Page 128 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

108 Cha pte r T h ree

The different credit subcategories in the Water Efficiency category are worth
different point values. The first credit subcategory, Water Efficient Landscaping, was
worth two points in LEED 2.2, one each for reducing potable water use by 50 percent
(LEED 2.2 WEc1.1) and one additional for using no potable water or no irrigation (LEED
2.2 WEc1.2). This subcategory is worth from two to four points in LEED 2009 in a
combined single subcategory notation (LEED 2009 WEc1), with two points earned for
the 50 percent reduction and an additional two points awarded for the cases of no
potable water use or no irrigation. The second subcategory, Innovative Wastewater
Technologies, was worth one point in version 2.2 and two points in version 2009. The
third subcategory, Water Use Reduction, has also been combined from two sections in
LEED 2.2 (LEED 2.2 WEc3.1 and LEED 2.2 WEc3.2) into a single notation for LEED 2009
(LEED 2009 WEc3). In LEED 2.2, the first credit was worth one point for a 20 percent
reduction in potable water use and the second worth an additional point for a 30 percent
reduction. In LEED 2009, the 20 percent reduction is now a requirement in the new
prerequisite (LEED 2009 WEp1) and in the combined credit section (LEED WEc3), two,
three, or four points are awarded for reductions of 30, 35, or 40 percent, respectively.
Summaries of the credits and points for both versions can be found in Table 3.0.0. There
are EP points under the Innovation and Design category available which relate to two
items in the Water Efficiency category. These are available for exceeding each of the
respective credit criteria to a minimum level as noted in the credit descriptions for WEc2
and WEc3. These are noted in Table 3.0.0.
In LEED 2.2, the Water Use Reduction subcategory could also be the basis for an
additional ID credit. It was not called an exemplary performance point per se, since it is
not exceeding the percentages in the credit, but it was given for indoor water use
reductions for water fixtures that are not specifically covered in LEED 2.2 WEc3.1 and
LEED 2.2 WEc3.2, although the basis for the calculations is dependent on the design
indoor water rates for the fixtures as regulated in LEED 2.2 WEc3.1 and LEED 2.2 WEc3.2.
It is based on a reduction in other fixture water uses (non-EPAct fixtures) equal to or greater
than 10 percent of the design water use rate for the fixtures (EPAct fixtures) as calculated for
LEED 2.2 WEc3.1 and LEED 2.2 WEc3.2. EPAct stands for the Energy Policy Act of 1992.
This is a federal act that addresses energy and water use in commercial, institutional, and
residential facilities. This innovative point is not mentioned in LEED 2009.
The second subcategory in the Water Efficiency category also has an EP point
associated with it for achievement of a 100 percent reduction of sewage conveyance or
treatment on-site in addition to a 50 percent reduction.
The items available for EP points in this category are shown in Table 3.0.0. Note that
only a maximum total of four exemplary performance points are available for a project
for LEED 2.2 and only a maximum of three are available in LEED 2009, and they may
be from any of the noted exemplary performance point options in any of the SS, WE,
EA, MR, or IEQ LEED categories (see Chap. 7).
Table 3.0.1 also has a column that notes the importance of the site boundary and
site area in the credit calculations or verification. As mentioned in Sustainable Sites,
these are variables that should be determined early in a project as they impact many of
the credits. Some of the credits are easier to obtain if the site area is less, while others are
easier to obtain if the site area is greater. Determination of the site area may sometimes
be flexible, particularly for campus locations, but it should be reasonable and must be
consistent throughout the LEED process. It must also be in agreement with other nearby
project submissions. The site area is mentioned again in Chap. 8 as an important variable
to analyze early and set in a project.