Model Condition

Overview

Provides the information concerning the condition of an element or a group of elements
Condition may be established to determine if an element requires maintenance in order to bring it to a required level of operating efficiency. This may be brought about either by the absolute condition or by the rate of change of condition. Ultimately, the condition of an element may become so poor as to require replacement
The condition of an element may be established by:

instrumentation in place that enables operating parameters to be continuously monitored; the parameters being selected such that they indicate the current condition of the asset (e.g. vibration).
periodic inspection that may be either visual, carried out with the assistance of instruments or a combination.

The condition of an element is considered to be determined by one or several condition criteria. Each criterion is a particular measured or assessed value that contributes to the overall condition of the element.

A criterion that is measured using calibrated instruments and whose value is repeatable by different instruments is considered to be objective. An objective criterion will typically be a measured value.
A criterion that is assessed by observation and whose value may not be repeatable between assessors is considered to be subjective. A subjective criterion will typically be measured against an arbitrary scale (e.g. 1 represents new condition whilst 10 represents poor condition requiring urgent replacement).
The actual condition of an element is considered to be determined by bringing together the various criteria within a group.
Particular target values may be established for maintenance or replacement operations to be carried out on an element. Such values are defined as constraints. When the condition of an element reaches or exceeds a value indicated by a constraint, it signifies that a particular action should be triggered. A condition based 'event' may be based on either objective or subjective criteria. For objective criteria, the potential exists for live reporting of condition data from fixed instrumentation. Through the use of condition criteria, IFC can therefore offer the potential for 'expert' automated decision making in maintenance.

Suggested modifications to IFC model and documentation
* Date and time values are currently held for each condition criterion individually and not for condition. Therefore, for tracking condition history, each of the criterion dates within a condition must be the same so that they can also be applied to the condition. It would be better if a date and time could also be explicitly applied to the condition as well as to the condition criteria.

Results

Specification of relevant information concerning the asset and the elements and/or sub-assets from which it is composed.

Description	Entity/Pset/Functional Part	MAN	REC	OPT
Establish Condition Criteria The actual condition of an element may need to be determined by reference to several condition criteria. Each criterion may measure a different aspect of the condition and may be either a subjective or objective assessment. Each condition criterion should be established in turn.
Assert general attributes for the criterion
Set the global unique identifier	IfcConditionCriterion.GlobalId::IfcGloballyUniqueId
Assert the owner history	IfcConditionCriterion.OwnerHistory::fp_apply_owner_history
Specify the name of the criterion. Each condition criterion must have a name that identifies it.	IfcConditionCriterion.Name::IfcLabel
Specify a description for the criterion The description of a condition criterion may be used to provide further information if required. However, if the name of the criterion conforms to an agreed standard that also incorporates a description of what the name means, it may be unnecessary to include a description with every criterion.	IfcConditionCriterion.Description::IfcText
Set the date and time
Set the date and time at which the condition assessment is made. Date and time values are required to establish the point at which the assessment is made. It may also be used as the basis for historical condition recording within which knowledge of the dates of condition assessment can be used to determine the rate of degradation; information which can be useful in predicting actual service life values (see fp_control_service_life) Note that for a set of condition criteria that are grouped to define an element condition, the date and time value asserted for each criterion should be the same.	IfcConditionCriterion.OwnerHistory::fp_select_date_time
Select whether a condition criterion will be subjective or objective A subjective criterion is defined as a condition that is assessed by human inspection (visual, audio, smell, touch etc) An objective criterion is defined as a condition that can be determined from the values of particular parameters found by reliable instruments
If the criterion is subjective, assess the condition criterion value against an available scale For subjective condition criteria, a scale of values should be established that can be easily understood and interpreted by subsequent condition investigators.	IfcConditionCriterion.Criterion::IfcLabel
If the criterion is objective, determine the value and units	IfcConditionCriterion.Criterion::fp_measure_with_unit
Assert the relationship that assigns the condition criteria that will establish the condition This is defined in a separate functional part. The relating group in this functional part will be the entity IfcCondition. The related objects will be the instances of IfcConditionCriterion that establish the condition. Note the rule that requires the date and time value for each condition criterion within the group to have the same value.	fp_assigns_to_group (condition)
Establish and identify the element whose condition is to be assessed
Specify the element or group whose condition is to be assessed Any subtype of IfcProduct can be identified for this purpose. Practically, certain subtypes may be excluded including site, building storey and space. However, this is not considered to form a general business rule since it may be appropriate to use e.g. space as a contained for a general condition assessment of all the elements that are contained within it. Occurrences of IfcSystem (including occurrences of IfcElectricalCircuit) and IfcAsset may also be subject to condition assessment.	IfcProduct <subtypes> OR IfcSystem <subtypes> OR IfcAsset
Assert the relationship that assigns the condition to the product or group
If the condition is being assigned to an element The relating product is the product subtype selected and the related objects is the condition that is being assigned.	fp_assigns_to_product
If the condition is being assigned to an asset or system The relating group is the asset, system or subtype of system selected and the related objects is the condition that is being assigned.	fp_assigns_to_group

