Energy efficiency is one of the key elements at each home. Nowadays, houses are built of materials with a very good thermal insulation. Unfortunately, such solutions have an adverse impact on humidity and the discharge of the used air, what may result in the formation of mould and fungi in the corners of the rooms. In hermetic houses, a previously used gravitational ventilation does not fulfil its task any more, and the use of extraction ventilation results in the consumption increase of energy (even by 40%) needed for heating the air supplied from the outside. The best solution here is to use a ventilation system with recuperation; thus, it is possible to decrease the ventilation heat losses even 10 times.