Enhancing the Thermal Comfort and Energy Efficiency of Air-conditioning Systems for Large-scale Rooms by Integrating robust MIMO Control and Wireless Sensor Network

Description

Large-scale rooms, characterized by large volumes, are widely used in university, government and commercial buildings to provide professional accommodation for lectures, seminars, conferences and large formal meetings. To condition large-scale rooms consumes energy heavily, especially in hot regions like Hong Kong. A typical control design for the air-conditioning systems for large-scale rooms is to use a single thermostat to synchronously control all variable-air-volume (VAV) supply air boxes according to the temperature differential between the measurement at the return air duct and the room temperature set point. Actually, this single-input-single-output (SISO) design may not ensure thermal comfort because the vertical temperature gradient and the uneven distribution of cooling load in the occupied level cannot be taken into account. Also it may not be energy efficient because areas without cooling requirement (e.g. no occupants) are conditioned simultaneously.This research will investigate how to improve the thermal comfort and energy efficiency of the air-conditioning systems for large-scale rooms by capitalizing a wireless sensor network and advanced control techniques. At least one sensor node will be installed at the occupied level in each area served by a single VAV supply air box. All of the sensor nodes and receivers constitute a wireless sensors network, which will be deployed to measure and transfer the temperature to a more sophisticated thermostat. In this thermostat, a robust multiple-input-multiple-output (MIMO) control algorithm will be developed to control each VAV box separately so as to deal with the unevenly distributed and time-varying load and improve occupants’ thermal comfort. This thermostat will also be designed to realize a demand-based temperature control, which will supply cooling only to areas with requirement and no cooling will be supplied if the areas have no requirement (e.g. no occupants).Energy saving potential of the new control design will be investigated and evaluated under different occupancy conditions by comparing it with the conventional design. Economic analysis will be performed to estimate the payback period for retrofitting the original control design. A large-scale lecture theatre in City University of Hong Kong will be used as an example platform to carry out this research. The outputs of this research will be used as a guideline for upgrading/retrofitting the conventional control design for large-scale rooms in terms of thermal comfort and energy saving.