IFC Entities Required

IfcAppliedValue
IfcCalendarDate
IfcCondition
IfcConditionCriterion
IfcControl
IfcCostValue
IfcGroup
IfcObject
IfcProduct
IfcRoot
IfcSystem

IFC Datatypes Required

IfcAppliedValueSelect
IfcConditionCriterionSelect
IfcDayInMonthNumber
IfcGloballyUniqueId
IfcLabel
IfcMonetaryMeasure
IfcMonthInYearNumber
IfcText
IfcYearNumber

IFC Functions Required

-

IFC Property Sets Required

-

IDM Functional Parts Required

fp_apply_owner_history
fp_assigns_to_group
fp_assigns_to_product
fp_measure_with_unit
fp_place_object
fp_represent_product
fp_select_actor
fp_select_date_time

EXPRESS-G

EXPRESS Schema

SCHEMA FP_MODEL_CONDITION;

  TYPE IfcDayInMonthNumber = INTEGER;
  END_TYPE;

  TYPE IfcGloballyUniqueId = STRING (22) FIXED;
  END_TYPE;

  TYPE IfcLabel = STRING;
  END_TYPE;

  TYPE IfcMonthInYearNumber = INTEGER;
    WHERE
      WR1 : { 1<= SELF <= 12 };
  END_TYPE;

  TYPE IfcText = STRING;
  END_TYPE;

  TYPE IfcYearNumber = INTEGER;
  END_TYPE;

  TYPE IfcConditionCriterionSelect = SELECT
    (IfcLabel,
     fp_measure_with_unit);
  END_TYPE;

  TYPE IfcMonetaryMeasure = REAL;
  END_TYPE;

  TYPE IfcAppliedValueSelect = SELECT
    (IfcMonetaryMeasure,
     fp_measure_with_unit);
  END_TYPE;

  ENTITY IfcProduct
    ABSTRACT SUPERTYPE
    SUBTYPE OF(IfcObject);
      Representation  : OPTIONAL fp_represent_product;
      ObjectPlacement : OPTIONAL fp_place_object;
    WHERE
      WR1 : (EXISTS(Representation) AND EXISTS(ObjectPlacement))
            OR (EXISTS(Representation) AND 
            (NOT('IFC2X2_FINAL.IFCPRODUCTDEFINITIONSHAPE' IN TYPEOF(Representation))))
            OR (NOT(EXISTS(Representation)));
  END_ENTITY;

  ENTITY IfcObject
    ABSTRACT SUPERTYPE OF (ONEOF(IfcControl, IfcGroup, IfcProduct))
    SUBTYPE OF(IfcRoot);
      ObjectType     : OPTIONAL IfcLabel;
    WHERE
      WR1 : SIZEOF(QUERY(temp <* IsDefinedBy | 'IFC2X2_FINAL.IFCRELDEFINESBYTYPE' IN TYPEOF(temp))) <= 1;
  END_ENTITY;

