The Metrics option on the advanced tab gives you an quick way of viewing the space consumed by the various tables and columns in your data model
Export Metrics This button lets you save the current metrics for the model you are connected to as a .vpax file. The .vpax file format is simply a zip file container with a number of json files that contain the results of running a number of DMV queries.
Import Metrics This button lets you open and view a previously exported .vpax file
View Metrics this button will display the metrics for the current model.