Section 2: Individual LEED Credit Reviews
LEED Credit WE-2:
Achieving the credit would therefore require one
of the following options:
Innovative Wastewater
Stormwater collection (from the roof or site)
Technologies
and treatment systems
Greywater collection and treatment systems
Blackwater collection and treatment systems
Intent
Composting toilets
Reduce the generation of wastewater and potable
These systems were not considered likely for most
water demand, while increasing the local aquifer
GSA buildings.
recharge.
Basis for Cost Assumption
Requirement
For the purposes of this study, this credit was not
Reduce the use of municipally provided potable
pursued in either the Courthouse or Office
water for building sewage conveyance by a
Building models. Water collection and treatment
minimum of 50%;
systems for interior uses typically have a significant
OR
first cost, and would be difficult to justify
economically in either of the model projects, which
Treat 100% of wastewater on site to tertiary
are assumed to be located in urban areas with
standards.
existing infrastructure. Additional considerations
include potential code-related obstacles and
(1point)
ongoing maintenance and operation costs for the
systems.
Cost Impact: Not Pursued
Water collection and treatment systems might be
feasible for buildings located on remote sites, such
as some of GSA's Land Port (Border Station)
1
2
3
4
5
projects.
GSA
No
Low
Moderate
High
Summary of First Cost Impacts
Standard
premium,
premium
premium
premium
(no cost)
psble svgs
(<50K)
(50-150K)
(>150K)
Practical Applications
Courthouse (New Construction, 262,000 GSF)
Fixture types that could contribute toward this
The credit was not pursued.
credit include:
Office Building (Modernization, 306,600 GSF)
Waterless urinals
Dual flush toilets (1.6/0.8 gallons per flush
The credit was not pursued.
[gpf])
Ultra low flush toilets (1.1 to 1.4 gpf).
Additional Considerations
LEED calculations, however, indicated that these
fixture types alone could not achieve 50 percent
None identified.
water use reduction for sewage conveyance. In
addition, the dual flush and ultra low flush toilets
Synergistic Credits
are currently available only as tank type fixtures, as
opposed to flush valve fixtures that would typically
Potential synergies exist between this credit and
be specified for large commercial or institutional
credits WE-3.1 and WE-3.2 (Water Use
buildings.
Reduction).
GSA LEED COST STUDY
60
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