Experimental Study of Unsteady Heat Transfer and Thermal Inertia of Ventilated Facades Under Solar Heating

Abstract

This study presents a comparative analysis of the thermal performance of a multilayer building envelope based on three research stages. The results show that the effect of accumulated heat transfer to the following day is not observed due to complete nighttime heat release. Quantitative analysis revealed a significant influence of solar radiation and air layer geometry. During peak hours, the cladding temperature exceeds the ambient temperature by 18-22°C under solar exposure. A pronounced thermal inertia effect is observed for eastern orientation, where the inner surface temperature exhibits a phase shift of 4-6 hours relative to the morning heating of the outer surface. Variation of the air gap configuration showed that doubling the inlet opening increases temperature by 1,5-2,0°C, while a closed configuration leads to overheating of 6-8°C for the cladding and 3-4°C for the inner surface, justifying the need for ventilation gap optimization.