Teaching Green
Environmental, Economical, and Educational Benefits: Proposal for a Green Roof at the University of California, Davis
University of California, DavisDepartment of Environmental Sciences
Landscape Architecture ProgramSenior Project: June 2007
Yanet Martinez
Teaching Green
Environmental, Economical, and Educational Benefits:Proposal for a Green Roof at the University of California, Davis
A Senior Project presented to the faculty of the program of
Landscape Architecture at the University of California, Davis
in partial fulfillment of the requirements for the degree of
Bachelors of Science of Landscape Architecture.
Presented by
Yanet Martinez
at
University of California, Davis
on
the Fiftheenth day of June, 2007
Acceptance and Approval by:
Professor Mark Francis, Senior Project Advisor
Assistant Professor Stephen Wheeler, Committee Member
Adjunct Assistant Professor Jeff Loux, Committee Member
Steve McNeil, Committee Member
Teaching Green
The overall purpose of this paper is to provide the students, faculty, and administration at the University of California, Da-vis with a general understanding of green roofs, as well as the potential benefits that a green roof would have on the campus. As new information arises and people become more conscious of global environmental issues, the need to design with envi-ronmentally friendly techniques has increased along with the de-mand for knowledgeable individuals capable of executing them. To fulfill this demand, it is crucial to educate individuals proper-ly on these issues and their potential solutions. Although green roofs alone are not enough to solve all environmental issues, re-cent research and improved technology have demonstrated the importance and positive impact that they have, especially in ur-banized regions where solutions for reducing pollution and heat islands, as well as expanding the use of vegetation are of prior-ity. Implementing a green roof at the University of California, Davis, would provide not only the environmental benefits that green roofs typically provide, but also a site for students and faculty to learn and conduct research. Through the information obtained from text and highly valuable web sources, as well as through the overview of campuses that have already applied a similar idea and through information gathered from case studies of successful green roofs, a general understanding of this long-standing yet recently improved technology has been provided. I formulated a conceptual design for Hunt Hall, the proposed site for this project, fromthe information collected. The de-sign is based on the integration of intensive and extensive roof gardens as well as the more recently developing semi-intensive roof garden. Suggested layering techniques to satisfy the roof of Hunt Hall will be reviewed as well as a suggested plant list that would serve as most functional for this region.
Abstract
ii
Yanet Martinez, a 2007 Landscape Architecture graduating
senior from the University of California, Davis, was born and
raised in southern California in the city of Carson, where she
attended school up through high school, while also helping her
parents part-time in the family business, a wholesale nursery.
Prior to transferring to the University of California, Davis,
Yanet, attended El Camino College in Torrance where she
completed her general requirements and was a writer for “The
Union,” campus newspaper, and an active officer/member for
the Rotoract Club. While still in Southern California, her interest
in landscape architecture grew as she became more involved in
the family business and dealt with different professionals in the
related field.
Biographical Sketch
iii
Since her arrival at the UC Davis campus in 2004, Yanet was
intrigued by the community, diversity and environment of the
campus, which led to her membership to Kappa Kappa Gamma
where she participated in philanthropic and community events.
In early 2005, Yanet was admitted to the Landscape Architecture
Program. That same year, she traveled to Japan, where she
participated in a study abroad program offered by the UC Davis
landscape architecture program. There she traveled to Osaka,
Kyoto, and Nara, among other places, as she studied the history,
tradition, and techniques of Japanese gardens. Upon her return,
Yanet remained an active student of the landscape architecture
program and also participated in ASLA functions.
In the summer of 2006, she began an internship with the
County of Sacramento Department of Regional Parks, where
she assisted in various projects. She continued to work until
she once again departed Davis for a study abroad landscape
architecture program led by California State Polytechnic
University, Pomona in Italy. During her studies in Italy she
traveled to cities like Rome, Florence, Arezzo, and Venice where
she studied architecture, gardens, and history.
Upon her return to Davis, Yanet continued her internship with
the County of Sacramento Department of Regional Parks, as
she completed her final courses. After graduation, Yanet will be
traveling to South America to see more of the world. Ultimately
Yanet will work to build a professional career in the field of
landscape architecture.
iv
To my loving family that just never stop giving of themselves in
countless ways, both direct and indirect.
A mi familia quierida que nunca para de dar de ellos mismos en
maneras innumerables, ambos directo e indirecto.
Dad.Mom.Nin.Gordo.Johanna.Jordan.
I luv u much!
Dedications
v
I would like to express sincere thanks to the entire faculty,
staff, and students of the Landscape Architecture program
for teaching me all that I know and helping me to become the
individual that I am.
Mark Francis, for the many conversations that helped clarify
my thinking upon deciding for a topic, thanks.
Stephen Wheeler, Jeff Loux, Jim Harding, Steve McNeil,
your collaboration to this project meant a great deal to me.
Celine Livengood and Guy Kolling thanks for your support.
To all the “fantabulous” LDA class of 2007 who made my
time at Davis as memorable as I could’ve wished, thanks!
Mooney, Micah, Eddie, and Jaime…you all are wonderful
friends. Thanks for all your help!
