A few appliances are much more difficult to measure. Refrigerators, for example, have hidden functions that can be difficult or impossible to turn off. Therefore, it is important to establish a time period over which the power draw is to be averaged. Our meter displays average power every second. In most cases, we monitor the power draw of a unit for about 30 seconds.
Readings tend to vary by only one or two tenths of a watt within that time.
Appliances that have microcontrollers sometimes perform functions on a cyclical basis. The readings for these types of appliances may vary by as much as one watt or more, depending on how many functions are being performed. Until now we have simply estimated the average power draw based on the readings. However, since a movement to reduce standby power consumption is gaining momentum internationally, we expect that a more specific and accurate power measurement standard will soon be established.