Energy-efficient microclimate formation in a historical religious monument building with wall paintings

In order to preserve complex historical objects with unique architectural, engineering solutions and monumental art that are of cultural and historical value, the task of maintaining the microclimate parameters determined by museum specialists is relevant. The object of the study is St. Sophia Cathedral – a monument of architecture, history and monumental painting of national importance, which is a UNESCO World Cultural Heritage Site. The location of it in the city centre determines the influence of adverse outdoor conditions, in particular, high air pollution, and the attraction of the site – a high level of attendance and, as a result, dynamic changes in the indoor parameters of the air environment. The existing regime of heat, moisture and gases in the St. Sophia Cathedral is periodic with characteristic maxima of temperature and relative humidity values in different areas of the building when people visit it. Three series of natural studies of the air environment parameters in the Cathedral were carried out. The first series was held on 02 October 2019 at an outdoor temperature of plus 18.9 °C and a relative humidity of 47.5 % with the ventilation system turned off and on before the start of the heating season. The second series of measurements was carried out on 12-14 November 2019 at an outside air temperature of plus 8.9 °C and a relative humidity of 73 % with the ventilation turned off and the heating turned on. The third series of measurements was carried out on 08 February 2020 at an outside air temperature of minus 3.2 °C and a relative humidity of 56.2 % with ventilation off and heating on. An analysis of the results indicates the need for reconstruction and modernization of the engineering microclimate systems and heat supply of the Cathedral. Currently, the physical deterioration of heating and ventilation systems is 75-85%. They need immediate reconstruction and change of operating mode. Taking into account the performed field studies, a project for the modernization of heating, ventilation and air conditioning systems was developed.