Please be careful and aware when you use the available spreadsheet:
Daylight and Views Calculator released 11152010.xls . The spreadsheet contains a mistake in its skylight roof coverage calculation but it still can be used as long as the project does not have two zones and skylight.

While we are waiting a revision, I would suggest to use another available spreadsheet such as:
Supplemental Daylight and Views Calculation Spreadsheet_NCandCS.xls .
This one has a correct formula.