Page 252 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

LEED Materials and Resour ces 225

Calculations and Considerations (LEED 2009 MRc7)
This credit encourages the use of Forest Stewardship Council (FSC) labeled wood
products. FSC products will be labeled as either FSC Pure or FSC Mixed, and both types
of labels ensure that the wood portions of the item are a specific percent FSC certified.
FSC-certified products will have a Chain-of-Custody (CoC) certification. CoC numbers
for all items are required in the submittals.
Note that this credit is based only on new wood, in both the numerator and the
denominator. Any reused or salvaged wood and wood products are included in other
credits. Also, even though the equations developed in this chapter to determine the
values of the FSC new wood and all the new wood on the project are based on mass
(weight) percentages of the items, there is the option for any item to be instead based on
volume percent or value percent if these are easier or more readily available ways to
determine the percent value. For instance, a cost percent value may be easier to do with
veneers. Some of the variables used in the equations are as follows:

WOOD$ Total value of new wood portions of all items installed in the project
T
WOOD$ Total value of FSC new wood portions of all items installed in the project
FSC
MASS Mass (weight) of the FSC new wood portion of unit i (Volume or value
FSCi
can be substituted for mass as appropriate for an item.)
MASS Total mass (weight) of all new wood in unit i (Volume or value can be
WOODi
substituted for mass as appropriate for an item.)
MASS Total mass (weight) of unit i (Volume or value can be substituted for
UNITi
mass as appropriate for an item.)
MATL$ Total cost of unit i
UNITi
MATL$ Value of the FSC new wood portions of unit i
FSCi
MATL$ Value of all the new wood portions of unit i
WOODi
For both versions 2.2 and 2009, one point is earned for MRc7 if the following is true:
100(WOOD $ )/WOOD $ ≥ 50 (5.7.1)
FSC T
Most items are not made entirely of new wood, and therefore the values of the
certified new wood and the wood portions are determined as a mass (weight), volume,
or cost percent of the total items. Usually the mass percent is used, as in the following
equations:
MATL$ = MATL$ (MASS )/MASS (5.7.2)
FSCi UNITi FSCi UNITi
MATL$ = MATL$ (MASS )/MASS (5.7.3)
T UNITi WOODi UNITi
And in a similar manner, the total values of the FSC new wood and total new wood
portions needed in Eq. (5.7.1) can be determined from the summation of the individual
unit contributions as follows:

WOOD$ =∑MATL$ over all units i (5.7.4)
FSC FSCi
WOOD$ =∑MATL$ over all units i (5.7.5)
T WOODi