To capture electricity use within the computer lab, we have installed high accuracy electricty monitors on main circuits within the building. These meters are Autometers' IC995, and provide overall power usage data, as well as the ability to measure additional data such as powerfactor and harmonics. These provide power information for the main circuits of the lab, such as electricity use per corridor.
These meters are connected via MODBUS over RS485, to a machine that collects and processes the data, and generates JSON files for the web front-end to use.
We have also created a USB current monitor that interfaces a Current Transformer to a machine through USB serial commands, and developed a Python interface to access data available as high-level python objects.
In addition we have data from the utility company on overall total power use for the entire building as a whole. This is reported to us, and made avalible at the top level of the meter tree.