Keeping your home warm / heating / energy crisis / insulation etc

A shitty built victorian terrace with solid walls and a bit of slate for a damp course would be a different proposition, but then I wouldn’t ever buy one as I prefer being warm and not paying a fortune to do so.

i am now living this...

I'm pretty sure we're going to use wood fibre panels, which ... sequester carbon.

Only if you bury them at the end of their life right?

I'd be interested in seeing how they well work, and whether they're not just a horrible compromise in the name of breathability.

Also depends on finance too. I could feasibly install IWI for a few rooms that we would benefit most from. I cannot afford to install external insulation...

I'm about to put in interior insulation on a few external walls in our solid-walled Victorian semi, and will likely use PIR instead of wood fibre.

Going by various calculators, the dew point will remain inside the PIR sheet itself, and applying the sheets properly, using foam all round, finishing with airtight tape, will/should prevent moist internal air from ever reaching the brick behind the boards. 50mm PIR will/should perform much better than 60mm wood fibre, and is significantly cheaper to boot.

will you be rendering the external to prevent moisture from coming inwards? how did you calculate dew point or did builder?

The external wall is being raked out and re-pointed with lime mortar (current pointing is cement and largely fucked), then left bare. It's a south-facing wall, so shouldn't ever get soaked through its 230mm thickness.

I used a few calculators to verify wall build-up and dew point etc, like Ubakus and Changeplan.

I mean, PIR is just going to be buried too. At best.

Sure, I guess my point is if you buy it because you're going to compost it or burn it or something at the end of it's life or similar then it's net zero atmospheric carbon. Possibly worse due to methane. It only sequesters if you bury it at the end, or I guess you could blast it into space

No Idea how much external is but we spent about 2k on materials and 1.5k on extra labour for 3 rooms 5 external walls, the rest was DIY. I did all the fiddly stuff like the rebates, boarding the window reveals and making the big lounge window sill level for new sills.
Plus the pipe channel covering with plasterboard level with the insulation and lining with superfoil.
The finishing details and edges are what take time.

Probably be several years to get that investment back along with 7k of secondary glazing but that’s not factoring in how it feels to be warm. Anecdotal from other flats with no energy saving measures beyond thick curtains they are spending £250 a month on gas/electricity right through the year. It would need a month of 0° or lower temps for us to pay that in winter with us here all day.

When we eventually move again I would insulate in whichever way possible as long as we could stomach the cost and DIY if able.
A bungalow with cavity walls and a big soffit overhang would be ideal as I don’t do working at height.

it was literally this 😭

Each case/property is different

This. I don't have anything against IWI. For a lot of older properties people aren't going to want to clad them in EWI and that's fair enough. We've decided to clad ours anyway, so EWI makes more sense.

Also feel like I should point out that I'm not some kind of wood fibre insulation zealot, it just seems to make sense for us from everything I've learnt so far.

most of the flat is cavity wall

I dream of a cavity wall tbh! It would make our house a lot warmer and easier to insulate.

When the construction industry talk about wood fibre insulation sequestering carbon it's talking about for it's lifetime, which is not unfair because there's nothing in the word sequester which implies permanence ;)

FWIW at least some wood fibre insulation (e.g. Gutex) can be recycled and it's typically carbon negative because more carbon is stored in it than is used in its production.

The ideal wood fibre insulation would be highly recyclable and have low amounts of energy used during its production, but in reality you have to choose between wet processed and dry processed boards. Wet contain few additives/glues so are better for recycling, dry are mixed with a PU based glue, so much less energy is used to make them (which makes them cheaper) but I imagine they're much less recyclable. Their capillarity isn't as good because of the glue too.

Of course if you compare wood fibre with conventional insulation, polystyrene can't be recycled, glass wool involves heating glass to 1,450 °C (and is the devil's work IMO anyway), mineral wool up to 1600 °C - that's a lot of energy - and both have very real potential health risks.

I'd be interested in seeing how they well work, and whether they're not just a horrible compromise in the name of breathability.

Wood fibre insulation has been used in Germany for years, most of the companies making it are German.

Dry processed boards are a newer thing but wet processed boards have been around for decades. Wood is a great natural insulator, not just for thermal insulation but also for sound (another reason it appeals to me!).

https://www.youtube.com/watch?v=qpFNArhll1w&ab_channel=BacktoEarth

My fucking gas boiler stopped at 1430 today. My usual plumber can do Monday or Tuesday late afternoon. I tried all the other local geezers on the gas safe register - no answer. So I've just got a hot water bottle from Argos for bobos time. I'm surprisingly miserable about the situation.

Have you got a plan to deal with the moisture from that internal air flowing through timbers or breaks around partition walls, sockets, joints etc then condensing when it meets your wall which will be colder due to the IWI?

My worry with this setup would be that the PIR will simultaneously stop your walls from drying towards the interior and lower heat flow through them, reducing their ability to dry and upping their moisture content. Which will speed up the rotting process of any timber in the wall.

This coupled with the point @apc raises about the lack of an external finish to keep rain out of the wall does seem to present some risk factors for interstitial condensation to me based on what I know so far.

Not wanting to poo on your parade at all and hopefully this is helpful*. You've clearly done a lot of research and IIRC you're getting a MVHR system which might make this theoretical internal moisture exactly that?!

*In due course I'd quite like some constructive criticism on whatever system I decide on because this stuff is flippin' complicated 😵‍💫

I dream of a cavity wall tbh! It would make our house a lot warmer and easier to insulate.

Is this purely because you can get cavity wall insulation? (With a cavity)

Interesting! I'm keen to follow how you get on.

If your setup works, this is what we'll be doing in space-year 2030 when we go all in on underfloor / heatpump / shitty extension overhaul.

Probably will have to internally insulate the crappy loft conversion though. The dot-dab plasterboard directly on the chimney stack acts as a lovely heatsink.

I'm wondering what planning departments are going to do when everyone wants to add 6 inches of foam to every external dimension of their house.

I'd like to put a few layers of PIR on the roof too.

And solar panels above that.

Solar panel PIR. I'm patenting that.©®™

The PIR will be adhered to the masonry with a foam seal around the perimeter of each board, along with a coat of liquid airtightness membrane. As you mentioned, continuous MVHR ventilation with auto-humidistat will be controlling humidity levels also.

The external brickwork will be properly re-pointed with lime mortar, and the walls in question are south-facing, so very unlikely to ever soak through (they haven’t in the 8 years I’ve been in the house).

I'm wondering what planning departments are going

If councils are going to be all like 'climate crisis declared!' then they need to get their planning departments to support initiatives that could help alleviate said crisis. Or stop being such twats.

MVHR ventilation with auto-humidistat will be controlling humidity levels also.

Does this work through trickle vents in each room venting out in to central spaces, or does it rely on you having doors open, or are you running ducting pipes to each room? Feels like it will have to shift a significant amount of air if the external surfaces of the room are made airtight?

'climate crisis declared!'

But you can only do something about it if it does not impact the aesthetic of a row of 1960s semis.

Well, yes. In which case folks be like 'crisis, what crisis?' and crack on with their woodburners.