JohnMo

No we didn't render at all, as I hate the stuff. I used stone slips and Scottish larch cladding. Inside we did a lime, cement parge coat for airtightness, and sevice void for from battens screwed to durisol and the dry lined with plasterboard. Doing it again I would miss the parge coat and use a smart air tight vapour barrier membrane, less mess and quicker.

You need a structural engineer for the rebar calcs. Durisol had a really good build manual, you should be able to find it online.

Yes DC over the long run, just use normal armoured cable of the correct size. The more vertical the panels the more even the production is over the year. You get a slight lower yield overall but more when you need it. Mine are vertical and more like a fence. I took the 9m2 as floor area it takes up. 40mm thick is a lot of panels

Durisol costs nothing to brace, well 4 sheets of osb and some screws. Nothing wrong with durisol, our external walls took us 4 weeks, (70m x 3m tall) neither of us (2 off) had done or used ICF and neither of are builders. Yes from recycling mostly old end of life pallets, very little cement, made in Wales. Easy for anyone to build from. Render and or plaster directly to the woodcrete. U value of 0.14 out the box, zero cold bridges, very little rebars required. You actually screw things to the woodcrete without issue. Lots of things to like.

A small heat runs out flow rate by the you get to +/-1m3/h. My 6kW heat pump was flowing just enough to drive 9 (7 in house and 2 in summer house) loops from about 15m away from the manifolds. Had a dT of 4 to 6 depending on room. But the return temperature from a thick screed/concrete floor will dominate max flow temp you can achieve during a heating cycle, without a mixer. Mine rarely has a return temp above 27 to 28 (electronic mixer set to 35), so no matter what flow temps I may ask the heat pump to do my flow is capped at about 32 to 33.and takes about 8 hrs to get there. So trying to spread the heat evenly between radiators and UFH without some form of mixer isn't going to work well. If I drop my mixer to control to 28, so I get plenty of floor water recycling the heat pump does increase flow temp because the house flow temp is less dominant. But I have to run the heating most the time.

At the start of the heating season I was trying to optimise running the house and summer house UFH systems on a common flow temp without mixers. Turned up the heat pump flow temp to 32 from 29.5, also increased the dT on the house UFH to decrease output as far as I could and keep the heat pump happy enough. Basically the house overheated after about 18 hrs was up to 24 degrees, even though the thermostat stopped the demand for heat, the floor had absorbed lots of heat. The summer house wasn't warm enough. If you want two flow temps use a mixer.

Maintenance needs would take several life times to recover the capital costs. How many people actually service their cylinder annually - would bet not many, as many would have no clue they needed to. Heat loss would suspect more heat is lost from the pipes than the sunamp or cylinder. Can't answer your question about energy lost over 24hrs as we keep using it.

But what is different - an UVC can do just the same functionality for a 1/3 of the cost of purchasing a cylinder instead of a sunamp? What am I missing?

Or down 2 if you start to melt

I would add an electric towel rail in to the bathroom as well. Other than that it looks good to me

Are you sure, mine is devoid of aluminium layer. Could you run 15mm inside it? That would reduce the lag

Anyone with a GSHP does it every day.

Think you may be confusing car glycol with that used in heating systems. Car poisonious - heat pump heating system food grade.

First question is your installer proposing a buffer? If so could deleting that free up space? Slim line cylinder in a corner? Loft or space outside for an insulated shed? Hybrid, heat pump for heating, a combi boiler for DHW

Little confused, you have said you are doing a passivhaus, there is nothing passivhaus about 0.18. You need 2.5x the depth with insulated concrete compared to PIR. Kingspan is just a brand name, plenty of competition in the marketplace. I bought online, it came direct from factory. I would limit my choice to either 300mm EPS, slip membrane, UFH pipes, the screed or concrete, circa 100mm will allow you use as as storage heater, thin more like a radiator. Or 200mm PIR in 2x 100mm staggered layers. Then as above. If you are doing UFH aim for 0.1 U value

Once you get to low outputs and flow temps below 30 or so you cannot notice. I didn't go under any kitchen fixed units, showers or baths, kitchen islands or beds. A Lot of the, "you better do this or that", only really applies to UFH installed in very high heat leakage houses and/or with little or no insulation below the pipes. Well insulated with heat output of 15W/m2 and below, you can do just about do any centres, any pattern, flow temp varies only by a couple of degrees.

They have been that price for quite some time.

I had some high and low areas., low self leveling compound. High an angle grinder attachment from Screwfix and a Henry hoover (lots of bags), then some 2 or 3 days grinding away.

My justification was, I am earning, if I don't spend on this, it will go on rubbish elsewhere. The spend now, while I can afford it, is a reduced utility bill when I can least afford it - retirement. It's a better return than a same money in a pension pot.

We just have green plasterboard, then tiles. Never seen why you need to tank. Every house I have lived in, has been the same (since the 80s).

That is one overly complex roof. I would be tempted to look at this the other way around. Ignore what's inside the house. So the roof will have insulation above the steel work. Now the only part exposed is that which is overhanging outside. Insulated the overhang steel, much smaller area, you can have a flat ceiling.

Not sure they recommend that

Looks pretty similar to what I did. Put loads more pipe in bathroom. I would do as close centres as you can.

Believe so

We have PV GivEnergy all in one. If battery is full and I start to export this picked up by the PV diverter and that electric goes to the immersion. If I was to get an electric vehicle I would just get a GivEnergy charger, then you can control better how it all works together.