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# Why is "average window height" in m2?

I'm using "Wind and Stack open area" in OpenStudio and my question is: why is the average window height in square meter? Shouldn't be it just a linear meter (because it is a height) ?

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That appears to be to just be a display error on the argument units by the measure writer. Looking through the measure.rb it does appear that the "window_height" argument is used as a length in meters as shown below.

#loop through exterior zones adding ZoneVentilationWindStackOpenArea object
used_exterior_zone_names.sort.uniq.each do |used_exterior_zone|

#IDF object text for ZoneVentilationWindStackOpenArea
string_objects << "
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}
"
end


You can comment on the measure on BCL, but I don't think authors get any notifications about comments, so we can contact them, since as a BCL moderator we have their contact info.

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One question. If I have just a normal window (not 2 small upper and lower windows), how can I find the height of NPL? @David Goldwasser

( 2016-12-28 12:20:16 -0600 )edit

May want to look at Chapter 16 of 2009 ASHRAE HOF as recommended here.

( 2016-12-29 11:31:19 -0600 )edit

The Add Wind and Stack Open Area measure no longer includes window height as an input and instead calculates the height difference from the model window geometry directly.

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