Adaptive Hierarchical Fuzzy controller for HVAC Systems in Low Energy Buildings

Proper control for low energy buildings is more difficult than conventional buildings due to their complexity and sensitivity to operating conditions. In this paper, Adaptive Hierarchical Fuzzy control is used to control Heating, Ventilating and Air Conditioning (HVAC) System which is time varying nonlinear system. The proposed Controller is capable of maintaining comfort conditions under time varying thermal loads. Adaptive Hierarchical Fuzzy is consist of two levels; first fuzzy level is to control (Air temperature and Air quality); the second fuzzy level is to control the Error and Change of Error that comes from first level. A hierarchical structure is used to reduce the number of rules, trim redundant information and reduce the computing time required for the optimization. The controller is developed using a computer simulation of a virtual building contains most parameters of a real building. Fuzzy rules are learned from experts and system performance observations. Matlab program is used to simulate HVAC system and to see the results of the new controller.