jack

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.

I don't think there is any, at least relating directly to PH certification. I think there's just anecdotal evidence that some surveyors will downvalue anything holding itself out as an "eco" house. I believe Jeremy Harris had that experience. I seem to recall someone else saying that PV can reduce the value of a house even if it's still going to have a cashflow associated with it for the balance of the FiTs contract. Here's feature that could give a windfall of thousands of pounds over the next 20 years. How much value do such people place on that feature? Negative thousands of quid! Bizarre. I don't believe the word Passivhaus by itself is a trademark. From memory they only have a trademark on the logo. There may be a question over whether the word "Passivhaus" is confusingly similar to the logo. Even if it is a trademark, to infringe you'd have to be using it in the course of business. A private individual can therefore describe their house as being of "Passivhaus standard" or "designed using Passivhaus principles", because that description isn't in the course of business. A developer, on the other hand, can't use such a descriptor when selling their houses unless they meet the standard AND have the certificate from the PH institute. The latter would effectively be a license to use the trademark. Irrespective of the TM position, you may be committing fraud if you're holding out that your house meets a standard when it doesn't (edited to add:) and you get some sort of financial gain from that assertion. Incidentally, the PH Institut had a big falling out with their US branch a couple of years ago. From memory the US branch ended up getting the rights to their US trademarks. It was all pretty nasty!

We did the same a couple of years ago. Adam and his family are lovely, and he's extremely knowledgeable (having co-written the Passivhaus Handbook). Worth the cost of staying just to pump him for info! I wonder whether we need to agree on what you mean by "Passivhaus". As you know, technically it's a (very!) detailed standard that a house can be built to meet. Everyone talks about airtightness and insulation, but there's a lot more to it than that if you want to go for certification. It sounds like what actually concerns you is a house having high levels of airtightness and insulation. On airtightness, as others have said, there's absolutely nothing to stop you keeping your windows open whenever you want to. We've only this week started closing windows in our Passivhaus-level airtight house - we typically leave loads of windows open upstairs through the shoulder seasons, and only close them in summer once the temperature outside gets higher than what's inside. The thing is, building airtight gives you options. If we have an extremely cold, wet and windy period and you need to keep windows closed, then you'll still have great air quality. If we have a hot period, you can close everything up, leave your MVHR on summer bypass, and hopefully keep the internal temperature low relative to the heat outside. If you don't build airtight, you don't have these options. Regarding insulation, even a building insulated to current building regs will overheat if it isn't designed with proper regard for solar gain. Get it right and your house won't overheat. In our case, we have around 500mm overhangs on most southern and western windows. We have a 5m long, 2m high slider to the south that gets quite a bit of sun through the middle of the day, because we don't yet have any external shading in this area. We also have external blinds on most southern and all western windows. We had a few days over summer where it was warmer inside than I'd have liked it, especially upstairs, but I'm doubtful having less insulation would have made much difference to that. That article repeatedly refers to things like poor positioning of vents and poorly designed systems that make fan noise noticeable even on the basic setting. If your MVHR system is designed and installed properly, there's no way you should hear anything meaningful on the basic setting. You might hear it a bit on boost, but that would be the case with a regular extractor. Same with vent positioning and flow rates - these are within your control. If you don't want to build to PH standards, that's cool. I personally think they're a little over the top in terms of the energy requirement, in particular. But don't compromise your one opportunity to build a really comfortable house based on misconceptions like not being able to open windows if you want to, or that adding more insulation is what causes overheating. Edited to add: I now wouldn't live in a house with a dog unless we had MVHR. I'm very sensitive to smells, and our house has absolutely no dog smell about it, despite us having a very energetic springer who goes paddling in the local stream twice a day when we take her for a walk.

Safe word?

As long as "moderating" is not some sort of codeword you use on your, erm, private forum.

It's all down to what the network in your immediate vicinity can handle. Having other PV installations nearby can affect this. We applied for, and were granted, the right to install an 8.5kW array in an ordinary suburban area. Took longer than expected (something like 7 weeks instead of a month? Can't remember!), but was granted without comment.