My team is working on a project that involves a high quantity of structural material and according to the handbook, "Structure and enclosure materials may not constitute more than 30% of the value of compliant building products. Projects with significant amounts of structural and enclosure materials may exceed the 30% limit by calculating an alternative structure and enclosure limit (See Calculations under Further Explanation)."
Where would we find calculations and allowable redefinitions of the structure and enclosure limits? We have some considerations as to what steel products may be redefined as to go under this limit, but we have not found literature explaining how we go about doing this.
Alternative Structure and Enclosure limit = (value $ of total building materials that are structural or enclosure) [divided by] (total actual materials value $)
Use the results of equation 3 to replace the 30% contribution factor limit in determining compliance with the credit.