Review of in situ methods for assessing the thermal transmittance of walls

Reducing the energy requirements of buildings is essential in order to address anthropogenic global warming. Among the various factors affecting the energy requirements of buildings, the thermal transmittance of the walls is critical in understanding heat loss. It is therefore necessary to assess the thermal transmittances carefully in order to develop effective means of energy conservation. Although various theoretical methods and methods using in situ measurements are available for this purpose, the correct use of such methods depends on many factors. In a detailed review of more than 150 publications (scientific papers, congress reports, books, and other documents), the best-developed methods in use by researchers and professionals are analysed. These methods are as follows: the theoretical method, the heat flow meter method, the simple hot box-heat flow meter method, the thermometric method, and the quantitative infrared thermography method. This review is intended to be a useful resource for researchers and professionals in that it covers the fundamental theoretical background, the equipment and material required for in situ measurements, the criteria for installing the equipment, the errors caused by metrological and environmental aspects, data acquisition, data processing, and data analysis.