To my dearest friends that helped me through my journey and
kept me sane through the senior project process,
Tereza and Justin, thanks, luv u!
Acknowledgements
vi
Abstract ............................................................................................ii
Biographical Sketch .......................................................................iv
Dedications .....................................................................................iv
Acknowledgements ........................................................................v
List of Illustrations & Photographs ..........................................vii
Introduction ....................................................................................1
What is a Green Roof? ..................................................................4
History of Green Roofs ................................................................6
Green Roof Layers ......................................................................11
Intensive Green Roofs .................................................................15
Extensive Green Roofs ................................................................18
Semi-Intensive Green Roofs .......................................................21
Benefits of Green Roofs .............................................................24
Disadvantages of Green Roofs ..................................................31
Universities and Green Roofs ....................................................32
Case Study: Yerba Buena Gardens ............................................38
Case Study: Union Square ...........................................................43
Case Study: YMCA ......................................................................48
Hunt Hall Site Analysis ................................................................53
Designing a Green Roof .............................................................58
Hunt Hall Conceptual Design ....................................................62
Plant List ........................................................................................65
Bibliography/References .............................................................67
Table of Contents
vii
1.1. Green Roof ...............................................................................1 1.2. Installation of green roof at UC of Florida .......................2 1.3. Hunt Hall ..................................................................................3
2.1. Depiction of the Hanging Gardens of Babylonia ..............72.2. Roof garden at Palazzo Piccolomini ....................................82.3. Traditional Scandinavian green roofs in Norway ...............9
3.1. Green Roof Layers ...............................................................113.2. Intensive green roof. Layer section ...................................163.3. Rockerfeller Center ...............................................................173.4. Millennium Park ....................................................................173.5. ACROS Prefectural International Hall ..............................173.6. Extensive green roof. Layer section ..................................193.7. Ocean Houses at Post Ranch Inn ......................................203.8. Heinz 57 Center ....................................................................203.9. Minneapolis Central Library ................................................203.10. Semi-instensive green roof. Layer section ......................223.111. The Calhoun School .........................................................233.12. The Culver House Residences ..........................................233.13. Library Square Building .....................................................23
4.1. Storm Water ...........................................................................254.2. Heat Island Profile ................................................................264.3. Green roof benefits chart ....................................................274.4. Vegetable roof garden at Trent University .......................284.5. Green roofs create ecological habitats (1) .........................284.6. Green roofs create ecological habitats (2) .........................284.7. Solaire building ......................................................................29
5.1. David Beattie and student at Penn State green roof (1) ......335.2. David Beattie and student at Penn State green roof (2) ......335.3. Ford Motor Company green roof ......................................345.4. U of Arkansa students on green roof (1) .........................34
List of Figures
viii
5.5. U of Arkansa students on green roof (2) .........................345.6. Rooftops at UC Davis ..........................................................355.7. Green roofs across America ................................................37
6.1. Yerba Buena Gardens. Plan view. ......................................386.2. Yerba Buena Gardens ...........................................................39 6.3. YBG. Site Analysis Photograph 1 ......................................406.4. YBG. Site Analysis Photograph 2 ......................................40 6.5. YBG. Site Analysis Photograph 3 ......................................406.6. YBG. Site Analysis Photograph 4 ......................................406.7. Vegetation at YBG .................................................................416.8. YBG. Site Analysis Diagram ..............................................42
7.1. Union Square Park. Plan view. ...........................................437.2. US. Site Analysis Photograph 1 .........................................447.3. US. Site Analysis Photograph 2 .........................................457.4. US. Site Analysis Photograph 3 .........................................457.5. US. Site Analysis Photograph 4 .........................................457.6. Vegetation at US ....................................................................467.8. US. Site Analysis Diagram ..................................................47
8.1. YMCA building .....................................................................488.2. YMCA. Site Analysis Photograph 1 ..................................498.3. YMCA. Site Analysis Photograph 2 ..................................508.4. YMCA. Site Analysis Photograph 3 ..................................508.5. YMCA. Vegetation at YMCA ............................................518.6. YMCA. Site Analysis Diagram ..........................................52
9.1. Hunt Hall vicinity map .........................................................539.2. Hunt Hall existing site photographs 1 ...............................54
9.3. Hunt Hall existing site photographs 2 ...............................55 9.4. Hunt Hall proposed site .......................................................59
1
Green roofs are a practice that within the later part of this
century has risen in popularity. Although it may appear that it
is a concept of recent emergence, green roofs actually date back
as far as B.C. (Osmundson 1999).
The term green roof is defined as any man-made structure, most
notably roofs, whose traditional material have been replaced
with vegetation (Green Roof 2007). Their unique ability to
produce a space for plants, which would normally not grow
vegetation naturally, is the result of continuously developing
technology which consist of roof layering. Two major types
of green roofs exist: intensive and extensive. However recent
Introduction
1.1. Green Roof.
2
developments have produced a hybrid referred to as a semi-
intensive green roof. Although these green roofs can be
beneficial environmentally, economically, and educationally,
each has qualities, which make them distinct from one another.
