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General: PHPP queries

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  1.  
    • CommentAuthorwookey
    • CommentTimeApr 13th 2019 edited
     
    PHPP has a slot for an 'exterior door' (on the areas sheet). But a lot of buildings have more than one exterior door. It's not clear to me how to deal with the other one. What does one normally do about this; add a row there for a 2nd exterior door, and hope that ading a row doesn't bugger anything up (dangerous game in a spreadsheet this complicated).

    I can put it in the windows sheet (and this door is a UPVC, mostly-glazed door so modelling it as a window is generally just fine), except that it goes into an unheated, but internal, area so it's not in an exterior wall, which all the other windows are. Or at least it is an exterior wall for the purpose of PHPP, but the outside temp is 'X', not 'A'. So I've currently put the door into it's own area with tempzone 'X' (which there is a space for already in 'areas').

    This worked fine on PHPP 2007 (v1.0), but things have got more complicated by PHPP2015(v9.3) and entering an area element which is only in a group, but does not also refer to a selected item from the U-values sheet seems to be broken.

    This seems like a common-enough circumstance - how does one normally deal with a 2nd external door? In this case into a lobby-type area.

    I have more PHPP questions after messing with it for way too many hours, but this will do for now :-)
    •  
      CommentAuthordjh
    • CommentTimeApr 13th 2019 edited
     
    I thought I'd have a look at ours to see if I could help, but it's just left me more confused as well :(

    Ours is PHPP v7.1

    The Areas sheet has a row labelled Exterior Door in the summary. It also has another row with the same title in the Area Input section. That has user entry fields for Quantity, the various dimensions and the U-value. The quantity is 2, which confuses me since we have a front door to the outside, a side door to an unheated space called 'bin store' and another side door to the unheated sun room/conservatory. The wall between the house and conservatory is a special zone 'X'.

    The Windows sheet lists those three doors as well as our patio door. The conservatory door is assigned to the special X group and that has a reduction factor of 75% assigned in the Areas sheet. So I assume the 2 outside doors are the other two, which are assigned to group 8 'Exterior Wall - Ambient'. The X 'Ex. Wall to conservatory' group includes the wall areas between the house and conservatory, as well as the door.

    The wall that includes the door into the bin store is part of group 8. So I think the bin store is entirely disregarded for PHPP, despite obviously being a few degrees warmer than the real outside.

    So maybe I'm not so confused now. If your door goes to somewhere that is a separate temperature zone, then it's not external but it is part of the wall that surrounds it that effectively defines the temperature zone. Both that and the wall that includes the bin store door are referred to the 'straw bale walls' U-value item.

    Hope that makes some sense and helps.
    • CommentAuthorwookey
    • CommentTimeFeb 26th 2024
     
    I have a question about volume for airtightness sums

    I carefully calculated an area and volume for my house (using internal measurements), including fiddly bits like skeilings.
    I got Volume:214m3, Area:249m2
    My airtightness test said flow was 326m3/h. @50Pa
    So that gives 1.52 ach (and permeability of 1.35 m3/h/m2)

    Which is fine. I can put the 1.52ach into PHPP. (and get an Annual Heating Load of 32kWh/m2.y, which isn't quite 25, but it'll do.)

    However. PHPP has a different number for volume ('Net Air volume for Pressure test': 260m3) (Ventilation.$P27)
    It gets this by multiplying the treated floor area by a room height of 2.50m and then adding 10%.
    If I tell the airtightess chap this number then I get:
    326m3/h / 260m3 = 1.25 ach (and permeability become 1.04 m3/h/m2)
    And now my annual heating load is 24kWh/m2.y.

    So as you can see which number is used for the volume is quite significant. In one case I've achieved EnerPhit, in the other I haven't.
    The PHPP volume seems to be very arbitrary. The 2.50m height is wrong. My house has 2.41m downstairs and 2.30m upstrairs, but PHPP says 'Residential buildings: In order to better compare the different exchange rates in different dwellings please enter 2.50'. Using 2.5 does allow for the space between dowstairs ceiling and upstairs floor, but it's still an overestimate.

    And then there is the 'times 1.1' to just arbitrarily add 10% to the calculated number. Possibly this is allowing for the fact that the TFA has stairs and other areas excluded?

