JohnMo

Unfortunately PV doesn't generate much electricity in the heating season, so using it for heating may not be very successful.

Not sure, generally putting wires in insulation isn't a good thing as you have to up the sizes of the cables - but why not use wireless, with wireless control centre. A lot on the market can now be recharged, so no faffing with batteries.

I've got an Atag combi, it seems well made, nice and quite. They do a system boiler i24S also

Our windows (which are much smaller) had to be approved by the structural engineer due to wind loads, would have thought that size sky light would need someone qualified to approve the design. 1cm X 1cm glass is huge, if it hits you. I would get professional advise. They have said the risk, so the responsibility could fall on your shoulders if all went wrong. I landed via a ladder fail, on glass side tables, the glass was all over the floor (6m X 6m), the shares as as sharp as a sharp thing.

We have semi flexible 90mm via plenums, and we are the best part silent, that with Scottish building regs requirements of 0.5 ACH, compared to England which I believe is 0.3 ACH. We have two MVHR Units, to enable short runs and low pressure drops, this keeps fan speed down, even on boost we are only at about half max speed. Keeping velocity through ducts low, fan speed low all contribute to low sound levels.

They would only guarantee us 6.0mb Went 4g can get between 12 and 40. Had to buy modem at £100, then £35/m free mobile calls on landline phone and unlimited data

Voulted ceilings depend on the design, our lounge is voulted, to be non voulted I would have to install a ceiling, so that is a cost adder, we are in a bungalow, so the loft would be huge and mostly a waste of space. With the voulted ceiling the airtight aspects were easy also. In fact all the ceilings match the roof line, it made the build simple

I would make appointments with a couple of local architects, I wouldn't bother if they are or aren't passivhaus experienced, unless you want it certified. Get a design your happy with, number of bedrooms, living space etc, then work on the thermal aspects. And also how you plan to build, method and if self build, turnkey, main contractor, or sub contractors under your control Decide early if you going single storey or two storey. I would say "fairly involved in project management", may not work for you or who is project managing, as you will end up stepping on each others toes. I would either project manage or let someone else. To project manage you need to be there a large amount of time. It may also depend on how you are building, turnkey, they may not even allow you on site without an appointment?

I wouldn't like to embed copper pipes as you say with joints, Pert-al-Pert or similar would be better, a manifold would be easy enough. You could almost run it like UFH, but with radiators. Assume the upstairs will be bedrooms, do you like the same temperatures in your bedrooms? A thermostat in each bedroom, would enable you run slightly cooler temps in one or more rooms.

I used a brush and shovel, don't overthink it

I added until I had a double cream thickness

Big gaps, sand cement. I did a parge with a thin cement mix, for this I used 3 sand (not sharp sand as it's too gritty), 1 cement, and about 1/5 lime. Applied with a broom.

You have air in the loops, from the sounds of it, UFH should be near silent

Thinking about it, under screed pipes they have to be installed in such a way that makes it possible to replace; hence the conduit. If you have joint below the screed, it cannot be replaced, so will not comply with Building Regs

Not greyed so far, overhangs were mostly completed in March, the rest finished in August, will get the last bits completed in the next couple of weeks. It wasn't kiln dried.

It's shiplap, I think

It came from Timber Central in Nairn

I bought a few bits from them, where the prices were ok and prior to that got a full installation cost, hence going DIY.

Going to be doing a UV protection to keep colour. Just need to find the time

I am due an invoice, was expecting it today, so should be here tomorrow, will let you know the final cost. I got from Timber Central in Nairn, they are on Facebook and that number is correct, the Google number is an old number.

Not sure what he drinks, but talks a by product of food

The guy that did my foundation block work, said I wasting my time insulating the floor and foundations as heat only rose upwards, just couldn't comprehend it went downwards and sideway

Why not Scottish larch, lower shipping costs, buy straight from the mill, much more stable prices.

Semi flexible is quite flexible. BRE do some design guidance notes also. Flexible duct is supposed to be pulled tight, but I wouldn't waste my time or money, to do it correctly is hard, so in a lot of cases, it's just installed badly. As said mix and match manufacturers, you don't need smart control, humidity control can be hit or miss as our humidity fluctuates greatly across seasons. Simple boost switch in wet rooms and kitchen.