Implementation of comfort-based air-handling unit control algorithms

Recent research has demonstrated that comfort-based control of HVAC systems gives superior performance over conventional set-point control in terms of human comfort and energy utilization. The idea of using predicted mean vote (PMV), based on P.O. Fanger's equation, as the reference to develop a control strategy for a residence was proposed in 1991. The authors have implemented this control concept in detail on an air-handling unit model. One major element in realizing this idea was the recent introduction of an economical electronic comfort sensor in the marketplace. In this paper, the PMV value has been integrated as the major control parameter in the control algorithms, which consider the indoor ambient temperature, relative humidity, localized air movement and mean radiant temperature, and metabolic rate and clothing of occupants. A typical office compartment is air-conditioned by a standard air-handling unit (AHU) under both conventional set-point and the new comfort-based control algorithms. Detailed mathematical models of all components in the simulation program are included in this paper so that interested researchers can reference them during further studies to test the new control scheme, not just for an office compartment, but for the whole building. In order to demonstrate the beauty of the newmore » control algorithms, simulations have been carried out under two typical weather conditions in Hong Kong, which is normally hot and humid, i.e., sunny and overcast. The emphasis is placed upon summer operations as summer accounts for the major energy consumption with respect to air-conditioning in Hong Kong. Results have proved that comfort-based control can provide the occupants with a very comfortable indoor environment. For energy consumption, it really depends on the weather conditions, e.g., higher consumption on a sunny day and lower consumption on a cloudy day, and the building type as well. The basic philosophy of this new control scheme is to supply what is required, and waste is minimized.« less