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graeme m

Passive Certification?

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I need to double check the actual penalty but let's say the claimed values for the glass are 0.52ug but can't be proven, they would apply a higher ug (let's say 0.6ug as an example).

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If that is the case (the actual numbers are not that important), it is what pisses people off about certification, especially if they are being charged for it.

Why a few of us fail to see the value in PH certification.

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If your being charged for certification and going down that route, then the consultants should be directing accordingly. 

 

Use a non certified product and the suppliers / manufacturers cannot verify the claimed values, of course you'll be penalised.

 

How do you know and how does the PHI know, that the product does what it says on the tin?

 

The numbers / values / certificates, are very important.

 

Edited by craig

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Except you can, for want of a better term' self verify the overall performance when you have finished i.e. your energy usage over unit time.

 

I seem to remember that PH standards are very hard to reach for small houses.

So take my neighbours, they have a 50 m2 house, that is an end of terrace.  The largest wall get virtually no sunlight as shaded by another building.

So the kWh.m-2.year-1 usage is relatively high compared to mine which is just a terrace.

Any standard that penalises small places is not a good standard as they generally use less energy overall.

Edited by SteamyTea

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It doesn't penalise small places, it's just harder to achieve due to issues such as heat loss, airtightness etc.

 

It doesn't penalise a smaller house, it's just "easier" to achieve on a larger build.

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51 minutes ago, craig said:

It doesn't penalise small places, it's just harder to achieve due to issues such as heat loss, airtightness etc.

 

It doesn't penalise a smaller house, it's just "easier" to achieve on a larger build.

 

One of my misgivings about PH is that it measures energy usage per m2, and doesn't value low usage in absolute terms.

So you end up with the situation where it can be necessary/advantageous to include basements etc in the heated envelope, since it pushes up the measurable area. It also increases the actual total energy use, which is at odds with the whole point of the scheme.

 

We don't judge our cars this way- we simply measure mpg, not mpg per tonne, or per seat.

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11 hours ago, SteamyTea said:

Except you can, for want of a better term' self verify the overall performance when you have finished i.e. your energy usage over unit time.

 

I think an important point is repeatedly being missed.

 

The PH standard is not just about a handful of measurements that you need to meet (eg, airtightness, primary energy usage, etc). It is also a quality and comfort standard. Gaining PH certification involves a lot more than just making sure two or three numbers are right, because as you say, if that was all it was you could just measure airtightness when you move in and energy usage over a year, say, and that would be the end of it.

 

The PH standard involves a significant amount more than that. It requires an independent third party to verify that the building meets all of the requirements of the PH standard, both as designed and as built. They include things like the noise of MVHR units, thermal bridge assessment, and loads of other things.

 

Yes, an individual with the time, capability and interest in working through all of the requirements for the standard could design and build a house that met it, then not get it certified (several on here have done that to varying degrees). But if it isn't certified, a subsequent buyer (for example) has no way of knowing that the standard has been met. Energy bills just say how much energy has been used. They don't deal with all the other stuff, like thermal bridging for example.

 

I get that you don't think certification is worth anything, and in certain circumstances (eg, where a self-builder builds or closely project-manages their build), I agree it may be of limited use. But if you, for example, contract a turnkey building company to build you a Passivhaus standard house, the only way to be sure they've actually built you one (assuming you're not actually onsite supervising them every moment) is to get it certified. Given that it appears people regularly spend hundreds of thousands of pounds on such properties, an extra few thousand to make sure you're getting what you pay for doesn't seem too crazy to me.

 

11 hours ago, SteamyTea said:

If that is the case (the actual numbers are not that important), it is what pisses people off about certification, especially if they are being charged for it.

 

It's the opposite of what you suggest - they do this because the numbers are very important! As @craig said, if the numbers are independently verified, that's fine. Do you think that using manufacturers' data should just be relied upon with no oversight?

