Blackmore House

11 minutes ago, jack said:

 

 

To be fair, 0.58 is a stunning result by any other measure - something like 10 times better than building regs requires. We managed 0.56, so only slightly better than you. The big slider in our kitchen seems to be the worst single contributor, and unfortunately it isn't adjustable.

 

You may be able to get some improvements by adjusting the windows so they pull in a little more tightly. We've done that as best we can, but a couple of windows just don't seem to be adjustable far enough to get a proper seal. We get definite air (and hence sound) leaks in those rooms. 

yes I dont have an issue with .58 happy enough just saying it pales a bit in comparison.

 

B windows are and were a debacle.  I am told all adjusted to properly now.  Very frustrating to have lovely windows ruined by cowboys who installed them and to get the leaks and cold spots after all the efforts.....I have a roll of the stick on sponge draught excluder from old house ( hardwood double glazed and leaky) if it was grey not brown might try sticking it on the Internorms LOL.  Will ask man sorting threshold problems if he thinks any more adjustment possible, thanks for the tip.

14 minutes ago, lizzie said:

windows are and were a debacle.  

 

We had cowboys too - not as bad as yours, for sure, but it's frustrating to pay good money for quality windows, only to have a poor result due to crappy installation.

1 hour ago, JSHarris said:

Depends on the volume. 

 

By comparison, our 0.48 ACH figure equatd to 0.652 m³/m²/h.

11 hours ago, lizzie said:

Mine came in at 0.58 so although within the MBC contracted limit of 6 and I’m fine with that it seems poor by comparison to others here. I suspect that the finished house is nowhere near 0.58 because it was very air (and water)  leaky for the test with windows not fitted properly etc (everything was just temp taped over by the air testers and I was told by the testers it needed to be properly sorted) the issues were never properly resolved afterwards and I have seriously cold areas around the window/wall junctions. The areas around the tilt and turn windows in the rendered walls seem worse than the sliders on the clad walls. I have areas in some rooms that feel colder to sit in if nearer windows/walls and I have altered positions of furniture to take account of these cold spots.

 

 

The 0.6 ACH is the PassivHaus Institut target figure, so anything under 0.6 ACH would get a tick in the box for air tightness as a certified PassivHaus, and there aren't many of those around in the UK (not sure, but I think the number is in the low hundreds in total, out of the thousands of new builds every year).

 

0.58 ACH is a damned good result, and as others have said probably 1/10th of the allowable leakage for a "normal" new build.  Given that mass housebuilders often really, really struggle to get airtightness that's around 10 times worse than yours, I'd be as chuffed as anything to get that figure.

 

In practice, I doubt that there would be any impact on overall practical, real world, thermal performance or comfort issues for any airtightness figure below about 0.6 ACH.

11 hours ago, HerbJ said:

By comparison, our 0.48 ACH figure equatd to 0.652 m³/m²/h.

 

To illustrate the impact of volume and floor area, we had a nearly identical permeability number to yours Herb (0.66 m³/m²/h), but the air change value was 0.56 ACH.

28 minutes ago, JSHarris said:

 

 

The 0.6 ACH is the PassivHaus Institut target figure, so anything under 0.6 ACH would get a tick in the box for air tightness as a certified PassivHaus, and there aren't many of those around in the UK (not sure, but I think the number is in the low hundreds in total, out of the thousands of new builds every year).

 

0.58 ACH is a damned good result, and as others have said probably 1/10th of the allowable leakage for a "normal" new build.  Given that mass housebuilders often really, really struggle to get airtightness that's around 10 times worse than yours, I'd be as chuffed as anything to get that figure.

 

In practice, I doubt that there would be any impact on overall practical, real world, thermal performance or comfort issues for any airtightness figure below about 0.6 ACH.

As I said I am fine with that as a result.  

 

My point is that it was the result on the day but I doubt it would achieve that again as the many leaky areas that were taped temporarily for the test were not properly dealt with afterwards.  My windows being the main problem, I definitely have cold spots and areas of rooms colder than others, you need a blanket to sit in one armchair that is next to a window. My bedroom is really cold and one side of our open plan area is very chilly. I have to have UFH cranked right up in those rooms.

 

If I knew then what I know now (thank you all) then the problem areas shown up at test time would have been properly dealt with but I didn't know and the people who were supposed to either didnt know or didnt care. Its too late now and its a lesson for those like me who in hindsight should have educated themselves more and not devolved responsibility.....I took the dog and bark yourself approach which now has been shown to be a big mistake. I blame no one but myself.

1 hour ago, jack said:

 

To illustrate the impact of volume and floor area, we had a nearly identical permeability number to yours Herb (0.66 m³/m²/h), but the air change value was 0.56 ACH.

I have looked at mine and it reads

 

Permeability at 50Pa (M3/h/M2) 0.479.

Air change is 0.58

Building volume is 474 with a floor area of 189.1 and an envelope area of 570.1

 

My house is single storey and quite a bit smaller than others.

Edited November 22, 2018 by lizzie

7 hours ago, JSHarris said:

In practice, I doubt that there would be any impact on overall practical, real world, thermal performance or comfort issues for any airtightness figure below about 0.6 ACH.

 

Five years ago a friend had an air tightness result of 0.9ACH and she was disappointed because she had put so much effort into taping etc. The house was very comfortable with no cold spots or draughts. To help her I ran the PHPP to see what the effect of different air tightness values would be on the space heating demand. Results below. I asked on the AECB forum why the PHI had set the maximum value at 0.6ACH and had an answer from Mark Siddall shown below. So until you get to relatively quite high air tightness values, space heating demand is not affected greatly. Of course the PHPP has been designed to work at the low end of air tightness.

 

Pressurisation Test Result ACH     Specific Space Heating Demand kWh/(m2.a)
               0.2                                                        12.1
               0.4                                                        12.3
               0.6                                                        12.5
               0.8                                                        12.7
               1.0                                                        12.9
               2.0                                                        14.0

A 2pa pressure difference (what you get over 2 a storey building) would mean that assuming a 1m long, 1mm wide gap would permit about 360g of water vapour to be transported through the gap in 1 day. On the basis of the internal temp being 20C/50%RH and ext. temp of 0C/80%RH then you can expect this moisture to hit the dew point as it passes through the insulation.
The air tightness threshold is 0.6 so as to protect structure from moisture damage.