THERMAL RESPONSE OF BUILDING MATERIALS AND COMPONENTS UNDER HOT AND HUMID CLIMATES

Abstract

An experimental investigation to determine the thermal performance of building sections under realistic conditions is reported. The results are compared with laboratory test data and analytical predictions. The first chapter reviews the methods used in the past to study the heat flow through building walls. Mathematical models used for predicting heat flow are described in chapter 2. Chapter 3 describes the calibration and use of the guarded hot box to test wall specimens under steady-state conditions. The design and fabrication of a calorimetric plate to test building walls subjected to actual outdoor weather conditions is described in chapter 4. The three different walls tested are: an actual laboratory brick wall, a ferrocement wall and a gypsum board/glass wool partition wall. The brick wall, being an actual wall, is tested in-situ while the other two wall specimens are tested outdoors. The actual heat flows measured using heat flow sensors are compared with predictions made based on two mathematical methods, namely, the Duhamel's method and Finite Difference method. For the partition wall, use of steady-state overall heat transfer coefficients to predict the heat flow for the transient case based on the wall temperature difference is also investigated. The brick and ferrocement walls exposed to actual or simulated rain are also tested. For the wet tests, the moisture evaporation from the wall outer surface after wetting is used to predict the heat flow and the results are presented in chapter 5. Overall results show that the predicted and actual heat flows agree well and that the reduction in heat flow through a wall caused by rain is due to (i) the initial cooling by rain water and (ii) evaporative cooling due to water evaporation from the wall surface after rain. The former has been shown to be a much more significant cause of heat flow reduction.