Patent ID: 8532839

Claim:
A controller for a building management system comprising: a processing circuit configured to at least one of receive or calculate an updated performance value for the building management system; wherein the processing circuit is further configured to maintain at least one threshold parameter relative to a history of performance values, to determine an exponentially weighted moving average of the history of performance values, and to determine whether the exponentially weighted moving average of the history of performance values is outside of a range defined by the at least one threshold parameter; wherein the processing circuit is further configured to generate an output that indicates a result of whether the exponentially weighted moving average is outside of the range defined by the at least one threshold parameter, and wherein the processing circuit is further configured to: generate a target parameter based on a median of the history of performance values; generate an estimator of scale of the history of performance values, wherein the estimator of scale reduces an effect of outliers in the history of performance values; and use the estimator of scale and the target parameter to update the at least one threshold parameter.