Each type of green roof mentioned will be discussed in further
detail within the following sections.
As many universities throughout the nation, as well as abroad,
are already endeavoring into the integration of green roofs as a
learning tool for students and faculty, it seems only appropriate
that as a university that is largely dedicated to addressing,
educating, and conducting research on environmental, ecological,
and agricultural issues, that the University of California, Davis
would consider the idea for a proposal of a green roof for the
campus. The addition of such a project to the campus would
assist in upholding Davis as one of the top universities and
research facilities in the nation and may perhaps even lead to
the development of other projects that share similar objectives.
Development of a green roof would also demonstrate the
concern of the university to address issues and educate students
on the issues that are currently of major importance such as
going green, environmental sustainability and global warming.
Through the exploration of green roof sources an overview of
the benefits said to be produced by green roofs will be covered
in this paper. Of the many benefits said to be produced by
the construction of green roofs, those that address possible
solutions for air and water pollution, heat island reductions,
additional recreational areas, ecological areas, insulation, and
increase roof life expectancy will all be discussed. A brief
overview of possible economical benefits will also be covered.
Possible disadvantages that may result from green roofs will
also be reviewed.
1.2. Installation of a green roof at the University of Central Florida.
3
Green roofs, sometimes referred to as roof gardens, were
also analyzed by visiting the sites in order to achieve a better
understanding of the components that make a successful green
roof. Case studies were conducted on the Yerba Buena Gardens,
Union Square and the roof garden atop the Central YMCA
located in San Francisco. Although there were limitations on
the information gathered about each case study, they still present
certain elements that could be integrated into the proposed
green roof for the university campus.
As a result of the data obtained, enough information was
gathered to provide a suggested preliminary conceptual design
for Hunt Hall at the University of California, Davis. The
conceptual design consist of the three types of of green roofs,
in an effort to familiarize possible users with all three. As Hunt
Hall is proposed to undergo renovation in the next couple
years and serve as the home for the Department of Landscape
Architecture, it seemed as the ideal location. Aside from a
conceptual design, a suggested plant list for each green roof
type was also formulated. The plants selected were based on
what would might possibly be suitable for the site.
By the end of this paper it is intended that the reader gain an
overall general understanding of green roofs. They should be
able to define what a green roof is, understand its layers, know
the different types of green roofs, and list the benefits and
possible disadvantages that come with building a green roof.
It should be noted that the intention of this paper is to get
the reader acquainted with the concept of green roofs and to
propose the possibility of the University of California, Davis
implementing a green roof on campus. This paper is not to
serve as a primary guide for the construction of green roofs.
1.3. Hunt Hall. Furture location for the Landscape Architecture Program.
4
A green roof is the concept of growing vegetation on a man-
made surface, generally the roof of a building (Green Roof
2007). Green roofs usually consist of different layers that make
the growth of vegetation on these otherwise non-vegetative
surfaces, possible. Generally green roofs consist of a vegetation
layer, growing medium layer, filter layer, drainage layer, protection
layer, and a waterproofing layer (Dunnett 2004).
Green roofs can be divided into two categories known as
intensive and extensive. Recently a third type of green roof
known as the semi-intensive green roof has emerged. When
distinguishing between green roofs, important factors to look
for include, soil thickness, vegetation selection, accessibility, and
weight. Intensive green roofs are typically the more elaborate
of the two green roofs and share the qualities of most gardens
that come to mind. Extensive green roofs on the other hand are
usually inaccessible, are composed of limited vegetation, and
usually designed with some of the ecological and environmental
benefits in mind. The emerging semi-intensive green roof can
be seen as a hybrid of the two established green roof types. This
recently emerging type of green roof integrates more of the
What is a Green Roof?
5
qualities that are found in extensive green roofs, however they
provide for accessibility and occasional interaction of people to
the garden (Dunnett 2004).
Green roofs should be looked upon as more than just plants
on a roof, as they have demonstrated environmental and
economical benefits. They have been applied as solutions for
air and water pollution, heat reductions, alternative recreational
and ecological space and more. Thus far, they have also been
credited with providing insulation to buildings, reducing energy
cost and increasing property values (Green Roofs for Healthy
Cities 2007).
The benefits that green roofs are credited with seem immense,
however additional research and for creating and understanding
new solutions, materials, and methods in the construction of
this new technology is still a essential. As with anything else, the
better we understand this technology the more beneficial it will
be to communities and the nation.
6
The concept of green roofs may seem like a moderately
innovative idea, however green roofs have actually been linked
back to ancient historic times. Throughout the historic evolution
of green roofs the role of these gardens seem to have shifted
from simply aesthetics purposes to adaptation for survival
and recently onto environmental purposes. The information
gathered in this section on the history of green roofs will give
an overview on the use of this garden system throughout its
history and throughout its role amongst different cultures. It
is only by studying the history of green roofs that a better
understanding and appreciation of the different gardens, i.e.
intensive, extensive, and semi-intensive, can be achieved. It
should be noted that throughout this section the terms, roof
garden, intensive, extensive, and semi-intensive may be used in
place of green roof, if considered more appropriate.
