Ventilation
Recommendations for efficient ventilation
Ventilation provides for fresh air in the rooms. Approximately a half of the air volume should be exchanged in one hour in each habitable room. In winter much heat can escape from the room during ventilation. On the other hand, in summer months hot air from outside can get into rooms we do not want to. This can be efficiently avoided by natural or forced ventilation.
Natural ventilation
Natural ventilation, i.e. opening of windows provides fresh air in the room but at the same time a lot of heat escapes from the room. Therefore, short, intensive ventilation is recommended in every season. If the windows are wide open for one – two minutes the ventilation is much more efficient than long ventilation by slightly open windows. In winter, it is only the air in the room that is cooled down but the inside walls and things stay warm (not enough time to cool them down). On the contrary, long ventilation, for example by a slightly open window, is very inefficient. This leads to the undesired cooling of the floor in winter.
Forced ventilation
Forced ventilation is provided by fresh air supply through ventilation technology. A very efficient solution in case of forced ventilation is the installation of a recovery unit which can adjust the features of the supplied air such as temperature and humidity. Recovery unit is a ventilation device which uses the heat from the waste air for the heating of the fresh air with an efficiency of ca. 70 % of sensible heat. The recovery system is usually combined with the heating system which supplements a part of the heat losses of buildings and additionally heats the air, if necessary. Forced ventilation with recovery can save you 20 to 25 % of the total heating costs. Recovery units are often used in passive houses where artificial ventilation is necessary. The external cladding of passive houses has minimum air permeability due to a high thermal insulation coefficient and ventilation through windows is inefficient in winter. Controlled ventilation provides for a regular air exchange in the house, stable humidity and cleaner air thanks to an efficient filter, which is convenient especially for people allergic to dust.
