Development and validation of a new method for determining humidification and dehumidification needs

The use of ventilation systems in buildings is increasing. In buildings such as libraries and museums, ventilation systems have been used to maintain optimal hygrothermal climatic conditions for important and extremely rare artefacts. Ventilation systems are now increasingly used for normal purposes in residential and commercial buildings. In cool temperate climates such as in Austria, winter exterior air is very dry. Because of dry outdoor air, when using a ventilation system in winter with constant air exchange, the relative humidity of indoor air is often under the comfort limit, requiring air humidification. In the summer, the same rooms must be dehumidified due to excess air humidity. Air humidification and dehumidification are processes that consume a large amount of electricity and humidification and dehumidification requirements should therefore, be minimized. Until now, the amount of necessary humidification or dehumidification has been undefined and could not be calculated easily. This paper presents a new simplified method for identifying the humidification and dehumidification needs taking into account the effective moisture capacity of a room. This model will be integrated into the Austrian energy certification program. The moisture capacity of a room was obtained in the course of the investigation presented in , using measurements from a number of different materials that were used as humidity buffers. For the moisture coupling of room to building components, an analytical solution was developed and presented in .