How much power do the ventilation fans use?
The power consumption of both fans amounts to about 50 watts in a middle-sized detached house.
In case of continuous operation during the heating period (for example 180 days) the power costs amount to 32 Euros at an electricity rate of 15 cents/kWh. The gain in comfort of an all-the-year operation hence costs additional 32 Euros.
The energy efficiency ratio (provided energy in relation to the used electrical energy), of the system Avent B95 for example, amounts to 15 on average. This means that the recovered energy is as 15 times as much as the electrical energy used. The average primary energy saving thus amounts to about 75 %.

