Building-Automation Systems in Mechatronics

Published:2011/9/26 6:17:00 Author:Amy From:SeekIC

It is said that buildings occupies over one-third of the energy consumption in the United States. According to information, the application of control and automation to buildings can contribute to energy saving, environment protection, health improvement and occupants safety. The widely use of automation in HVAC consumes 20% of the energy in the United States.

A survey of the literature pertaining to controls for HVAC and building systems shows a lack of a systematic dynamic analysis and control design approach. The algorithms in this sector usually employ ad hoc, table-based rules, which engineers modify and improve using field experience rather than rigorous modeling and dynamic analysis. A need exists for hybrid-building systems that integrate emerging component- and control-system technologies into the broader HVAC-building system and that increase building-system energy efficiency.

An air-conditioning system must provide the cooling capacity of the system and must be as efficient as possible. The increase of enthalpy—a measure of the total energy of a thermodynamic system—across the evaporator, or the amount of heat an air-conditioning system removes from the environment, is a measure of evaporator capacity. The system coefficient of performance, a measure of system efficiency, is the ratio between the changes in enthalpy. Maximizing this value is a key system-level priority because it minimizes energy usage for a given amount of cooling. In addition, to prevent the possibility that liquid will enter the compressor inlet, it is important to maintain a prescribed level of superheated vapor at the evaporator’s exit. The control of superheat and capacity are regulation problems, whereas the energy use is a minimization problem.


Since the time scales is involved, it needs to use algebraic formulas to describe the compressor and the valve and dynamics of varying degrees of complexity to describe the energy-flow devices, depending on the approach you take.

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