  ENTITY IfcRoot
    ABSTRACT SUPERTYPE OF (ONEOF(IfcObject, IfcRelationship));
      GlobalId      : IfcGloballyUniqueId;
      Name          : OPTIONAL IfcLabel;
      Description   : OPTIONAL IfcText;
      OwnerHistory : fp_apply_owner_history;
    UNIQUE
      UR1 : GlobalId;
  END_ENTITY;

  ENTITY IfcControl
    ABSTRACT SUPERTYPE
    SUBTYPE OF(IfcObject);
  END_ENTITY;

  ENTITY IfcConditionCriterion
    SUBTYPE OF(IfcControl);
      Criterion          : IfcConditionCriterionSelect;
      CriterionDateTime : fp_select_date_time;
    WHERE
      WR1 : EXISTS(SELF\IfcRoot.Name);
  END_ENTITY;

  ENTITY IfcSystem
    SUBTYPE OF(IfcGroup);
    WHERE
      WR1 : SIZEOF (QUERY (temp <* SELF\IfcGroup.IsGroupedBy.RelatedObjects |  NOT('IFC2X2_FINAL.IFCELEMENT' IN TYPEOF(temp)))) = 0;
  END_ENTITY;

  ENTITY IfcGroup
    SUPERTYPE OF (ONEOF(IfcCondition, IfcSystem, IfcAsset))
    SUBTYPE OF(IfcObject);
  END_ENTITY;

  ENTITY IfcCondition
    SUBTYPE OF(IfcGroup);
  END_ENTITY;

  ENTITY IfcCalendarDate;
      DayComponent   : IfcDayInMonthNumber;
      MonthComponent : IfcMonthInYearNumber;
      YearComponent  : IfcYearNumber;
    WHERE
      WR21 : IfcValidCalendarDate (SELF);
  END_ENTITY;

  ENTITY IfcCostValue
    SUBTYPE OF(IfcAppliedValue);
  END_ENTITY;

  ENTITY IfcAppliedValue
    ABSTRACT SUPERTYPE;
      AppliedValue    : OPTIONAL IfcAppliedValueSelect;
      UnitBasis      : fp_measure_with_unit;
      ApplicableDate : fp_select_date_time;
      FixedUntilDate : fp_select_date_time;
    WHERE
      WR1 : EXISTS (AppliedValue) OR 
            EXISTS (ValueOfComponents);
  END_ENTITY;

  ENTITY IfcAsset
    SUBTYPE OF(IfcGroup);
      OriginalValue        : IfcCostValue;
      CurrentValue         : IfcCostValue;
      TotalReplacementCost : IfcCostValue;
      Owner                : fp_select_actor;
      User                 : fp_select_actor;
      IncorporationDate    : IfcCalendarDate;
      DepreciatedValue     : IfcCostValue;
    WHERE
      WR1 : SIZEOF(QUERY(Temp <* SELF\IfcGroup.IsGroupedBy.RelatedObjects | NOT('IFC2X2_FINAL.IFCELEMENT' IN TYPEOF(Temp)))) = 0;
  END_ENTITY;

  ENTITY fp_apply_owner_history;
  END_ENTITY;

  ENTITY fp_assigns_to_group;
  END_ENTITY;

  ENTITY fp_assigns_to_product;
  END_ENTITY;

  ENTITY fp_measure_with_unit;
  END_ENTITY;

  ENTITY fp_place_object;
  END_ENTITY;

  ENTITY fp_represent_product;
  END_ENTITY;

  ENTITY fp_select_actor;
  END_ENTITY;

  ENTITY fp_select_date_time;
  END_ENTITY;

END_SCHEMA;

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