Monday 20 December 2010

Comparison of Gopal and Enrico's data

From the experiments I carried out last week, it became clear that houses with different occupants and appliances generate hugely different data. A problem with this is that some techniques will be useful on one data set and useless on another. To illustrate this, I've plotted the changes in power in both Gopal and Enrico's houses over a 1 week period. Increases in power are represented by red points while decreases in power are represented by blue points.



There are some similarities between these graphs in the density of data points. Each graph has a dense band of power changes between 0 and 300W. This band is visible 24 hours a day so it is most likely due to continuously cycling appliances, e.g. fridge, freezer, heating. Unfortunately, these cycling appliances do not have consistent 'on' and 'off' jumps and might therefore disguise the features of other low power appliances, e.g. TV, computer, lighting. Above this band (300-3000W), the data points are more sparsely distributed. These are likely to correspond to appliances that generate a large amount of heat, e.g. kettle, toaster, microwave.

However, there are also some differences between the two plots. Enrico's graph has a third visible band, between 0 and 20W. This is likely due to a cycling appliance with a consistent 'on' and 'off' change in power.

Another clear difference between the plots is the time of day at which the sparsely distributed data points occur. On Gopal's plot they occur throughout the night, whereas on Enrico's they only occur during the day. This is because Gopal has an electric boiler which runs during the night, and it is clear that this is hard to distinguish from other high power appliances.

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