Throughout time, the mention of green roofs has come about
in many literary documents with the first recorded reference
toward the Hanging Gardens of Babylonia, which existed since
before B.C.. Although no physical evidence seems to have ever
been discovered of these gardens existence, the mentioning by
History of Green Roofs
7
creditable individuals such as Strabo and Diodorus Siculus has
lead to the belief of their existence. The majestic description
of these gardens has even listed them as being one of the seven
original World Wonders (Hanging Gardens 2007).
The story behind the creation of these gardens is said to be the
result of king Nebuchadrezzar II, as a way of consoling his wife
Amytis in her longing for the landscape of her homeland, which
is described as abundant in vegetations and green hills. These
gardens are said to have been built upon Babylonian ziggurats,
pyramid like buildings with large landings that allowed for
placement of these gardens (Osmundson 1999).
Early depictions described the construction of these gardens
upon “stone beams some sixteen feet long and over these were
laid first a layer of reed set in thick tar, then two courses of
baked clay brick bonded by cement, and finally a covering of
lead to prevent the moisture in the soil penetrating the roof
(Osmundson 1999).” Plants were then situated on top and
irrigation was made possible through pumping of the river.
As the gardens of Babylonia were described as being elaborate
and mainly for aesthetic pleasures it can be said that the first
historical recorded green roofs were what we refer to today as
intensive.
The preservation of the town of Pompeii in Italy, as the result
of the infamous Mount Vesuvius eruption in A.D., lead to the
uncovering of a roof garden atop the roof of Villa of Mysteries.
Similar to the Hanging Gardens of Babylonian, the gardens
uncovered in Pompeii were situated atop a building that had
arched walls for ventilation. As a result of the volcanic eruption,
the garden was preserved rather well so that archaeologist have
been able to identify the type of vegetation that was used, by
casting molds of their roots (Osmundson 1999). 2.1. Depiction of the Hanging Gardens of Babylonia.
8
Pompeii wasn’t the only Italian town to have gardens growing
atop its roofs; Pienza, Lucca and Careggi are towns that had
roof gardens as well. In Pienza, a garden constructed atop the
Palazzo Piccolomini during the 1460s, by orders of Pope Pius
II, is one of the most well preserved roof gardens to this date
(Osmundson 1999). The garden is built atop a masonry building
and composed of primarily small manicured plants, making this
an intensive roof garden.
In Careggi, the well-known Medici Family also had a roof
garden. The garden was composed primarily of a collection
of exotic plants that the Medici family collected and served as a
representation of their wealth (Osmundson 1999). As the main
purpose of this roof garden was entertainment purposes, this
garden was most definitely held intensive qualities. Similar to the
garden at Palazzo Piccolomini, this garden was built atop of the
roof of the building, covered in a layer of soil and vegetation.
On the other side of the world in the island city of Tenochititian
Mexico, during the same time roof gardens were emerging in
Europe, a completely different civilization had also developed
this similar technology of creating roof gardens. As the
Spanish conquerer Hernan Cortez described in a letter to
Charles V, 1520, “numerous wealthy citizens who also possess
fine houses… in addition to the large and spacious apartments
for ordinary purposes, have others, both upper and lower, that
contain conservatories of flowers (Modern History Source
Book 1998).” The description in this letter led to the indication
that roof garden in Tenochititian existed around 1520, before
the invasion by the Spaniards.
In the 1600s even more roof gardens emerged throughout Europe
and other parts of the world. Like most gardens documented
up to this period, roof gardens built in this era were quite similar.
2.2. Roof garden at Palazzo Piccolomini.
9
Today we would describe these roof gardens as intensive, as
they were quite elaborate and primarily designed for aesthetics
and entertainment. Two gardens in Russia, the Kremlin Palace
in Moscow and the Hermitage in Saint Petersburg are examples
of the gardens built in this era (Osmundson 1999).
Prior to the 1800s the notion of a roof garden was usually
associated with wealth, power, aesthetics and entertainment,
and were what we may now refer to as intensive gardens. In
the early 1800s however gardens atop roofs started to develop
in Germany that were unlike any of the gardens that had been
created before. Whereas before gardens were created primarily
for the aesthetic pleasures of the wealthy, in Germany a transitions
had begun that evolved these gardens into a functional building
material. Middle class people in German adopted the idea of
growing vegetation on the roof of their homes as a method of
insulation for their homes during harsh seasons. During the
cooler seasons the vegetation and soil layer helped retain heat
in the building and to cool it during warmer seasons. These
new types of roof gardens seemed to share similar building
approaches as those found in the roof gardens before them.
These new versions of roof gardens were usually consisted of
a layer of soil, which served as the base for grasses and low
growing vegetation, to grow. Because these gardens were
generally planted atop smaller dwellings, they weren’t intended
for larger vegetation or as being accessible hence maintaining
them was less necessary (Dunnett 2004).
Middle class in the United States also seemed to have adapted
this method of insulations, as homes, schools, and other building
were being constructed with extensive roofs. Towns within the
states of Dakota and Nebraska especially demonstrated a liking
for this technique (Dunnett 2004).
