Section 2: Individual LEED Credit Reviews
Synergistic Credits
Shrubs in "barrier gardens": Mix of Wax Myrtle,
Beautyberry, Wild Hydrangea
Potential synergies exist between this credit and
Shrubs and perennials in planter areas: Mix of Wax
credit SS-5.1 (Reduced Site Disturbance: Protect or
Myrtle with various perennials (New England
Restore Open Space), credit SS-6.1 (Stormwater
Aster, Wild Bergamont, Blue False Indigo,
Management: Rate and Quantity), and credit WE-
Early Coneflower, Black-eyed Susan and
1.2 (Water-Efficient Landscaping: No Potable Use
others)
or No Irrigation). These synergies are addressed in
Groundcovers: Mix of Leadwort, Striped
this study when credit WE-1.2 is pursued.
Wintergreen, Fragrant Sumac, Mountain
Stonecrop
Supporting Calculations
Turf grass: Fescue blend sod
Calculations were performed, using the procedures
The listed plantings are not intended to constitute a
developed in the LEED Version 2.1 Reference
full landscape design, but rather are used to
Guide, to evaluate how different strategies and
indicate the types of species that could be chosen
systems could contribute to a 50 percent reduction
to meet the credit criteria in the specified climate.
in irrigation water use. A key consideration in the
calculation procedure was defining a "typical"
Summary of First Cost Impacts
landscape scheme with which to compare. For a
commercial/institutional project of this scale (with
approximately 34,600 square feet of planting area),
Courthouse (New Construction, 262,000 GSF)
it was assumed that the following planting
breakdown represented a reasonable baseline:
No identified cost premiums.
Turf grass: 65 percent of the planting area
Office Building (Modernization, 306,600 GSF)
Mixed vegetation (shrubs, groundcovers,
perennials, understory trees): 15 percent of the
The credit is not applicable.
planting area
Groundcovers only: 15 percent of the planting
area
Additional Considerations
Street trees: 5 percent of the planting area
Water reduction measures must be balanced with
Additional assumptions for the baseline included
other landscape design issues (e.g., aesthetics,
the following:
functional use of the exterior spaces, maintenance
The turf grass, mixed vegetation, and
requirements, stormwater management). In some
groundcover areas are all served by a pop-up
projects, these parameters may limit the viability of
sprinkler system. The irrigation efficiency of the
achieving this credit.
system is 0.625. No automatic controls are
Also, while the Base Case planting scheme for the
included.
Courthouse was budgeted to include a high
Other key aspects of the LEED calculation -
percentage of groundcovers and mixed plantings, it
the Species Factor, Density Factor, and
is acknowledged that other projects may have a
Microclimatic Factor are assumed to be
landscape budget that assumes a high percentage of
"average."
turf grass. The initial costs for groundcovers can be
approximately 5 to 10 times higher than those for
A more detailed breakdown of the baseline is
sod. Mixed planting areas can be significantly more
included in Table WE1.1-1 at the end of this
expensive, depending on the number of shrubs and
section.
trees included. Reductions in landscape
From the baseline, the following comparisons were
maintenance and water use can partially offset the
made:
initial costs of the more expensive plantings.
GSA LEED COST STUDY
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