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# How to determine the open area and average window height in measure " Add Wind and Stack Open Area"?

how to determine the open area and the average window height in measure Add Wind and Stack Open Area?

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( 2017-07-24 03:36:46 -0600 )edit

Yes. I'm talking about Add Wind and Stack Open Area. and I didn't found any results for it in IDF file.

( 2017-07-24 04:43:33 -0600 )edit

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Ok so the BCL is back online so I was able to download and open the measure.

What the measure does:

• Find all Zones that have at least one exterior wall, by looping on on all BuildingSurface:Detailed
• Create one ZoneVentilation:WindandStackArea for each of these "exterior" Zones. There is no fancy calculations whatsoever done in the measure, the user inputs are used as is.

Resulting, where used_exterior_zoneis the current "exterior" zone found earlier, the rest are user input.

ZoneVentilation:WindandStackOpenArea,
#{used_exterior_zone}_WindStack,         !- Name
#{used_exterior_zone},     !- Zone Name
#{open_area},              !- Opening Area {m2}
Always On Discrete 1 WindStack,    !- Opening Area Fraction Schedule Name
autocalculate,           !- Opening Effectiveness {dimensionless}
0,                       !- Effective Angle {deg}
#{window_height},       !- Height Difference {m}
autocalculate,           !- Discharge Coefficient for Opening
#{min_indoor_temp},        !- Minimum Indoor Temperature {C}
,                        !- Minimum Indoor Temperature Schedule Name
#{max_indoor_temp},                     !- Maximum Indoor Temperature {C}
,                        !- Maximum Indoor Temperature Schedule Name
#{delta_temp},                    !- Delta Temperature {deltaC}
,                        !- Delta Temperature Schedule Name
#{min_outdoor_temp},                    !- Minimum Outdoor Temperature {C}
,                        !- Minimum Outdoor Temperature Schedule Name
#{max_outdoor_temp},        !- Maximum Outdoor Temperature {C}
,                        !- Maximum Outdoor Temperature Schedule Name
#{max_wind_speed};                      !- Maximum Wind Speed {m/s}


Therefore you just have to read the I/O reference guide in detail for ZoneVentilation:WindandStackOpenArea, especially Open Area and Height Difference.

For this measure, you would calculate the average total area of the openings in the zones. Zone A: Window 1 = 1x1 Zone B: Window 1=2x1, Window 2=1x1

$$area = \frac{(1 \times 1) + (2 \times 1 + 1\times1)}{2}$$

For the height, it's a little bit more complicated... Depends on where you think the neutral plane(s) actually are.

For what it's worth, my two cents about this measure is that it's only appropriate if you have fully compartmentalized buildings (in which case I wouldn't use a ZV:WindandStackArea at all, but that's another thing...), where you could speculate that there is actually one neutral plane per zone/floor, in which case you would enter for Height: $z_{ceiling} - z_{avg,window}$ where z is defined as the height from the floor of the zone

Otherwise, if you have a standard building, a common case is where the neutral plane for the entire building is actually located roughly at the middle floor in the building. In which case, I'd suggest revamping this measure to have the height difference be calculated for each zone...

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thanks for answer.@Julien Marrec what is z.avg window and how to determinate its value?

( 2017-07-24 08:57:56 -0600 )edit

@Julien Marrec another question. I Need to calculate the open area for each zone individually? or all the zones together in one measure?

( 2017-07-24 10:00:51 -0600 )edit

z_avg_window = the mid point of the window... If you have a window has a still at 0.8, and is 1m heigh, that's 0.8 + 1/2... The measure assigns the same area to all exterior zones. so you need to enter the average.

( 2017-07-25 10:33:26 -0600 )edit

thanks @Julien Marrec, can you please take a look for my details building in this question. https://unmethours.com/question/25699... . need for your help

( 2017-07-25 12:02:26 -0600 )edit

@Julien Marrec, whats is mean of (still)? is the still that dimension from floor to under the window?

( 2017-07-25 21:46:32 -0600 )edit

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