See also: YearlyShape, ShapeNone, ShapeFlat, ShapeDefault, ShapeFromDemand
If you have included Load Shapes as part of the scope of your analysis on the Settings: Scope & Scale screen, then in Analysis View you will see a top-level category branch named Load Shapes sitting immediately after the top-level Demand category branch in the Analysis View tree. Under this branch, you will specify the System Load Shapes () for each fuel of those specified on the Settings: Scope & Scale screen.
Using the System Load Shape variable, you can specify the load shape for each fuel using standard expressions such as the YearlyShape function that lets you reference a load shape stored in the General: Yearly Shapes library, or you can use the preset functions: ShapeFlat, indicating that every time slice has equal loads, ShapeNone, which tells LEAP to ignore variations in loads among time slices, ShapeDefault, which tells LEAP to use the first load shape from the Yearly Shapes library, or ShapeFromDemand, which will cause LEAP to calculate the system load shape from all of the individual loads for all demand-side devices using that fuel. After you set ShapeFromDemand, once you return back to your demand device branches, you will see the Load Shape variable displayed for devices using that fuel. This is the variable where you can specify the yearly load shape for each device (again, typically by using the YearlyShape function to reference a load shape stored in the Yearly Shapes library).
You can use different load shape methods for each fuel. For example, you might use demand-side calculated load shapes for electricity demands, and simpler exogenous (supply-side) load shapes for all other fuels. Load shape methods can also differ among scenarios. Yearly load shapes can be entered as either a percentage of the peak load, or as a percentage of the annual energy load. LEAP supports both formats and will internally convert shapes as needed to a common format.