Use the check box to specify whether to enable load calculations for loads in spaces. 
Running calculations may slow system response. 
- Load Classifications - Click this button to open the Load Classifications dialog. See 
	 Load Classifications. 
  
- Demand Factors - Click this button to open the Demand Factors dialog. See 
	 Demand Factors. 
  
- Run calculations for loads in spaces - Since calculations of loads on space may slow system response, you can disable calculations to improve performance. 
  
- Apparent load calculation method - Specifies how 
	 Revit sums electrical loads: Sum true load and reactive load or Sum apparent load. The selected method applies to all loads, circuits, and panels in the model.