Green Building Forum - What is the lowest airtightness test result achieved in the UK to date ? Fri, 07 Aug 2026 19:40:00 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=89826#Comment_89826 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=89826#Comment_89826 Mon, 20 Sep 2010 19:42:04 +0100 Paul in Montreal
http://www.icynene.ie/pdf/Super_E_article.pdf

"In the first house completed in
Rosslare, blower-door tests returned an
astonishing air-tightness result of 0.29
air changes per hour at 50 Pascals – less
than half of the requirement for a certified
passive houses."

Paul in Montreal.]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90254#Comment_90254 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90254#Comment_90254 Fri, 24 Sep 2010 23:41:18 +0100 sinnerboy
" A new timber framed house in the Wicklow mountains could lay claim to being the most airtight building in Ireland. The latest blower door test on Jeremy Rynhart's house produced an air changes per hour (ACH) figure of 0.15 and an air permeability figure of of 0.19m3/hr/m2 "]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90349#Comment_90349 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90349#Comment_90349 Mon, 27 Sep 2010 08:52:45 +0100 jules
I guess if all but one wall of your house is buried, it makes airtightness less difficult to achieve!]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90352#Comment_90352 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90352#Comment_90352 Mon, 27 Sep 2010 09:09:29 +0100 tony What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90355#Comment_90355 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90355#Comment_90355 Mon, 27 Sep 2010 09:23:47 +0100 James Norton
J]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90365#Comment_90365 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90365#Comment_90365 Mon, 27 Sep 2010 10:08:43 +0100 Canute What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90383#Comment_90383 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90383#Comment_90383 Mon, 27 Sep 2010 11:58:48 +0100 MarkBennett Posted By: julesI'm surprised there hasn't been a thread on it unless I've missed it, but Grand Designs last week featured an underground passivhaus in the Cotswolds, and they showed the airtightness being measured at 0.24 ACH/hr IIRC, which the testers said was the lowest they'd ever recorded (they said that building regs require 10 ACH/he, and Passivhaus requires 0.6).

I guess if all but one wall of your house is buried, it makes airtightness less difficult to achieve!

I visited the house yesterday, and final figure they achieved was slightly better at 0.22AC/h, but still not quite so good as the best being described here. Given that it is an L-shaped building with lots of glass it's probably a pretty good result.]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90388#Comment_90388 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90388#Comment_90388 Mon, 27 Sep 2010 12:10:31 +0100 MarkBennett Posted By: CanuteAnd wasn't that Grand Designer so very pleased with herself. I wonder how Ben Law's house scores. I know which one I'd rather live in.

Helen is rightly proud. They have achieved something that is very impressive on just about all counts from planning through to implementation, one of only a very few (10 I think nationally ever) country houses built under special planning rules due to the outstanding architecture, and the first English certified PassivHaus. If an architect isn't allowed to be proud of that then I don't know what they could be proud of.

BTW, Helen is an occasional visitor and participant in this forum.

The two are very different. The AI PassivHaus is a very nice building, even if the industrial styling don't float your boat. The site is beautiful, even after the house was built, and I think it would be a great place to live. Personally, I would have done things differently for the room layout, but what they have works.

The Ben Law house is also fantastic, but is about as diametrically opposed to the AI PassivHaus as it's possible to get. You say tomato and I say tomato.]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90390#Comment_90390 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90390#Comment_90390 Mon, 27 Sep 2010 12:20:45 +0100 tony What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90392#Comment_90392 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90392#Comment_90392 Mon, 27 Sep 2010 12:34:37 +0100 StuartB
BTW - here is a link to the guys that certified it.

http://www.sphc.co.uk/]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90395#Comment_90395 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90395#Comment_90395 Mon, 27 Sep 2010 13:10:59 +0100 MarkBennett Posted By: tonyI wasnt so happy with the above ground office bit which will have HUGE heat losses and energy requirements.

The above ground building was thermally isolated and is completely separate from the main house. They hope to renovate it to close to PassivHaus standards, but it clearly won't be as good.

I think they were pretty disappointed that the planners wouldn't let them knock it down and rebuild it in a more energy efficient manner. Apparently the barn wasn't considered worth saving and had been left to fall into ruin until the planning application was made and then it's preservation suddenly became critical.

I'm convinced that they will do the best they can with the building that is there.]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90397#Comment_90397 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90397#Comment_90397 Mon, 27 Sep 2010 13:12:48 +0100 MarkBennett Posted By: StuartBDoes anyone know what solar set up was used on the roof of the office building? Looked like lengths of rubber tubes covered with glass tiles. Home made or off the shelf?


