Tony L

Yes, sorry, I forgot to mention him. So he's £2300 + VAT, but we have quite a few steels going in. I shouldn't think you'd have to pay quite so much, @Crofter if you design a house that's a similar shape to your last one.

I suppose when I get my test done it will be easy enough for the tester to give me an ACH figure & a permeability figure (if I've worked out the m2 figure). I now realise that because my house has poor form factor (thanks to the horrible people at my planning dept.) it's going to be quite a lot more difficult for me to get close to the PH 0.6 ACH target than it will be for most people that are building an actual PH house, with good form factor.

I'm leaving the answers for 1) & 2) for the BH experts. I'm definitely not one of those, but I have recent experience of 3)... I did my own drawings to get PP (& if I can do it, it will be no trouble for you to do it). It's a 1.5 storey 4 bed house. 3 dormers; each dormer is different. I employed an arch tec to turn my drawings into construction drawings & deal with BC. The AT's fee was £4,200 + another £200 perhaps, for some add-ons, & no VAT. He turned out to be no good (I think he may have age related cognition problems). The new AT will cost £6,000 + VAT, but there are no add-ons & he'll keep going with amendments until BC are happy & I'm happy, & this is covered by the £6k. I'll have to pay extra for the BC submission fee, SAP, proper heat calcs if I want them, QS/bill of quantities - perhaps you can do this yourself, given your experience. Hope this helps. I'm normally the one asking loads of questions, so it's good to be able to try to help someone.

There's more on ACH measurement vs permeability measurement here, with some diagrams, if anyone's interested: https://efficiencymatrix.com/commercial-enclosure-air-tightness-testing-targets/

I am very grateful for all the advice I'm receiving regarding building my house & the first few pieces of advice on how I might best deal with my partner, whose views don't always align with my views & don't align with the general views of the BH community, but you haven't convinced me that your way of dealing with somebody you've never met will work better than my way. This is because I've had thousands of conversations/negotiations/arguments with her over the past two decades - so I think I'm in the best position to judge which approach might work best. None. There's no architect. I drew the house & did the PP negotiation. I've just appointed a new arch tec to draw it all up properly & specify all the construction details, which I'll be able to check, thanks to everything I've learnt here on BH. I'm not going to share my postcode, only because I'm trying to maintain some level of anonymity, so I can speak freely about the planning dept & BC dept at my local authority without getting myself into trouble. For the same reason, I refer to my partner as my partner/her/etc because she has an unusual name. It would be nice to use her name, but then it would be easier to identify our location. It would be great to meet some other BHers at some point, but I'm too busy over the next couple of months. Thanks, Terry, & thanks @ToughButterCup for your response too.

I don't think it has to be the front door. I think it can be the "back door" (on the side of the house in my design) so long as your WC can be easily accessed, in a wheel chair, from the back door.

Thanks, everybody, especially @SteamyTea for putting the spreadsheet together. I've not started playing with this yet, but I have learned about Bin Method.

Thanks, Nick. I've been completely into the airtight + MVHR way of thinking since I first read about it here 18 months or so ago. I've just been improving my knowledge over the past few days to help keep my partner on board with these ideas after she was fed some mis-information by somebody who we were considering using to deal with our building reg.s & construction drawings. I'll have a look at that link when I get a chance, just to improve my understanding. I will likely be paying an expert from Wales to deal with my MVHR when the time comes. My design will leave spaces in all the right places.

Surely you need an evidence-based conversation and come to a joint decision. Several evidence-based conversations have already happened. I will keep going with more of these & eventually I may bring her around to our way of thinking, (“our”, referring to you & me, rather than her & me). The design already has much less glass than she wants & no wood burner. I’m making her sound like an idiot, so I must point out, she does have some excellent & rare qualities. If she doesn’t get it then I may just go ahead & do what you & I think should be done anyway, or more likely, we’ll endure a hot summer then fork out for some a/c or fan coils (with no VAT reclaim). I’ve got to bear in mind that her trade-off between how the house looks & how comfortable/economic it might be is different from mine. & it’s difficult to influence some people’s beliefs by presenting evidence to them. Within the build hub community, almost all of us like evidence, science, logic, & we’re open to having our views corrected by others who present persuasive evidence to us. A lot of people aren’t like that. There are millions of people in this country who believe in all sorts of strange ideas that aren’t supported by real evidence. I could go on & on, but I’ll stop there, just in case I land myself in a load of trouble for upsetting one or more of the strange belief people who may stumble across our forum. Thanks for your post – I’ll be quoting your, “8-10 the U Value”, when we next discuss the windows - that’s if I can persuade her to believe in U values.

Don't say that - I had to work really had to get her to agree to the chimney being deleted from the early design.

Not even a little bit? What am I not understanding here: I'd have thought that if the air outside is cooler than the air inside & my MVHR system is taking warm air from inside, bypassing the heat exchanger in summer mode, & replacing the exhaust air with cool air from outside, this will help keep the inside temperature lower. Of course, MVHR won't be the entire answer to the summer overheating problem, but I think it must be having some effect.

Thank you very much for your post, @Nick Laslett. I am persuaded I should spend time on Jeremy's spreadsheet as soon as the time can be found. At the very least, I will read the thread about how it all works. I have considered a plan for summer hot air purge, involving a small as possible window at the highest point on my east gable, which is shaded from the afternoon/evening sun (& can have the glass fully covered anyway). The window will connect to a vent duct, with a super efficient fan inside, that will suck air from near the apex of the vaulted ceiling above the landing & dump it outside. I'll open a downstairs window. I can see this being more effective than just opening a few windows, & it could be left to run when the house is unoccupied. Good idea/bad idea? I haven't fully thought this through yet.

That's good. I've got those in the right order then. I'm planning external motorised blinds on the two small Fakros in the two south facing bedrooms. I'll make provision for (ie a long hole where the eaves overhang) external Venetian blinds for the French windows to the patio. I don't think my budget will allow for PV. I'd really rather just plan to work a few more months before I retire & have some PV, but my partner doesn't like that plan, so I'll give her that one & I won't feel so bad about overruling her wishes when something really important comes up.

I've just put one of these fans in my rental property. There's a PIV in there too. V good. It was part of my strategy to deal with a black mould problem.

That's an excellent explanation. Thank you, @IanR. Yes, I didn't think it did - the way I explained my understanding of how the test works could have been better.