Airflow Networks Definitions
Term | Definition | Units |
Airflow Network Model | A simulation method in EnergyPlus that calculates the airflow through building components and zones based on pressure differences. | - |
Node | A point in the airflow network where air properties like temperature, pressure, and humidity are defined. | - |
Linkage | A connection between two nodes that represents a pathway for airflow, such as through a door, window, or duct. | - |
Zone | A space or collection of spaces within a building with uniform air properties used in airflow calculations. | - |
Surface | The physical boundary in a building, such as walls, floors, ceilings, and roofs, that interact with airflow. | - |
Pressure Coefficient (Cp) | A dimensionless number that characterizes the effect of wind pressure on building surfaces. | - |
Crack | A small opening in the building envelope that allows uncontrolled air leakage, typically due to construction imperfections. | - |
Opening | A controllable opening like windows, vents, or doors that can be adjusted to regulate airflow. | - |
Infiltration | Uncontrolled air leakage into a building through cracks, gaps, or openings in the building envelope. | m³/s |
Ventilation | Controlled air exchange between the building and the external environment, which can be natural or mechanical. | m³/s |
Exfiltration | Uncontrolled air leakage out of a building through cracks, gaps, or openings in the building envelope. | m³/s |
Mechanical Ventilation | The use of mechanical systems, such as fans and ducts, to supply, distribute, and exhaust air within a building. | m³/s |
Natural Ventilation | The process of supplying and removing air through natural forces like wind pressure and thermal buoyancy, without mechanical assistance. | m³/s |
Airflow Path | The route taken by air as it moves through the airflow network, including through openings, ducts, and around obstacles. | - |
Local Wind Pressure | The wind pressure exerted on specific building surfaces, which varies with wind speed, direction, and building geometry. | Pa (Pascals) |
Air Distribution System | The network of ducts, vents, and registers that distributes conditioned air (heated, cooled, or ventilated) throughout the building. | - |
Stack Effect | The movement of air into and out of buildings due to temperature differences between the indoor and outdoor environment, creating pressure differences. | Pa (Pascals) |
Wind-Driven Ventilation | Natural ventilation driven by wind forces, where the wind creates pressure differences across the building envelope, promoting airflow. | m³/s |
Buoyancy-Driven Ventilation | Natural ventilation driven by buoyancy forces, where warmer air rises and cooler air enters the building to replace it, creating airflow. | m³/s |
Duct Leakage | Air leakage from ducts in the air distribution system, which can lead to energy losses and reduced system efficiency. | m³/s |
Effective Leakage Area (ELA) | A measure of the total area of all leaks in a building envelope, standardized to a reference pressure difference, indicating the tightness of the building. |
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