Stormwater Academy: Green Roofs
Green Roof and
post equal pre volume
control
By Marty Wanielista
January 4, 2006
OUTLINE OF DISCUSSION: Green Roofs
•
•
•
•
History
Green roof basics
UCF research projects.
Research Discussion -­ Application to stormwater mgt., stormwater quality, evapotranspiration, etc
• The state of the industry -­ practical applications and practices
• Future directions -­ discussion
5000 year old Passage Grave near Dublin
Hanging Gardens of Babalon: Green Roofs
English Tea Time: Green Roofs
Stuttgart Germany: About 60 Years
Over 30% of the roofs are green Photo of the Mercedes Offices
Stormwater Academy: Green Roofs
European Examples: Green Roofs
A US Office View: Green Roofs
Some Definitions: Green Roofs
What is a Green Roof?
• Covered with vegetation
• Intensive - deep overburden
roof garden
• Extensive - thin overburden
large area
Intensive Green Roofs
Extensive Green Roofs
Stormwater Academy: Green Roofs
TYRONE, PA
ROOF PLANTED JULY 2001
Benefits of Green Roofs
Why should we plant green roofs?
• aesthetically pleasing, useful space
• reduce city “heat island” effect,
• reduce noise,
• reduce air conditioning,
• lengthen roof life 2-3X,
• remove nitrogen in rain,
• neutralize acid rain,
• reduce stormwater runoff volume.
Plans for Replacing Pavements and Roofs.
An 8 County Region
Replace roofs and road surfaces
Cool Surfaces
Surface Temperatures and Heat Islands
Washington, DC
Surface Temperatures
Houston, Texas
Irrigated Florida Native Plant Green Roofs
Four Main Objectives:
1) maintain water balance,
2) reduce stormwater pollution mass, 3) reduce internal energy demand for cooling and heating, and
4) enhance the aesthetic appeal compared to conventional roofs.
USING an irrigated plant and 6 inch media roof in Central Florida
A cistern is used
to recycle green roof runoff as
irrigation water.
An Interdisciplinary Team
Appreciate the support of:
UCF Team
UCF Team
Marty Wanielista
Martin Quigley
Mart Wanielista
Jeff Sonne
Martin Quigley
Clint Finstad
Jeff Sonne
Mike Hardin
Clint Finstad
Kelley Dragon
Matt Kelly
Mike Hardin
Steve Maxwell
Kelley Dragon
Jen McDaniel
Matt Kelly
Natalie Shaber
Steve Maxwell
1. Eric Livingston, FDEP
1. Eric Livingston, FDEP
2. Steve Iwinski, Applied Polymer Systems Inc.
2. Steve Iwinski, Applied Polymer Systems Inc.
3. Charlie Miller, Roofscapes, Inc
3. Charlie Miller, Roofscapes, Inc
4. SchenkelShultz Architects
4. SchenkelShultz Architects
5. Burton Braswell Inc, Structural
5. Burton Braswell Inc, Structural
6. UCF Student Government and students
6. UCF Student Government and students
7. Randy Jones, Hardin Construction Co.
7. Hardin Construction Co.
8. Mark Towle, Big River Industries
8. Mark Towle, Big River Industries
9. Outdoor Essentials
9. Harvey Harper, ERD
10.Harvey Harper, ERD
Stormwater Academy: Green Roofs
Typical Section Student Union UCF
Stormwater Academy: Green Roofs
The Construction Process
Temperature sensors installed
Protection fabric
(no metal)
1600 square feet of
Green roof and 1600 square feet of Control roof (Conventional
Materials – polyester made
By Fibertite)
Drainage media over protection fabric
Stormwater Academy: Green Roofs
The Construction Process (continued)
Growth Media Expanded Clay
Irrigation Pipe Lots of Plants: Green Roofs
Construction Completed in March 2005
March 2005
July Growth
Weather
measures
Media Blends: Green Roofs
Media Selection Criteria
1. Lightweight
2. Plants can take root in it
3. Capacity to hold water
4. High albedo
Selected Media Blending of:
1. Lightweight Rock: 42-­52 LBS/CF
2. Tire crumb: 30 LBS/CF
3. Organcis
4. Others
Three Media Blends for Testing
Selected Media Blending of:
1. Expanded Clay: 3. Cool Substrate
60% Expanded Clay 60% Light rock
15% Peat Moss
20% Tire crumb 15% Perlite
10% Vermiculite
10% Vermiculite
10% Organics
2. Tire Black and Gold:
40% Tire Crumb
20% Expanded Clay
15% Peat Moss
15% Vermiculite
10% Perlite
Polymer Testing: Green Roofs
Polymer Blended Tackifier Results
Expanded Clay Mix before PBT 8.90 NTU
Expanded Clay Mix after PBT 2.90 NTU
Tire Crumb Mix before PBT 5.40 NTU
Time Crumb Mix after PBT 0.59 NTU Polymer Testing: Green Roof
Results after 24 inches of rain
Added to each cell
Source: Applied Polymer Inc. and UCF
REV Design Curves
Design Of the Cistern: Assume a reuse rate of 0.3 inches per day per equivalent green roof area.
