JohnMo

You be worth having a read of the regs, to make sure you have the required ventilation strategy in place https://www.gov.scot/publications/building-standards-2017-domestic/3-environment/314-ventilation/

The regulations state the size minimum for the shower, use that dimension and add to drawing. Activity space then adjoins the defined shower space.

But they are all estimated, the estimate will change hugely, based on building shape, size, build type, external and internal finish, flat roof, pitch roof, insulation levels, ventilation/ airtightness, heating type (gas, ASHP,gshp, UFH radiators) etc etc. Two different kitchen designs can change a build budget by £50k, the amount windows can change it again by £20 to 30k with ease, uPVC or Ali clad can change it again by the same amount. My thoughts are for a basic start point. £2k to £2.5k per M2 with someone else doing all the work will be a basic ok performance house, so 400k for 200m2 two storey. Add a good 10 to 15% on for single storey but depends on roof complexity (our roof added about 25% to m2 cost). The more bells and whistles and any changes you make along the way will add quite quickly. The above assumes limited or no landscaping, painted internally a single colour.

What about a solar assist heat pump, they are generally around 2kW, come with 2 off 2x1m panels for outside though and they need to be mounted. Or if you like engineering something, could you use a car Aircon condenser and car fan, instead, mount in a custom box. Use it to heat a 50/100 litre cylinder with coil and take the UFH water from that. Or a Willis heater, CoP 1 though, so may be costly to run. Or an all in one air to air heat pump, for cooling and heating. But that doesn't used the UFH. But no outside unit.

Is the cartridge adjustable, our is a different make but behind the temperature knob is an adjustable temperature screw, if that is adjusted the wrong way it is just be hot all the time. Worth a read of the instructions

Something like this - other makes available. Would be my recommendation. https://www.vent-axia.com/range/lo-carbon-nbr-dmev-dmeve Runs continuously and is silent, humidity stat options available.

No particular warning on my Titon units. My thoughts are. For what it saves why switch off and risk not switching on when you have closed the windows. Mvhr sucks in moisture from wet rooms, so be definition the extract side is wet or damp. Switching off for a prolonged period would allow these damp areas to generate bugs, mould etc. Neither is healthy for the unit or you.

We had one similar to that, was great. £2k or put kettle on at your required temp, it's hot when you back from a visit to the toilet.

What are you referring to "these"? dMEV fans go in the following rooms. Utility, bathroom, shower room, en-suites, kitchen, anywhere where moisture is generated. The combination of all the fans must give an air change of 0.3 an hour. So calculate the internal volume of the house, divide by 0.3,this will give you are target M3/HR flow rate. Read building regs related to ventilation that will tell you exactly what is needed, for flow rates in each room, but base any discussion on an airtightness of less than 5.

One thing not mentioned is during winter you will get very little hot water from PV. As it doesn't generate much.

I would say they both look cramped. How about putting the bath where the sink is, or where the toilet is on the first sketch. then sink and toilet where the bath is.

All vaulted, except a small part of hall. Spray foam insulation between and under rafters.

I have wet UFH, electric towel rads. If I did it again, I would do electric towel and electric UFH.

Based on that figure, the fans specified as intermittent are fine. But with a polystyrene ICF build you may be a lot more air tight and could end up with mould, poor air quality etc. As a minimum I would get dMEV installed, these fans will fit into the existing/planned holes in the wall, match the windows you may have already been installed/ordered, with trickle vents and give you the least hassle. Best of all they are silent. The way dMEV works, the fans run at a low speed continuously, extracting air from the wet rooms. Air is drawn in through tickle vents in dry room windows. The air cross flows through the house/under doors etc. and out through the wet room fans. Think you are aiming for 0.3 ACH through the ventilation system.

Easy to work out read building regs for your region. In Scotland it's basically 0.5 ACH. So calculate the internal volume, divide by 2. That's the basic normal flow, add 25% for boost. Choose a unit that flows your boost figure at about 70% or lower it's rated capacity. Extract in wet rooms and kitchen, supply everywhere else. As Dave say semi rigid is easy to install, just plan ahead.

Had MVHR flow rates set per Scottish planning the other day. As soon as the guy left I put mine on to setback (mid way between min speed and current set point). Considerably lower flow rates, closer to passivhaus and no noticeable increase in CO2 levels, in living space and bedrooms.

Out of interest what airtightness figure was used to get an 88 from SAP?

Not sure of the rules where you are, but in Scotland if your final airtightness is 3 or better you would have to have it installed. ICF builds tend to be quite airtight. dMEV is a good option if worse than 3, anything from 3 to 5. This would require trickle vents, and continuously running (silent) fans in wet rooms and kitchen. This can be made to run on condition (humidity etc), so run at a low output, until required. We have MVHR, my wife has COVID, and somehow I don't. Not sure if it's the continuous ventilation or I'm lucky so far.

https://ecostream.org.uk/d-mvhr/ Not used or seen

Your going to have to play with setting, including flow temperature. Change one thing at a time. See what happens for the next 24 hrs. Write down what you did and energy consumption and things felt. This will make the whole process reversible and see what works and what doesn't. But you should be able to reduce flow temperature, by setting the runs times longer. Lower flow temps equal higher COP. Was your ASHP a retrofit, did you increase the radiator size? Read your manual to see if you can set to weather and/or load compensation.

Rockwool, Knauf and plenty others do something similar to frametherm. Look at insulation hub, they tend to have good prices and normally free delivery. Found what ever centres you have it all needs cutting.

I assume your heat pump is loaded with a heat curve based on outside temperature. So basically it should work the same as weather compensation system on a gas boiler. Where the heating is designed to run 24/7. Each room has a TRV, to manage the room temp, but not call for heat. The system will operate a setback of a couple degrees during night, so the pump has an easy time of it during the next morning. Running this way your circulation temp can be reduced. Don't try to operate as normal gas boiler, with lots of on/off, as you will wasting large amounts of energy. Long, low and slow should be the way to think of it. Run for long periods, to allow a slow build up in temperature at a low circulation temp. Then let the system maintain it. Set the hall thermostat higher and let the room stat/trvs manage the room temps.

Don't see any issue. Cold water feed to HP cylinder, then the outlet fed to oil cylinder. So long as both have the cylinder protection on (relief valves etc), should be no issues. Why heat to 60, a lower temp should be fine. Even maintaining the second cylinder at 40 or just above would be fine, as you will have 550 l of water available.

Some of the pipe diameters will be larger for a HP, not sure why but have seen it mentioned quite a few times. Someone should be able to advise. Your cylinder will need a larger coil for the HP. You don't say what boiler you have currently, but it may be able to run weather compensation, if so with the HP set up for the rest of the system, you may be able to run in WC mode at heat pump flow temperature, to save on gas costs. other things to consider Plenty of insulation in the ground floor to limit downwards heat loss from UFH Draft proofing, airtightness. Look at a condition based ventilation system or MVHR. https://www.aereco.co.uk/knowledge-centre/how-to-choose-between-a-humidity-controlled-mev-and-mvhr/

We got BT to tell us the speed we would get before committing, 6Mb was all they could offer. There is broadband supplied by radio towers, by line of sight, which a friend has, super fast (WiFi Scotland). Or 4g router. We did 4g router.