Section 2: Individual LEED Credit Reviews
Turf grass: 15 percent of the planting area
Employing Irrigation System Efficiencies Only
Mixed vegetation (shrubs, groundcovers,
In this evaluation, the planting areas remain the
perennials, understory trees): 40 percent of the
same as in the baseline; however, the irrigation
planting area
system efficiencies are improved. Irrigation for the
Groundcovers only: 40 percent of the planting
groundcover- and mixed-vegetation-areas is
area
changed from sprinklers to drip irrigation. In
Street trees: 5 percent of the planting area
addition, the sprinkler system used for the turf
grass areas includes timer and rain sensor controls.
In addition, the sprinkler system (used for all
The controls are assumed to reduce the sprinkler
plantings except for the street trees) includes timer
system water use by 25 percent (the efficiency
and rain sensor controls.
improves from 0.625 to 0.825).
Overall, these measures reduce the overall water
Overall, these improvements reduce the overall
use for irrigation by 35 percent, as shown in Table
water use for irrigation by 26 percent, as shown in
WE1.1-3.
Table WE1.1-2.
GSA Base Case With Low Water Use Groundcovers
GSA Base Case Planting Assumptions
This scenario is the same as the previous, with one
In this evaluation, a combination of planting
exception: the groundcover plantings, which
changes and irrigation controls was reviewed. A
represent 40 percent of the overall planting area,
"GSA Base Case" of site planting assumptions was
are selected to be low-water use species. Thus, the
developed for the Courthouse model, based on a
Species Factor of the groundcovers is changed
review of several current GSA Courthouse
from "average" to "low."
projects. The planting assumptions for the model
were as follows:
This scenario results in 50 percent water use
reduction, as shown in Table WE1.1-4.
Table WE1.1-1
Generic Institutional Building Baseline Site
Landscape
Species
Microclimate
Area
Density
KL ETL
IE
Area
TPWA
Factor
Factor
%
Factor
Type
(ks)
(kd)
(kmc)
[%]
[SF]
[gal]
Trees
5%
1,729
Avg
Avg
Avg
1.0
None
0.000
Groundcovers
15%
5,187
Avg
0.5
Avg
1.0
Avg
1.0
0.5
4.00
Sprinkler 0.625
33,197
Mixed
15%
5,187
Avg
0.5
Avg
1.1
Avg
1.0
0.6
4.40
Sprinkler 0.625
36,516
Turfgrass
65%
22,477
Avg
0.7
Avg
1.0
Avg
1.0
0.7
5.60
Sprinkler 0.625
201,394
Net GPWA [gal] 271,107
Total
34,580
GSA LEED COST STUDY
55
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