    The critical question is which number should I use to calculate the air-changes per hour that goes in the sheet? The sheet doesn't ask for airflow, it wants ach, which is calculated by the tester from a stated volume.

    This all seems rather unsatisfactory, and I'm not at all sure what's right. I guess PHPP is expecting its "Net Air volume for Pressure test" value to be used? It certainly makes my numbers a lot better, but it seems innacurate (or I calced the volume incorrectly).

    Does anyone know how this is supposed to work?

    Spreadsheet here: http://wookware.org/house/retrofit/calcs/PHPP2015internorm.xlsx
    •  
      CommentAuthordjh
    • CommentTimeFeb 26th 2024
     
    I don't know the answer (I always thought PHPP is too difficult and so I paid professionals to enter the data)

    But maybe https://passipedia.org/planning/building_services/ventilation/differentiation_between_vv_and_vn50_values helps?
    And https://www.passivhaustrust.org.uk/UserFiles/File/Technical%20Papers/BRE_Passivhaus_Airtightness_Guide.pdf

    Who is doing the airtightness test? A PH one is different to (more comprehensive than) the building regs one but the tester should do both. Mine (Paul Jennings) calculated the volume from the PHPP data.

    I don't think the 2.5 m is anything but a default. You're supposed to use actual numbers AFAIK. I don't recollect a 1.1 fudge factor at all.

    My libreoffice won't open your spreadsheet. "Too many columns". Maybe it's just too old.
  5.  
    There's a good exploration on this here:

    http://www.greenbuild.ie/PassiveHouseBlowerDoorTesting.pdf

    See page 15 onwards for volume parameters.

    As you suggest, the 2.5m height is about standardising the methodology for calculation terms, but it is also important to understand that there can be net and gross volumes just as there can be with floor areas. Which means you end up with no less than 3 different volumes for consideration. The image below hopefully summarises these.

    "In terms of using a floor area * mean ceiling height, it can be argued that the Treated Floor Area could be used as the floor area, yet this counts some spaces as 50%, and others as 60%, and so may be usable but not ideal, as we are really looking for the full net internal air volume.

    The standardised volume used for Passive House style tests then is generally a room by room width*length*height calculation for all applicable rooms and spaces. This width*breath*height calculation takes in only the volumes to the finished surfaces of the room, and not the hidden spaces behind/over or under the visible surfaces. This is the so-called 'clear air volume'."

    NB: What he calls VRAX is what the PHI call Vv
      Ventilated Volumes.JPG
    •  
      CommentAuthordjh
    • CommentTimeFeb 26th 2024
     
    Thanks Tom. Yes, in my PHPP the ventilation worksheet has two volumes:

    G8 is labelled "Room ventilation volume" and is 369 m³ and is AnnualHeatingDemand.O27 which is TFA * 2.5 m. AIUI this is to avoid overventilation of spaces with high ceilings and underventilation of spaces with low ceilings.

    P27 is labelled "Net Air Volume for Press Test" and is 415 m³ and is hand entered, not calculated.

    Things have changed a bit since mine was done, I suspect.
    • CommentAuthorwookey
    • CommentTimeMar 2nd 2024 edited
     
    Posted By: djh
    My libreoffice won't open your spreadsheet. "Too many columns". Maybe it's just too old.


    I use libreoffice too - it seems to work fine with PHPP. My version is 7.4.7.2
    So it's a bit off that should complain - that file was written with libreoffice. I've been using it since at least 2013 (when libreoffice was v4.0)

    Thanks for the links. I'll have a read. I could ask a professisonal, but I'm not convinced that all of those will know what the right answer here is either. I shall try asking one :-)

    I'm not sure where professionals go to discuss stuff like this - one would assume people regularly have such questions.
    •  
      CommentAuthordjh
    • CommentTimeMar 2nd 2024 edited
     
    My LO is 6.2.7.1. I tried a newer one - 6.4.7.2. That made the same complaint but then loaded the spreadsheet anyway. (the spreadsheet shouldn't have a huge number of columns anyway - why does it?)

