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Zone Airflow

The Zone Airflow input object group provides a way to model the airflow between zones and airflow due to natural ventilation (e.g., open windows) or mechanically-induced ventilation (e.g., exhaust air fans).

  • ZoneInfiltration:DesignFlowRate - provides a way to describe the air infiltration into a building through leaks in the envelope including around windows or the normal operation of doors. The leakage can be a function of temperature and wind speed and can be expressed as either a total flow rate, a flow rate per floor area, per wall area, or as an air change rate. This input object appears in most example files.
  • ZoneInfiltration:EffectiveLeakageArea - similar to the previous input object but uses a different equation to express the infiltration rate. The DirectIndirectEvapCoolers.idf file contains an example.
  • ZoneInfiltration:FlowCoefficient - also similar to the ZoneInfiltration:DesignFlowRate input object but uses yet a different equation.The DirectIndirectEvapCoolers.idf file contains an example.
  • ZoneVentilation:DesignFlowRate - a method to add outside air to a zone with similar inputs to the ZoneInfiltration:DesignFlowRate but this would represent a purposeful introduction of outdoor air into the space. See the 5ZoneNightVent2.idf example file.
  • ZoneVentilation:WindandStackOpenArea - describes the natural ventilation driven introduction of outdoor air into the zone using a simpler method than an AirflowNetwork model. The inputs include the opening area and effectiveness as well as simple controls based on zone or outdoor temperature or the difference between the two or wind speed. See the VentilationSimpleTest.idf file.
  • ZoneMixing, ZoneCrossMixing, and ZoneRefrigerationDoorMixing - these three input objects provide simplified treatments of air exchange between zones.
  • ZoneEarthtube - provides a way to model an earth tube which is a way to draw outdoor into the zone through an underground pipe in order to cool the air in the summer and heat it in the winter. An example of this input object is in the EarthTubeSimpleTest.idf file.
  • ZoneCoolTower:Shower - models a passive downdraught evaporative cooling tower (sometimes also called a shower cooling tower or a wind tower) using natural ventilation and water evaporation to providing cooling in typically arid climates. See the CooltowerSimpleTestwithVentilation.idf for an example of this input object.
  • ZoneThermalChimney - models a passive solar driven thermal chimney that utilize the buoyancy of air heated by the sun to provide ventilation. See the file ThermalChimneyTest.idf.
  • ZoneAirBalance:OutdoorAir - calculates the combined outdoor airflow including the interactions between mechanical ventilation, infiltration, and duct leakage and is usually applied to residential buildings. See the SingleFamilyHouse_TwoSpeed_ZoneAirBalance.idf file for example.

The input objects described in this section are further explained in the InputOutputReference under the heading "Group-Airflow."