Insulating from the outside: wood fibre vs rockwool vs perforated polystyrene

[Garald]

1 hour ago, Mike said:

At least one - https://www.propassif.fr/. But the database in international - https://database.passivehouse.com/en/components/list/ventilation_small? - and Efficiency Ratio is the key number.

 

I see a lot of units. What is really important (beyond getting a quiet unit with a high efficiency rate, I know) is to find a unit that can be installed at all, and an installer who can install it! Remember that this is an old house. There are the conduits for the PIV (not extremely broad, and only one "mouth" per floor) and the old chimney conduits. I think the installation will be easy in the ground floor, thanks to a false ceiling, but I'm not sure of how it would be done in the other floors.

 

(I take the 'heart' of the unit could go in the garage, which is inside the house?)

 

So really what I want is good MVHR installer who is technically wily and also frank about what can and cannot be done.

[Mike]

24 minutes ago, Garald said:

(I take the 'heart' of the unit could go in the garage, which is inside the house?)

Yes, ideally in an insulated cupboard.

 

26 minutes ago, Garald said:

the old chimney conduits.

If you can get some insulated duct through them, and if the adjacent flues are dead, then it's a possibility - preferably the intake down one and the exhaust up another, so that the air from the latter doesn't contaminate the former. Though if connecting to a unit in the garage you'd ideally you'd take them through the garage wall / roof.

 

[SteamyTea]

8 hours ago, Mike said:

The French new-build standard (q4) requires  ≤ 0.6 m3/h.m² at 4pa

Thanks for that info.  Not that I am allowed to more to France easily any more.

[Garald]

5 hours ago, Mike said:

Yes, ideally in an insulated cupboard.

 

If you can get some insulated duct through them, and if the adjacent flues are dead, then it's a possibility - preferably the intake down one and the exhaust up another, so that the air from the latter doesn't contaminate the former. Though if connecting to a unit in the garage you'd ideally you'd take them through the garage wall / roof.

 

 

Let me upload the plans here, so that it's clear what we are discussing. Attention, these plans are edited versions of the fake architect's, so they are accurate only to within 10cm or so, and they are also lacking in details that are all-important in this discussion (ducts) - I think she just took some sloppy measures and put them in her CAD software back home.

 

Where I am observing/guessing some ducts are:

- current VMI ducts:

* fed from the courtyard at ground level

* in the ground-floor studio: going above the false ceiling, particularly above the bathroom and kitchen; the output 'mouth' of the VMI is in the studio wall next to them;

* in the first floor: behind and above the shower, with the 'mouth' in the corridor next to the shower room

* in the second floor: mouth on the short wall on that same side, roughly above the shower

- old chimney ducts: bit of a mystery to me, except they obviously have to be close to the two current chimneys (the one in the library, which I could in principle still use, and also the one in the bedroom, which I will never use - the contractor knows that and may already be using part of the ducts) but also possibly to one or two chimneys that no longer exist and whose departed ghosts are non-obvious to me.

 

 

IVRYHH Isolation plan corrige-1.pdf

[Garald]

Just got the actual report. In the end, the final result is not nearly as good as I was made to expect verbally. It is

 

Q4Pa-surf en m3/(h.m2) : 0,98

 

whereas the objectives are 1 in new build and 1.7 in renovation.

 

Here are the actual measurements:

 

 

So, in summary, this is an n50 of 4.15, right? And that's pretty mediocre, and what people guessed?

 

Here's their take on the result, but it just shows that local standards are not very demanding.

I got a long list of suggestions, which I will post next (it's pretty much the ones I mentioned). I take I should put them all into practice and then shell out for another test? Or what would be an educated guess as to what the effect of putting them into practice would be?

 

[Garald]

Here are the recommendations. As I said - what would be a ballpark guesstimate of how much they will help?

suggestions_airtightness.pdf

[Garald]

Ah, the test people just got back to me. They estimate, informally (I asked), that, if I put all their recommendations into practice, I ought to be able to go from a Q4_{Pa-surf} of 0.98 to one of about 0.7.

 

(a) Does this sound like a reasonable guess?

(b) Should I be happy with 0.7? Is that enough for a good double-flux setup? What sort of thing would I have to do to go further down?

[Mike]

@Garald Nudge me in a week's time and I'll take a look if you like - going to be tied up until then...

[Garald]

On 07/11/2024 at 23:19, Mike said:

@Garald Nudge me in a week's time and I'll take a look if you like - going to be tied up until then...

 

OK, I will gladly nudge you.

[Garald]

On 07/11/2024 at 23:19, Mike said:

@Garald Nudge me in a week's time and I'll take a look if you like - going to be tied up until then...

@Mike Considered yourself nudged.

 

I've already implemented the suggestions for the ground floor (mainly further weatherstripping); a carpenter came to fix the leaky first-floor window today, and he seems to have done a good job. An electrician will come in a few hours to look at all those electrical fixtures in the attic.

Edited Thursday at 00:18 by Garald

[Iceverge]

3 hours ago, Garald said:

@Mike Considered yourself nudged.

 

I've already implemented the suggestions for the ground floor (mainly further weatherstripping); a carpenter came to fix the leaky first-floor window today, and he seems to have done a good job. An electrician will come in a few hours to look at all those electrical fixtures in the attic.

 

Carpenters are second only to joiners in particular-ness. 

 

It's probably the reason that almost all ultra low energy houses are made from timber. 

 

If money were no object I'd get joiners to build me a house.

 

If I actually wanted to get it finished this century though I'd settle for carpenters. 

 

 

 

[SteamyTea]

28 minutes ago, Iceverge said:

If money were no object I'd get joiners to build me a house.

 

If I actually wanted to get it finished this century though I'd settle for carpenters. 

