Empirical model of hygrothermal behavior of masonry wall under different climatic conditions using a hot box

Abstract

In this work, the evaluation of a solid block wall is presented to obtain an empirical model that relates the global heat transfer coefficient (U-value) with temperature and vapor pressure, the latter variable associated with relative humidity. To evaluate the hygrothermal behavior of the sample, a hot box was designed, built, and instrumented. The hot box was calibrated using a reference sample of extruded polystyrene plate to quantify the heat gains through its envelope. The solid block wall sample was evaluated in three configurations: simple wall (B), wall with a mortar coat (RB), and a wall with a mortar coat on both sides (RBR). As a result, three empirical models were obtained to determine the U-value. The temperature was the variable with the most significant influence on the determination of this parameter. The models were applied under six different climatic conditions, identifying the hygrothermal behavior of each solid block wall configuration. The RBR configuration was the one that presented the lowest heat gain for cities with a warm-humid climate with a U-value of 4 W m−2 °C−1, while the highest heat gain was obtained with the RB configuration in dry weather. The obtained empirical models allow selecting the appropriate configuration for a specific geographic location, according to the user needs.