Untitled Quiz

The process of unwanted air entering or leaving a building through cracks and openings.

How air leaks are spread throughout a building's envelope.

Techniques for quantifying the amount of air entering or leaving a building.

Air leaking into or out of a building through openings.

Openings, flaws, or gaps in a building's exterior shell that allow for air transfer.

Basic principles governing the flow of air.

Maintaining the temperature in a building effectively while minimizing energy consumption.

Methods to determine the volume of air leaking.

The process of unwanted air entering or leaving a building through openings and cracks in the building envelope.

Air movement induced by mechanical systems, such as fans or range hoods.

The continuous, enclosed exterior of a building composed of walls, roof and windows. This is what outside air encounters before entry.

Ventilation system removes air from a building.

Determining the amount of unwanted air flow into or out of a building.

Openings in a buildings envelope that allow air to enter or exit.

Difference in air pressure between inside and outside of the building.

A dimensionless number that predicts whether fluid flow is laminar or turbulent. It's calculated based on fluid velocity, density, viscosity, and the characteristic length of the flow path.

The amount of air leakage through cracks and openings depends on various factors like pressure difference, crack geometry, air velocity, and fluid density.

The first term in the airflow equation represents the geometry of the crack or duct. It's the part of the equation that describes the shape and size of the opening through which air passes.

The second term represents the properties of the air itself, such as density and viscosity. It accounts for how easily the air flows through the opening.

The third term in the airflow equation represents the pressure difference driving the air flow. It's the force that pushes the air through the opening.

The flow regime, whether laminar or turbulent, determines frictional losses within the flow. This affects the pressure difference needed to maintain the same flow rate, influencing the overall airflow equation.

The airflow equation has three terms: one for the geometry of the opening, one for the properties of the air, and one for the pressure difference driving the flow.

The air infiltration equation is based on the airflow equation, with additional terms related to the pressure difference, the shape of the opening, and the properties of the air. It accounts for the specific characteristics of air infiltration into buildings.

A formula used to calculate airflow through openings, like cracks in a building. It considers the area of the opening, the pressure difference across it, and the air density.

A factor that accounts for the real-world imperfections of an opening, making the calculated airflow more accurate.

The actual area of cracks and openings in a building's envelope that air can pass through, measured by a blower door test.

A type of fluid flow that occurs in narrow cracks, where the air moves in a parallel pattern due to viscosity.

Because the flow through sharp-edged openings is mostly turbulent, the Reynolds number, which indicates the flow regime, doesn't significantly affect the discharge coefficient.

Due to variations in pressure differences across cracks and openings, as well as different geometries, the Cd value can vary significantly.

A blower door test is used to calculate the ELA by measuring the air flow rate under a specific pressure difference.

Sharp-edge orifices have turbulent flow characterized by the Standard Orifice Flow Equation, while small cracks exhibit laminar Couette flow.

The pressure difference caused by temperature variations between indoor and outdoor air, leading to density differences and pressure gradients.

Stack pressure is caused by the difference in density between indoor and outdoor air. This difference is due to temperature variations.

Air infiltration can increase energy consumption by allowing heated or cooled air to escape, make the building uncomfortable, and potentially introduce pollutants.

Measuring air infiltration helps identify areas of leakage, understand building performance, and determine the effectiveness of insulation and sealing measures.

Air infiltration is influenced by factors such as wind speed, building design and construction, temperature differences, and the presence of cracks and openings.

Unwanted air flow entering or leaving a building through cracks and openings in the building envelope.

It creates a negative pressure inside the building, drawing air out.

It creates a positive pressure inside the building, forcing air in.

Wind pressure, stack pressure (due to temperature differences), and pressure from mechanical ventilation systems.

By adding up the pressure contributions from wind, stack, and mechanical ventilation, taking into account their signs (positive or negative).

The height at which the internal and external pressures are equal, resulting in no air infiltration.

A graph showing the relationship between airflow and pressure for a specific fan.

A graph showing the relationship between pressure difference across the building envelope and the resulting airflow.