public ElementFilter GetFilter()
{
var rule = ParameterFilterRuleFactory.CreateGreaterOrEqualRule(new ElementId(BuiltInParameter.RBS_REFERENCE_INSULATION_TYPE), ElementId.InvalidElementId);
return new ElementParameterFilter(rule, true);
}
var collector =
new FilteredElementCollector(doc, doc.ActiveView.Id)
.OfCategory(BuiltInCategory.OST_DuctCurves)
.WhereElementIsNotElementType();
var elements = collector.WherePasses(GetFilter())