    Cell P27 is coloured yellow, I think (it's not very clear in that copy of LO for some reason). That indicates, I believe, that the value is to be entered by hand. But it has the formula N9*1.1. So I suggest investigating wherever that value came from. I don't believe it should be a formula.

    Do you have the original version of PHPP before you entered any data. I suggest looking there.

    PS The newer LO suffers from the problem of opening maximised and then when you unmaximise it, it goes to a ridiculously small window size. I believe that bug has been present for about four years now :cry:
    •  
      CommentAuthordjh
    • CommentTimeMar 2nd 2024 edited
     
    FWIW the dimensions of the sheets in your .xlsx file are as follows:

    xl/worksheets/sheet10.xml: dimension ref="A1:AMK258"/>
    xl/worksheets/sheet11.xml: dimension ref="A1:BI145"/>
    xl/worksheets/sheet12.xml: dimension ref="A1:RL414"/>
    xl/worksheets/sheet13.xml: dimension ref="A1:JF204"/>
    xl/worksheets/sheet14.xml: dimension ref="A1:DN170"/>
    xl/worksheets/sheet15.xml: dimension ref="A1:AI139"/>
    xl/worksheets/sheet16.xml: dimension ref="A1:DB161"/>
    xl/worksheets/sheet17.xml: dimension ref="A1:AI75"/>
    xl/worksheets/sheet18.xml: dimension ref="A1:AH159"/>
    xl/worksheets/sheet19.xml: dimension ref="A1:AJ102"/>
    xl/worksheets/sheet1.xml: dimension ref="A1:D59"/>
    xl/worksheets/sheet20.xml: dimension ref="A1:V49"/>
    xl/worksheets/sheet21.xml: dimension ref="A1:AJ176"/>
    xl/worksheets/sheet22.xml: dimension ref="A1:AS184"/>
    xl/worksheets/sheet23.xml: dimension ref="A1:AX205"/>
    xl/worksheets/sheet24.xml: dimension ref="A1:CH114"/>
    xl/worksheets/sheet25.xml: dimension ref="A1:AB238"/>
    xl/worksheets/sheet26.xml: dimension ref="A1:AQ366"/>
    xl/worksheets/sheet27.xml: dimension ref="A1:AR185"/>
    xl/worksheets/sheet28.xml: dimension ref="A1:AT547"/>
    xl/worksheets/sheet29.xml: dimension ref="A1:AV48"/>
    xl/worksheets/sheet2.xml: dimension ref="A1:BL88"/>
    xl/worksheets/sheet30.xml: dimension ref="A1:DJ73"/>
    xl/worksheets/sheet31.xml: dimension ref="A1:DJ100"/>
    xl/worksheets/sheet32.xml: dimension ref="A1:AU45"/>
    xl/worksheets/sheet33.xml: dimension ref="A1:AD43"/>
    xl/worksheets/sheet34.xml: dimension ref="A1:BJ57"/>
    xl/worksheets/sheet35.xml: dimension ref="A1:AU204"/>
    xl/worksheets/sheet36.xml: dimension ref="A1:AP475"/>
    xl/worksheets/sheet37.xml: dimension ref="A1:AMJ989"/>
    xl/worksheets/sheet38.xml: dimension ref="A1:AH530"/>
    xl/worksheets/sheet39.xml: dimension ref="A1:BD67"/>
    xl/worksheets/sheet3.xml: dimension ref="A1:G491"/>
    xl/worksheets/sheet40.xml: dimension ref="A1:AA55"/>
    xl/worksheets/sheet41.xml: dimension ref="A1:AH1154"/>
    xl/worksheets/sheet4.xml: dimension ref="A1:DG754"/>
    xl/worksheets/sheet5.xml: dimension ref="A1:AY125"/>
    xl/worksheets/sheet6.xml: dimension ref="A1:R160"/>
    xl/worksheets/sheet7.xml: dimension ref="A1:AMJ308"/>
    xl/worksheets/sheet8.xml: dimension ref="A1:FH1009"/>
    xl/worksheets/sheet9.xml: dimension ref="A1:DA1758"/>

    1024 columns is the max that LO accepts (my versions at least). I understand this is a longstanding problem that has it's origins in Excel's bad habit of adding an extra column every time a spreadsheet is saved.

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