jack

Banging tune! Video's not bad either

10%? It's worse than I remembered! Given that there's very little chance of overheating for most of the year, this suggests that maybe 20-50% of the days in the hottest part of summer will result in temps above 25 degrees. I don't think that's acceptable at all. One thing I do wish we'd factored in is insect screens, at least in bedroom windows. That way we could leave them open all night in summer to maximise purging of hot air without letting mosquitoes in.

It's been ages since I looked at this, but from memory one of the sheets has an overheating factor, which is the amount of time (as a percentage of days? Not sure) the house will be above a target temp. You can set that temperature as well. From memory, the default setting aren't very conservative - something like 24 or 25 degrees for 5% of the days each year. That's actually quite hot in a Passivhaus, and quite a lot of days. I seem to recall reading that you should reduce the temp setting and do what you need to do to bring the 5% down to 1-2%.

We did the same, although bear in mind that they only come in one or two standard sizes. If you have a higher than usual first floor you may need to make some sort of extension.

Hey, size isn't everything.

I think it's fair to say that this thread has been a lively experience for all. To summarise: 1. Bit of an impasse reached on the "Passivhaus (and current airtight + MVHR approach in particular) = problems" question. Personally I'd like to see some real hard data one way or the other. All of the research I read before making my own decision was very positive, but we do have a different winter climate in the UK compared to that in the countries where most of the research was done. 2. Planning is a bit of a mess and most people would like to see some changes one way or the other. If people want to continue the planning conversation, may I suggest that they start a new topic in the relevant area? If anyone thinks there's still useful discussion to be had on the Passivhaus air quality question given where we got to in this thread, I suggest starting a new topic with a new focus. I can link this thread to it if that happens, so the information remains linked.

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.