Source: www.stormwater.ucf.edu and click on publications
Reduce Runoff Reuse IT: Green Roofs
The Cisterns
Designed to hold 1.5 inches of runoff (90% of the runoff assuming no initial abstraction)
Florida: Green Roofs
Updated Estimated Mass Balance and % Discharge from Green Roof Cistern
For a 3 month period
P is approximately 26 inches
I is approximately 7.5 inches
Estimated are:
1. ET = ~ 0.20 inches per day
2. For a “dry” substrate, no rain
or irrigation for three days, 0.73 inches of irrigation resulted
in 0.06 inches of runoff. 3. % of rain not discharge = ~ 80%
Stormwater Academy: Green Roofs
Water Quality Comparisons for 6-­22-­05
Sampling from the Cisterns
CONTROL
ROOF
GREEN
ROOF
PARAMETER
UNITS
pH
s.u.
6.12
7.63
Alkalinity
mg/l
7.3
191
NH3-N
µg/l
234
566
NO3-N
µg/l
127
6
Total N
µg/l
855
2443
SRP
µg/l
<1
745
Total P
µg/l
103
1243
Quality control source: Environmental Research & Design, Inc.
Water Quality Comparisons: Green Roofs
PARAMETER
CONTROL GREEN
ROOF
UNITS ROOF
Cadmium
µg/l
<2
30
Copper
µg/l
43
88
Nickel
µg/l
<2
9
Lead
µg/l
<2
99
Zinc
µg/l
48
56
Quality control source: Environmental Research & Design, Inc.
Florida: Green Roofs
Water Quality Comparisons Using two Green Roofs in Florida
FL West Coast
GREEN Roof
1.5 in Media
Typical Plants
UCF
6 in Media
Florida
Native plants
Control
Roof
At UCF
PARAMETER
UNITS
Copper
µg/l
70
88
43
Zinc
µg/l
30
56
48
NH3-N
µg/l
370
566
234
NO3-N
µg/l
860
6
127
Total N
µg/l
3500
2443
855
SRP
µg/l
300
745
<1
Total P
µg/l
450
1243
103
Note limited number of samples.
Grass Cover Green Roof Nitrogen Research
Input Concentrations for Sand media and Grass 4 foot of media and irrigated using 3 (2’x2’) chambers
Year of operation June 2004 –June 2005
Rainfall Input Volume was 67.22 inches (high)
63 events sampled for water quality
pH: Mean = 6.22
SD = 1.44
NO3-­N: Mean = 0.41mg/L
SD = 0.28 mg/L
NH3-­N: Mean = 0.16mg/L SD = 0.23 mg/L
Irrigation Input Volume was 23.24 inches (low)
43 events sampled for water quality from the source water
pH:
Mean = 7.20 mg/L
SD = 0.37
NO3-­N: Mean = 0.02 mg/L
SD = 0.01 mg/L
NH3-­N: Mean = 0.14 mg/L
SD = 0.18 mg/L
Org–N: Mean = 0.39 mg/L
SD = 0.38 mg/L
Notes: chamber 1 NO3-­N input was increased to 1 mg/L
chamber 2 NO3-­N input increased to 2 mg/L
and chamber 3 was the source concentration (0.02 mg/L)
Grass Covered Green Roof
Effluent Concentrations from Sand Media and Grass
4 foot of media and irrigated – 3 chambers
Chamber 1
Chamber 2
Chamber 3
n
Mean
St. Dev.
Mean
St. Dev.
Mean
St. Dev.
pH
166
6.69
0.13
6.66
0.17
6.77
0.19
Alkalinity (mg/L as CaCO3)
34
447.44
101.68
390.00
72.41
356.09
36.93
NO3-­N (mg/L)
118
0.03
0.01
0.03
0.02
0.03
0.02
NO2-­N (mg/L)
12
0.00
-­
0.00
-­
0.00
-­
NH3-­N (mg/L)
56
7.04
2.93
7.67
2.92
5.87
1.90
Org-­N (mg/L)
5
0.00
-­
0.00
-­
0.00
-­
Notes: The effluent pH was similar to that of the soil (pH=6.6).
NO3-­N decreased, and NH3-­N increased.
There was significant Org-­N and NH3-­N (750 mg/kg) in the sandy soil.
The ET was estimated as 42.3 inches per year (from mass balance).
