public class FunctionOutputResult : Result 

// Get the FunctionOutputResult from the trace results
FunctionOutputResult functionOutputResult = traceResults.OfType<FunctionOutputResult>().First();

// First() can be used here if only one Function was included in the TraceConfiguration.Functions collection.
// Otherwise you will have to search the list for the correct FunctionOutput object.
FunctionOutput functionOutput = functionOutputResult.FunctionOutputs.First();

// Extract the total load from the GlobalValue property
double totalLoad = (double)functionOutput.Value;