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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://aecb.net/wp-content/plugins/aecb-publication-library/librarian.php?id=8132&file=8098
              https://aecb.net/forum/index.php?action=dlattach;topic=1463.0;attach=257
              https://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: Re: Re: Performance Monitoring Equipment #39073
                      Mark Siddall
                      Participant

                        Mark
                        This response may be alittle late now…

                        What is it that you want to monitor? Determining the brief is the first step. Energy use, temperature, humidity? Average of the building or specific to rooms etc.? What is your budget?

                        For a limited budget you may look at:
                        http://www.geminidataloggers.com/data-loggers

                        For the works you may look at:
                        http://www.eltekdataloggers.co.uk/

                        in reply to: Re: Re: PHPP sensitivity to air tightness #39060
                        Mark Siddall
                        Participant

                          In a small building (house) 0.6 ach@50pa is similar to 0.6 m/h@50pa. I'm aware of Canadian (De Leonardo) and German (PHI/Fiest) studies that remark upon the importance of airtightness with regard to protecting against moisture damage by achieving good airtightness (circa 0.6 m/h@50pa.)Tthese are the only papers that I've come across the put numbers against max. desirable level of exfiltration. I've come across some Canadian papers from 30 or so years ago that describe the problem but don't define a performance requirement (see http://archive.nrc-cnrc.gc.ca/obj/irc/doc/pubs/bpn/54_e.pdf)

                          Tom,
                          Please could you provide a link to Fraunhoffer info that you have (assuming that they are online resources.)

                          Mark

                          in reply to: Re: Re: PHPP sensitivity to air tightness #39055
                          Mark Siddall
                          Participant

                            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.

                            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.

                                Viewing 15 posts - 1 through 15 (of 915 total)