Ventilation
Ventilation is outdoor air brought into the building mechanically to meet IAQ requirements. They are applied to the zones in the room properties screen. TRACE 3D Plus has standard library members that include ventilation rate requirements from several sources. There are two categories for ventilation: ASHRAE 62.1 and 170 (550) and General Ventilation. Library members are available from multiple different release years of the standards. Each member will specify where it came from under the Source Field.
ASHRAE 62.1 and 170 (550)
The ventilation library members under this category will be used along with Zone Properties and System Sizing Inputs to calculate ventilation rates per ASHRAE Standard 62.1. In this category, the ventilation library member details screen displays the following fields that must be defined:
People Based Rate
The design outdoor air volume flow rate per person for this zone in cubic meters per second per person. The default rates are from table 6-1 of ASHRAE Standard 62.1.
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Default Value: Per ASHRAE 62.1- 2010 table 6-1 depending on the Occupancy Category
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Typical Range: 5 to 20 cfm/ person
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Min & Max: 0 to 1,000,000
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Units: cfm/person; (L/s)/person, (m3/hr)/person, (m3/s)/person
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Area Based Rate
The design outdoor air volume flow rate per floor area. The default rates are from table 6-1 of ASHRAE Standard 62.1.
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Default Value: Per ASHRAE 62.1- 2010 table 6-1 depending on the Occupancy Category
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Typical Range: 0.06 to 0.18 cfm/ ft2
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Min & Max: 0 to 1,000,000
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Units: cfm/ft2 ; (L/s)/m2, (m3/hr)/m2, (m3/s)/m2, ACH (Air Changes an hour)
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Room Exhaust Based Rate
The design outdoor air volume flow rate relative to the Room Exhaust Flow rate. Only shows with General Ventilation option, not with ASHRAE 62.1 option.
Can be matched to the Room exhuast schedule using the checkbox or set as a relative percentage of Room Exhaust as seen below.
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Min & Max: 0 to No Max Value
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Units: %
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The following fields are part of the ASHRAE 62.1 calculations. They are defined in the Building & Site section, Create Zones subsection, for each zone.
Cooling and Heating Ez
The Zone air distribution effectiveness is a measure of how thoroughly the cooling supply airflow mixes with the air in the breathing zone (the air up to six feet above the floor). This effectiveness is based on the location of the supply and return air grilles, the velocity of the airflow, and the proximity of the makeup air grille to the exhaust air grille. The available values are from table 6-2 of ASHRAE Standard 62.1- 2010 depending on the type of air distribution for the room.
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Default Value: Per ASHRAE 62.1- 2010 table 6-2 depending on the Air Distribution Configuration
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Typical Range: 0.5 to 1.2
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Min & Max: N/A
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Units: N/A
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Er
The recirculation effectiveness is used only when the air handling system has a secondary ventilation path, such as a fan-powered VAV or dual duct VAV system. These systems can draw air from the plenum, and this field gives credit for the unused outside air in the plenum airstream. This input defines the local recirculation air fraction for the system return air.
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Default Value: 0
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Typical Range: 0.1 to 1.2
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Min & Max: 0 to 100
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Units: N/A
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Select the type of recirculation for this room from the drop-down list and the corresponding effectiveness will automatically be displayed. If the specific Er for the room is known, this percentage can be entered manually by choosing Custom. The types of recirculation are listed in the table below. The percentage of effectiveness can only be modified if Custom is chosen.
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Type
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Percentage
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Custom
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User entered
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Default based on system type
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blank
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Recirculate from ceiling plenum (for example, fan-powered VAV)
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30
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Recirculate within room
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0
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RA is fully mixed before recirculation (for example, dual duct VAV)
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100
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Same vent quality as zone
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0
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