Question-and-Answer Resource for the Building Energy Modeling Community
Get s tarted with the Help page

# Natural vented cavity

I have created a model in SketchUp with OpenStudio.

How can I avoid to losing data in the switch between osm and idf? For example, I created a natural vented cavity with idf editor. Then, if I need to change the model with graphic input (as I use SketchUp) I lose that information.

Now the natural vented cavity is actually the most boring input overall when you have about 20 surfaces with it. How can maintain the information?

edit retag close merge delete

Sort by » oldest newest most voted

I would write an EnergyPlus measure to edit the surface objects and add the natural vented cavity to the idf when you run your OpenStudio model. The run portion of the measure would probably look something like this:

# create other side conditions model object
sideConditionModel = "
SurfaceProperty:OtherSideConditionsModel,
ScreenCavityModel,          ! OtherSideConditionsModel Name
GapConvectionRadiation;         ! Type of Modeling used to determine Boundary Conditions
"

# get all building surfaces in the starting model
heat_transfer_surfaces = workspace.getObjectsByType("BuildingSurface:Detailed".to_IddObjectType)

surface_names = []

heat_transfer_surfaces.each do |surface|
# change outside boundary condition based on surface construction name
construction_name = surface.getString(2)
if construction_name.match("Ext wall - Insulated metal siding")
surface.setString(4,"OtherSideConditionsModel")
surface.setString(5,"ScreenCavityModel")
end
# put surface name in array
surface_name = surface.getString(0)
surface_names << surface_name
end

naturallyVentedCavity = "
SurfaceProperty:ExteriorNaturalVentedCavity,
Vented Cavity Exterior Surface,     ! Name
ScreenCavityModel,      ! OtherSideConditionsModel Object Name
0.02,                       ! Area Fraction of Openings
0.9,                        ! Thermal Emissivity of Exterior Baffle Material
0.92,                       ! Solar Absorbtivity of Exterior Baffle
0.05,                       ! Height scale for bouyancy-driven ventilation
0.05,                       ! Effective Thickness of Cavity Behind Exterior Baffle
0.97,                       ! Ratio of Actual surface area to projected surface area
Smooth ,                    ! Roughness of collector
0.1 ,                       ! Cv, Effectiveness for perforations with respect to Wind
0.5 ,                       ! Cd, Discharge Coefficient for Openings with respect to bouyancy-driven flow
#{surface_names.join(",")} ;            ! Surface Name
"

more

I took the liberty of marking this answer as accepted (answered a year and a half ago). @giofer, remember to mark answers as accepted if they solved your problem in the future. Thanks!

( 2017-01-31 07:38:14 -0500 )edit