ilmanvuotoluku

Ilmanvuotoluku, often translated as air leakage rate, is a measure used in building science to quantify the amount of uncontrolled air that passes through a building's envelope. This uncontrolled air movement, also known as air leakage or infiltration/exfiltration, can have significant impacts on energy efficiency, indoor air quality, and building durability. The ilmanvuotoluku is typically expressed in terms of volume of air per unit time per unit of building surface area or volume, for example, liters per second per square meter of building envelope (L/s/m²) or air changes per hour (ACH).

Measuring ilmanvuotoluku is commonly done using a fan pressurization test, also known as a blower door test. In this test, a powerful fan is mounted in an exterior doorway, and it either pressurizes or depressurizes the building. The fan speed required to maintain a specific pressure difference (e.g., 50 Pascals) is then used to calculate the air leakage rate. A lower ilmanvuotoluku indicates a tighter building envelope with less air leakage, which is generally desirable for energy conservation and comfort. Conversely, a high ilmanvuotoluku suggests a leaky building, leading to increased heating and cooling loads, potential moisture problems, and reduced indoor air quality due to the ingress of pollutants. Building codes and standards often specify maximum allowable ilmanvuotoluku values for new construction.