On the Development of a Thermal Comfort Control for Classrooms Conditioned by Split-Type Systems

Abstract

Abstract Thermal comfort conditions may vary substantially within an air-conditioned room equipped by split-type systems. In this work, the comfort conditions in a classroom were evaluated experimentally based on the PMV index, according to ISO 7730 Standard that defines the thermal satisfaction in occupied environments. The experiment was carried out at three different supply airflows (high, medium and low) and three set-point temperatures (23, 24 and 25°C). The results showed that there is a considerable variation in the air velocity field in the room as well as in the PMV values for three different supply airflows, consequently significant changes of thermal comfort indices can be noticed. Several curves were adjusted aiming to express the values of PMV, deriving a simplified comfort index for rooms conditioned by split-type systems based on dry-bulb air temperature and air speed. The purpose of this adjustment is to obtain an equation that provides the value of the comfort index for cooling purposes. Thus, for a certain condition of use, one can predict what will be the value of PMV in an occupied environment, enabling the implementation of a control system of the comfort according to this new index (ICS). The variables considered in obtaining the curve were the air temperature (Tar) and the air velocity (Var), since these two variables can be controlled directly by the split-type system. The general purpose of this work is to provide experimental data for the development of a low-cost device to automatically control ICS-based thermal comfort in a space conditioned by a split-type system through a single and representative point within the classroom.