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Thermal transmittance assessment of building walls by using in-situ infrared thermography

Sayın, Murat
The main concerns of the study are the thermal transmittance (U, Wm-2K-1) assessment of building walls by quantitative analyses of surface temperature data obtained by infrared thermography (IRT) and the identification of thermal failure types in terms of measurable parameters. Mainly six types of non-insulated and insulated wall compositions belonging to three different buildings were examined. The actual thermal performances of the walls (UINSITU) determined with in-situ quantitative IRT (QIRT) was assessed in comparison with their theoretically-expected thermal transmittance values (UCALC) calculated with standard methods. The progress in thermal resistance of one type wall with thermal insulation treatment was monitored with in-situ QIRT investigation and the estimation annual heating energy consumption of the building (θ, kWh). Thermal failures, which weaken the thermal resistivity of a wall, were identified in terms of temperature index, TI (unitless). Adverse impact of thermal failures was examined with the comparison of thermal transmittance values belonging to the problem area (UDEF) and reference area (UREF). The actual thermal performances of the existing walls were determined to be poorer than the theoretically-expected performances. The walls designed with low thermal resistance were observed to be highly-susceptible to thermal failures resulting in considerable heat loss. In-situ use of QIRT allows practically-assessing and monitoring the actual thermal performance of building walls in terms of thermal transmittance and that makes this method preferable for the studies on Energy Performance Certification (EPC) of buildings. The common use of QIRT in the studies of building diagnostics and monitoring has to be encouraged.