Tilluften

Tilluften, or tilluft, refers to the air that is supplied to an indoor space as part of a ventilation system. It is one of the key components of building ventilation and is contrasted with fromluft, the air that is exhausted from the space. Tilluften can be outdoor air drawn from outside the building, outdoor air that has been conditioned, or a mixture of outdoor and recirculated air that has undergone filtration and treatment.

In practical terms, tilluft is delivered through ducts and diffusers from an air handling unit or ventilation system. The system controls the volume of tilluft to meet ventilation requirements, maintain indoor air quality, and support thermal comfort. Before entering occupied spaces, tilluft is often filtered to remove particulates, and it may be tempered or dehumidified to achieve a comfortable temperature and humidity.

Energy efficiency in modern systems frequently relies on recovering energy from the exhaust air (fromluft) to precondition the tilluft. Heat recovery ventilators, energy recovery wheels, or heat exchangers reduce heating and cooling loads while maintaining adequate fresh air supply. Some installations use variable or demand-controlled ventilation, adjusting tilluft flow based on occupancy, CO2 levels, or other air quality indicators.

Tilluften design considerations include appropriate outdoor air rates, filtration needs, distribution to occupied zones, and building pressurization. Standards and codes in different regions specify minimum ventilation requirements and testing procedures to ensure that the supply of tilluft supports healthy and comfortable indoor environments without excessive energy use.

See also: fromluft, ventilation, HVAC, energy recovery.