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  • in reply to: Airtightness of concrete block walls #39250
    Mark Siddall
    Participant

    Adam,

    Two questions:
    1) What do you want to achieve?
    2) How does he define “good”?

    I hope the answer to 1 would agree with AECB Silver/Passivhaus standards. …If that's the case then the Project Manager's “good” solution is pretty much doomed to failure.

    However, if you are aiming for something that satisfies the Building Regulations then you may have a chance (it all depends upon what the 'paint' is).

    …What I can say is, without a great deal of research and investigation (including reviewing test results) I would not use or advise the use of this technique on any of my projects.

    Hope this helps,
    Mark

    in reply to: Airtightness of plaster #39239
    Mark Siddall
    Participant

    A polished finish as you describe it may offer some small improvements, but what I've read in research papers you'll get 99% of the way there simply using unfinished wet plaster.

    in reply to: Insulation cover to steel frames in roof #39234
    Mark Siddall
    Participant

    If your only goal is to address condensation risk then, yes. 90mm PIR will do the job.

    One additional thing to consider will be how the detailing prevents thermal bypass caused by any air gaps.

    in reply to: The use of a single room MVHR – are they any good? #39232
    Mark Siddall
    Participant

    For units so small you'll be challenged to achieve Passivhaus (do the PHPP to verify), nonetheless you could create a good super insulated cabin.

    The Lunos is an interesting option for small units. There are a growing number of suppliers. I've linked to one below:
    http://www.partel.co.uk/product-details.php?ID=242

    Noise ratings are fine. Though there is a risk of wind blow through undermining actual performance.

    Mark

    Mark Siddall
    Participant

    Hi Flo,

    This interface is a challenge for many retrofits.

    For one example of how this has been resolved see Andy Simmonds retrofit:
    http://www.passivhaustrust.org.uk/UserFiles/File/Projects/Awards2012/Grove%20Cottage_Simmond%20Mills.pdf
    https://www.aecb.net/wp-content/plugins/aecb-publication-library/librarian.php?id=8132&file=8098
    https://www.aecb.net/forum/index.php?action=dlattach;topic=1463.0;attach=257
    https://www.aecb.net/forum/index.php?action=dlattach;topic=1463.0;attach=258

    Foam could make the issue worse (traps moisture into timber as evaporation is prevented.)
    Consider treating the timber in order to help improve resistance to moisture damage.

    HTH
    Mark

    in reply to: Purge Ventilation in Basements #39216
    Mark Siddall
    Participant

    Hi Andy,

    Achieving the supply/extract volume you require is indeed onerous. Strictly speaking 'purge' ventilation relates to the winter condition and removing moisture/smells. For the summer you should also be able to address overheating.

    I would suggest that if you were trying to keep cool in the summer, but could not sleep due to fan noise, there would be a failing in the design.

    In this respect, if the building is to satisfy the Passivhaus Standard, then all criteria (noise etc.) must be met. …arguably the need to minimise noise should be met in all cases no matter what standard.

    Perhaps there is a common sense solution to the AD-F aspects of this question.

    May be the question needs to be “why do the rooms need purge vent rates?”

    …Cooling and/or fresh air?

    Can cooling be provided by another means? If so why do you need a purge vent rate?

    …Maybe due to moisture? As there is no bathroom (just bedroom and office) humidity/moisture loads are not onerous.

    in reply to: Enerphit ground floor insulation and temperatures #39169
    Mark Siddall
    Participant

    Hi Rachel,
    1) Use thermal bridging calcs to determine the surface temp at the junctions.

    2) You can model two types of perimeter insulation – you copy/clone the worksheet.

    HTH

    in reply to: PHPP – Opaque exterior door #39172
    Mark Siddall
    Participant

    You can use the thermal bridge inputs further down the worksheet.

    M

    in reply to: Foil Insulation in PHPP #39139
    Mark Siddall
    Participant

    Hi Kirsty,

    I recall that Dr Feist suggested considering that you'd need about 200mm of foil insulation before it actually achieves the required performance (and even then you'd need to think about thermal bridging at compression points, dulling of foil reflectance, etc.)

    …Basic idea: not a good idea.

    HTH,
    Mark

    in reply to: Passivhaus Design Question #38711
    Mark Siddall
    Participant

    Jean-Marc
    I fail to see how these case studies address your initial query to Nick. Furthermore, Nick's comments recognised that the reported “slow down” of heat loss arising from the use of thermal mass is an inappropriate, and incorrect, proposition.

    in reply to: Basements #39009
    Mark Siddall
    Participant

    Passivhaus Basements for German speakers: http://passiv.de/en/05_service/03_literature/030307_basements.htm

    Jean-Marc,
    No I don't know about the school. Sorry.
    (In my view zero carbon buildings is a fools game. Once energy efficiency has been maximised focus upon the efficiency of other valuable things instead – like transport and food. This is likely to be much more cost effective and have greater success at reducing environmental impact.)

    in reply to: Basements #39006
    Mark Siddall
    Participant

    An interesting summary of conventional basement design for the UK may be found here
    http://www.basements.org.uk/
    http://www.basements.org.uk/iimni/dlfiles/alan_tovey.pdf

    (Perhaps not the greatest resource for low energy detailing however.)

    Jean-Marc. Show me (and others) the data for IFC basements; case studies backed up with moisture and thermal measurements would be ideal. Thanks.

    in reply to: Passivhaus Mandatory Critera #39015
    Mark Siddall
    Participant

    Hi John,

    Dave is correct. Speak to your certifer. The main thing with the windows is to avoid the risk of thermal discomfort from down draft and low radiant temperatures. For this reason the internal surfanpce temperature of the window should not fall below 16.4C on the design day (-10C). Whilst the 0.8 W/m2K is a good marker, and in the eyes of PHI applies to the UK, there are arguments for relaxation in the U-value if you are, broadly speaking, “south of Manchester”.

    With regard to install: The position of the window within the wall (between int. and ext. surfaces) and the overlap of the insulation across the frame (where utilised) are key elements, as are the used of equivalent insulation types (cellulose, mineral wool, EPS, XPS etc). Again, firm this up with your certifier before this is set in stone.

    in reply to: Basements #39002
    Mark Siddall
    Participant

    Thanks to Nick Devlin for this link. (Some interesting scientific papers on basement design.)

    http://www.ibp.fraunhofer.de/en/Publications/contributions_to_conferences.html#tabpanel-2

    in reply to: Window installation Psi value in accordance to the PHI #38947
    Mark Siddall
    Participant

    Tom,I
    What is being discussed is not “PHPP” it is a convention for calculating thermal bridges. This information may then be entered into PHPP. The main thing is that consistent and clear points of reference are used so as to avoid error.

    Thanks for nitpicking though. Error now ammended.

Viewing 15 posts - 1 through 15 (of 584 total)