2.3. Traditional Scandinavian green roofs in Norway.
10
After a project demonstrating the functions of this new roof
technology was revealed at the World Exhibition of 1868 in
Paris, the international launch of the extensive roof garden
seemed to have taken place as people became fascinated with
the concept (Dunnett 2004). At the same time, however, the
intensive roof gardens began to emerge once again, as they
became a popular entertainment asset especially for theatre and
hotels. Again it seemed as if gardens where returning to the
intensive type gardens. In large developing cities such as New
York, the luxury of open space was limited and so the idea of
converting roofs into an open space began to sprout yet again.
The gardens that developed during this era were much like the
first roof gardens wherein they were being built for the pleasure
of the wealthy (Osmundson 1999).
During the twentieth century, technological advancements
allowed for improved construction of roof gardens in general.
Roof gardens such as those at the Kensington, Rockefeller Center,
and Union Square of San Francisco, which have inspired many
of today’s roof gardens, were built during this era (Osmundson
1999). In Germany, the development of technology for
extensive roof gardens has made it the leader on extensive
gardens. Along with Germany, regions in Scandinavia and
Kurdistan also developed this technology. Similar to the original
extensive gardens of the 1800s, the gardens of the twentieth
century were designed for the benefits that they provided to the
buildings and their dwellers. Insulation, extended roof life, and
aesthetics were the purposes of the emerging extensive roof
gardens (Dunnett 2004).
From the 1950s to today, a stronger emphasis has been put on
studying roof gardens and distinguishing between the two main
types, intensive and extensive. As more research is conducted
on the subject matter, it is becoming apparent that these gardens
are beneficial to societies on many levels, especially when dealing
with the latter of the two types, the extensive green roof. As
a result of these recent findings, a third type of roof garden
referred to as semi-intensive, which is a mix of intensive and
extensive, has emerged.
11
The production of a green roof is more than simply the
placement of vegetation on a rooftop. Green roofs consist of
multiple layers that make the establishment of such vegetation
possible. Whether its an intensive, extensive, or semi-intensive
green roof, all green roof types usually consist of six main
layers. These layers are commonly identified as the vegetation,
growing medium, filter, drainage, protection and waterproofing
layers (Living Green Roofs). Although layers vary according to
the type of green roof, the overall objectives of these layers is
the same in for all green roof types. For the purpose of this
project, a general overview of green roof layers will be provided.
An overview explaining the purpose of each layer and how each
Green Roof Layers
I.1. Green Roof Layers.
12
functions will be given. Specific information for each green
roof type are within Intensive Green Roofs, Extensive Green
Roofs, and Semi-Intensive Green Roofs sections.
1. The VegeTaTion Layer
The vegetation layer, is the part of a green roof individuals are
most familiar with as it is the layer that adds the “green” to the
roof. Depending on the type of green roof and the climatic
region where a green roof project is located, the material used
within this layer is bound to vary highly, in comparison to
the other layers. The main objective in creating a successful
vegetation layer for any green roof type, is to use plant material
which is typically drought tolerant, able to withstand high
temperatures and wind (Dunnett 2004). Selecting plants with
these characteristics will help ensure their longevity and the
success of the green roof. Also when selecting plants size and
root depth of the plants need to be considered especially when
designing an extensive green roof (GR-Cooling L.A. 2006). For
these reasons some of the most commonly used vegetation in
green roofs include succulents and ground covers. Each green
roof type is designed to support particular type of vegetation,
it is important to study the type of plants which are appropriate
for a particular type of green roof. Extensive green roofs, for
example are designed to support the lightest weight possible,
which limits the plant selections to mainly ground covers,
particularly sedum, which are not only light, but whose roots
don’t require much depth in the growing medium layer. Intensive
green roofs on the other hand, are design to accommodate larger
plants, providing a larger plant selection for this type of green
roof (Dunnett 2004). In the end, when selecting plant material
for ay green roof, “it is necessary to choose plants suitable for
each climate, whether the conditions are periodically very dry,
very hot, very cold, or very variable (Living Green Roofs).”
2. The growing MediuM Layer
The growing medium or substrate layer is located directed
beneath the vegetation layer and above the filter layer. Unlike
most gardens, green roofs can not be planted with the typical
“garden soil or topsoil... because it is too heavy and too fertile
(Dunnett 2004).” When selecting a growing medium for a green
roof it is important to consider weight, especially with extensive
green roofs. Instensive green roof may usually use typical garden
13
soils, but using a growing medium specialized for green roofs
is ideal. A major concern when selecting a growing medium
has to do with safety as “soil containing a lot of peat or other
organic substances is liable to shrinking, and can be a fire hazard
(Living Green Roofs).” Companies specializing in green roof
material often carry specialty growing mediums or substrates.
These growing mediums are usually lightweight and contain
natural minerals, however artificial soils are also available which
usually include “vermiculite and perlite (Dunnett 2004).” “A
good roof soil is therefore mainly a mineral soil, not containing
clay, which is too impervious. To make the soil lighter, crushed
brick or lava can be mixed in (Living Green Roofs).”