 

Why would anyone be "pissed off" about certification? No one forces you to get certification, so I can't understand why people get so cranky about it. You can use the PHPP to design your house, pay close attention to how it's built, and you'll likely get all the benefits of living in a PH. If you figure out the PHPP yourself, the cost of doing this is literally the cost of the PHPP package (a couple of hundred quid, I think) and your time. I think that's a pretty good deal myself. 

 

10 hours ago, Crofter said:

One of my misgivings about PH is that it measures energy usage per m2, and doesn't value low usage in absolute terms.

So you end up with the situation where it can be necessary/advantageous to include basements etc in the heated envelope, since it pushes up the measurable area. It also increases the actual total energy use, which is at odds with the whole point of the scheme.

 

Yes, this is rightly one of the major criticisms of the PH standard. It should definitely be modified to take occupancy into account and house size.

 

The other major criticism is that it offers no flexibility around climate. It's easy to meet the standard somewhere like northern Europe where there are long periods of sun in winter. It's a lot harder somewhere like Seattle, where it's relatively overcast throughout winter, so solar gain is hard to come by. The US PH people split off from the main PH lot a few years back, based at least partly on this issue. I have some sympathy with their objections, and again this is an area where the PH Institute has been overly rigid imo.

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In practical terms, people vary a great deal in what they find comfortable, or intolerable.  I hate traffic noise, for example, others happily live next to main roads and never notice the constant noise.

 

Any standard that seeks to apply very rigid and very expensive to demonstrate absolute compliance voluntary standards, seems to be as if it would be better placed as to have them as an objective to aim for, rather than a rigid set of restrictive rules.

 

Personally, I think that all the many super-duper house performance standards should be just scrapped, and our building regulations made fit for purpose.  If Part L1a was improved to require near-PH levels of insulation and airtightness, and Part F was changed to mandate heat recovery ventilation, then we would be 99% of the way towards having houses with as low a practical energy use, and high comfort levels, as we can get, bearing in mind that the biggest variable by far is the way people choose to live in a house.

 

PH certification is completely pointless if someone buys the house and then insists on leaving all the windows open for fresh air, for example, or insists of hanging up soaking wet washing indoors, so increasing the internal humidity and making the house less comfortable.  By the same token, we don't have the luxury of being able to build new houses only in quiet areas, to the noise level from ventilation system really is a very minor consideration, if heavy traffic rolling past outside 24/7 drowns out any ventilation system noise.

 

We've had over 30 years for the world to adopt PH as a standard, and it has failed, dismally.  Only a very, very tiny proportion of new houses built over the years since it came about have been built to that standard.  The same goes for the valiant efforts of the AECB, with their Gold, Silver etc standards, except they've had far less success in getting anyone to take notice of them.

 

Ireland is going in the right direction.  They are mandating better building standards in their regulations, but far more importantly, they are trying very much harder to enforce those regulations.  It took a housing disaster, during the boom years of the "Celtic Tiger" to ram the need for this home, with "ghost estates" of sub-standard new homes that will probably end up having to be demolished, but nevertheless the Rialtas na hÉireann have had the testicular fortitude to tighten both regulations and their enforcement whilst coming out of a deep recession.  New homes in the UK are dire by comparison with the performance of those now being built in the RoI, especially in those areas where PH-type standards are being applied in the form of local building regulations.

 

Edited by JSHarris

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12 hours ago, craig said:

I need to double check the actual penalty but let's say the claimed values for the glass are 0.52ug but can't be proven, they would apply a higher ug (let's say 0.6ug as an example).

 

AFAIK, there is no penalty in PHPP for uncertified windows, but there is one for uncertified MVHR units:

 

For windows, from Green Building Store website:

 

*It is not necessarily required to use a Passivhaus Institut certified window when designing or certifying a Passivhaus.  The actual requirement for Passivhaus Institut certification is either that the Uw value should be < 0.8 W/m2K when modelled with glazing Ug of 0.7 W/m2K, or that the Uw installed should be < 0.85 W/m2K with the same glass, and including the linear thermal bridging coefficient of the installation.

