The best way to report on your portfolio-level performance is to download the "Portfolio Sustainability Report" in the "Reports" tab. The professional PDF file includes visual breakdowns of your portfolio's performance across energy, water, and carbon. It also lists out your portfolio's top and bottom performing sites for each of those metrics.
The report lists all projects, audits, certifications, and ratings from the specified time periods, along with a list of included sites.
After clicking to generate the report, you'll first choose a primary and comparison time period of whatever length you'd like. Then you can filter the sites to include based on property type, location, year built, and size.
You can also set the units of measure you'd like to see, even if they differ from the units you've set in your account preferences.