The Fini fresh air fan has been revised, optimised and also equipped with a filter element consisting of five layers. This has increased the air purification efficiency to 99.9 per cent. An electric motor with frequency converter saves more energy, while the heat exchanger has an efficiency of 90 per cent. Thanks to the multidimensional design, the air purifier operates in the range of 28 dB, which is roughly equivalent to the ticking of an alarm clock and thus comparatively quiet.