This topic describes how to utilize actual lighting and other electrical loads in a space to contribute to Heating and Cooling Load calculations in Revit MEP.
This information applies to Revit MEP 2011 and Revit MEP 2012.
First, for the Actual Lighting and Power load to tabulate on spaces, you need to make sure the 'Run calculations for loads in spaces' option is turned on. This option is turned off by default in most templates. The option is found in Manage > MEP Settings > Electrical Settings > Load Calculations. With this option on, Actual Power Load and Actual Lighting Load parameters will now tabulate to reflect the loads in the spaces.
For the Heating and Cooling Load calculations to use these Actual values, you need to configure each space accordingly. In a Space Schedule, you can add the two parameters: "Base Power Load On" and "Base Lighting Load On" with the options: Default, Specified, and Actual. You can also set the basis to Actual in the Properties Palette with Space(s) selected, under Energy Analysis > Electrical Loads > Edit... Lighting/Power Values. You see the same three options.
You also need to be aware of how a load is associated with the Lighting or the Power loads on the spaces. Each Load Classification (Manage > MEP Settings > Load Classifications) is associated with a space by its 'Set load class for use with spaces' property, which has the options: None, Power, and Lighting.
When you create a Space Schedule, you can add the Parameters "Actual Lighting Load" and "Actual Power Load"... you will note that there are two of each of these in the default templates. This is because there are Electrical Load Classifications called Lighting and Power, which will tabulate loads for the loads explicitly set with the Load Classification Lighting or Power, in addition, the Space has the Actual Lighting/Power parameter which is a sum of all the Load Classifications that have the 'Set load class for use with spaces' set to Lighting or Power. To avoid confusion you could rename the Lighting and Power load classifications (just make sure you follow suit in your content!)
Finally, when running a heating and cooling load (Analyze > Heating and Cooling Loads) the Actual Power and Actual Lighting loads contribute (as heat gains) only to cooling loads. To take the loads into account for Heating Loads, make sure to check the box 'Use Load Credits'.