Lufttillluft

Lufttillluft is a term used in ventilation and heating, referring to systems that recover energy by transferring heat between the outgoing indoor air (frånluft) and the incoming outdoor air (tilluft). The aim is to reduce energy use for heating or cooling while maintaining adequate ventilation and air quality.

The most common mechanisms are plate heat exchangers, which transfer sensible heat through solid plates without mixing the air streams, and rotary heat wheels (enthalpy wheels), which can transfer both heat and moisture. Some systems use energy recovery wheels that combine heat and humidity transfer. The choice of technology affects efficiency, pressure drop, and the potential for moisture transfer.

Lufttillluft systems are widely used in mechanical ventilation with heat recovery in residential, commercial, and institutional buildings. They are central to MVHR (mechanical ventilation with heat recovery) and ERV (energy recovery ventilation) systems. In colder climates, heat recovery helps reduce heating demand; in mixed or warm climates, it can also limit cooling needs and maintain indoor comfort while ensuring ventilation.

Benefits include lower energy consumption, reduced greenhouse gas emissions, and improved indoor air quality by enabling continuous ventilation without significant heat loss. The overall effectiveness depends on the chlor entry type, system design, and climate. Limitations can include condensation and frost risk on outdoor air intakes, airflow resistance and pressure drops, the need for filtration and regular maintenance, and higher initial costs. Related concepts include MVHR, HRV, and ERV systems.