Further development of a thermal comfort based fuzzy logic controller for a direct expansion air conditioning system

The primary purpose of A/C is offering occupants with acceptable indoor thermal comfort levels. Thermal comfort is a complicated result of non-linear interactions between six parameters. However, many of current A/C systems solely control air temperature. Whenever anyone of the five parameters other than temperature varies significantly, an occupant may feel thermally uncomfortable. To address the issue, a comprehensive thermal comfort index should be used as regulator in A/C systems.& para;& para;One fuzzy logic controller is available. However, the approach to the fuzzy logic controller is complicated. In this paper, one previous established fuzzy logic controller is simplified for its real application. Test results demonstrated that the simplification would not reduce the control performances in terms of control accuracy and sensitivity. A local fan was installed in the conditioned space to act as personalized ventilation. It is shown that at the same thermal comfort level, about 4-7.6% energy saving of the A/C system could be achieved when a higher local fan speed was used. With simplifications, the thermal comfort based fuzzy logic controller has a high potential of commercialization. It can contribute to the realization of low carbon A/C systems while improving indoor thermal comfort for building occupants.