Indoor air climate requirements for Russian churches and cathedrals.

UNLABELLED: In the article a verification of indoor climate requirements for Russian churches and cathedrals and recommendations on maintenance are given. From the point of view of building physics and longevity of building materials, frescos, icons, wood, paper, leather, parchment and natural textiles are regarded as capillary-porous physical bodies partly filled with moisture which includes dissolved salts. Porosity can be divided into three groups: large, moderate and small. What happens with these physical bodies when the indoor temperature and humidity changes is that deformation occurs and this may lead to breakage. Research to determine the dependence of deformation on the humidity of the surrounding structural materials of the cathedrals was carried out by a holographic interferometer. Diagrams of humidity and temperature deformation show the following results: the graphics of humidity and temperature are alike, the temperature deformations are not extensive, deformation due to humidity is more serious than deformation caused by temperature. The investigations of temperature and humidity deformation made it possible to give recommendations for the level of indoor air temperature and humidity in cathedrals. On the basis of these investigations, the Russian standard "Orthodox temples. Heating, ventilation, air conditioning" was developed (ABOK, 2002). PRACTICAL IMPLICATIONS: Temperature and humidity changes can affect building materials and the building structure. In the case of Russian cathedrals and churches, traditional artefacts are also affected.