3. The FiLTer Layer
The filter layer is located between the growing medium and
the drainage layer. Typically a fabric material is used and is
neccessary “to stop the substrate from disturbing the drainage
function.” Use of this layer prevents the blockage to the
drainage layer, which may be caused by possible debris from
the growing medium and also serves as “an erosion control that
holds the substrate in place (Living Green Roofs).”
4. The drainage Layer
The drainage layer located below the filter and above the
protection layer, is one of the most important layer in the
construction of a green roof. The drainage layer is essential
in determining where water directer toward after it has reached
the green roof. “If drainage is inadequate on a flat green
roof, then damage to the roof membrane may ensue (Dunnett
2004).” Other issues that may result from a faulty drainage
system include puddles, erosion of growth medium, rotting of
plants, and unwanted plants (Living Green Roofs). In order
to achieve a green roof which will be beneficial especially in
treating storm water it is necessary to install a drainage system,
appropriate for the specific roof type. The drainage layer should
provide the function to store some water which is available to
the vegetation layer (Dunnett 2004). The material typically used
in the drainage layer, is available from all nature to manufactured.
Materials commonly include gravel or crushed rock, crushed
lava, crush leca or crushed bricks, rockwool, foam material, and
plastic sheets (Living Green Roofs).
14
5. The ProTecTion Layer
Located under the drainage layer, most green roofs typically
include a protection layer. The main purpose of the protection
layer is to create a barrier between the roots of the plants and
the waterproofing layer. This layer essential prevent damage
to the roof structure which may result from root penetration.
“Root protection membranes are usually composed of rolls of
PVC and laid out over the weatherproofed roof deck or suface
(Dunnett 2004).” Other root repellant alternatives also include
chemicals, copper sheets, and rubber seals (Living Green Roofs).
In some cases, especially with extensive green roofs, this layer is
left out as it is believed that the roots of ground covers, such as
sedum, will not damage the roof. However each potential green
roof project should consider installation of the protection layer
unless otherwise specified by a professional.
6. The waTerProoFing Layer
The waterproofing layer, essentially the first layer to be applied
to any green roof, is important in sealing the building from
water. This layer is important in order to keep the building from
any damage which may result as a excessive water or moist soil.
“Unless the roof memebrane is damaged while laying the green
roof, the soil and vegetation cover will protect the membrane
from these types of injuries later (Living Green Roofs).” Three
types of materials which are typically used for this layer include
the built-up roof, the single-ply membrane, and the fluid-applied
membrane (Osmundson 1999). Each type consist of the
following: built-up roofs consist of “bitumen/asphalt roofing
felt or bitumized fabrics,” single-ply membranes are “sheets of
inorganic plastic or synthetic rubber material” sealed heat or
adhesive, and fluid-applied membranes are liquid “sprayed or
painted on the surface of the roof and forms a complete seal
(Dunnett 2004).”
15
deFined
The idea most people get when they think of a green roof is
what is referred to as an intensive green roof. Intensive green
roofs can be considered of higher popularity because they are
generally aesthetically appealing, have garden-like features and
are accessibility. As Snodgrass describes, intensive green roofs
are the combination of “deeper, more organic substrates and rely
on irrigation system to recreate full-scale gardens above ground
(Snodgrass 2006).” Because intensive green roofs are a more
elaborate garden, they sometimes require more components
or more of each component, than either an extensive or semi-
intensive green roof would require. Due to the large-scale
intensity of this green roof, the structure of the building should
be able to support additional weight “typically from 80 to 150
lb/sq ft,” to be able to support the various layers, additional soil
which may exceed 12 inches, and the vegetation of moderate size,
not to mention the weight added by the activity of individuals
that access the site (GR-Cooling L.A. 2006). Intensive green
roofs are often also referred to as roof gardens. Intensive green
roofs are typically the more elaborate of the two green roofs
and share the qualities of most gardens that come to mind.
Intensive Green Roofs
16
adVanTages and disadVanTages
The following is a list of the positive and negative factors that
may result from an intensive green roof.
Pros cons
Accessibility High maintenanceGood use of otherwise non used space
Heavy weight load
Allows for recreational uses and multi-purpose activities
High cost/Expensive
Wider vegetative selection May require additional structural support
Provides the best insulation Usually requires profes-sional installation
Aesthetically appealing Requires irrigation
coMPonenTs
Green roofs of all types usually consist of similar layers. The
difference for each usually seen in the thickness of each layer,
plant selection, and weight. Because intensive green roofs are
more elaborate and require more support its layers are thicker
than extensive are semi-intensive. According to the specific
project, the layer thickness will vary. Often the thickness of
the growing medium layer, which is minimally 6 inches and can
exceed over 1 foot in depth, will help determine that a green
roof is indeed intensive (Dunnett). Plant material used is usually
enough, however to identify the type of green roof. Instensive
green roofs are the only capable of supporting trees and large
shrubs in it vegetation layer, and contains the largest plant
selection of all three types, and as a result bear more weight.
The figure below shows two sections illustrating the layers of an
intensive green roof. Intensive green roofs may also require an
additional irrigation layer, not shown in the figure below.
