Abstract
Meet the requirements of regulating temperature, humidity and fresh air inside the buildings is not cost-effective due to high energy consumption (EC). In this study, a control system based on proportional-integral-derivative (PID) controllers was installed for mixing the supply air and return air in two strategies including installing phase change material (PCM) and a new layout for air intake from the return air were introduced for a constant air volume air handling unit (CAVAHU). Considering a setpoint of 25 ?C, the reference CAV-AHU was devised by the summer multiple design months technique, and it was observed that it is not likely to satisfy the setpoint requirement all the time. The first strategy was implemented, and it was found that although the final energy consumption declined by 15.3%, indoor temperature distribution was not acceptable. To regulate the indoor temperature, five scenarios were defined in which the share of return air utilization was variable. Establish the first scenario in a system that uses PCM provides less energy consumption by 177 Wh/m2 and better internal temperature distribution. In the second, third and fourth scenarios, the final energy consumption was reduced by as much as 404, 638 and 905 Wh/ m(2). In the best-case scenario (fifth), not only energy consumption reduction of 1277 Wh/m(2) (5.5% reduction) was achieved but also the setpoint requirement was met. The addition of PCM and the variable share of return air utilization let the designer to design a lower rated power CAVAHU (by 33%), thus reducing the initial investment cost and, in addition, the final energy consumption of the modified CAV-AHU is lower by 20%.