The housebuilding standard is changing rapidly due to the Ecodesign directive because the use of energy is more and more limited. Less energy consumption can be achieved step by step with tighter and better-insulated houses. These new houses cause a change of living as well. New houses demand new responsibilities, for instance, to ventilate. It is not easy for people to get used to this! The result of poor ventilation is bad indoor air quality and very often high humidity.
The safest way to ensure right ventilation is to install a residential ventilation system that extracts used air, odour, exhalations from furniture, paints, etc. and humidity in wet rooms like bathrooms or kitchens.
At cold outdoor temperatures, the outside air has low water content and during heating, the relative humidity (RH) will decrease rapidly (outside air at -10°C and RH of 90%, warming up to 20°C the RH decreases down to 10%!). Mixing constantly dry supply air with indoor air in wintertime the indoor air humidity can go down to an uncomfortable and unhealthy level. It is not unusual to have RH indoors of 20% or even lower which is much too low.
Why is it now sometimes necessary to limit the moisture recovery as well?
Nowadays a new challenge is coming up: there is often no time for investors to dry out the newly built houses during the first winter! Therefore in more and more countries due to the development of house standard, we are faced with too high humidity indoors.
You can count on problems caused by too high humidity:
We know that an RH above 60% increases the growth of mould and mould damages the building and causes allergies. That means in some cases we have to take care of the moisture transfer as well. The engineers from Systemair uses the possibility of rotor speed control with the new EC rotor drive to decrease the moisture transfer when needed. Therefore we have added a humidity sensor and EC rotor drive together with the new SAVECair control in all rotary units to offer these functions to all our users. This helps a lot to keep the indoor humidity in a comfortable range.
Humidity transfer is also possible with the alleged enthalpy counterflow exchangers but they cannot control it. Best possible influence on indoor air quality is given by our new units with clean, filtered air, comfortable temperature and a humidity level that helps to keep well.