1. Waterproofing Layer
2. Protection Layer
3. Drainage Layer
4. Filter Layer
5. Growing Medium Layer
6. Vegetation Layer
3.2. Intensive green roof. Example of two layer types.
inTensiVe green rooF Layers
17
exaMPLes
The following are examples of Intensive Green Roofs:
1. Rockefeller Center, New York, New York
2. Millennium Park, Chicago, Illinois
3. ACROS Prefectural Int’l Hall, Fukuoka, Japan
4. Fairmont Hotel and Tower, San Francisco, California
5. The Hilton Palacio de Rio, San Antonio, Texas
6. Equitable Plaza, Pittsburgh, Pennsylvania
7. Pershing Square, Los Angeles, California
8. Union Square, San Francisco, California
9. University Green, Cambridge, Massachusetts
10. Theodore Hall, Davis, California
(3.4.)
(3.3.) (3.5.)
18
deFined
Unlike intensive green roofs, extensive green roofs have qualities
that make the better choice for achieving greater ecological
and environmental benefits (Dunnett 2004). Originally,
the function of these gardens was to provide insulation for
primarily residential homes in regions such as Germany,
Ireland, and the Scandinavian countries. As the Scandinavian
Green Roof Institute defines, extensive green roofs consist
of “very thin layers, drought tolerant plants and require littler
or no maintenance (Living Green Roofs).” Because the main
functions of extensive green roofs are typically for insulating
and ecological reasons, the accessibility of this type of green
roof is limited to maintenance, which usually requires only
seasonal or yearly access. For the same reason, extensive green
roofs are not necessarily designed to be aesthetically pleasing, as
intensive green roofs are, but the replacement of typical roof
surfacing with live vegetation usually still provide improved
scenery. Extensive green roofs may commonly also be referred
as turf green roofs, or eco-roofs.
Extensive Green Roofs
19
adVanTages and disadVanTages
The following is a list of the positives and negatives factors that
may result from an extensive green roof.
Pros cons
Light weight Limited plant selectionLow maintenance InaccessibleYields high percentage of ecological benefits
Less aesthetically pleasing
Less expensiveCan be placed on smaller structures
coMPonenTs
Extensive green roofs are composed of the similar layers as the
other two green roofs mentioned. Because extensive green roofs
are the least complex, its has the thinnest layers and in some
cases some layers, such as the protection layer, are not used at
all. The plant material used in the vegetation layer, as well as the
roof itself, will usually help determine if it is possible to leave out
layers. The growing medium layer in an extensive green roof has
a minimum of 3 inches and maximum of 6 inches. As a result of
the growing medium layer, the plant selection for the vegetation
layer is limited to mostly low growing grasses and groudcovers,
such as sedum. Extensive green roofs are not designed to
support shrubs or larger plants. Finally the combined system
of an extensive green roof typically has a “saturated weight of
15-30 lbs/sq ft (Green Roof Types 2005).”
1. Waterproofing Layer
2. Protection Layer
3. Drainage Layer
4. Filter Layer
5. Growing Medium Layer
6. Vegetation Layer
3.6. Extensive green roof. Exampe of two layer types.
exTensiVe green rooF Layers
20
exaMPLes
The following are examples of Extensive Green Roofs:
1. Ocean Houses at Post Ranch Inn, Big Sur, California
2. Heinz 57 Center, Pittsburgh, Pennsylvania
3. Minneapolis Central Library, Minneapolis, Minnesota
4. Premier Automotive North American Headquarters, Irvine,
California
5. California Academy of Sciences, San Francisco, California
6. School of the Future, New York, New York
7. Cornell University Dept. of Horticulture, Ithaca, NY
8. Carnegie Mellon University, Hamerschlag Hall, Pittsburgh,
Pennsylvania
9. Life Expression Wellness Center, Sugar Loaf, Pennsylvania
10. Mashantucket Pequot Museum, Mashantucket, Connecticut
(3.8.)
(3.7.) (3.9.)
21
deFined
The most recent type of green roof to emerge, is known as a
semi-intensive green roof. A semi-intensive green roof can
be described as having characteristics of both intensive and
extensive green roofs. As with extensive and intensive green
roofs, the main factor in distinguishing a semi-intensive green
roof usually has to do with vegetation type, soil thickness
and weight. Semi-intensive green roofs are determined to be
“usually 6-12 inches deep with a saturated weight of 30-50 lb/
sq ft (Green Roof Types 2005).” For this type of green roof,
vegetation that can be used rangings from ground covers to
herbs, shrubs and grasses. Since the vegetation for this type of
green roof is larger than that found in extensive green roofs,
maintenance is required on a regular basis, even though it’s not
as intense as intensive green roofs. Semi-intensive green roofs
are designed for occasional or low impact use (Green Roof
Types 2005).
