JohnMo

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.

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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.

No! This thermal bridge would remain, your aercrete blocks get rid of this.

So 4. does not contribute as not in an unvented cavity. If in a service void it would. 7. Reflective layer faces outwards, so again doesn't help keep heat in, but will help keep it out. So you end up with slightly different inward and outward U values. Manufacturer instructions.

Makes sense now.

Why are they noisy - what's noisy in yours?

@JamesPa is quoting So half on the dB scale so magnitudes less noise

The key word here! Lot of nonsense in the building world, you have to filter out what appropriate and useful for you.

Currently sat on our hill, main road about 800m away, with road and wind noise sound meter records 60dB to 88dB (conversation to heavy traffic noise levels). Moving down the hill to where the heat pump is, it's 40 to 60 quiet library to conversation noise levels), with heat pump off. We are classed a rural. So they want a heat pump half background, someone talking next door should be reported immediately - you will end up deaf. What nonsense.

Same calculation I did when I did mine.

An unvented void without reflection is around 0.14 R value, without the reflective your U value moves from 0.13 to 0.14. But is also directional, so is reflecting heat from outside, so in summer useful (?), not sure about any real use in winter as it cannot reflect heat back in to the house because of it's position. Take the marketing blurb with a pinch of salt.

Sorry slight redraw, shown in blue

Marketing?

If that was the case you just hold your hands up and say I will switch off the cooling, not sure you would move and also declare you were in dispute with the neighbours. But the complaint could have been about equally about heating DHW water, as that in reality is all they would ever hear. Not many people know enough about heat pumps, let alone understand some can actually cool as well as by magic make heat.

First remark, is you are obviously young and like stairs and steps, so won't be your "forever home" as many like to say, without a few changes. I would consider making it a little more by wheelchair friendly, you never know what the future holds. Slopes outside instead of steps. Maybe somewhere on the ground floor for a bedroom. Lots of wasted space with stairs also, something to think about. Plant room and ground floor WC, I would possibly shift thing about there, to make the plant room part of the utility, then everything for the heat pump is just through the wall. Your planned position for heat pump may preclude a propane filled one due to the door being pretty close. Assuming your plant room will house UVC, MVHR, hot and cold water manifolds, UFH manifold for ground floor, and even lower ground floor and not much else. Upper floor heating I would just do fan coil in bedroom and study (run same temp as UFH) and electric UFH towel rad in ensuite.

Yes, but make a thick as practical especially if you have UFH. Start at top of screed and down 2 levels. DPC to keep aerated blocks dry

I would doubt they would even realise, they make so little noise doing cooling, especially if you are flowing 14 to 16 degs Mine just runs at the lowest it can modulate, can't it hear it from about a metre away.

Hi, need more details - what are you insulating - roof, walls or floor. What is the construction method of the house? Is the roof a normal loft of room in roof? What is the floor, ground bearing or with a void below?