Off the shelf - http://www.solexenergy.co.uk/

Approximately 40m2 combined with a 1000l Tisun Pro-Clean stratified thermal store.]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90402#Comment_90402 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90402#Comment_90402 Mon, 27 Sep 2010 13:28:28 +0100 Canute
Sorry if my remark seemed a bit pointy. I wasn't impugning Helen's professional integrity; within its context her house is magnificent and I'm sure very comfortable and inexpensive to run - her pride justifiable.

But while watching I was thinking : how many Ben Law-type houses could you build for that budget? How would the cradle-to-grave eco figures compare? What would someone in a cinderella profession trying to create a green family home on a tight budget be thinking?

Just because we can doesn't necessarily mean we should...

Canute]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90408#Comment_90408 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90408#Comment_90408 Mon, 27 Sep 2010 13:41:35 +0100 JTGreen
How many Victorian terrace houses, surburban semis or 1980s Barrett homes could be retrofitted for this budget? A lot - I don't think it would make particularly good telly though.]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90428#Comment_90428 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90428#Comment_90428 Mon, 27 Sep 2010 15:29:49 +0100 James Norton
J

:devil:]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90430#Comment_90430 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90430#Comment_90430 Mon, 27 Sep 2010 15:40:46 +0100 MarkBennett Posted By: CanuteBut while watching I was thinking : how many Ben Law-type houses could you build for that budget? How would the cradle-to-grave eco figures compare? What would someone in a cinderella profession trying to create a green family home on a tight budget be thinking?

Obviously, I'm sure this building would be fantasy for most/many people, especially those on lower incomes. By building these kind of exemplar projects (AI PassivHaus, Denby Dale etc.) we help to develop the knowledge and skills in the UK. It will take time.

I'm convinced that low energy houses (maybe not PassivHaus, but certainly better than most mainstream builders) are possible on a reasonable budget if it is important enough to the creator. It does require a bit of a mind-shift from traditional building approaches and house appearances to maximise the floor area to thermal envelope area etc. but I think that it can be done.

I suspect that the AI PassivHaus will have a long lifetime and that the total cradle to grave eco figures, including the running energy, amortized over the life of the building will not be too bad. Most of the materials used contained a relatively high proportion of secondary and recycled materials, but of course still included concrete.

Timber frame would probably be better still, but for basements and underground houses there is little realistic choice - at present at least. Of course, we then get into the discussion about thermal mass and the ability of a lightweight structure to capture and store passive solar gain without overheating.

Posted By: CanuteJust because we can doesn't necessarily mean we should...

Canute


And because the poorest can't it doesn't necessarily mean we shouldn't? (flippant response.)]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90433#Comment_90433 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90433#Comment_90433 Mon, 27 Sep 2010 15:51:37 +0100 jules
Of course this house is not realistic for 99.9% of the population, but nor were the Apollo moon landings, and yet many everyday things ultimately derived from those. It's easy to be judgemental, but I think that it's more productive to make use of this test case, and to learn from some of the things they did and how they did them.

Anyway, apologies for starting the hijacking of this thread. Maybe we need a separate one...]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90447#Comment_90447 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90447#Comment_90447 Mon, 27 Sep 2010 18:51:13 +0100 sinnerboy Posted By: James NortonWhat is the actual performance effect of going from 1 to 0 Ac/H @ 50Pa...? (Say for a 180sqm family house...).

J

House in Manhcester

Floor Area Volume n50 cAir Gt
m2 Avg Height m³ 1/h Wh/(m³K) kKh/a kWh/a Fuel Cost Annual cost
180 2.5 450 * 1.000 * 0.15 0.33 * 79.968 = 1781 £0.07 £124.69

180 2.5 450 * 0.900 * 0.15 0.33 * 79.968 = 1603 £0.07 £112.22

180 2.5 450 * 0.800 * 0.15 0.33 * 79.968 = 1425 £0.07 £99.75

180 2.5 450 * 0.700 * 0.15 0.33 * 79.968 = 1247 £0.07 £87.28

180 2.5 450 * 0.600 * 0.15 0.33 * 79.968 = 1069 £0.07 £74.81

180 2.5 450 * 0.500 * 0.15 0.33 * 79.968 = 891 £0.07 £62.35

180 2.5 450 * 0.400 * 0.15 0.33 * 79.968 = 713 £0.07 £49.88

180 2.5 450 * 0.300 * 0.15 0.33 * 79.968 = 534 £0.07 £37.41

180 2.5 450 * 0.200 * 0.15 0.33 * 79.968 = 356 £0.07 £24.94

180 2.5 450 * 0.100 * 0.15 0.33 * 79.968 = 178 £0.07 £12.47

180 2.5 450 * 0.000 * 0.15 0.33 * 79.968 = 0 £0.07 £0.00

Posted By: James NortonDid anyone watch X factor last night...?

