Waterside Economic Optimization of HVAC Systems in Commercial BuildingsMichael Risbeck
Heating and cooling account for a significant fraction of energy expenditure in commercial buildings. Because of fluctuating occupancy levels and weather conditions, the demand for heating and cooling fluctuates significantly throughout the day. For cooling systems in particular, this results in varying demand for electricity. Knowing this, power companies will change different electricity prices in concert with demand. Thus, if electricity usage can be shifted to times of low cooling demand, then significant electricity cost reduction can be achieved. This is possible, for example, by generating chilled water at night (when electricity prices are low), storing it, and then using it to cool buildings during the day (when electricity prices are high).
With this idea in hand, my work aims to establish a modeling and control framework in which waterside production can be optimized. This requires the use of weather forecasts and equipment models to determine the optimal production schedule that meets specified heating and cooling load. The most challenging aspect of this project is the fact that, in addition to continuous variables like temperature and flow, there are discrete decision variables, such as whether or not to turn on a piece of equipment. Thus, existing methods suited only to continuous variables will have to be modified to meet the needs of this problem. Through a hybrid of control and scheduling techniques, an optimization scheme can be developed to balance complexity, robustness, and tractability while also providing meaningful cost savings.
This project is in collaboration with Johnson Controls, Inc.