ISO weeks are an easy way of talking about dates and weeks. Here's some useful formulae for use in Excel.

Day of Week, ISO Week and Year to Date

Using a named input for Year, and a Table Column called ISO week and the day of the week as a number (1 being Monday) in Day of Week - Number.

=DATE(Year,1,3) - WEEKDAY(DATE(Year,1,3)) + 7 * [@[ISO Week]] + [@[Day Of Week - Number]] - 6