The Pie Chart viewlet can be used to show the relative value of multiple variables over time. For each interval over the selected time period, the viewlet can plot the Max, Min, Average, or Sum of the variable. This particular viewlet can be displayed in a standard pie, a doughnut, or a polar area chart. 
Configuration
Configuration Options
Title: Set a custom viewlet title.
- Data: Select from available trends using either the Picker or Query mode.
- Date: Fine tune when the trend's data is shown. Can be set to auto (global control), a preset date range, or a user selected date range.
- Rollup: Select auto, or manual for more rollup control over rollup time, and rollup types such as Avg, Min, Max, Sum values of the trend based on selected date ranges.
- Convert To: Convert the data to comparable units such as kWh to MWh or kWh to BTU's.
- Chart Type: Select the format the data is displayed as either a Pie, Doughnut, or Polar Area (displayed).
This feature requires the part number PER-ENERGY