Set Space Ventilation

Overview

Describes the setting of values required for the ventilation of a space. It includes the setting of both natural infiltration and mechanical ventilation rates.
A prior requirement to the execution of this functional part is that a space has already been modelled using the functional part fp_model_space.

Concept: Set space ventilation [natural]

Natural ventilation or infiltration represents the rate at which air is replaced in a space due to natural factors including internal/external pressure or temperature difference, the air exchange taking place through gaps occurring within or between building elements.
Natural ventilation rate is typically expressed as the number of air changes per hour for the space concerned.

Concept: Set space ventilation [mechanical]

Mechanical ventilation represents the rate at which air is replaced in a space due to air being forced into or out of a space through mechanical methods. The primary driver for the air exchange is a fan driven ventilation system which inputs or extracts air directly (through the fan) or indirectly (through grilles or diffusers and a ducted system)
Mechanical ventilation rate is typically expressed as the number of air changes per hour for the space concerned.

Concept: Set space ventilation [person_outside_air]

This concept identifies the minimum outside (fresh) air requirement per person within a space. It also takes into account the fact that people may move into and out of a space over time and therefore specifies a diversity factor in relation to the planned number of people within the space at a given time.

Concept: Set space ventilation [design_airflow]

This concept allows the values of design air flow rates within a space to be specified under various requirements..
Certain of these values may be derived from other properties specified and attributes of the space.

Results

Natural ventilation rate for the space is specified
Mechanical ventilation rate for the space is specified
Outside air requirements per person and for a space are specified
Design air flow rates for winter and summer and for supply and exhaust are specified.

Description	Entity/Pset/Functional Part	MAN	REC	OPT
It is assumed that the space for which the ventilation is required has already been modeled using the functional part fp_model_space.
Concept: Set space ventilation [natural] It is assumed that a property set Pset_SpaceCommon exists which contains mandatory naming information required by the functional part has been defined for the space.
Indication that the space is required to have natural ventilation. The value of this property must be set to TRUE for a naturally ventilated space.	Pset_SpaceCommon.NaturalVentilation::IfcPropertySingleValue::IfcBoolean = TRUE
Set the value of natural air change rate required for the space concerned This value is given in air changes per hour for the space which is a dimensionless value.	Pset_SpaceCommon.NaturalVentilationRate::IfcPropertySingleValue::IfcCountMeasure
Concept: Set space ventilation [mechanical] It is assumed that a property set Pset_SpaceCommon exists which contains mandatory naming information required by the functional part has been defined for the space
Indication that the space is required to have mechanical ventilation. The value of this property must be set to FALSE for a mechanically ventilated space.	Pset_SpaceCommon.NaturalVentilation::IfcPropertySingleValue::IfcBoolean = FALSE
Set the value of mechanical air change rate required for the space concerned This value is given in air changes per hour for the space which is a dimensionless value.	Pset_SpaceCommon.MechanicalVentilationRate::IfcPropertySingleValue::IfcCountMeasure
Note that if values are set for both natural and mechanical air change rate then the setting of the Boolean attribute TRUE/FALSE for natural ventilation will determine which of the values is to be used.
Concept: Set space ventilation [person_outside_air]
Set the design quantity of outside air to be provided per person in the space.	Pset_ThermalLoadDesignCriteria.OutsideAirPerPerson::IfcPropertySingleValue::IfcVolumetricFlowRateMeasure
Set the diversity factor that may be applied to the number of people in the space. In determining the total fresh air requirement for people in a space, the planned maximum number of people, the diversity factor and the design quantity of outside air per person required are taken into account.	Pset_ThermalLoadDesignCriteria.OccupancyDiversity::IfcPropertySingleValue::IfcPositiveRatioMeasure
Concept: Set space ventilation [design_airflow]
Set the air flow rate required during the peak cooling conditions. This value may be determined in conjunction with the mechanical air change rate identified above.	Pset_SpaceThermalDesign.CoolingDesignAirflow::IfcPropertySingleValue::IfcVolumetricFlowRateMeasure
Set the air flow rate required during the peak heating conditions. Note that this value could also be determined by minimum ventilation requirement or minimum air change requirements. This value may be determined in conjunction with the mechanical air change rate identified above.	Pset_SpaceThermalDesign.HeatingDesignAirflow::IfcPropertySingleValue::IfcVolumetricFlowRateMeasure
Set the total ventilation outside air requirement for the space. This value may be determined in conjunction with the minimum outside air per person requirement indicated above.	Pset_SpaceThermalDesign.VentilationAirFlowrate::IfcPropertySingleValue::IfcVolumetricFlowRateMeasure
Set the design exhaust air flow rate for the space. Note that for a space that is to be under negative pressure, this value may be the same as the air flow rates indicated above. For a space that is to be under positive pressure, this value will be less than the values indicated above.	Pset_SpaceThermalDesign.ExhaustAirFlowrate::IfcPropertySingleValue::IfcVolumetricFlowRateMeasure
Identify whether a ceiling plenum is to be used for return air or not. If a ceiling plenum is to be used then the value should be set to TRUE; otherwise it should be set to FALSE. By default, the value should be set to FALSE.	Pset_SpaceThermalDesign.CeilingRAPlenum ? IfcPropertySingleValue :: IfcBoolean

