Numerical analysis of thermal transmittance of hollow concrete blocks

Abstract

Since the 1970s, due to the worldwide energy crisis, some countries have adopted severe legislation to promote energy efficiency in buildings. The electrical power utilized in buildings is directly related to the equipment required to provide thermal comfort to occupants. In this context, one of the most important factors that determine the choice of these systems is the conduction load through the building envelope. In several countries, hollow concrete blocks have become common over the past few years. Therefore, for the assessment of building energy efficiency, the thermal transmittance evaluation of hollow blocks is required. This study obtains values of thermal transmittance for different cavity configurations of concrete blocks by performing computational fluid dynamics simulations. These transmittances are compared to those calculated using the methodology presented in international standards. In the “Results” section, it is shown that large cavities provide higher transmittance values due to convection and that thermal radiation may play an important role in the overall heat transfer through concrete hollow blocks. Some methods used to reduce the thermal transmittance are presented and discussed. Finally, thermal transmittance of cavities with the same wall height has been compared with the ones of a single block and different strategies are considered for reducing the thermal transmittance of concrete hollow blocks.