JohnMo

What is that? All heat pums are suitable! Not all cylinders are suitable for heat pump heating. We just heat our cylinder now via immersion, we are on Octopus cosy tariff and it allows heating 3x a day on cheap rate. So although there are advantages using the heat pump we have just stopped bothering and immersion adds very little in real terms to our bills.

If your digging the floors out, are you doing UFH? Would be a simple and pretty cheap way to add heating downstairs. If so, the more insulation the better. Not a fan of your hot water solution. Electric showers are just rubbish after having a unvented cylinder. Make room for a small/medium cylinder heating via immersion. Add a decent shower mixer. Your going to be running cold pipes anyway an additional pipe is easy while your at it any way.

What is the assumed U value for your windows and doors? Lots of glazing is different things to different people and can make a huge difference to the heat loss. I would go through the SAP report line for line to see what assumptions have been made, sounds shite in shite out to me somewhere. Post your report

All seems fine, been doing cooling at 14.5 degs since mid May as well, going by the flow meters on the UFH manifold which are nice and clear.

Sort of. Treatment plant and soakaway are around 400m apart, and although it should gravity feed SEPA insisted on a pumped solution. So we feed from treatment plant to another tank with a pump at the bottom.

Couldn't agree more. Doesn't matter industry you are in. Definitely not a necessary unless one side or the other is an arse or full of their own self importance (maybe the same thing). Had one designer that wouldn't entertain any input from me (not really the designer but his boss), so the company got sacked on the spot very early in the design process. Design is a two way process, it may look pretty if it can't be built easily it's a rubbish design by a poor designer. But back to the slab, your structural design should detail rebar and concrete specification fully. If it doesn't it should. Scottish system makes this all blissfully easy, structural design not completed - no building warrant - no permission to build. Curing agent or not depends on few things, such as outside temperature, so in winter in Scotland is completely different from summer in England. Get advise from your structural engineer, as they should be giving you the structural design certificate.

On a new build - I doubt it. Our max flow temp is only 28 at -9. So well below body temp, actual floor temp a few degs above room temperature so even cooler. Even without the previous how long will you be spending walking on the steps. If well insulated they will be close to room temperature?

I would divert around the steps completely - they do not need UFH. So first image with stairs going up to next floor, take pipes along and down wall then transition to floor, behind the stairs. Other bit again do the transition via the wall not the steps.

Not really correct - we have a fail and you go to the same place in the design rules if it's a fail for too fast or too slow. So the same design would be applicable to yourself also. Ours effectively sits on a thick layer of gravel, tops with more gravel. Suspect as you say disappearing pretty quickly. But our layout (due to elevation changes) has a limit switch operated out flow tank (with pump) from the treatment vessel. So around 500L is pumped at any time, then most likely off for a few days.

This is our design - effectively a fail on perc test as stated in the text. This is a early revision of the drawings shown as a 10 person drainage field (final was a 6 person) Big area, but simple design. Don't overthink it just follow the rules

Ours were 45x47. Just batten it out and don't bother with the insulation. If your already well insulated the additional insulation compared to an unventilated cavity isn't with the effort.

With a decent tariff and a battery the spark gap is well below that (Cosy fixed) it's at 1.4:1 add in a boiler running at 90% efficiency it 1.3 and that's not taking into account the gas standing charge will is eliminated. So for at least half the year you are on pretty close to 1:1.

It's going to be pretty cold in there without heating insulation or not. If the only heat source is the battery. Sounds like fire ready to happen.

Maybe next week? But likely not, although there is rumours about the pricing structure may change and somethings being moved to general taxation, instead on the kWh pricing. Who knows in reality. Get you solar panels up and then add some more.

@Alan Ambrose What are blue squares on the roof and walls