The OpenStudio GUI supports only supports adding specific component types (Materials, Constructions, and Ductless Heat Pumps). This is done via the "Components and Measures / Find Components" menu item.

The API can access any kind of component on the BCL. This is demonstrated in the Get BCL Weather File user script in the sketchup plugin.

I have a few unpublished measures that exercise the api (One to get site components, another to get construction). I'll see if I can get one of these posted on BCL as en example The trick to using a measure that accesses BCL components is planning it in a way so that the search results that populate the choice list are not too long. The user script can iterate (e.g. first pick city, then pick from sub-set of weather files for that city). A measure has to do it in one pass.

Here is a short snippet if you already know the UID of the component you want.

# download from BCL
remote = OpenStudio::RemoteBCL.new
remote.downloadComponent(uid)
component = remote.waitForComponentDownload()
if component.empty?
  runner.registerError("Cannot find local component")
  return false
end
component = component.get

# get osc file
files = component.files("osc")
if files.empty?
  runner.registerError("No file found")
  return false
end
construction_path = component.files("osc")[0]
construction_file = OpenStudio::IdfFile::load(construction_path)
vt = OpenStudio::OSVersion::VersionTranslator.new
constructionComponent = vt.loadComponent(OpenStudio::Path.new(construction_path))

# get model object
if constructionComponent.empty?
  runner.registerError("translateSurfaceConstruction: Cannot load construction component '#{construction_file}'")
  return false
else
  object = constructionComponent.get.primaryObject
  if object.to_Construction.empty?
    runner.registerError("translateSurfaceConstruction: Construction component '#{construction_file}' does not include a construction object")
    return false
  else
    componentData = model.insertComponent(constructionComponent.get)
    if componentData.empty?
      runner.registerError("translateSurfaceConstruction: Failed to insert construction component '#{construction_file}' into model")
      return false
    else
      new_construction = componentData.get.primaryComponentObject.to_Construction.get
    end
  end
end

Here is the entire run section of a measure that creates model objects from all the OSC files from a "resources" directory within the measure.

# define what happens when the measure is run
def run(model, runner, user_arguments)
super(model, runner, user_arguments)

# use the built-in error checking
if !runner.validateUserArguments(arguments(model), user_arguments)
  return false
end

# report initial condition of model
runner.registerInitialCondition("The building started with #{model.numObjects} objects.")

# get all objects in directory
files = Dir.entries("#{File.dirname(__FILE__)}/resources/")
files.each do |new_object|
  next if not new_object.include?(".osc")
  runner.registerInfo("importing component from #{new_object}")

  #load the osc file
  new_object_path = OpenStudio::Path.new("#{File.dirname(__FILE__)}/resources/#{new_object}")
  new_object_file = OpenStudio::IdfFile::load(new_object_path)

  if new_object_file.empty?
    runner.registerError("Unable to find the file #{new_object}.osc")
    return false
  else
    new_object_file = new_object_file.get
  end

  vt = OpenStudio::OSVersion::VersionTranslator.new
  new_objectComponent = vt.loadComponent(OpenStudio::Path.new(new_object_path))
  if new_objectComponent.empty?
    runner.registerError("Cannot load new_object component '#{new_object_file}'")
    return false
  else
    object = new_objectComponent.get.primaryObject
    componentData = model.insertComponent(new_objectComponent.get)
    if componentData.empty?
      runner.registerError("Failed to insert new_object component '#{new_object_file}' into model")
      return false
    else
      new_new_object = componentData.get.primaryComponentObject
    end
  end

end

# report final condition of model ...