Authors considered the thermal inertial properties of some building envelope constructions which included the changes of internal surface layer materials. Researchers described the thermal and physical characteristics of 6 building surface layer materials. It has been determinate the radiant temperature of building envelope inside surface with changes of wall construction after 225 hours cooling process and initial temperature equal to +23 оС. Authors defined the cooling time of building envelope inside surface to 0 оС at different types of surface layer materials. Numerical experiment was done with modern program complex “Stf”. Modeling process was completed in program which was realized with finite difference method and constant heat transfer coefficient. There are new experimental results which were determinate during the research and realizing the mathematical model of non-stationary element’s cooling process. Results could be interested for researchers of thermal phenomena in building envelopes and designers of microclimate engineering systems in buildings and structures.

Keywords: air temperature, radiation temperature, stationary regime, non- stationary regime, building envelope, emergency regime, thermal inertia, inside surface layer, program, building materials