Thermal Resistance of Masonry Walls—Analysis and Test Results

Testing of thermal resistance of masonry walls is very expensive and can be accomplished only on fabricated blocks. Manufacturers and designers thus need a reliable tool for the prediction of the r‐values before producing forms. The paper compares results obtained by the two common simplified computation methods with those derived from a more‐accurate three‐dimensional (30) finite‐difference thermal analysis. The paper shows that the method of combined parallel heat‐flow paths yields a better approximation to the accurate analysis than the method of series of layers perpendicular to the main heat flow. Theoretical results are also compared to data from test measurements of 18 hollow‐core blocks with side indentations and two other blocks. Computations overestimate the measured values by up to 20%. Since measurements have their own inaccuracies and uncertainties, it is concluded that a reliable conservative value can be obtained by reducing the values estimated with the 3D method by 20%.