Page 245 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

218 Cha pte r F i v e

calculate the value of the recycled cementitious material content in concrete as the
weight percent of only the cementitious materials and multiply by the cost of the
cementitious materials.
As related to the recycled content credit subcategory, this use of fly ash is promoted
as an environmental benefit as it recycles waste from another process which might
otherwise be landfilled, and it also promotes a reduction in the use of energy and the
production of carbon dioxide from the cement-making process.
There is also a default postconsumer recycle content value for steel of 25 percent
which can be used regardless of documentation as steel is usually made from at least
25 percent postconsumer recycled steel. In cases where the steel recycled content is
greater than 25 percent, documentation should be provided.
In LEED 2009, an additional EP point can be earned for recycled content if the
following is true:

100[MATL$ + (0.5 × MATL$ )]/MATL$ ≥ 30 (5.4.7)
RECPOC RECPRC T
Since it is usually not certain during the design phase of the exact amounts of recycled
content that might be purchased for each item, this subcategory is listed as a
construction phase submittal. The contractor should keep records of recycled content
and costs. LEED 2009 cautions about indoor air emissions from certain recycled
materials and if they are used, then their emissions should be included in the IEQc4
if applicable. The equations for this credit subcategory are summarized in Tables 5.4.1
and 5.4.2.
Some examples of carpet systems made with materials which can be included in the
recycle content subcategory can be seen in Fig. 5.4.1.

Postconsumer Total Preconsumer Total
Recycled Postconsumer Recycled Preconsumer
Content Recycled Content Recycled
Value of Unit i Content Value Value of Unit i Content Value
(MATL$ ) (MATL$ ) (MATL$ ) (MATL$ )
RECPOCi RECPOC RECPRCi RECPRC
Equations MATL$ × ∑MATL$ MATL$ × ∑MATL$
UNITi RECPOCi UNITi RECPRCi
(MASS )/ (MASS )/
RECPOCi RECPRCi
MASS MASS
UNITi UNITi
Some Value of recycled Recycled
exceptions steel content is supplementary
at a minimum cementitious
of 25% or materials used
greater with in concrete
documentation are valued per
weight percent
of cementitious
materials

TABLE 5.4.1 Summary of Recycled Content Material Value Equations