's no reason in that situation why you wouldn't use the the new build standards.

01:06:11:20 - 01:06:24:21

Speaker 2

Yeah, that's fair. So we've got two more questions we're breaking ground and forming foundations. Councilors Commencing Works. Before June 20, 23.

01:06:24:21 - 01:06:48:13

Speaker 3

Yes, it I think it's got to be more than breaking ground, as I understand it. I think you've got to be foundations and and out of the ground. I'm probably not the right person to confirm but that's my understanding is it's got be more than breaking ground. You certainly got to do foundations. Hi Fi. You've got to be, you know, attached to the ground.

01:06:48:13 - 01:07:21:09

Speaker 3

I'm not sure. But certainly foundations. And if not, I don't know if that question applies to new dwellings. But the one thing I still skipped over for time on my last slide was in transitional arrangements, but for New dwellings, the requirements on I want a per dwelling basis rather than on a per development basis, which for bigger developers is quite significant because you can't have a 200 home development, for example, get building recs approval and all of those, and then they just build with the show home and expect to build the rest of the site.

01:07:21:09 - 01:07:27:12

Speaker 3

According to the old recs, everything is assessed on a per dwelling basis, not on a per development basis.

01:07:28:08 - 01:07:54:12

Speaker 2

Interesting. I can always look into that a bit further and respond to the person bear the recording later. So last question. I'm really intrigued by your response and saying why does the government not provide second tier guidance for listed and traditional buildings to prevent all this confusion and the improved document, which mainly applies to modern buildings? I'm being mean, but I thought it was a good question.

01:07:55:20 - 01:08:35:09

Speaker 3

Yeah, yeah. I mean, yeah. So the building regulations are setting out minimum standards and they try and capture a are all buildings to some degree. And um, whether, I mean, whether it's heritage buildings, buildings that need greater levels of protection, then obviously a proof documents would be even more complicated than they were previously. Not not the new addition, of course, simplified, but it took to cover every single building types and to assess the risk.

01:08:35:09 - 01:09:06:09

Speaker 3

And it would just be a very complex document. So instead I think they're referring to historic England's guidance on that and I'm sure Historic England are producing well. I mean obviously the approved document refers to your guidance on that, but I understand that this further work underway on an providing guidance for specific buildings.

01:09:07:02 - 01:09:27:12

Speaker 2

Always further work on the way. And just to let everyone know when Harry Potter our guidance is being updated as we speak, just to align with the new approved documents for 2021 that Ian has been talking to today. I think we've gone 10 minutes over and I'm sure everyone's got stuff to go back to. So Matt, John, to wrap us up.

01:09:28:05 - 01:09:56:21

Speaker 1

Absolutely. Joanne, thank you so much, everybody, for an absolutely fantastic and insightful presentation, though. So there was some great comments and questions coming through. We will actually be posting the questions and answers on the website along with the recording and the transcript of the recording. Just moving on, closing up what you see here, we have a little word cloud in the middle.

01:09:57:08 - 01:10:27:08

Speaker 1

So please feel free to populate that with with any you have with regards to future topics for our webinars, not just building regs, anything you like, you name it, as long as it's got to do with technical conservation or heritage, etc., that's absolutely fine. We're not we're not going to do webinars or fluffy kittens, that's for sure. Anyway, so just down the bottom there, you'll see next the chat room there is a copy of in slides in PDF form.

01:10:27:21 - 01:10:55:10

Speaker 1

Please feel free to click on that and download a copy of the slides which you may find to views in the middle. There at the bottom there are some links. If you hover over those links, you'll see the option to copy or otherwise click on the link and it'll take you straight to that site. So the first one, webinars, that's the webinar page is on the historic England website that'll list all future webinars and all the recordings as well.

01:10:56:01 - 01:11:16:04

Speaker 1

The webinar survey, that's your chance to tell us what we're doing right and indeed what we're doing wrong. Sorry, I need to send that word cloud on. There you go. So just just type in the words there in the middle of topics you want us to cover for future webinars, just the webinar survey. Just tell us what we're doing right, what we're doing wrong, what we can do in the future.