 

For MVHR, from "PHPP Illustrated" by Sarah Lewis:

"If a non-certified unit is being used you must take 12 percentage points off the manufacturer's stated efficiency e.g. 90% becomes 78%"

 

The PHPP manual is a bit more of a difficult read, but it says this re MVHR:

"if there is no certificate, then the value  ....... is assumed with a deduction of 12% for ventilation outputs up to 600m3/h"

 

There may well be other components that are penalised, but these are the ones that I am aware of.

 

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2 hours ago, jack said:

It's the opposite of what you suggest - they do this because the numbers are very important!

I was referring to the number that @craigcould not actually quote.

 

2 hours ago, jack said:

 quality and comfort

As anyone that has does both quantitative and qualitative research will tell you, qualitative data is unreliable and often misleading.

 

2 hours ago, jack said:

Why would anyone be "pissed off" about certification?

I was referring to the certification process. This is not unique to just PH stuff.  It is rife in many industries.  Take electrical engineering.

A highly qualified 'Dr.' should not do some wiring in their own home and self certify it without the same Part P certificate that I have.  Though may well be capable of getting a job writing the national standards.

Same with driving.  My friend from the USA could drive as a visitor in the UK, but not now she is a resident.

Edited by SteamyTea

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10 minutes ago, SteamyTea said:

I was referring to the certification process. This is not unique to just PH stuff.  It is rife in many industries.  Take electrical engineering.

A highly qualified 'Dr.' should not do some wiring in their own home and self certify it without the same Part P certificate that I have.  Though may well be capable of getting a job writing the national standards.

Same with driving.  My friend from the USA could drive as a visitor in the UK, but not now she is a resident.

 

Sometimes we do seem to tie ourselves in knots when it comes to certification, in so many areas.  Building standards is an area where a great deal of certification is being shown to be deeply flawed - look at Grenfell Tower and the can of worms that is uncovering about allowable certification procedures as a recent example.

 

One major problem seems to be that we have diluted the focus from certifying equipment, materials and procedures into certifying people, and we have created a significant problem in doing so, not just because someone holding a certificate may not actually be competent (and we've all seen examples of that on this forum), but because we have taken common sense out of the equation.  Something that is ludicrous may well be perfectly allowable under the rules, because it complies with the letter of a particular bit of certification.

 

We do also have a major problem with the way we educate and train people, with the focus being on gaining a certificate of some sort, rather than on being competent to do what they have been trained to do.

 

I fear that the whole certification "industry" that has grown up in recent years is being increasingly threatened with being brought into disrepute, because of so many examples of poor workmanship, plus the gradual drifting apart between what is allowable in different parts of the UK.  Take the example of treatment plant discharge and the difference between the rules that the EA apply in England and Wales and the rules that SEPA apply in Scotland.  Both have a common objective; to minimise the risk of environmental pollution, but both apply completely different sets of rules.  All this does is make both organisations seem a bit incompetent, if they cannot even agree on something as straightforward as this.

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2 hours ago, SteamyTea said:

I was referring to the certification process. 

 

Exactly. So who exactly are you saying is "pissed off" about the certification process? This isn't like SAP, where people have every right to be frustrated about a compulsory box-checking exercise that they need to pay for when they sell their house. This is a voluntary option, that a proportion of people who build to (or towards) the standard choose to pay for.

 

I've already said twice now why certification might make sense to some in certain situations. I personally didn't see it as being good value in mine. I'm not even slightly annoyed about that. The certification process isn't the problem. Some elements of the standard itself could certainly do with some tweaking.

 

2 hours ago, SteamyTea said:

As anyone that has does both quantitative and qualitative research will tell you, qualitative data is unreliable and often misleading.

 

And that has to do with PH certification how?

