Ilmankulku

Ilmankulku is the movement of air within and between spaces, driven by pressure differences, temperature gradients, and mechanical systems. In English it is commonly referred to as airflow. The term is used across physics, meteorology, and building science. Etymologically, it comes from Finnish ilmankulku, combining ilma (air) and kulku (movement).

Natural airflow occurs due to wind pressure on structures and buoyancy from temperature differences, known as the stack effect. Mechanical ventilation uses fans and ductwork to supply outdoor air and exhaust indoor air, balancing indoor air quality with energy use. The patterns of ilmankulku are influenced by openings, vents, leaks, obstacles, and the relative temperatures inside and outside a space.

In practice, controlling ilmankulku is central to building design, where it affects indoor air quality and energy efficiency. HVAC engineers specify air change rates and ventilation effectiveness to ensure sufficient dilution of pollutants while minimizing energy losses. On a larger scale, ilmankulku describes wind patterns and the dispersion of airborne substances in environmental science, and in technical contexts such as automotive or aerospace engineering it refers to the behavior of air flow around bodies and components, including distinctions between laminar and turbulent regimes.