A method for determining state changes of devices in a building, the method performed by a monitoring device in the building, the method comprising: receiving an electrical signal, wherein the electrical signal corresponds to electrical usage of a plurality of devices, and wherein the electrical signal comprises at least one of voltage signal, a current signal, a power signal, or a reactive power signal; identifying an electrical event in the electrical signal, wherein the electrical event corresponds to a first time; computing a first feature using a first portion of the electrical signal, wherein the first portion comprises the first time; computing a second feature using a second portion of the electrical signal, wherein the second portion comprises the first time and wherein an end time of the second portion is later than an end time of the first portion; performing first processing comprising: computing a first score using the first feature and a model, wherein the model corresponds to one or more devices and a state change of the one or more devices and wherein computing the first score does not use the second feature, and selecting, using the first score, a first device and a first state change; and performing second processing comprising: computing a second score using the first feature, the second feature, and the model, and selecting, using the second score, (i) the first device and the first state change, or (ii) a second device and a second state change. receiving an electrical signal, wherein the electrical signal corresponds to electrical usage of a plurality of devices, and wherein the electrical signal comprises at least one of voltage signal, a current signal, a power signal, or a reactive power signal; identifying an electrical event in the electrical signal, wherein the electrical event corresponds to a first time; computing a first feature using a first portion of the electrical signal, wherein the first portion comprises the first time; computing a second feature using a second portion of the electrical signal, wherein the second portion comprises the first time and wherein an end time of the second portion is later than an end time of the first portion; performing first processing comprising: computing a first score using the first feature and a model, wherein the model corresponds to one or more devices and a state change of the one or more devices and wherein computing the first score does not use the second feature, and selecting, using the first score, a first device and a first state change; and computing a first score using the first feature and a model, wherein the model corresponds to one or more devices and a state change of the one or more devices and wherein computing the first score does not use the second feature, and selecting, using the first score, a first device and a first state change; and performing second processing comprising: computing a second score using the first feature, the second feature, and the model, and selecting, using the second score, (i) the first device and the first state change, or (ii) a second device and a second state change. computing a second score using the first feature, the second feature, and the model, and selecting, using the second score, (i) the first device and the first state change, or (ii) a second device and a second state change.