jack

I wouldn't have believed this was possible until one of our friends' young teenagers someone how managed to turn the boiling water tap on to wash his hands! No serious damage done but a fair bit of shock for all concerned. Personally I'm amazed he got it going at all (there's a knack), and also a bit puzzled about why he used this small tap off to the side rather than the stonking big one in the middle!

We did this. Our ASHP is on the north wall of our attached garage, which is on 300mm insulation (no idea why - easier to work to the same level across the site I guess). I made two trenches in the middle layer (of three) by cutting some EPS pieces. I then foamed in some 60mm (from memory) polypropylene pipe. The next layer of EPS held it all in place. We then got some 28mm (I think) pushfit barrier pipe and some long rolls of stick-on 3 or 4mm thick nitrile insulation tape. This was just wide enough that two parallel runs covered the outside of the barrier pipe. I greased it up with a little washing detergent and it pulled straight through the duct. There seems to be very little temp drop over the 8 or 9 metres the pipe travels to the plant room, even when running at 55 deg C. The temperature at the top of the UVC gets to exactly 55 deg C every morning throughout winter. The one thing that worried me a little was that we had to go through the ring beam. I used some foil-covered rockwool sleeves wrapped in DPC plastic to protect the pipe and insulate it from the ringbeam. Seems fine. The area where it comes through is one of the lowest stress points of the house, and the heat going through the pipes every day, at least in winter, should avoid condensation (I hope!)

On cost grounds? Must say, I wasn't 100% sure when we chose to install one, and now I wouldn't be without it. Forgot to do veggies for kids' tea? Frozen peas, boiling water tap, done faster than even the microwave can manage! Not to mention the ability to make a cup of tea in about 20 seconds start to finish, which comes in handy if you watch a lot of BBC (no ads).

Yes, should have been clearer. The question was "is it essential?". The strict answer is "no". If the question is "should you do it?", then the answer is "yes". I would have had a more relaxed time if I'd gotten around to doing it before the slab was poured. As it happened, it was the follow-on trades that I should have worried about! Edited to add: So what do you do as, say, the third of four lined-up concrete trucks starts dumping its load into your slab and you suddenly note a drop in pressure? What could realistically you do at this point? Stop the pour? Start digging around in the stuff already poured to look for the leak? Genuine question - sounds like a very unpleasant position to be in!

Yes, I read that too - several weeks after our slab had already been poured!!! I believe one of the major reasons this is done is to stop the pipes floating up when the slab is poured. If they're tied down properly, this shouldn't be an issue. So, "essential"? Not necessarily. Disclaimer: I know nothing.

Yes, one of these, but blinking!

It irks me to agree with the plumber, but I think he might be right this time. Stopped clock, twice a day, etc!

The problem is that you'll get little to no power output from a PV panel for potentially days on end in the middle of winter.

Oops, sorry. I thought that product was one that used outgoing air through the MVHR to extract energy for DHW. I stand corrected!

I think the proof of the Ecocent system will be how it works in the middle of winter.

I know that feeling so well!

Looks great. How do you get the pallets apart? I occasionally tried that on a few of ours and they seem almost impossible to take apart without damaging the wood.

Glad to hear this isn't just my experience. Of course, if there are issues, they're likely to be slower to appear than in something like the Taylor Wimpey house you're referring to. Perhaps we should all compare notes in 3-5 years when we have a few seasons under our belts!

We had good and bad, but very little terrible and very little that blew me away in a positive sense. Scaffolders were absolute carp - had them back onsite three times to do what was shown on a very simple drawing. They just couldn't cope with the idea that the scaffolding didn't just follow the ground-floorplan because of a couple of overhangs.

No builder other than MBC. We oversaw all trades (which can be stressful, for sure). We knocked the bungalow down in November 2014, groundworks happened over Christmas and into January. MBC came onsite in February (from memory). We moved into the house before Christmas 2015. I don't doubt we could have knocked 2 months off that if we'd pressed harder (and had any idea what we were actually doing!) The house was designed by a local architect. He did a great job, both on the design and detailing (other than one or two weathering details we redesigned with help from others and ebuild).

Wowzers! Nice one Ed!

I could easily have written that paragraph (except for the bit about starting a spreadsheet!)

I haven't had the time (/nerve!) to do the final calcs yet, but we're in a suburban area on the Surrey/Hampshire borders, and I'd say our house came out at between £1500 and £1600 per m2, excluding landscaping. That was with an MBC foundation and frame, and us managing follow-on trades (mostly using local tradespeople). Oh, and that includes the cost of an attached double garage and workshop/store, which I haven't factored into the floor area when doing the calcs The kitchen was from a local supplier, based on Crown carcasses (they use Blum hardware). We have 2 ensuites and a family bathroom upstairs, polished concrete floors throughout downstairs, MVHR and an ASHP. The MVHR was installed by us, and the ASHP was installed by us with the help of a very handy electrician. Most everything else was done by tradespeople rather than us. Windows and doors are high quality German triple glazed. Looking back now, there are areas we could definitely have cut some costs with better knowledge of the process, but overall I don't know that we'd have come in much below £1500/m2 unless we drastically changed the spec. I also have no idea what our VAT rebate will look like. The numbers above assume that will be zero, but I suspect it could reduce the cost by a few quid per m2.

An anecdote is not evidence, but my regular bouts of sinusitis stopped dead the moment we moved into the new house (which is 0.6ACH airtight with MVHR). I'd had 2-5 attacks a year for the last 10-15 years, but haven't had a single one since moving into the new house a year ago.

In a way, this sounds to be less an air exchange rate problem, and more an issue of internal air paths. I guess the paths are too difficult to model (especially given the different ways in which people use houses) so the simplest solution is to increase ventilation rates.

This is in houses to current regs without MVHR though. When most of us talk about "beyond regs" levels of airtightness, we're generally talking about implementing MVHR at the same time. I assume the main concerns with moisture are the interstitial kind, rather than the "black patch in the corner" that you sometimes get on external walls of poorly insulated houses?

Genuine questions: are these "leading experts" all unbiased researchers without links to large builders? Do you believe that the sole or dominant reason for stopping here is that independent experts have concerns? And while the rules may in theory be strict, do you believe that when a developer builds 10 or 100 or 1000 houses, all of them are built to fully meet the regs?

That may well be the case, but the story Jeremy relayed was that the surveyor specifically told him that "eco" houses, such as Passivhaus standard houses, were worth 10% less because the eco angle put people off. Nothing about the construction method (although that may have framed - pardon the pun - the surveyor's thinking). I tried to find the thread over on ebuild, but it's tough given he had nearly 11,500 posts!

I'd love to hear more about this. What little I've been able to find in the past suggested that UK regs ventilation rates actually resulted in too much air exchange, leading to unduly low levels of moisture during dry winter months.

I agree completely. I treat PH certification as being something like very modern design. It may well put off a lot of people, but it's just as likely to spark greater interest in at least some of those who aren't put off. Whether that impacts the final price is probably very situation dependent.