luftutbyte

Luftutbyte, literally “air exchange,” is a term used to describe the transfer of air or gases between two compartments. It is applied in both biology and building science to refer to how gases move across interfaces, and to how ventilation systems control airflow between indoor spaces and the outdoors.

In physiology, luftutbyte describes gas exchange in living organisms. The best known example occurs in the lungs, where oxygen from inhaled air diffuses into the blood, and carbon dioxide diffuses from blood to be exhaled. This diffusion depends on partial pressure differences, the surface area of the exchange membranes, and the rate of ventilation. Gas exchange also occurs in other tissues and in plants, where stomata regulate the exchange of CO2, O2, and water vapor.

In the context of buildings and indoor environments, luftutbyte refers to the exchange of indoor air with outdoor air. It is quantified by metrics such as air changes per hour (ACH) or volumetric flow rates. Adequate luftutbyte supports indoor air quality by diluting and removing pollutants, excess moisture, and carbon dioxide, while also affecting thermal comfort. Insufficient exchange can lead to poor air quality and health issues, whereas excessive exchange can raise energy use and cause drafts.

Measurement and design methods include tracer gas techniques, CO2 decay testing, and ventilation modeling. Standards and guidelines specify appropriate luftutbyte levels for different settings, such as residences, offices, healthcare facilities, and laboratories, balancing health, comfort, and energy efficiency. The term encompasses a fundamental concern across disciplines: how efficiently gases are moved between spaces to sustain life and maintain healthy environments.