Udeluft

Udeluft, in Danish and Norwegian, refers to air drawn from the outside environment for use in buildings. In HVAC terminology it denotes outdoor air that is supplied to indoor spaces, either directly or after conditioning. Udeluft is used to dilute indoor pollutants, dilute CO2, and support thermal comfort. It is typically managed together with recirculated air to balance indoor air quality and energy efficiency.

Source and conditioning: Udeluft enters through makeup air systems and is filtered and conditioned—heated or cooled, humidified or dehumidified—before mixing with indoor air. In energy‑efficient buildings, outdoor air may be introduced through economizers when conditions permit, or via energy recovery ventilation that transfers heat or moisture between outdoor and exhaust air, reducing energy penalty.

Standards and considerations: Outdoor air fractions are guided by IAQ standards such as ASHRAE 62.1 or EN 16798-1. Controls include dampers, sensors, and variable air volume systems to adjust the outdoor air rate based on occupancy and air quality. Outdoor air must be clean enough to avoid introducing pollutants; filtration, preconditioning, and monitoring are common. In polluted or pollen-heavy environments, outdoor air management is especially important.

Notes: Udeluft is a common term in Nordic HVAC literature and is often contrasted with recirculated air. While providing ventilation benefits, increasing outdoor air can raise energy use, leading to design trade-offs between comfort, IAQ, and efficiency.