Why does the Minimum IAQ Performance calculator excel spreadsheet have a formula to truncate the calculation of the Average outdoor air fraction (Xs) to only 2 digits by rounding down? In my particular case it is rounding 0.199 down to 0.19 and pushing the required outdoor air flow above what I would otherwise design to. This rounding down seems unnecessary. Is there a way to get USGBC to fix the spreadsheet or are there other spreadsheet's available?