Two new normalized EWMA-based indices for control loop performance assessment

Abstract

Modern buildings can have hundreds if not thousands of control loops that regulate variables such as pressure, temperature, flow rate, etc. The amount of data available to operators can be overwhelming and, because of this, many faults and poorly controlled loops often go undetected until complaints arise from building occupants or a more serious failure occurs. Methods are thus needed that can convert big data sets from buildings into more managable metrics that can be used to identify problems. This paper proposes two new indices that quantify control performance in a normalized way so that different control loops can be compared on the same scale. These normalized indices can be used to generate a quick ranking of control loop performance so that poorly performing loops can be identified. The paper describes the new indices and presents results from both simulation and field tests.