Effect of solar radiation and humidity on the inner core of walls in historic buildings

•Monitoring constructions materials by means of wireless sensor networks.•Solar radiation and humidity effects in historic buildings of Cultural Heritage.•The impact of outdoor conditions on the inner wall and microclimatic conditions.•Relationship between thermal lags and tendencies with comfort inside the buildings.

The structure of historic buildings and the materials used in their construction, along with outdoor conditions, affect indoor temperature and humidity. The walls of San Juan Bautista Church at Talamanca de Jarama, Madrid, Spain, exhibit differences in water absorption, whose explanation is to be found in the various types of construction involved in its over seven centuries of building history, the weather conditions and the walls orientation. The south wall fluctuations in inner temperature and humidity produce 11–16 h thermal lag and a very low decrement factor ensuring comfortable interiors all year round with minimal fluctuations in temperature.