A key new feature in the Revit 2011 subscription upgrade which was recently released, is the ability to perform energy analysis on conceptual massing models within Revit.
These videos describe how to use Revit Architecture to perform conceptual energy analysis during the early design stages of a project. These videos are recorded using Revit Architecture. However, the concepts and procedures also apply to Revit MEP.

AECbytes has published a review of these and other features that were added to Revit functionality lately ..

Choosing the Project Location and Weather Station
Describes how to specify the location and a weather station for the project, so the correct climate information will be used during energy analysis

Using Automatic Form Rationalization
Demonstrates how intelligent energy settings are used to rationalize the mass form into mass surfaces and zones for energy analysis.

Changing Energy Settings
Demonstrates how you can modify energy settings to change zoning, glazing, and skylights before performing energy analysis on the model.

Customizing Form Rationalization
Demonstrates how to use custom form rationalization to maintain the design intent by creating custom zones and glazing layouts.

Performing Conceptual Energy Analysis
Demonstrates how to start a conceptual energy analysis and view the results.