Florida: Green Roofs
Comparative Water Quality and ET Experimental Design
Control Roof
SU alternative
Florida: Green Roofs
18 -­ 4 feet x 4 feet Chambers
Comparing two growth media Comparing two irrigation schedules (volumes)
Controls (conventional roof and no-­vegetation)
Duplicate of each
Water tight and
Insulated
Florida: Green Roofs
Chamber Mass Balance Results
For a one month period
P is approximately 5.9 inches
I is approximately 3.8 inches
S1+P1+I1-­F1-­ET1=S2 Estimated are:
1. ET = ~ 0.20 inches per day
2. For a “dry” substrate, no rain
or irrigation for three days, 0.50 inches of irrigation resulted
in 0.05 inches of runoff. 3. % of rain not discharge = 60%
(held in cistern for irrigation)
Native Plants: Green Roofs
Plant Selection based on
1. Perennial with color, preferably woody (having secondary growth) creeping prostrate, or shrubby plants with full sun, high temperature, low soil nutrient, and severe drought tolerances.
2. Shallow, fibrous rooting habit.
3. Cold hardiness to just below freezing.
Plant Selection: Green Roofs
Continued: Plant Selection based on
4. No severe pest problems or special horticultural requirements.
5. Florida native species preferred when suitable and available.
6. Evergreen foliage preferred, to maintain higher ET and cover and attractiveness all year.
7. Bloom or fruit display desirable but not mandatory.
Florida Native Dune or Beach Sunflower Helianthus Deblis
Florida: Green Roofs
Lonicera sempervirens
(Coral honeysuckle)
A perennial vine-like shrub
with bright red flowers in a
shape much loved by
hummingbirds. Common to
central and north Florida.
Typically found in wooded
areas.
Florida: Green Roofs
Gaillardia pulchella
(Firewheel Daisy)
Large flowers, have a wide
variation in form and
yellow/red combinations.
This is a hardy annual that
easily grows from self-sown
seeds. Often found growing
in hot, dry, difficult areas
throughout Florida. Grows
up to 24 inches tall.
Florida: Green Roofs
Myrcianthes fragrans
(Simpson’s stoppers)
This evergreen shrub has
fragrant white flowers that
produce a red fruit with
edible seeds. The leaves,
when crushed, smell of
eucalyptus. They start out
red, turning green later in
the growing season. Found
throughout south and
central Florida, these
shrubs provide shelter and
food for a variety of birds
and animals.
Florida: Green Roofs
Muhlenbergia capillaris
(Muhly grass)
Various natural varieities
found in pine flatwoods,
sandhills, moist hammocks
and beach dunes. Grown
throughout the entire state,
and very drought tolerant.
This grass reaches up to 3 ft
when in flower. The flowering
part resemble pink or purple
plumes. Blooms in the
summer and early fall.
Florida: Green Roofs
Helianthus debilis
(Beach or Dune daisy)
A low-lying, spreading
daisy that tolerates
harsh conditions: salt
spray, drought, acid or
alkaline soils. Often
used to stabilize dunes
that are subject to
erosion.
Florida: Green Roofs
AESTHETICS AND HABITAT CONSERVATION
A HAVEN for POLLINATORS
Florida: Green Roofs
Future native candidates for use on green
roofs:
Salvia coccinea (Tropical sage)
Monarda punctata (Spotted Beebalm)
Hamelia patens (Firebush)
Erythrina herbacea (Coral bean)
Mimosa strigillosa (Powderpuff)
Solidago spp (Goldenrod)
Hypericum hypericoides (St. Andrew’s Cross)
Oenothera laciniata (Cutleaf primrose)
Scoparia dulcis (Sweet broom)
Phyla nodiflora (Carpet flower)
Scutellaria integrifolia (Rough scullcap)
Florida: Green Roofs
Example Temperature Comparisons oF
Conventional Roof (red) versus Green Roof (green) at the roof surface
In the evening,
radiation is
present and conditioned space losses
to the roof. Source: www.stormwater.ucf.edu and click on roof monitoring data
Florida: Green Roofs
Example Temperature Comparisons oF
Top of Media (green) to Bottom of Media (red) at green roof surface
Source: www.stormwater.ucf.edu and click on roof monitoring data
The New American Home for 2007 Expected completion in November 2006
Design based on post discharge less than pre discharge or 4 inches of rainfall storage and 95% reuse (2.5 inch discharge/yr)
www.stormwater.ucf.edu
Conclusions
•
•
•
•
Post equal Pre volume control is possible
Many benefits
Use of native vegetation
Pollution concentrations higher from green roofs
• Stormwater cisterns designed for 3 inches of rainfall provides at least 95% reduction in discharge in the average year based on Florida rainfall.
Florida: Green Roofs
For additional information: Marty Wanielista, 407.823.4144
[email protected]
For web cam and other publications:
www.stormwater.ucf.edu