Légcsereszám

Légcsereszám, meaning "air exchange rate" in Hungarian, is a crucial concept in building science and ventilation. It quantifies the number of times the entire volume of air within a building is replaced by fresh outdoor air in one hour. This rate is typically expressed in units of air changes per hour (ACH).

A higher légcsereszám indicates more frequent ventilation, which can be beneficial for removing indoor air pollutants, controlling humidity, and preventing the buildup of odors. This is particularly important in tightly sealed modern buildings, which often have lower natural infiltration rates. Mechanical ventilation systems, such as exhaust fans, supply fans, or heat recovery ventilators (HRVs), are commonly used to achieve specific légcsereszám targets.

Conversely, a very high légcsereszám can lead to excessive heat loss in colder climates and increased energy consumption for heating and cooling. Therefore, achieving an optimal légcsereszám is a balance between maintaining good indoor air quality and minimizing energy waste. Building codes and standards often specify minimum légcsereszám requirements for different types of buildings and spaces to ensure occupant health and comfort. Factors influencing légcsereszám include building design, airtightness, occupant load, and the operation of ventilation systems.