Wed, 22 Apr 2026 10:34:51 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274612#Comment_274612 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274612#Comment_274612 Thu, 18 Jul 2019 18:57:09 +0100 nigel
Its in an area where house prices are not particularly high but I would like to build a couple of houses to Passiv Haus standards but I am concerned that it will be uneconomic.

Does anyone have an idea of what a typical premium there would be to build to that standard over and above the building regs requirements.
I know building costs vary geographically and I would say build costs in this area are about average.

Thanks]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274615#Comment_274615 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274615#Comment_274615 Thu, 18 Jul 2019 19:43:04 +0100 djh Posted By: nigelDoes anyone have an idea of what a typical premium there would be to build to that standard over and above the building regs requirements.
Some people say it can be done for the same cost. That seems very unlikely to me, but I don't really know.

The main additional costs IIRC are: (1) doors & windows to PH spec. (2) insulation ditto. (3) MVHR & airtightness

The costs can be minimised by (0) choosing a simple building shape, (1) buying European triple-glazed units, ideally in quantity, or maybe from Munster or Russell (2) building in block and using EPS EWI, (3) Use the internal plaster as the airtightness layer.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274616#Comment_274616 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274616#Comment_274616 Thu, 18 Jul 2019 19:58:19 +0100 gravelld https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274617#Comment_274617 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274617#Comment_274617 Thu, 18 Jul 2019 20:15:12 +0100 Nick Parsons https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274619#Comment_274619 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274619#Comment_274619 Thu, 18 Jul 2019 22:01:32 +0100 nigel
I presume it’s possible to build in block and insulate externally otherwise block cavity and render.

Do windows have to ph certified or just to ph specs?

I have access to triple glazed European windows but they are not ph certified.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274624#Comment_274624 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274624#Comment_274624 Thu, 18 Jul 2019 22:43:51 +0100 djh
Whether the windows have to be certified depends on whether you're going to get the houses certified, and how much aggro you want. Certification is easy with certified components; more difficult without. It's also more difficult to trust any window manufacturer's statements that aren't on a bit of PHI paper in my experience. They'll spin and twist anything they can.

edit: FWIW, I'm in favour of certification. It's the best way to prove that it really is built to passiv standards, and it concentrates builders' minds.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274628#Comment_274628 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274628#Comment_274628 Fri, 19 Jul 2019 06:18:08 +0100 tony
My house sits way below PH energy use, not certified, no heating system, repair or maintenance costs etc

Do you need certification?

Are you costing only the build or the ongoing costs too?

Cheapest simplest approach is solid blocks with 200 or 300 EWI and any cladding you like.

They always used to say 10% extra for PH but Exeter City Council now do it for the same cost but get a far superior product and it looks like Norwich are following:-

https://www.theguardian.com/artanddesign/2019/jul/16/norwich-goldsmith-street-social-housing-green-design]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274630#Comment_274630 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274630#Comment_274630 Fri, 19 Jul 2019 07:50:27 +0100 nigel
I would prefer to spend the cost of certification on the build as I understand it can be quite expensive.
Maybe add PV instead.

Looks like the way to go is solid block and EWI, with some other cladding as well to break up the render.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274631#Comment_274631 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274631#Comment_274631 Fri, 19 Jul 2019 08:21:51 +0100 Peter_in_Hungary Posted By: nigelLooks like the way to go is solid block and EWI, with some other cladding as well to break up the render.
+1 for block and EWI

What they do here to break up the appearance of the render is to add 20mm extra EPS about 150mm wide around the windows (fixed to the base EPS with the same adhesive) to stand out as a relief and when the final colour render coat is applied the relief is done in a contrast colour, typically a pastel shade for the main part and white for the relief.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274633#Comment_274633 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274633#Comment_274633 Fri, 19 Jul 2019 09:15:58 +0100 nigel
I have no idea.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274637#Comment_274637 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274637#Comment_274637 Fri, 19 Jul 2019 10:28:00 +0100 fostertom
tony mentions Exeter City Council, which have adopted PH v widely incl currently for giant leisure centre under construction. Some years ago they gave £1400/m2 cost for small mixed PH social housing projects - typically say 12 units, mixture of terraces and flats, saying that was same cost as 'mere' Bldg Regs standard at the time. But that cost would be with advantages of scale - a larger project than yours - but possibly also by same token additional complications.

If you're developing for sale, you might get a premium for Passive House, but I'd have thought you'd need the Certification to support that. In a build for a private/user client, Certification is a cost that can be saved. Or indeed full-PH standard itself - a super-decent job can be done without going all the way.