01:11:17:18 - 01:11:45:21

Speaker 1

That would be really helpful to us to basically advise as to what topics to run in the future and historic England advice and guidance that takes you to the England website guidance pages, where you'll find links to all the relevant resources that are including the building recs, resources that we have on the website. So there you go. There's some thoughts coming in for people from people as to what topics said.

01:11:45:21 - 01:12:07:14

Speaker 1

Like I love the way that works. You have to love a piece of interaction, don't you? I noticed in the chat there that people were talking about case studies so that that's maybe something we can look at in future for for the building regs. That said, I'm going to say thank you all for attending today. I hope you've enjoyed the session.

01:12:07:14 - 01:12:28:24

Speaker 1

I Hope you found it as interesting and as informative as I have. We'll leave the session open just for a couple of minutes to give you time to cut and paste some links and download the slides and populate that word cloud. That's case study seems to be looking very popular right now, isn't it? That's subsequent. Thank you very much for that.

01:12:29:14 - 01:12:44:21

Speaker 1

Yes. We'll keep the session open just for a couple of minutes so you can download resources and so forth. And that said, once again, thank you very much for joining us this afternoon and we hope to see you all again very, very soon. You take care. Bye bye.

Q: It is my understanding that Part O only applies to specifically newly constructed buildings (as opposed to retro fit/conversions/change of use). Is that correct?

A – Correct. Part O only applies to new residential buildings. This includes dwellings, residential care homes, student accommodation, etc. It does not include non-residential buildings with sleeping accommodation, e.g. hotels and hospitals.

Q: How important/relevant is air tightness for conversions?

A – Part L doesn’t require conversions to be tested, but reasonable provision may be demonstrated by following guidance in para 4.23 that measures have been taken to limit unwanted heat loss through infiltration.

Q: When will it change such that new heating systems must reduce CO2?

A – This new Part L 2021 is an interim step toward the Future Homes Standard. The new requirement is for replacement heating systems to be capable of efficient operation when connected (now or later) to a low carbon heat source. In terms of heat source/fuel, it is now not possible to switch to a more carbon or primary energy intensive fuel. Requirements for carbon/PE intensity of heating systems may become more onerous when the FHS comes in (2025)

Q In percentage terms how much of an improvement are the 2021 Part L regs?

A – In terms of carbon reduction, Part L 2021 is a 31% improvement over Part L 2013

Q What methods are available to demonstrate whether energy efficiency measure do or do not cause long term deterioration? Are there specific reports which will establish this?

A - A building surveyor, architect or structural engineer or other specialist needs demonstrate why the energy efficiency measure would cause long term deterioration. There is not an explicit requirement for the type of justification or report. This could include, e.g. hygrothermal risk assessment calculation/model which shows that there is a risk of deterioration, or it could simply be demonstration through experience where deterioration has occurred on a previous scheme.

Q: Does "long term deterioration" include loss of significance through changes? E.g. removal of historic windows?

A - Removal of a window does not count as long-term deterioration as this is a planned intervention. However, you do not need to remove windows to improve u-values of a building - https://historicengland.org.uk/images-books/publications/traditional-windows-care-repair-upgrading/

Q: Can you clarify the changes to the definition of a heritage building again? And how are locally listed buildings affected by Part L.

A – There are no changes as such to the definition of heritage buildings. Some of the explicit considerations have been removed, such as buildings located in registered parks and gardens, or those that are referenced in a LA development plan. The list in AD L1B 2016 was too limiting and may, unintentionally, disqualify heritage buildings if they did not fit the published list. Agreement for what type of protection a building is afforded, and where exemptions may apply, e.g listed building CA’s, etc., has not changed. Exemptions only apply to these buildings if the energy efficiency requirements would unacceptably alter the character or appearance (Para 0.9)

Q: Are they changes to the process for registering listed buildings as exempt - there is need for clarity over the exemption of listed buildings esp if rented or leased?

