The development of advanced control algorithms for BEMS

The adoption of direct digital control (DDC) methods in building energy management systems (BEMS) has become the widely-accepted norm for the control of building services systems. Energy savings have been achieved, but these are often the result of the consequential features offered by a BEMS-data logging, information retrieval/presentation, and simple trend plotting. These have given building operators a deeper insight into the behaviour of the building/plant/climate system than was ever before possible with the analogue control methods, and it is often this which has led to more energy-efficient system performance. There has been little change as regards the control laws utilised, however; the majority of current BEMS simply apply, in digital form, the well-known PID control method which had its origins over fifty years ago. Other fields, such as the aerospace industry and process control, have seen the successful implementation of more advanced techniques: these include optimal, robust, stochastic and predictive control. As yet, such advanced methods have not been used for practical building services control. This paper presents the results of a preliminary investigation into the use of a stochastic predictive strategy for the control of the internal air temperature of a test cell