On construction, a lot depends on the Planning requirement for external finish. It looks like in your case render finish is OK? That leaves all methods open. Advice here seems to be single skin blockwork EWI'd, but I'd have thought that a pair of simple-shape semis would be ideal for prefabricated timber frame. If it's good enough for the big housebuilders .... Denby Dale was driven by the Planning requirement for natural rubble stone finish.

Single skin blockwork - Building Regs deemed-to-satisfy is 190mm thick, which means 215 blocks laid-flat in practice. That is far more than necessary - get a Structural Engineer to design it, can be mostly 140, even 100 blockwork.

For small PH, the EWI will be at least 300 thick. That gives you walls nearly 600 thick overall with the blockwork solution, but only 400ish thick with timber frame, as the frame's thickness is useful insulation. On a tight site, thick walls may mean less internal floor space, and/or increase the effective 'footprint' for £/m2 calculation.

With blockwork you'll likely be driven more to conventional trenched foundations, though can be done with PH-preferred 'floating' slab solution. With timber frame the latter is the way to go.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274638#Comment_274638 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274638#Comment_274638 Fri, 19 Jul 2019 10:48:18 +0100 Doubting_Thomas Posted By: nigelAnyone any idea of ballpark cost of certification.

I have no idea.

I would budget £3-4k for the certification route if it's your first time. Most certifiers will offer consultation services as part of that sum and I'd say that part has been most useful for us. Let me know if you want details of who we used.

The actual certification part is probably only about £1k of that, so if you went with a one-stop-shop passivhaus architect or other consultant then they may include the rest in their design fees anyway.

When you look at all the other things you pay for on a house build/purchase, it really isn't that much extra.

I really hate render on our grey-skied shores, so went with timber cladding instead. Bear in mind this (or any other rainscreen) will be a deeper build than a render coat though, so each time you switch cladding you'll likely have some form of drip detail or flashing.

It's now a few years old but I recommend the Dadeby's book 'The Passivhaus Handbook' as a really good introduction to the whole thing. Most other books tend to be either too technical and specific or very vague at the other extreme. That said, the Passivhaus Trust have put together a handy 'rules of thumb' pdf that you can download too.

Good luck!]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274639#Comment_274639 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274639#Comment_274639 Fri, 19 Jul 2019 10:58:18 +0100 nigel Will order book and have contacts with PH designers and a very sound structural engineer who has worked on a lot low energy housing.

I am not a big fan of render but if its used sensitively and broken up it can be done. As these are going to be small properties then it isn't such a slab effect.
I have considered TF but access isn't great so a crane may be out of the question and there are boundaries so too much timber cladding will fall foul of fire regulations.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274642#Comment_274642 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274642#Comment_274642 Fri, 19 Jul 2019 12:05:29 +0100 fostertom
Any cladding other than render or brick slip direct on the EPS or whatever, will have weight and outboard depth (incl ventlated cavity) which can't simply be supported by horizontal fixings/screws through thick EPS, relying on their bending strength and/or friction to prevent all from gradually sliding downward.

The cladding needs vertical support, either by hanging from strong projecting rafter ends or similar, or by support from below, which implies something solid at or below GL, thus an outboard foundation line - just when you've managed to greatly reduce the floor/founds footprint by putting all other loadbearing on the inner skin.

'Wallpaper' needs to be light and thin!]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274643#Comment_274643 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274643#Comment_274643 Fri, 19 Jul 2019 12:20:58 +0100 djh Posted By: tony
https://www.theguardian.com/artanddesign/2019/jul/16/norwich-goldsmith-street-social-housing-green-design

Thanks for that link, Tony. I hadn't come across that project before and it looks very good. There's one bit in the story that seems odd to me:

"Passivhaus means windows have to be raised up around half a metre from the ground"

Anybody know what that is all about? (speaking as somebody with windows to the floor in a passivhaus)

And yes, central government policy about council housing is a big mess.

