Adrian Walker

You don’t need to extract cooking in an air tight and well designed MVHR system.

Not necessary and ozone is not good for you.

That is the least of any developers worries, worst case is sprinklers or misting system.

Losses in a cable are the square of the current, so increase voltage to keep current low for same power. So 230V is better than 110V

I2R losses

I’m self-building in Hampshire, neat Andover. Happy to help.

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What are the weaknesses of an insulted slab?

Are you looking for self levelling concrete. CEMEX do Evolution which works well.

Isn't it better to be happy for 12 months rather than just six? I put my winter clothes & duvet away for 6 months?

have you thought of using self levelling concrete. CEMEX have Evoloution which is very good and need minimal work after the pour.

It shouldn't feel stuffy at all. If this is the case then it hasn't been commissioned correctly IMHO. A CO2 reading is the quickest way to confirm this. Every home should have one.

People gather around an island and the sink can be a messy place, plus all that extra plumbing. It's a no from me and many other

That's how most suppliers quote, especially SIP and ICF.

If you haven't built yet then consider an insulated slab, so no need for a screed.

You can get a price for the square area of the walls themselves, just not the square area of the building footprint.

Per sqm is never a good way to price any job, too many variables IMHO

"The builder advised it was pd and I went along till I later realised through a architect it wasn't..." I guess this was verbal and not in writing from the builder?

You need to use your phone with a straight edge to get it accurate results. This can be anything about a metre long including a walking stick.

"regardless of construction type, the air in a building will react more to external inputs than internal inputs i.e. solar gain, ventilation and a heating system versus thick stone, brick or concrete walls." isn't that fairly obvious?

Rather than "concrete / insulation / uhf / concrete layer approach " why not just insulation (foamed glass or poly) and concrete with UFH?

What's the need for a concrete sub-foundation? Clay soil?

Tim This podcast from Ben Adam-Smith is worth a listen. Tim Nicholson, Joanne Bowlt and their two boys live in a 1960s end of terrace house in Oxford. Recently they started work on upgrading the property but why did they choose to retrofit? https://www.houseplanninghelp.com/why-retrofit-a-house-for-energy-efficiency/

The PH15 uses I beams. https://www.phhomes.co.uk/ph15-projects/

You said "... until shortly before the basement works started, leaving me with no option but to proceed with the basement." You did have an option and could have stopped the works. IMHO it's very rare to see a basement (below ground) constructed of block work. If basements leak then it costs £1000s to correct. I presume that the basement company is providing a good guarantee.