OXeN is a heat recovery ventilation system which is simpler and more economical than all other similar products. OXeN reuses energy recovered from ventilation of a building and therefore can save up to 74-94% of the energy normally used. It was designed especially for large spaces like production halls, warehouses, exhibition, sport and commercial facilities. In comparison with existing solutions it is ductless, independent and compact. It has an innovative, light and fully recyclable EPP housing. These features allow OXeN to be mounted fast and easy and significantly reduce the elements needed for a proper ventilation system.