1. A portable system for logging sensor data and creating energy consumption patterns in an area comprising:a low-power and/or low accuracy clock; and
a processor in communication with a memory, the processor;
receiving data items from each of a plurality of sensors;
associating a time stamp generated by the low-power and/or low accuracy clock with each data item received from each of the plurality of sensors;
storing the received data items for a predetermined period of time; and
processing the stored data items to determine a high accuracy clock time stamp for each of the stored data items, wherein determining said high accuracy clock time stamp comprises:
determining a time usage pattern of the area during a period of receiving the data items;
approximating a correction of the time-stamp associated with the low-power and/or low accuracy clock based on the time usage pattern;
determining an occupancy pattern during a period of receiving the data items;
refining the correction based on the occupancy pattern associated with a second known time usage pattern; and
applying the correction to the time-stamp associated with the low-power and/or low accuracy of the stored data.