Air Leakage Rate refers to the measurement or quantification of the amount of air that leaks into or out of a building per unit of time. It represents the rate at which air infiltrates or exfiltrates through gaps, cracks, openings, or other pathways in the building envelope.
The Air Leakage Rate is typically measured in units of cubic meters per hour (m³/h) or cubic feet per minute (CFM). It provides a quantitative value that indicates the volume of air leakage occurring within a specific time frame.
Measuring the Air Leakage Rate is crucial for assessing the airtightness of a building and evaluating its energy performance. It helps identify areas of concern, quantify the extent of air leakage, and guide air sealing efforts to improve energy efficiency and indoor comfort.
The Air Leakage Rate can be determined through various methods, such as blower door tests or air leakage tests. These tests involve pressurising or depressurising the building and measuring the airflow rate required to maintain a specific pressure difference. The test results provide an indication of the air leakage rate and may be reported as the air changes per hour (ACH), the Leakage Rate Index (LRI), or the airflow in cubic meters per hour or cubic feet per minute.
By addressing and reducing the Air Leakage Rate, building owners and professionals can enhance the energy efficiency, minimise heating and cooling loads, improve indoor comfort, and promote better indoor air quality by controlling the infiltration of outdoor pollutants, allergens, and moisture.