Section 2: Individual LEED Credit Reviews
LEED Credit SS-5.1:
LEED program defines open-site area as
everything outside of the building footprint.
Reduced Site Disturbance
The urban nature of most of GSA's project sites
Protect or Restore
may limit the applicability of this credit. On urban
lots where the building footprint occupies the vast
Open Space
majority of the site, the remaining open area may
require significant paving for pedestrians and
vehicular access, thus limiting the viability of
Intent
achieving the 50 percent planting area criteria.
Conserve existing natural areas and restore
For other sites, however, this credit may be readily
damaged areas to provide habitat and promote
achievable if it is called for as a programmatic goal
biodiversity.
of the project site design. For example, GSA's new
courthouses have significant security-driven
Requirement
setback requirements that result in relatively large
site areas surrounding the buildings. It is viable in
On greenfield sites, limit site disturbance
these cases to achieve the LEED credit by
including earthwork and clearing of vegetation to
requiring the site design to accommodate the 50
40 feet beyond the building perimeter, 5 feet
percent native vegetation threshold. The
beyond primary roadway curbs, walkways and
requirement will likely limit the amount of paved
main utility branch trenches, and 25 feet beyond
areas and lawn areas used in the project (note:
constructed areas with permeable surfaces (such
lawns areas are not considered native/adaptive
as pervious paving areas, stormwater detention
vegetation in LEED) and will require more site
facilities and playing fields) that require
area dedicated to groundcovers, shrubbery, and
additional staging areas in order to limit
trees. Designing to these site parameters can
compaction in the constructed area.
potentially reduce project costs, because
landscaping areas can be less expensive overall than
OR
paved site areas.
On previously developed sites, restore a
minimum of 50% of the site area (excluding the
Basis for Cost Assumption
building footprint) by replacing impervious
surfaces with native or adapted vegetation.
For the purposes of this study, Credit SS 5.1 was
pursued only in the Courthouse model--the scope
(1 point)
of the Office building modernization does not
include site work.
Cost Impact = 2
For the Courthouse, a Base Case of site
development features was defined based on several
current GSA courthouse projects. In the Base
1
2
3
4
5
Case, approximately 60 percent of the open site
area is dedicated to paved surfaces (sidewalks,
GSA
No
Low
Moderate
High
plazas, roads, service areas), while 6 percent is
Mandate
premium,
premium
premium
premium
(50-150K)
(>150K)
(no cost)
psble svgs
(<50K)
dedicated to turf grass. The remaining 34% of the
site area consists of groundcovers, perennials,
shrubbery and trees, which are assumed to be
Practical Applications
native or adapted plantings per GSA's P100
recommendations (listings of site plantings used in
As the majority of GSA's projects involve
the study are included in the descriptions for
previously developed sites, this credit will typically
credits WE-1.1 and WE-1.2).
involve restoring 50 percent or more of the open
site area with native or adaptive landscape
In the credit-compliant design scenario, the paved
vegetation. For the purposes of this credit, the
surfaces are reduced to 47 percent of the site area,
GSA LEED COST STUDY
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