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negative zone volume and Total wall area by ASHRAE 90.1 definition

asked 2023-04-28 05:26:34 -0500

budich's avatar

updated 2023-04-29 07:52:14 -0500


I have two warning :

  1. one of my zone become negative, how to solve this? * Warning * Indicated Zone Volume <= 0.0 for Zone=ATAP TAMBAHAN

  2. Total wall area by ASHRAE 90.1 not same with user entered Wall class surfaces * Warning * WriteVeriSumTable: InputVerificationsAndResultsSummary: Wall area based on [>=60,<=120] degrees (tilt) as walls * ~~~ * differs ~8.9% from user entered Wall class surfaces. Degree calculation based on ASHRAE 90.1 wall definitions.

Would you please help me on this please find the file of "Nara Tipikal 57.idf" in gdrive link

thank you very much regards, Budijanto Chandra

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answered 2023-04-28 07:35:52 -0500

Zone "Atap tambahan" is indeed fully enclosed, yet its Wall and sloped Roof surfaces all have inverted vertex sequences: they're defined clockwise (when looking at them from outside the zone), e.g.:

    F4A4D5,                  !- Name
    Wall,                    !- Surface Type
    Exterior Wall,           !- Construction Name
    Atap tambahan,           !- Zone Name
    Outdoors,                !- Outside Boundary Condition
    ,                        !- Outside Boundary Condition Object
    SunExposed,              !- Sun Exposure
    WindExposed,             !- Wind Exposure
    ,                        !- View Factor to Ground
    3,                       !- Number of Vertices
    8.656687477963,          !- Vertex 1 X-coordinate {m}
    9.879976463316,          !- Vertex 1 Y-coordinate {m}
    4.600000000000,          !- Vertex 1 Z-coordinate {m}
    6.456687477963,          !- Vertex 2 X-coordinate {m}
    9.879976463316,          !- Vertex 2 Y-coordinate {m}
    3.400000000000,          !- Vertex 2 Z-coordinate {m}
    6.456687477963,          !- Vertex 3 X-coordinate {m}
    12.229976463316,         !- Vertex 3 Y-coordinate {m}
    3.400000000000;          !- Vertex 3 Z-coordinate {m}

... they should be counter-clockwise, given the IDF's geometry rules:

    UpperLeftCorner,         !- Starting Vertex Position
    Counterclockwise,        !- Vertex Entry Direction
    Relative;                !- Coordinate System

Incidentally, the 2x sloped Roof surfaces (like "F4A4D5" above) are labelled as Walls. That likely triggers the 90.1 surface tilt warning.

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Great Denis, You always have a great solution, and you are correct.

After I changed F4A4D5 to the roof, it also solved the negative zone problem.

Thank you very much Regards, Budijanto Chandra

budich's avatar budich  ( 2023-04-28 09:17:20 -0500 )edit

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Asked: 2023-04-28 05:26:34 -0500

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Last updated: Apr 28 '23