Experimental evaluation of insulation materials for walls and roofs and their impact on indoor thermal comfort under composite climate

Better insulation having low thermal conductivity is a significant contributor for new construction and retrofitting existing buildings, when the emphasis is on energy efficiency. The objective of the study is to determine the impact of the thermal insulation materials in buildings enabling effective energy savings with minimal occupation of space. Although, the Energy Conservation Building Code (ECBC), India defines the prescriptive and mandatory requirements for the U-factor and R-value but the way to achieve these values is left to the designer and there is no published data on these values. To accomplish these objectives, the experiments for computation of thermal resistance and over all heat transfer coefficients have been carried out by measuring the thermal conductivity of the various types of materials available in the Indian market having different thicknesses by Automatic Guarded Hot Plate Apparatus. One hundred and twelve combinations of wall and roof sections have been computed and compared with different thicknesses of insulating materials for determining U-factor and R-value to satisfy ECBC requirements. The results of the study show that 50 mm thick Elastospray with conventional roof and wall satisfy the ECBC requirements whereas, other insulation materials require higher thickness to fulfill the recommended values. To validate the results, two prototype buildings are constructed at CSIR–CBRI campus; one with conventional burnt clay brick wall, reinforced cement concrete roof and 50 mm thick outside thermal insulation and the other without insulation. The results of the winter and summer season for six months are presented.