A heating, ventilation, and air conditioning (HVAC) system for a building includes a plurality of actuation devices, a plurality of sensors, and a controller. The actuation devices receive actuation signals and operate in accordance with the actuation signals to affect one or more variables in the building. The sensors measure the variables affected by the actuation devices and provide sensor response signals including values of the measured variables. The controller generates actuation signal timeseries including samples of the actuation signals and sensor response timeseries including samples of the sensor response signals. The controller applies a discrete cosine transformation (DCT) to each actuation signal timeseries and each sensor response timeseries. Each DCT generates a set of DCT coefficients. The controller identifies a similarity between two or more of the actuation signal timeseries and the sensor response timeseries by comparing the DCT coefficients resulting from the DCTs.