JohnMo

Have done hopefully a clearer sketch

Think you have missed my point. If you are charging every day you are not fully charging the battery every time. It's little and often. If everyone has 200kWh batteries bang goes the time of use tariffs as well, because peak time becomes night time - premium rate, so we don't get grid collapse.

So overall just like dry lining with plasterboard. Dry lining done properly has zero issue with knocks or bangs or scruffs. Personally I am not sure I would use anything else other than plasterboard. Use the correct fixings you can hang whatever you want from plasterboard. We are using 12.5mm plasterboard and have big mirrors hanging from it no issue. Same mirrors were in the last house - no issue in 10 years.

Making the wooden frame and having it shorter in height than insulation gets rid of any possible bridges. So if you have 200mm of insulation above the roof make the timber upstand about 170mm, the Compafoam then is 150mm plus 30mm, plus any boards on to of the insulation and your roof finish, so about 200mm high Compafoam. Yes

Fully agree, but the government investment, is really the tax payer investment. Should just stop the install grants, spend the money on plumber compulsory, low temp heating system design and installation training - do as part of Gas Safe and or G3 training so little or no escape. Heat pump is just a heat source, it's system design that is important bit for ASHP, GSHP and condensing boilers. The system shouldn't look or act any different, irrespective of heat source.

If using larch use stainless fixing. We have larch cladding on house all stainless not a black streak anywhere, our garage was done by others, and they insisted galvanized fixing would be no issue, black streaks everywhere. Don't compromise you will regret it.

Does this make more sense?

I would build a wooden frame from the roof structure and around the aperture, to a height just below the top of insulation, so the roof insulation has something to butt up to also, use this framing to secure the Compafoam too. Then build up in two layers of Compafoam to get the correct height you need. Glue and screw the layers together to form the upstand

Yes it was, I read it. First thing I thought, our van and car never get refueled at the same time and it's several weeks between refueling generally. Even if you did charge both cars every night and you did a 1000 miles in each car, every month, the charge time each night (for each car) would be 0.8hrs using an 11kW charger assuming the car is doing around 3.5kWh per mile.

Yes the whole upstand is made from pieces of Compafoam, it looks like polystyrene, is light, but like a stone for hardness. I used 75mm x 100mm, screwed through directly in to the roof structural timber, with a mastic in-between to seal. The roof light is then screwed directly to the Compafoam with mastic to seal. Sorry never got any photos.

I gulped at the cost of Compafoam, but took joiner all of about 15 min to do two roof lights upstands. So overall good value.

Roof maker, do a Passivhaus approved one, it's got a U value of 1.0. don't pay for there upstands they are naff. Sit them on Compafoam CF200 upstands to get thermal bridge free install.

Well done, looks tidy. Now all you need is the cooling chip, read up on here, the one they uses in gas boiler for some other reason is the same and a 1/10 the price.

First question is what did the structural engineer specify? That should be your first port of call. If you haven't had any structural engineer involved you should. Would have thought they would be on hangers built into the wall. Handbook here https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.pasquill.co.uk/wp-content/uploads/2019/01/posi-joist-technical-handbook-2019.pdf&ved=2ahUKEwjQhdOhup-IAxW0WEEAHa8QNB8QFnoECB4QAQ&usg=AOvVaw30F2fl_4HxO29xMSPYJ6bu But having said the above - these are good. https://www.screwfix.com/p/dewalt-aerated-concrete-anchor-nylon-60mm-50-pack/454HT?tc=TA5&ds_rl=1247848&ds_rl=1241687&ds_rl=1245250&gad_source=1&ds_rl=1245250&ds_rl=1247848&gclid=Cj0KCQjw_sq2BhCUARIsAIVqmQvplppZTIs9pnhfHl1drL8qml8jhlOHJ2sxVX3WU1QsF5v912lcgHkaAtUGEALw_wcB&gclsrc=aw.ds You install them one turn in half a turn out until they are driven home. Or the other option is a chemical anchor, such as this https://www.screwfix.com/p/rawlplug-r-kem-ii-styrene-free-polyester-resin-300ml/32863

My thoughts on the whole thing, if you need to draw more than 23kW (100A) at a time, you need to step back and really ask your why - especially in a new build. Most people on this forum seem to want to build low energy houses on one hand, while on the other want a dedicated power station feeding it. Who needs 69kW, who wants to pay a bill that warrants that electric demand.

The example from the OP is a twin skin block and brick with insulated cavity. The external skin is isolated from the building by cavity insulation first, any openings in the cavity are blocked off with cavity closers. Windows and doors straddle the insulation, so as not to compromise or generate a new thermal bridge. Example

Think you are missing the point and what thermal bridge is being discussed, this for a thermal bridge that exists between the house internal wall and the ground. But to answer your question above - yes, because that area of the wall is in direct contact with the ground so will suffer downwards heat loss unless mitigated. None of your other examples are relevant.

If you want a bush cutter that's easy to start, powerful and do heavy duty as well grass, with different attachments. https://www.stihl.co.uk/en/p/brushcutters-grass-trimmers-clearing-saws-fs-491-petrol-clearing-saw-183362#fs-491-c-em-petrol-clearing-saw-183362

They look clever, but for me a couple guys testing with a couple of the same make heat pumps isn't enough. Do you have room for a small shed outside? Have you thought about a small insulated shed outside and put a cylinder in there, with most the other bits and pieces for the heating system, expansion vessel etc? That's where most my stuff is (except the cylinder).

Two blocks high becomes 440mm .44/0.18 = 2.44, 1/2.44 so a U value of 0.4. So U value downwards, but really with the buildup by the time you have got to the second block it's depth is being comprised by plenty of sideways cold areas. So as said maybe one block would be enough.

Or just fit an R32 heat pump where ever you want. Nothing special about R290 it doesn't make the heat pump more efficient. R290 has a lesser global warming effects - but only if it all leaks out.

Sorry not following, your question was about plasterboard fixings popping, not air gaps. My point was nails are or should be history for fixing plasterboard, screws when installed correctly are less likely to pop.

They would or should use screws now. Our plasterboard is all on battens, have noticed about 3 or 4 heads popping, out of thousands over a 3 year period. We are dry lined not plaster, so way less forgiving.

Yes correct. Just about and take the dpm up inside the cavity to keep the aircrete blocks dry. Or even paint with a bitumen paint on the cavity side would work.

Couple of basics, Heat always moves towards cold, in any direction. Sideways, up or down it doesn't matter. You need to be able to draw an unbroken line around any cross section of the building, the line follows the insulation. This line determines if you have a thermal bridge. Below the red line is broken by the concrete block. So with the cavity fully filled with insulation. And no aercrete blocks, you have a gap in you insulation. The heat inside the room will pulled down toward the ground. Insulation within the cavity has no effect on this. Having insulation in the area I have cross hatched in yellow serves no gains.