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59 minutes ago, jack said:

So who exactly are you saying is

People like Jeremy and myself.

We both like the idea of low energy usage housing, but fail to see and credibility in the hoop jumping that is PH.

59 minutes ago, jack said:

And that has to do with PH certification how?

As soon as you take things like air quality and noise into account you are generally into the area of qualitative opinion.

I hate the noise of barking dogs, crying babies, wailing women and dot matrix printers.

At least one of them seems to have disappeared from our lives.

 

As the old saying goes, from Lord Kelvin:

"To measure is to know".

 

Which just about brings me back to my first point:

 

On 07/09/2017 at 15:52, SteamyTea said:

Sounds to me, but not looked at the methodology, that they started with a bunch of data, created a model that fitted, then checked it against the data.

 

Edited by SteamyTea

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What, the noise of wailing women has disappeared?!! I missed this!! 

I've chosen an Architect who is a passive house certificate designer and has a good track record in Ireland so I'm already paying a premium for that but at least it's a fixed €€ and not a %%. That said I doubt I'll ever go for full passive certification. There's no price premium for it if you sell, not even for the fact that it's a passive house or the comfort levels it provides in todays' market. I wonder if you can get the plaque on ebay?! 

 

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4 minutes ago, mike2016 said:

What, the noise of wailing women has disappeared?!! I missed this!! 

Sadly not, but, apart from a few accounts offices and building suppliers, dot matrix printers have gone.

Interesting that the quietest office in a company is the accounts office until the last week of the month.  Then it is the noisiest and most panic stricken.

 

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7 minutes ago, SteamyTea said:

I hate the noise of barking dogs, crying babies, waling women and dot matrix printers.

Most of these are simple to solve, remain well outside the relms of environmentally friendly building in the round and seem to me to be stretching your argument, already it seems to me erring on the side of thin and perhaps even somewhat lacking balance, a little too far9_9.

 

In some senses I am with you, we may not get our build certified, but the credibility of the model is none the less sound it seems to me. Additionally you can probably, with a little tweaking / extending, take your original bunch of data idea and apply it to any research / development / profling / financial situation provided after you have validated against the original data it continues to work when presented against more recent data in this way you do have a valid model. This in the same sense that Newtons laws remained able to fit the data until we got mixed up with new data on a different scale, quantum, in such places where Newtonian physics do not apply or have limited application. So what the PHPP does is predict how a building will perform given a number of inputs and provided you stick with the units and scale it is not a bad predictor, although perhaps not as absolute as Newtons laws (where they apply).

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2 minutes ago, MikeSharp01 said:

Newtons laws (where they apply)

Why they are called Laws.

I suppose it is the difference between Physicists/Mathematicians and all the other sciences.

I was speaking to a neuroscientists the other day who was saying that the verify their research at the 5% confidence level i.e. 1 in 20 results may be wrong due to chance.

I asked if they would get in a car with a drive that was that confident.

But all this is moving away from the problem of actually building low energy usage homes and just becomes very polarised.

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53 minutes ago, SteamyTea said:

People like Jeremy and myself.

 

So you're literally "pissed off" about an optional certification process? One that you admit you're ignorant about:

 

53 minutes ago, SteamyTea said:

Sounds to me, but not looked at the methodology,

 

I also think you're still conflating the standard itself with certification.  Most (all?) of your criticism seems to be about the standard itself rather than certification.

 

If you want to discuss shortcomings of the standard in the context of certification (bearing in mind the thread is about the latter), then the argument goes something along the lines of "The PH Standard sets a number of requirements that will add cost and perhaps complexity to a building's design and the building process. If you don't plan to certify, you may avoid some of this cost and complexity by focusing on a core subset of the PH Standard requirements, such as airtightness, insulation and heat recovery."

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Another twist to this certification lark is schemes like FIT, RHI and MCS certification.

