> For the complete documentation index, see [llms.txt](https://docs.betterbuilding.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.betterbuilding.io/user-guide/workflows/designer-mode/airflow-networks/airflow-networks-definitions.md). # 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. | | --- # Agent Instructions This documentation is published with GitBook. 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