Get a cabinet maker in if you want to listen to constant droning/whining all week.

[Garald]

4 hours ago, Iceverge said:

 

Carpenters are second only to joiners in particular-ness. 

 

It's probably the reason that almost all ultra low energy houses are made from timber. 

 

If money were no object I'd get joiners to build me a house.

 

If I actually wanted to get it finished this century though I'd settle for carpenters. 

 

 

 

I thought: should I say « carpenter » or « joiner » here?

 

The French word is « menuisier « . A menuisier takes care of small wooden things rather than large wooden beams; he also takes care of other finicky stuff, such as windows.

[saveasteading]

4 hours ago, Iceverge said:

Carpenters are second only to joiners 

Ouch.

The terms reverse according to UK location, and one is not better than the other.

 

[Garald]

While we wait for @Mike to respond to nudging, here are some photos of what I've been up to, with a friend's help (meaning he did a lot of it).

 

After a lot of trying, we managed to stick a stopper made out of sheep's wool up the bedroom chimney. Now I wonder whether I should get an even bigger stopper, to make sure there are no airgaps.

 

I did some weatherstripping a couple of days ago. (I had already done plenty of weatherstripping some months ago, but one has to be thorough - the airtightness testers noticed every missing bit, and even parts where the weatherstripping had been deformed. This is an inside door leading to the garage.)

 

My visiting friend was particularly neat when caulking the staircases with acrylic. He let me do two steps.

 

 

A bit of cork and some acrylic was enough here. All of this is of course hidden from view ordinarily.

 

Now for the major gap in the attic ceiling (hidden between two rafters):

This was a very big hole (about 14cm by 8cm)! It's a good thing the roof insulation is mostly rockwool - imagine if it had been fiberglass or some other severe irritant. I put together a made-to-measure stopper made out of two differently sized cork layers, 2cm thick each, and then my visitor sealed it with acrylic.

 

 

 

 

 

[Mike]

On 07/11/2024 at 17:21, Garald said:

Here are the recommendations. As I said - what would be a ballpark guesstimate of how much they will help?

That's a very helpful report. I wouldn't want to quantify the difference, but I'd expect it to be substantial. It looks like you've made a good start! I'd guess the chimneys would be the weakest point afterwards due to their size, though you obviously have a good steer on them.

 

On 07/11/2024 at 05:59, Garald said:

Let me upload the plans here, so that it's clear what we are discussing.

So the chimneys seem to be at the foot of the drawing; not very helpful for the main intake & exhaust ducts if the garage is the MVHR location.

 

I've marked in red a couple of spaces on the top floor plan - if those are (or could become) fairly unobstructed voids they could be useful duct routes - and the one on the left potentially another location for the MVHR unit and / or distribution manifolds.

 

 

 

[Garald]

37 minutes ago, Mike said:

So the chimneys seem to be at the foot of the drawing; not very helpful for the main intake & exhaust ducts if the garage is the MVHR location.

 

Right. The guy who did the renovation said that he's using 'the old chimney ducts' for an extractor that was noisy and turned out to be pointless (just had it turned off) - I was never sure what he had in mind; the ducts of a chimney that went the way of the dodo?

 

38 minutes ago, Mike said:

I've marked in red a couple of spaces on the top floor plan - if those are (or could become) fairly unobstructed voids they could be useful duct routes - and the one on the left potentially another location for the MVHR unit and / or distribution manifolds.

 

 

 

I suspect a bit of the red space on the left may already be used in part for the PIV ducts - the attic PIV outlet is just outside it, in front of the leftmost part of the computer desk in the above drawing. But yes, I think it's mostly empty space (which could not be used otherwise; I had no desire to crouch while using the toilet, as would have had to be the case if the toilet had been set further back).

 

I also think the red space on the top right is empty. It's right above the kitchen - I imagine what lies under it must be used as ducts for the extractor above the stove. But how could it be connected to the rest of the ventilation system? Would there be a different heat exchanger here?

[Mike]

44 minutes ago, Garald said:

I also think the red space on the top right is empty. It's right above the kitchen - I imagine what lies under it must be used as ducts for the extractor above the stove. But how could it be connected to the rest of the ventilation system? Would there be a different heat exchanger here?

With an MVHR system you'd swap to a recirculating hood, so that would free up some more space 'top-right' for MVHR ducts - for example for the MVHR kitchen ceiling extract & the supply to the living room (so the right-hand side of the floor). Drop more ducts through the left-hand space and you're potentially able to connect up the rest of the 1st floor.

[Garald]

7 hours ago, Mike said:

With an MVHR system you'd swap to a recirculating hood, so that would free up some more space 'top-right' for MVHR ducts - for example for the MVHR kitchen ceiling extract & the supply to the living room (so the right-hand side of the floor). Drop more ducts through the left-hand space and you're potentially able to connect up the rest of the 1st floor.

 

Not sure where I'd drop those ducts. Perhaps the simplest thing is to have two systems - one for the right-hand of the first floor and possibly the right hand of the attic, housed in that empty hidden space in the attic, and the other one on the left side of the house. At the same time, it seems a bit of a waste not to use the garage at all - that would be the natural place for a potentially noisy machine.

Edited yesterday at 09:55 by Garald

[Mike]

3 hours ago, Garald said:

a potentially noisy machine

They're not that noisy - at least good ones aren't. If installed in a cupboard with a sound-resistant door + decent walls + either fixed onto something very solid or on anti-vibration mounts + with duct attenuators, you're unlikely to hear anything except, perhaps, on boost.

 

Edited 21 hours ago by Mike

[SteamyTea]

8 hours ago, Garald said:

potentially noisy machine.

If it is noisy, then it is undersized.