For the purposes of this functional part, the IFC subset schema and all requirements for entities, datatypes, functions property sets and functional parts are considered to be exactly the same as for the functional part fp_model_space.
Refer to the functional part fp_model_space for further information.

Examples of Setting Ventilation Rates

Example 1: Setting a natural ventilation rate

The space used here is as defined in example 1 of fp_model_space with attributes as illustrated.
Note that the space in this case is set to use natural ventilation at 2 air changes per hour (shown in bold in the sample code below).

#2=IFCOWNERHISTORY(...);

/* defining the space */
#901=IFCSPACE('abcdefghijklmnopqrst901',#2,'W-001',$,'Living Area',#1284,#1300,'Master Bedroom',.ELEMENT.,.INTERNAL.,0.);

/* relating the space and the property set */
#911=IFCRELDEFINESBYPROPERTIES('abcdefghijklmnopqrst911',#2,$,$,(#901),#921);

/* definition of occurrence property set */
#921=IFCPROPERTYSET('abcdefghijklmnopqrst921',#2,'Pset_SpaceCommon',$,(#931,#932,#933,#934,#935,#936,#937,#938,#939,#940,#941));

/* definition of common properties for a space */
/* note that the optional values given in #938 and #940 relate to IFC 2x3 */
/* - a value must be asserted for prior IFC releases - */
#931=IFCPROPERTYSINGLEVALUE('Reference',$,'Bedroom',$);
#932=IFCPROPERTYSINGLEVALUE('OccupancyType',$,'Sleeping',$);
#933=IFCPROPERTYSINGLEVALUE('OccupancyNumber',$,2,$);
#934=IFCPROPERTYSINGLEVALUE('PubliclyAccessible',$,.FALSE.,$);
#935=IFCPROPERTYSINGLEVALUE('HandicapAccessible',$,.TRUE.,$);
#936=IFCPROPERTYSINGLEVALUE('NaturalVentilation',$,.TRUE.,$);
#937=IFCPROPERTYSINGLEVALUE('NaturalVentilationRate',$,2,$);
#938=IFCPROPERTYSINGLEVALUE('MechanicalVentilationRate',$,$,$);
#939=IFCPROPERTYSINGLEVALUE('Concealed',$,.FALSE.,$);
#940=IFCPROPERTYSINGLEVALUE('GrossPlannedArea',$,$,$);
#941=IFCPROPERTYSINGLEVALUE('NetPlannedArea',$,$,$);

/* placement and representation are not elaborated in this example */
#1284=IFCLOCALPLACEMENT( ... );
#1300=IFCPRODUCTREPRESENTATION ( ... );

Example 2: Setting a mechanical ventilation rate

Using the same space as above but in this example, mechanical ventilation is specified at a rate of 10 air changes per hour.
Note that in this example, the value for the natural ventilation rate is set but not used.

