When dealing with the indoor microclimates of cultural and historical heritage cult buildings, it is important to know the types of these buildings by their spatial volumes and by the types of enclosing structures, and it is also important to understand the moisture transfer processes in these buildings, which would allow one to generate solutions on how to more effectively control the indoor microclimate. Due to the antiquity and specific load of these buildings, the existing standards are not applicable. This study summarizes 275 churches in Latvia, dividing them both according to five spatial volumes and according to the types of the materials used, which makes it possible to create potential air flows for all spatial volumes and to predict condensation risks in the future. Additionally, the results of temperature and humidity measurements in two different churches from one region of Latvia are given and the absolute humidity was calculated, and the data were analyzed depending on the outside air temperature. These measurements have yet to be followed up with the data of a full year.

There are 320 historical cult buildings as cultural monuments of national significance in Latvia. Cultural and historical art monuments and artifacts (paintings, organs, chairs, altars, pulpits) must be preserved and protected in these cultural buildings. Specific indoor climate is necessary to maintain in historical cult buildings to pass on to future generations, but those specific requirements often are complete opposite of the actual microclimate and what the user wants. Indoor climate measurements have been carried out in five brick wall and two wooden churches with and without heating systems. Potential condensation risks are determined using calculations. Typical air flow has been formed using building’s termography measurements. Heating systems and making use of buildings influence historical buildings and this has been determined. The main aim of the article is to determine potential indoor climate type of control in historical cult buildings avoiding humidification and dehumidification, and it is similar in the coastal climate of the Baltic Sea. Results show that: great humidity fluctuations have been observed in buildings which have been used during winter, outdoor air has a great impact to buildings, less humidity fluctuations have been observed in buildings with controlled heating systems.