Go to Google Calendar in your browser and login
Click the plus sign next to "Other Calendars"
Click "Browse resources" from the pop up menu
Find the calendar(s) you would like to add within the building lists and click on the box next to the name of the resource/calendar
If you have access to the calendar/resource it will be added to your calendar
NOTE: you will need to check the box next to the calendar in your list of calendars for it to show up