JohnMo

Sorry not read whole thread, but can see the steel lintel, have you plans to mitigate the cold bridge that will cause?

Give us a clue, what are we looking at is this heat pump energy consumption? Red could indicate heating and blue cooling. Did you have DHW heating selected in the red zones?

Most likely true, we have wood, tiles and carpet. Every day usage you don't even notice the transition between floor covering and am mostly in bare feet. Winter with UFH floor not not cold not even warm but not cold, summer with cooling nice and cool.

We explored passive raft type, but went for something ground workers around us are used to doing. Zero novelty, zero learning. Labour becomes cheap they don't need much steering in the right direction. We went ground bearing slab, all bog standard structural engineer stuff. Then paid attention to eliminate any cold bridges and had that added into the design by the structural engineer. Just keep it simple, do what is normal for your area, then pay attention to detail, but make sure you understand the heat flows, making sure any cross section, in any direction, has no gaps (cold bridges). YouTube videos can be good, I watch loads, but plenty are utter nonsense. But a better source of information is Passivhaus.

If your only option is stick panels at silly prices I wouldn't bother, just get a battery and that allows a TOU tariff and use cheap periods during the peak ones

Another thread on this last week - have actually looked a price? Shockingly expensive, not sure how you could ever justify PV going that route. Anything other than standard panels is really an expensive folly. Ground mount and fence mount are other cost effective options

You may want ufh to help it set hard, have this picture of someone walking through wet sludge if it all goes wrong. Maybe ok for a mud hut, not sure I would bother for a house. At least you can dig your way out of it - literally

Two normally closed valves or X plan one normally open the other normally closed for PDHW?

You can if you want, you can get smal.coul units for small ducts so you can get individual room control if you want it. But with an air change every 3 hrs suspect it's feast and famine for heat if the additional thermostat to each room, it's not really a big issue anyway as room temp equalise whether you want them to or not. If heating via UFH and at no more than 10W/m2 your floor temp is about 1 to 2 degs higher on the coldest day than the room, so floor pretty much regulated itself without thermostats getting in the way. Your real issue is getting a heat source that modulates well enough to drip feed energy into the floor. My heat load is about 15W/m² at -9 so average days even our 4kW ASHP has to batch heat, so runs a few hours then off the rest of the day. Cooling via MVHR is pretty rubbish, your flow rates need to about 5-6x higher than your ventilation rates, so pointless.

He seems to be an S plan install, which is even odder on an ASHP

You can heat and or cool anyway you want, each has it's merits. Some A2A systems include humidification for heating, usually by introducing new air, as you can over dry the air I believe with a constant recirculation air heater (A2A). I would look into that before you commit. You are a pretty good airtightness, so will have MVHR, this will give a quite low humidity anyway. So my main concern therefore,⁶ would be low humidity in winter, low enough it's not good for your health. Future buyers, may not understand the concept of using Aircon for heating? Slab heating/cooling isn't the norm either, it maybe on here, but in the real world most people have radiators. Which are rubbish for cooling.

If you are doing liquid dpm, do yourself a favour and use a 2 part epoxy based system. Easy to apply, chemical hardening, so sets in a predetermined time. Apply one day time the next. None of the tacky nonsense. Not cheap but works well.

Not sure it actually applies to ASHP either. Now had two and both performed the same on heat and cooling. My ASHP is currently chugging away cooling the floor at a CoP (EER) of 7.5, so doing well for a heat pump designed for heating. A2A will switch between either as long as it is not a cheap as chips cooling only one and includes defrost functionality.

Or maybe don't do ducted, do wall mounted and no cross talk

10W/m2 ties into passivhaus heating requirements, that can be done via MVHR if you want, but doing any cooling via MVHR is not really that successful. A2A could do both. Do DHW via direct immersion heating. Not really cost effective to do much else with A2A. Even with an ASHP I do direct anyway, not noticed any uplift in electric cost since I changed over. But for primary heat source, buy carefully, do your research as performance can vary hugely. As can the I'm fukced off with air always blowing at me factor. Maybe if doing A2A look at ducted systems.

Personal choice

Basically, same design really one uses water the other refrigerant

No not noisy, but there is some fan noise depending on fan speed.

Be careful if you bother doing a cooling heat gain calculation, as instantaneous solar gains can give you a huge heat gains. Others on here have tried it got 20kW cooling requirements and 2kW heating requirements. Then got bogged down with indecision. Size your heat source for heating needs, accept cooling isn't perfect, but better than nothing. Or go full A2A. Be pragmatic or pay £20k for a good plated solution. Think @Nickfromwales did a cooling solution where he cooled the upstairs/downstairs hallway instead of the bedrooms directly. That sort of solution cuts the number of fan coils needed, moves noise away from bedrooms and any drafts away caused by fan coils.

So assuming this is without all the plasterboard etc fitted. Going better than 0.64 is chasing numbers, to say look at me. Further gains aren't worth the cost. Get a couple of tubes of air tight mastic if needed.

Fan coil brands. Brand doesn't matter for ASHP. Good ones let you adjust the temp of water to enable the fan to start with a different temp for heat and cool. Poor ones are operated on a fixed water flow temp, which may not suit your setup. I have Myson iVector MkII fan coil, which is good. Panasonic, Daikin, Cool Energy all have good fan coils and many others. If you have time look on eBay many bargains come up or shop around as prices can vary hugely for the same thing. Some cheap fan coils are set up to just heat, so be careful read the install manual. Yes, one circuit feeding UFH and fan coils. But to this you need to size the fan coil to the expected flow temperature.

Why not spend a bit more and get one that does cooling and heating well. If the performance isn't quoted as good, maybe the indoor unit isn't that good either, noisy and drafty.

Depends on inside temp and humidity not outside. Easy way is set to a fixed flow temp. Generally keeping flow temp above 14-16 degs is fine. It depends on the first sentence, that depends on ventilation system etc

One thing stands out and it the price, if compare to an ASHP it has nearly all the same components, it will have an air to refrigerant condenser/evaporator, fan, compressor, a casing, a controller, only the thing is the refrigerant to water heat exchanger and pump are missing. But its 10x cheaper - and everyone says an ASHP has to be expensive because it's complex, this sort of proves the point it doesn't. It may not have have a defrost cycle built in but if it does heating and cooling it will have all the hardware, which is a 4 way valve.

I did mine almost the same as yours, but stopped doing block work at dpm level. Then backfilled floor to get a level site. This allowed the DPM to be installed and taken up the external walls. Above you can see where my internal wall block work stops DPM in place with rebar ready for concrete pour. Once you have poured your concrete, you build the internal walls up from the concrete directly above your foundations. This image show the top of the stub structural walls (after floor insulation and UFH added and prior to floor being poured) You have just carried away and built too high. You need detailed drawings and make sure your workers understand them. Suspect you need to remove the engineered bricks and Marmox blocks only, depending on where you have defined the DPM/DPC levels