Ed Davies

Yep, got a few of those. But I wish they'd label the strength in bigger writing. Sort of obvious, really.

All good stuff. To add to this, another reason that practical infiltration is typically lower than the air test is that when it's wind driven one side of the house is pumped up in pressure and one is sucked down so the effective area available for the total flow (which has to both be in and out) would be something like a quarter to a half that under test conditions. A rule of thumb I've heard is that the practical infiltration rate is about 1/20th of the test conditions. Apart from the lack of supporting evidence for that I'd also be concerned that the heating season when infiltration really matters tends also to be the windier time of year. It seems to me that this would be more pronounced on a well insulated house where the heating season is short. Also, it must matter if your house is exposed (as mine is) or well sheltered (as Jeremy's is).

Good plan. That's my motto, too. I consider mains electricity to be (largely) combustion, though, which is probably more extreme than what you have in mind.

Can you cite some examples where Monbiot has intentionally misled? In the quote given there @JSHarris didn't say he intentionally mislead, just that he failed to check facts so may have mislead either intentionally or otherwise. I too generally agree with the direction of Monbiot's thinking though perhaps sometimes he goes a bit far. I went off him, though, at the time of the climategate “scandal” when he immediately took the out-of-context quotes at there worst possible interpretation and called for Phil Jones and co's sacking. To be fair to him, he did apologise and take it back later when it became clear there was nothing to the whole thing but the damage was largely already done by then and he really should have been a bit more careful in the first place. He also did some moderately silly raging about court cases related to the early shutdown of German nuclear power stations following Fukushima which didn't make sense in the context of previous negotiations between the nuclear industry and the German government regarding the taxation of power stations and their lifetime extensions. So I regard him as interesting source of ideas but not really a reliable source of information.

With a lot of labour and some thermal bridging for the blocking which I-beams need.

Friend built a large extension with screed with UFH over a beam and insulation floor then had an oak frame put up on that. No problems with weather as far as I recall. I don't think it needed covering, certainly wasn't while the oak frame went up before the roof went on.

For simple layers you don't really need a special tool or calculator - an ordinary calculator will do as you're just doing multiplication or division. Ultimately you want to be comparing the U-value (conductance, W/m²·K) or R-value (resistance, m²·K/W) for the two layers. These are inverses of each other: if a layer has a conductivity of 0.1 W/m²·K then it has an R-value of 10 m²·K/W. Lower U-value or higher R-value is better. If you know the conductivity of the material (often written k or λ (lambda), W/m·K) and the thickness of the layer you can work out the U-value as the conductivity / divided by the thickness (in metres). E.g., if you have 400 mm of rockwool, λ= 0.035 then U = λ/t = 0.035 W/m·K / 0.4 m = 0.0875 W/m²·K. In general, if you have any two of these numbers and want to work out another then you can do so by multiplying or dividing the numbers you have. It's pretty obvious how each contributes to the result: if the material has a high conductivity then the resulting conductance will be higher so the λ value goes on top, if the layer is thicker then it will have a lower conductance so the thickness goes underneath. So long as you use the correct units (e.g., metres rather than millimetres) it should all come out right. If you use American units you're firkined. For example, if you want to work out the thickness of PUR (λ = 0.022 W/m·K) needed to have the same U-value as the 400 mm of rockwool then the higher the conductivity of the material the thicker the result will be and the higher the U-value you're willing to accept the lower the thickness needed so t = λ/U = 0.022 W/m·K / 0.0875 W/m²·K = 0.2514… m ~= 250 mm. A useful check is to write the units out and make sure they cancel properly: W/m·K / W/m²·K = 1 / (1/m) = m which is nice.

Quite content with my Stanley Cross Line and 90° Laser. https://edavies.me.uk/2016/03/laser-level/ https://edavies.me.uk/2018/09/laser-check/ Haven't used the 90° beam out the side very much though did the other day: https://edavies.me.uk/2019/05/windows/ It simply hadn't occurred to me that using a distance measuring laser would be accurate enough for anything serious other than maybe cutting cables and things you leave a bit extra on anyway. Am I wrong?

Pure sine wave or modified square wave?