A - Listed buildings are not exempt from obtaining an EPC as this is only an assessment and cannot cause harm to a listed building. Where the measures outlined in the EPC could damage the building you can apply for an exemption to your listed building via a third-party consent exemption. Note listed buildings can apply for other exemptions as well.

Q: Hello, Is conversion from barn to dwelling. for example, considered 'Extensions' or 'Renovations' to obtain Part L compliance for U Values?

A – Hi! A conversion from barn to a dwelling would be classed a material change of use, whereby the guidance laid out in paras 11.5 to 11.8 should be followed (generally renovation standards rather than extensions). However, greater clarity is needed to cover e.g. when a modern house is converted into flats. It is possible that the FHS may include further provisions for material change of use.

Q. Do you think the ventilation provision needed Category C encourages people to make less upgrades and building improvements? (to avoid needing to upgrade ventilation)

A – In general, if falling into Cat C, it is quite likely that this will reflect a deep retrofit where upgrading the ventilation is likely to be integral to the work (one would hope). Most buildings will fall into Cat B, which will mean that many building works to improve energy efficiency will require the ventilation to be reviewed and upgraded as necessary. It is possible that this could put some people off doing any work but, in my opinion, this is not likely to be a significant barrier.

Q: does the trickle vent requirement still apply to listed buildings? How does this work in relation to having to draughtstrip and reduce ventilation and then add it back in?

Q: If replacing an isolated modern window on a listed building is there a requirement for trickle vents... will LBC be granted?

A – (answers both questions above) Similarly to Part L, Part F includes provisions, which may mean exemption for listed buildings (paras 0.5 to 0.8). However, if including a background ventilator on a replacement window(s) does not affect the character of building then it is likely that Paras 3.14 to 3.16 would apply, i.e. background ventilator may be required depending upon the ventilation strategy.

Q: what options are there other than trickle vents?

A – Supply air into habitable rooms can be via background ventilators or via a supply air fan. Background ventilators can take many forms. They do not have to be white plastic units in the window head. There are many types of background ventilators available, from window frame-mounted, glazed-in, wall-mounted, etc.

Q: Re window trickle vents, could part open lockable handles work to allow ventilation for traditional buildings?

A – Unlikely, see note following para 1.52. night latch handles should not be used in lieu of background ventilators for the reasons set out. Furthermore, night latches are less likely to be routinely used year-round for background ventilation – they will create draughts in winter, for example.

Q: Do replacements windows in Listed building now have to have ventilators

A – see earlier answer

Q: Would breaking ground and forming foundations count as commencing works. before June 2023?

A - The Government have confirmed that the following would constitute a commencement for the purposes of the building regulations:

• excavation for strip or trench foundations or for pad footings
• digging out and preparation of ground for raft foundations
• vibrofloatation (stone columns) piling, boring for piles or pile driving
• drainage work specific to the building(s) concerned.

Q: Why does the government not provide second tier guidance for listed and traditional buildings to prevent all this confusion in the approved documents which mainly apply to modern buildings

A – The Building Regulations and associated guidance in the Approved Documents set out reasonable provision for meeting minimum standards, e.g. maximum allowable U-values. The government usually look to industry or other organisations (such as HE) to provide specific guidance for best practice, or appropriate treatments. Imagine the size and complexity of the Approved Documents if, e.g. Part L included a ‘pattern-book’ to capture every building archetype, construction methods, conservation techniques, etc., and Part F had similar but included all possible ventilation scenarios for each building type and cover all technologies. The ADs may dwarf the Britannica Encyclopaedia collection!

Q: Part F is sometimes used as an excuse to introduce air conditioning. How best to discourage AC?

A – Part F requires that there is adequate means of ventilation for people in a building. The guidance in AD F provides means of meeting this requirement, and considers the pollutants listed in Appendix B. This does not account for heat as a pollutant. Hence, Part F cannot be used as an excuse for introducing comfort cooling. For new buildings, the new Part O specifically addresses overheating, and there is a provision to allow comfort cooling, but only if it can be demonstrated that the building will overheat, and this cannot be mitigated through passive measures alone.