The Leakage Flow Coefficient, also known as the Flow Coefficient or simply C-factor, is a parameter used to quantify the air leakage characteristics of a specific building component or an entire building system. It represents the amount of air that can pass through a particular opening or pathway under a given pressure difference.
The Leakage Flow Coefficient is typically expressed in units of cubic meters per second per Pascal (m³/s·Pa) or cubic feet per minute per square foot per inch of water (CFM/ft²·inH2O). It provides a standardized measure of the airflow rate through a component or system, considering both the size and geometry of the leakage path.
By measuring or estimating the Leakage Flow Coefficient, it is possible to assess the expected air leakage performance of a building or component. This information is useful for evaluating energy efficiency, estimating heating and cooling loads, and designing effective ventilation systems.
The Leakage Flow Coefficient is influenced by various factors such as the size of the leakage opening, the pressure difference across the component or system, the shape of the opening, and the properties of the surrounding materials. It is often determined through laboratory testing, numerical simulations, or by referring to published data and standards.
Understanding the Leakage Flow Coefficient allows building professionals to make informed decisions about air sealing strategies, ventilation system design, and the selection of appropriate building components to achieve desired energy efficiency, indoor air quality, and occupant comfort.