I think it's worth being clear exactly what jobs you want this membrane to do. Things I can think of to usefully do under insulation in timber floor above a crawl space (I'm also building this) are: 1) support the insulation. 2) prevent windwashing of the insulation (wind blowing through the mineral wool or whatever and taking all your lovely heat away). 3) keep out critters. None of these are particular strengths of breather membranes. What I'm doing with mine is supporting the insulation on sarking boards (150x19 or 22mm treated timber boards) nailed to the bottom of the joists. They're fitted slightly wet then dry out to leave a mm or so gap between the boards (i.e., every 150mm) to allow evaporation from the structure above. https://edavies.me.uk/2018/03/some-flooring/ I could just drop the insulation directly on these and it'd probably mostly work fine but I'm a bit worried about windwashing as I'm on a very exposed site (hilltop overlooking the Moray Firth). I could lay a membrane but I'd want to staple and tape to the joists so I'm considering laying 25mm EPS sheets first (and taping those at the edges). The incremental cost of 25 mm of EPS per m² vs the extra volume of mineral wool is a wash against the cost of cheap membrane but I think it'd be less hassle to fit and easier to get a good seal round the edge.

How do you know custom size isn't cheaper? Ages ago I was looking at a site for multiwall polycarbonate which did standard sizes but could also cut custom sizes. Wondering what the penalty for custom sizes was I used their calculator to work out the cost of one of their standard sizes. It was less than the normal price. I emailed them to ask what I was missing (e.g., do the standard sizes come with the sealing along the edges) but, no, that was right, it was just the way they did it and they didn't seem to think it was odd. ¯\_(ツ)_/¯

No, the R-value (higher is better) or U-value (lower is better) is what you need to look at. Conductivity (often written k or λ) is a property of the material independent of the thickness, so only makes sense for comparison if you have two sheets of the same thickness. It's useful, though, if you know how much insulation value you want and then need to work out the thickness needed to achieve it.

From the article: If there's really a pocket of cool air on the floor (I'm sceptical) then there will be a very limited amount of water vapour available to condense so these two statements are contradictory.

Seems like an awful lot of layers for a small roof. What's “insulation membrane” and what would it achieve at that point? What insulation do you have in mind? Are you planning exposed rafters on the underside? Do you have the height to do that without it looking odd against the gable to the main house? Is the span large enough to need purlins? If you want some sort of warm roof, how about: rafters with insulation between, OSB?, insulation, sarking?, vertical battens, horizontal battens, metal sheeting. Probably only need one out of OSB or sarking.

Assuming a thick slab, would the slab have cooled much even if the air in the house had dropped quite a few degrees? Obviously if you've had the doors open in cool weather for a few days the slab will have cooled down but then you'd expect a long warm up but if the slab's still close to the right temperature surely the warm up will be pretty quick.

Scotland, but I think the other UK countries are likely to be similar: https://www.gov.scot/publications/building-standards-2017-domestic/4-safety/48-danger-from-accidents/ 4.8.2: So that means toughened glass, I think.

Does BS7671 actually require isolators for this application? I.e., is @ProDave's (rhetorical?) question “why does BS7671 require isolators?” or is it “where in BS7671 or elsewhere is there a requirement for isolators?”? Also, how many question marks can I fit into one sentence?

Brakes as well. It's happened a couple of times with a glider to being off the field with the brake binding slightly and loose grass getting up into the wheel and catching fire. At least one case burnt out the glider.

If you're happy with using Linux live systems and the CF card is as big as or bigger than the HDD then just use dd to copy the whole HDD to the CF. No need to format or anything. Just be careful that you get the right output disk otherwise ? If the HDD is, say, sdb and the the CF card is sdc then make sure none of the partitions on the either disk are mounted then something like: $ sudo dd if=/dev/sdb of=/dev/sdc bs=10M and away it should go copying one disk to the other byte for byte. bs=10M sets the blocksize for the copy, it doesn't make much difference but will likely speed things up a bit. If you've got spare space on the in the CF card you can expand the file system later to use it all (fdisk, e2fsck, resize2fs). If the CF is smaller than the HDD then it's all a bit more complicated.

Water?

Stainless steel is also a lot less conductive [¹] that ordinary. [¹] Thermally and, by the way, electrically.

For mine, I got the contractors doing the site access to do the pits and the architectural technician/house designer to record the results. He wasn't a structural engineer but had the appropriate ticket, whatever that is, to do this. So I don't think you could do it yourself, but perhaps ask your SE what they can accept. Note, this was after planning permission was granted so the digging work could be part of a zero-VATed contract, though the professional services of peering in the hole and writing things down could not.

How about a thermostatic switch on the pipe by the slowest-to-reach tap?

@JSHarris, yes, just looked at the Thanet Earth Wikipedia article which appears to use both waste heat and CO₂ from a CHP plant. But all the other thermal plants should do the same (except nuclear won't produce CO₂).

If one neighbour is pumping heat out to keep potatoes cool and another is pumping heat in to keep tomatoes warm it seems to me that a deal should be done. Similarly, thermal (coal, gas, nuclear) power stations should be surrounded by greenhouses to exploit the low-grade waste heat.