 

My plasterer visited this morning, he is about to embark on a new build for himself. We were discussing heat pumps, and he told me he had a quote from the local Renewables company for a heat pump for a little over £7K  He doesn't yet know what amount of RHI payment that would qualify him for, but I showed him my £500 heat pump that I will be self installing, and asked him to check carefully that the RHI payment will indeed exceed the "MCS premium" he would be paying to get an approved installer to fit it, just so he can claim the RHI.

 

What "pisses me off" is I can't self install my own solar PV and then claim the FIT. What pisses me off more than that is I can't claim the FIT until I have an EPC for my building, and I can't get that until it is pretty well complete. Nobody would give me an EPC for the static caravan (I tried and hit brick wall after brick wall) but neither would anybody agree is was an exempt building and certify it as such.  The result of all this stupid red tape, is I have spent the last 3 years watching the solar PV FIT drop to the point of being worthless, when I would have liked to have installed my ground mount solar PV 3 years ago.  So much for encouraging me to fit a genuine source of renewable energy.

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The problem with blind adherence to a particular performance standard, as if it may be the saviour of the planet, is that some models fundamentally work to such a fine level of performance detail as to be nonsensical in terms of how people will actually live in such houses, or how other local factors may affect real-world comfort and performance.

 

@SteamyTeas point about the neuroscientist working to a 5% confidence level is apt, except that I would say that we probably don't actually even need that sort of confidence level for a theoretical house performance modelling standard.

 

I would argue that a house performance model doesn't really be very accurate at all, as there are so many factors that any model like this will fail to model well, and making the model ever-more complex (which is exactly what has happened with PHPP over the years) is just an exercise in futility, in practical terms.  My view is coloured by having produced a very simplistic heat loss model, and then having been surprised as to how close it comes to predicting real performance, or, dare I say it, how close it comes to matching PHPP heat loss predictions (as others here have found).

 

Take our build as an example.  I used a couple of models, plus the mandatory SAP thing.  Both SAP and PHPP have an over-heating risk model, neither showed an appreciable risk of over-heating for our local climate data.  I went to some pains to get accurate local data, too, looking at the plots on the Met Office historical data site and interpolating to get what I thought would be the best fidelity I could from the available data.

 

In reality, it quickly became clear that both SAP and PHPP are very deeply flawed when it comes to dealing with a house that is partially set back into a South-facing hillside, and near the bottom of a steep valley with much lower than typical wind speeds for the area.  Luckily this first became clear during the ground works, when we had temperatures up towards 40 deg C in the corner where the big retaining wall was being erected.  At that point I made the decision to re-check the data and the models, and realised that the temperatures we were seeing that July were much hotter than the maximum predicted by the Met Office data.  The impact this had on the house was large, it massively increased the effective solar gain and decreased the heat losses.  I made some on-the-fly changes, but was restricted to only being able to change the MVHR from a passive system that had originally been planned to a system with a built-in air-to-air heat pump, to provide cooling.  I also found that we needed to add additional measures after the house was completed in order to reduce the heat gain still further, by fitting heat reflective film to the outside of some of the glazing and incorporating cooling into the slab.

 

How big was the error in the PHPP prediction?  Around 30% or so.  I should stress that PHPP as a model is fine, as far as it goes, but that the unforeseen microclimate we created made much of the modelling in such fine detail open to question.  Why model something to, say, 5% confidence, when a simple and unforeseen external climate difference can create a 30% error?

 

On the plus side, the microclimate effect is a definite positive in the heating season, as we get more winter solar gain than anticipated and slightly warmer local air temperatures, too.  I've now had two PHPP certified people look over the house and data, and both have taken on board the sensitivity of the modelling process to very local conditions.  Both admitted that they were unaware of the extent that microclimate could have on modelled performance.

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15 hours ago, JSHarris said:

On the plus side, the microclimate effect is a definite positive in the heating season, as we get more winter solar gain than anticipated and slightly warmer local air temperatures, too.  I've now had two PHPP certified people look over the house and data, and both have taken on board the sensitivity of the modelling process to very local conditions.  Both admitted that they were unaware of the extent that microclimate could have on modelled performance.

