afluft

Afluft is a Danish term for exhaust air or air removed from a space as part of a ventilation system. It describes the portion of air that is extracted from rooms to outside to remove heat, humidity, odors, or pollutants. In HVAC design, afluft is contrasted with tilførsel, the fresh or supply air that is brought into the space. Afluft can be produced by fans or natural ventilation. Mechanical afluft systems use exhaust fans connected to ducts leading to roof or exterior walls; natural afluft relies on pressure differences and openings.

The rate of afluft is expressed in liters per second or cubic meters per hour and is selected to maintain indoor air quality and comfort while balancing energy use. In balanced systems, the afluft rate matches the tilførsel rate, with heat recovery sometimes employed to reduce energy loss. In kitchens, bathrooms, and industrial facilities, afluft typically represents the portion of ventilation that governs humidity and odor control.

In building codes, afluft requirements may specify maximum allowed pressure differences, noise levels, and duct sizing. The term may also appear in processes outside buildings, where air is evacuated in a controlled manner from a chamber or reactor.