Section 2: Individual LEED Credit Reviews
Table SS6.1-2: Vegetated Roof to Achieve 25% Stormwater Runoff Reduction
Total Lot Area (SF):
133,423
Non-Building Site Area (SF):
86,450
Design Case Table
% of Non-
Area
Runoff
Impervious
#
Surface Type
% of Total Lot
Area (SF)
Building Site
(SF)
Coefficient
Courthouse Building:
1
Lower Roof
2.8%
n/a
3,700
0.95
3,515
Upper Roof - Vegetated, 4" thick
22.9%
n/a
30,550
0.50
15,275
2
(65% of total roof area)
3
Upper Roof (IRMA)
9.5%
n/a
12,723
0.95
12,087
Building Total
25.7%
--
46,973
--
30,877
Paving:
4
Vehicle access paving
3.2%
5.0%
4,323
0.95
4,106
5
Sidewalk paving and curb
10.4%
16.0%
13,832
0.95
13,140
Plaza paving
21.4%
33.0%
28,529
0.95
27,102
6
Steps and landings
3.2%
5.0%
4,323
0.95
4,106
7
Paving Total
38.2%
59.0%
51,006
--
48,455
Water Feature:
8
Pool/fountain
0.6%
1.0%
865
0.95
821
Water Feature Total
0.6%
1.0%
865
--
821
Street Trees:
9
Street Trees (3" caliper)
0.6%
1.0%
865
0.35
303
Street Trees (2" caliper)
0.6%
1.0%
865
0.35
303
10
1,729
--
605
Trees Total
1.3%
2.0%
Mixed Vegetation:
11
Shrubs/Trees in Barrier Garden
7.1%
11.0%
9,510
0.20
1,902
4,323
0.20
865
12
Shrubs and Perennials
3.2%
5.0%
13,832
--
2,766
Mixed Total
10.4%
16.0%
Groundcover only:
13
Groundcover mix
10.4%
16.0%
13,832
0.20
2,766
13,832
--
2,766
Groundcover Total
10.4%
16.0%
Turfgrass:
14
Turf areas
3.9%
6.0%
5,187
0.35
1,815
Turfgrass Total
3.9%
6.0%
5,187
--
1,815
Total Area:
133,423
Total Impervious Area:
88,107
Imperviousness:
66.0%
Baseline Case Table
Area
Runoff
Impervious
% of Non-
#
Surface Type
% of Total Lot
Building Site
(SF)
Area (SF)
Coefficient
Buildings and Site Paving:
Existing building roofs and site
1
90%
--
120,081
0.95
114,077
paving surfaces
Impervious Area Total
90%
120,081
114,077
Landscape:
Existing site plantings
10%
n/a
13,342
0.35
4,670
2
Landscape Area Total
10%
13,342
4,670
Total Area:
133,423
Total Impervious Area:
118,746
Imperviousness:
89.0%
Imperviousness decrease is:
25.8%
GSA LEED COST STUDY
44
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