 

This is an area I looked at when running PHPP. I tried different weather data sets but the effects on the overall results were small. In practice the local semi? microclimate has more of an effect on comfort in the house. Living a few miles from the sea in East Kent produces a very different climate from further inland. In the summer, on sunny days, we have Easterly onshore winds every afternoon which seems to reduce the effect of decrement delay. We also have much lower maximum temperatures. The maximum temperature here this year was 26C when further inland it was reported to be 32C. The humidity is also much higher all year round which should affect MHRV. In winter we have higher night time temperatures. These effects are presumably magnified in Cornwall.

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22 hours ago, Cambs said:

 

AFAIK, there is no penalty in PHPP for uncertified windows, but there is one for uncertified MVHR units

 

 

That is correct, no penalty exists when 3rd party certification is produced. However, when no 3rd party certification is available a penalty is applied until the documentation is received. Doesn't need to be certified but a 3rd party certificate,proving the claimed values must be or the penalty stays intact.

 

All values must be proved and I'll double check the actual penalty on Monday with our certifier.

Edited by craig

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14 minutes ago, PeterStarck said:

This is an area I looked at when running PHPP. I tried different weather data sets but the effects on the overall results were small. In practice the local semi? microclimate has more of an effect on comfort in the house. Living a few miles from the sea in East Kent produces a very different climate from further inland. In the summer, on sunny days, we have Easterly onshore winds every afternoon which seems to reduce the effect of decrement delay. We also have much lower maximum temperatures. The maximum temperature here this year was 26C when further inland it was reported to be 32C. The humidity is also much higher all year round which should affect MHRV. In winter we have higher night time temperatures. These effects are presumably magnified in Cornwall.

 

I keep meaning to do some practical experiments to see the effect of accelerated convective heat loss due to wind on the outside of a house.  It won't be easy, as the surface texture plays a big part in the effect, due to the large impact texture has on the boundary layer thickness.  My gut feeling is that the variation in wind-related accelerated convection heat loss from external surfaces is probably quite significant, more so in a moist climate, where the external surface are more likely to be wet, and so suffer the added impact of evaporative heat loss as well.

 

Whether it's worth modelling this is debatable, though, as just increasing the overall decrement delay factor as a part of the design process may swamp out any variation from accelerated convective loss.  It would be easy to get sucked down into another rabbit hole of wanting to add ever more detail to a heat loss model!

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I modeled our house taking into account solar gain, and separately taking into account solar gain and wind. 

 

For modelling wind, I lifted the PHPP / SAP methodology, as having discussed it on the old forum, it was going to prove challenging to develop my own model.  I validated as best I could by modelling a house that had recently been built by my builder where I knew the energy usage. 

 

Our micro-climate is the exact opposite of Jeremy's, i.e. very exposed so getting a realistic idea of how much of an impact wind has was very important to me.  Looking at the results of both models there is upwards of a 30% difference in the heating requirement where wind has been taken into account. 

 

I suspect one could use a simplified wind penalty, i.e. increase by 10%, 20% etc depending on local wind data rather than having to go into detailed models.  

 

One thing that is very clear having lived in our house for 6 or so months, is that high wind speed has a significant impact on fabric heat loss.

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14 minutes ago, Stones said:

 

One thing that is very clear having lived in our house for 6 or so months, is that high wind speed has a significant impact on fabric heat loss.

 

Very interesting - we are also in a very exposed location surrounded by sea. Since the heating system has been connected we haven't experienced simultaneous cold temperatures and high winds and rain. It will be interesting to see what the combined effect is.

I would imagine the construct of the external wall will have some effect as will the amount of glass. We have a block and render wall with a ventilated air gap surrounding the timber frame. Hopefully this will reduce the impact.

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