#2=IFCOWNERHISTORY(...);

/* defining the space */
#901=IFCSPACE('abcdefghijklmnopqrst901',#2,'W-001',$,'Living Area',#1284,#1300,'Master Bedroom',.ELEMENT.,.INTERNAL.,0.);

/* relating the space and the property set */
#911=IFCRELDEFINESBYPROPERTIES('abcdefghijklmnopqrst911',#2,$,$,(#901),#921);

/* definition of occurrence property set */
#921=IFCPROPERTYSET('abcdefghijklmnopqrst921',#2,'Pset_SpaceCommon',$,(#931,#932,#933,#934,#935,#936,#937,#938,#939,#940,#941));

/* definition of common properties for a space */
/* note that the optional values given in #938 and #940 relate to IFC 2x3 */
/* - a value must be asserted for prior IFC releases - */
#931=IFCPROPERTYSINGLEVALUE('Reference',$,'Bedroom',$);
#932=IFCPROPERTYSINGLEVALUE('OccupancyType',$,'Sleeping',$);
#933=IFCPROPERTYSINGLEVALUE('OccupancyNumber',$,2,$);
#934=IFCPROPERTYSINGLEVALUE('PubliclyAccessible',$,.FALSE.,$);
#935=IFCPROPERTYSINGLEVALUE('HandicapAccessible',$,.TRUE.,$);
#936=IFCPROPERTYSINGLEVALUE('NaturalVentilation',$,.FALSE.,$);
#937=IFCPROPERTYSINGLEVALUE('NaturalVentilationRate',$,2,$);
#938=IFCPROPERTYSINGLEVALUE('MechanicalVentilationRate',$,10,$);
#939=IFCPROPERTYSINGLEVALUE('Concealed',$,.FALSE.,$);
#940=IFCPROPERTYSINGLEVALUE('GrossPlannedArea',$,$,$);
#941=IFCPROPERTYSINGLEVALUE('NetPlannedArea',$,$,$);

/* placement and representation are not elaborated in this example */
#1284=IFCLOCALPLACEMENT( ... );
#1300=IFCPRODUCTREPRESENTATION ( ... );

Example 3: Setting outside air requirement

In this example, the outside air requirement per person is set for two spaces (whose attributes are not elaborated). A diversity factor of 0.5 is set for the spaces identifying that only half of the planned maximum number of people to occupy the space can be expected to be in the spaces at a particular time.

#2=IFCOWNERHISTORY(...);

/* defining the spaces */
#901=IFCSPACE(...);
#902=IFCSPACE(...);

/* relating the spaces and the property set */
#914=IFCRELDEFINESBYPROPERTIES('abcdefghijklmnopqrst914',#2,$,$,(#901,#902),#921);

/* definition of occurrence property set */
#921=IFCPROPERTYSET('abcdefghijklmnopqrst921',#2,'Pset_ThermalLoadDesignCriteria',$,(#931,#932,#933,#934,#935,#936));

/* definition of thermal load design criteria properties */
/* properties not referenced are shown with optional values */
/* this is suitable for IFC 2x3 and above, previous releases require values to be set */
#931=IFCPROPERTYSINGLEVALUE('OccupancyDiversity',$,0.5,$);
#932=IFCPROPERTYSINGLEVALUE('OutsideAirPerPerson',$,0.15,$);
#933=IFCPROPERTYSINGLEVALUE ('ReceptacleLoadIntensity',$,$,$);
#934=IFCPROPERTYSINGLEVALUE('AppliancePercentLoadToRadiant',$,$,$);
#935=IFCPROPERTYSINGLEVALUE('LightingLoadIntensity',$,$,$);
#936=IFCPROPERTYSINGLEVALUE ('LightingPercentLoadToReturnAir',$,$,$);

Example 4: Setting design air flows

Refer to the example of 'Setting Outside Thermal Design Conditions' in the functional part fp_set_space_thermal_design which shows setting of values in the same property set as is used for design air flow rates.

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