A system for disaggregating residential electricity consumption by appliance

Research on Non-Intrusive Load Monitoring (NILM), a technique for discerning individual appliance operation from whole-house measurements, has been underway for over 20 years [4],[5]. Most implementations utilize changes in the total real (P) and reactive (Q) power of a building as signatures for each appliance state transition. There are a small number of commercially available systems that implement NILM, albeit marketed for utilities as a tool for performing load research. As a proof of concept, and in order to obtain preliminary data that would help us evaluate the feasibility of using NILM to support electricity audits in a residential building, we decided to focus our attention on one of the top residential loads: the refrigerator. We installed a NILM prototype system in an apartment building, and a plug-level power meter was used to accurately track the individual consumption of this appliance. The experiment consisted in monitoring this load for a week, using the two methodologies (NILM and pluglevel meters), and then comparing the estimated energy consumption as computed by each.