There's another article at https://www.architecture.com/awards-and-competitions-landing-page/awards/riba-regional-awards/riba-east-award-winners/2019/goldsmith-street that has more detail. It mentions the main contractor was RG Carter, who IIRC were involved with North Kesteven's straw bale houses.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274644#Comment_274644 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274644#Comment_274644 Fri, 19 Jul 2019 12:49:35 +0100 djh
The picture below shows our render. The grey boxes around the windows are just sculpted in the lime render to give a different height, texture and colour. The line around at first floor height is purely decorative and is just render supported on some extra bits of woodwool board. At the time the photo was taken, the render was finished with simple limewash, which gets that patchy colour effect when it's wet from rain. We've since painted it with Beeck silicate paint, which stays much the same colour whether wet or dry.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274646#Comment_274646 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274646#Comment_274646 Fri, 19 Jul 2019 13:30:03 +0100 fostertom https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274647#Comment_274647 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274647#Comment_274647 Fri, 19 Jul 2019 14:40:24 +0100 djh https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274648#Comment_274648 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274648#Comment_274648 Fri, 19 Jul 2019 14:50:59 +0100 fostertom https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274649#Comment_274649 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274649#Comment_274649 Fri, 19 Jul 2019 15:05:14 +0100 tony https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274655#Comment_274655 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274655#Comment_274655 Fri, 19 Jul 2019 17:27:13 +0100 djh
PS sorry if we've hijacked your topic a bit, Nigel :(]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274663#Comment_274663 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274663#Comment_274663 Fri, 19 Jul 2019 18:24:55 +0100 Doubting_Thomas Posted By: djh"Passivhaus means windows have to be raised up around half a metre from the ground"

Anybody know what that is all about? (speaking as somebody with windows to the floor in a passivhaus)

We also have windows to the floor in places - namely patio doors.

However on the Carbonlite course they did point out that it's not 'useful' window area - basically the views and deep plan daylight generally come from the upper part of the window so the tops of windows should go as high up as possible and you should limit the sill heights to a desk top level wherever you can. Everything below that level is arguably extra solar gain in the summer and net heat loss in the winter from a PHPP viewpoint.

The other benefit is you get a nice window seat due to thick walls...]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274668#Comment_274668 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274668#Comment_274668 Fri, 19 Jul 2019 20:05:01 +0100 fostertom
My philosophy is to make construction method as easy as possible, geometry to minimise surface-to-floor area ratio, and other optimisations, thus saving costs - which can then be spent on the 'frills' and non-optimums which make life worthwhile!]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274670#Comment_274670 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274670#Comment_274670 Fri, 19 Jul 2019 20:45:38 +0100 djh Posted By: Doubting_ThomasHowever on the Carbonlite course they did point out that it's not 'useful' window area - basically the views and deep plan daylight generally come from the upper part of the window so the tops of windows should go as high up as possible and you should limit the sill heights to a desk top level wherever you can. Everything below that level is arguably extra solar gain in the summer and net heat loss in the winter from a PHPP viewpoint.
Ah, thanks, that explains the quote I suppose. So it's not a requirement, just an optimisation. In our case, the architect generally aligned the top edge of all the windows and varied the sill height according to requirements. And yes, the ones that go to the floor are doors.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274788#Comment_274788 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=274788#Comment_274788 Thu, 25 Jul 2019 09:30:16 +0100 Doubting_Thomas Posted By: djhSo it's not a requirement, just an optimisation.

Yes exactly that.

There is, of course, an exception to the rule. In as much as anything going all the way to the ground (and with a head height of 2m) can be counted in PHPP as extra floor area without increasing the envelope. So a way to increase the treated floor area ratio if you really need it (though they argue you shouldn't be grasping at those extra few sqm to meet the target anyway).

Depending on depth of walls, this can add a square metre or so in places. So doors are the best way to get low level glass to 'pay for itself', but this will be offset by the solar gain/heat loss mentioned above. Definitely avoid a sill of, say 150mm off FFL, as this would be the worst of both worlds.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=275022#Comment_275022 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=275022#Comment_275022 Sun, 11 Aug 2019 07:54:59 +0100 nigel
It would appear that most mainstream lenders consider the construction to be non standard if it doesn't have an external solid wall.

Wouldn't be an issue for em but if I am trying to sell these on the open market I don't want to be stuck if no one can get a mortgage.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=275025#Comment_275025 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=275025#Comment_275025 Sun, 11 Aug 2019 11:03:08 +0100 djh https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=275026#Comment_275026 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=275026#Comment_275026 Sun, 11 Aug 2019 12:32:26 +0100 tony https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=275027#Comment_275027 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=275027#Comment_275027 Sun, 11 Aug 2019 12:35:33 +0100 nigel
The problem being that most will only lend where external envelope is brick or block. To build in that will make the walls very thick.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=275029#Comment_275029 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16178&Focus=275029#Comment_275029 Sun, 11 Aug 2019 13:12:22 +0100 djh