J

>


Never miss it . We want the Tesco lady to win round here :wink:]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90464#Comment_90464 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90464#Comment_90464 Mon, 27 Sep 2010 21:12:13 +0100 James Norton
...but isn't that only £112 if your house was pressurised at 50Pa all year...?

J]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90466#Comment_90466 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90466#Comment_90466 Mon, 27 Sep 2010 21:17:34 +0100 James Norton http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=4872&page=1#Item_25]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90467#Comment_90467 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90467#Comment_90467 Mon, 27 Sep 2010 21:17:55 +0100 James Norton Posted By: sinnerboyQ50 test result / 20 = ac hour at normal pressure is a reasonable rule of thumb

So a saving of 60p...? or is the 50 Pa to 'normal' already accounted for..?

(or, more likley I'm missing something very obvious and should shut up....?)

J]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90469#Comment_90469 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90469#Comment_90469 Mon, 27 Sep 2010 21:26:12 +0100 Paul in Montreal Posted By: James NortonSo a saving of 60p...? or is the 50 Pa to 'normal' already accounted for..?

(or, more likley I'm missing something very obvious and should shut up....?)


The airtightness figures are quoted at 50Pa, but the cost savings are at normal pressure. If you like, divide the airtightness figures by 20, but keep the cost savings the same.

Paul in Montreal.]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90482#Comment_90482 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90482#Comment_90482 Tue, 28 Sep 2010 07:07:01 +0100 James Norton
But surely only during the heating season...?

J]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90488#Comment_90488 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90488#Comment_90488 Tue, 28 Sep 2010 09:19:42 +0100 sinnerboy
building volume multiplied by
air loss* multiplied by
the specific heat capacity of air multiplied by
heating degree days

The aim is to provide 24/7 365 days of constant indoor temp of 20 degrees - no "heating season" as I think you mean it James .

The n50 test result feeds into air loss* . It is multiplied by several factors including an adjustment back to normal atmospheric pressure and also an adjustment is made to take account of losses due to the HRV system falling short of 100% efficiency and also an adjustment factor comprised of the calculation volume vs the actual volume of the building . This will vary from building to building** ( I have no intention of expanding on this by the way I will prevail upon you to take my word for all this )

The table of values I posted earlier ( which was nicely formatted in Excell - bit of a mess here , sorry about that ) includes the adjustment factor 0.15 **. I used this factor here after spot checking a couple of PHPP calcs .

So the example I posted is real-ish .

The true significance of this PHPP calculation method is not actually to €/£ cost the effect on the annualised heat demand . It is to determine the heat load . If you don't get that at or below 10w/m2 you can't deliver heat via the HRV system alone because you will overheat the air reducing the relative humidity to unhealthy and uncomfortable levels .

PH is not just about thermal cost efficiency . It the very heart of it is thermal comfort and occupancy health .

So I applaud Helen most warmly . Those who "go for" PH in a half arsed way and produce stuffy and uncomfortable buildings will discredit the process unfairly . I have spoken to some people here ( Ireland ) who have experienced such buildings which has put them off PH .

One visit to a REAL PH will not do this .....]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90490#Comment_90490 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90490#Comment_90490 Tue, 28 Sep 2010 09:21:03 +0100 RobinB cheers
RobinB]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90492#Comment_90492 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90492#Comment_90492 Tue, 28 Sep 2010 09:23:28 +0100 sinnerboy

....answers on a postcard please :bigsmile:]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90498#Comment_90498 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90498#Comment_90498 Tue, 28 Sep 2010 09:55:27 +0100 RobinB What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90499#Comment_90499 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=90499#Comment_90499 Tue, 28 Sep 2010 10:31:21 +0100 James Norton
Thanks.

:bigsmile:

J]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=92254#Comment_92254 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=92254#Comment_92254 Thu, 21 Oct 2010 00:58:20 +0100 sinnerboy

http://www.constructireland.ie/Vol-5-Issue-2/Articles/Insulation/Irelands-most-airtight-house-This-West-Cork-stick-build-timber-frame-eco-home-will-be-hard-to-beat.html]]> What is the lowest airtightness test result achieved in the UK to date ? https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=273507#Comment_273507 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1198&Focus=273507#Comment_273507 Sat, 27 Apr 2019 14:12:52 +0100 wookey
Info from latest issue of passivehouse+]]>