adVanTages and disadVanTages
Since the semi-intensive green roof can be seen as somewhat
of a hybrid of extensive and intensive green roofs, most of its
Semi-Intensive Green Roofs
22
qualities are moderate. When studying all three green roof types
together, factors such as cost, maintenance, weight, all appear
to be moderate for semi-intensive green roofs. Advantages
and disadvantages for this green roof can be made only when
compared one-on-one with another type. The following is a list
of some of the more obvious positives and negatives that may
result from semi-intensive green roofs:
Pros cons
Accessible Partly limited plant selectionAesthetically pleasing May require irrigationProvides moderate recre-ational space
Require regular mainte-nance
coMPonenTs
Since semi-intensive green roofs share qualities of both extensive
and intensive green roofs the components are a mean of the two
green roofs. As mentioned earlier, the vegetative layer for the
semi-intensive green roofs consist of primarily “grass, herbs,
and shrubs,” which require little to moderate maintenance (Int’l
Green Roof Association 2007). The growing medium layer is
typically 6 inches to 12 inches in depth. The semi-intensive 3.10. Semi-instensive green roof. Example of two layer types.
roof system has a “saturated weight of 30-50 lb/square feet.
(Green Roof Types 2005).” Because semi-intensive green roofs
combine the benefits of extensive and intensive green roofs,
they are becoming more appealing.
1. Waterproofing Layer
2. Protection Layer
3. Drainage Layer
4. Filter Layer
5. Growing Medium Layer
6. Vegetation Layer
seMi-inTensiVe green rooF Layers
23
green exaMPLes
The following are examples of Semi-Intensive Green Roofs:
1. The Calhoun School, New York, New York
2. Culver House Residences, Chicago, Illinois
3. Library Square Building, Vancouver, British Colombia (3.13.)(3.11.)
(3.12.) 4. Bell Museum of Natural History, Minneapolis, Minnesota
5. Bamboo Holding Shed, Asia Trail - Smithsonian
National Zoo, Washington, DC
6. University of Michigan Cyclotron Building Addition,
Ann Arbor, Michigan
7. Earth Pledge Foundation, New York City, New York
8. Museum Place Lofts, Portland, Oregon
9. HSBC Bank Green Roof, Mexico City, Mexico
10. Inter Continental Resort, Berchtesgaden, Germany
24
Through the recent research that has been dedicated to green
roofs, it has been demonstrated that the application of this
technology has resulted in a range of benefits. “Green roof
technologies not only provide the owners of buildings with a
proven return on investment, but also represent opportunities
for significant social, economic and environmental benefits,
particularly in cities (Green Roofs for Healthy Cities 2007).”
Socially, they have been credited with providing recreational
and open space for communities, as well as making them more
aesthetically appealing and even a widely recognized attraction
(Noyes 2006). Economically they reduce cost by improving
building insulation, extending the longevity of roofs, and
increasing property value. Environmentally, green roofs are
said to improve air and water quality, and reduce heat islands
(Dunnett 2004). The information in this section provides a
general understanding of some of the major benefits that green
roofs have been credited with.
Benefits of Green Roofs
25
to around 5 percent for a forested area.” This extra surface
runoff is water that eventually finds its way to natural bodies
of water and sewage systems. Natural bodies of waters such as
rivers and lakes are effected “not only by the quality of runoff
but also by its quantity, as a high volume of flow contributes to
erosion and sedimentation, and impacts aquatic habitats (Storm
sTorM waTer PoLLuTion
Within recent years, the importance of addressing water
quality issues has become the priority of many city and state
governments. As cities become more and more urbanized and
man made structures and surfaces out number square footage
of natural vegetative areas, the problem of storm water run off
and pollution will increase. Because these man made surfaces
are not permeable, rainwater is unable to penetrate into soil or
natural substances, which would otherwise filter out pollutants.
In fact, materials such as concrete and asphalt that are used
in large on roads, parking lots, and buildings, collect many
contaminates that collect in a city like “oil and other synthetic
hydrocarbons, heavy metals, road salt, pesticides, and animal
waste,” which hence pollutes the storm water (Dunnett 2004).
Green roofs would not only be beneficial in reducing the
amount of pollutants that storm water collects, but also in the
prevention of storm water flow in sewage systems and natural
bodies of water, in erosion, and in lowing temperatures by
retention of water. As Dunnett states, “75 percent of rainfall
on towns and cities is lost directly as surface runoff compared
4.1. Storm water from residential and urban areas collect pollutants that eventually make their way into natural bodies of water.
26
Water Pollution Prevention 2006).” In a similar way, sewage
systems and water treatment facilities become overloaded when
dealing with large amounts of surface runoff.
By installing green roofs on building especially in large urban
cities, storm water pollution would be reduced, as water
absorption would take place from the vegetative and soil layers.
The soil would hold and release water as needed, while plant
processed the water through the transpiration process (Dunnett
2004). This not only decreases the percentage of surface runoff
but also helps cool the area down.
reduced heaT isLand eFFecT
As cities grow, vegetative spaces are being replaced by man-
made surfaces, resulting in a regional heat increase. As defined
by the Environmental Protection Agency, “’heat island’ refers
to urban temperatures that are higher than nearby rural areas
(Chang 2000).” Heat islands result from surfaces such as asphalt,
concrete, and roof materials that absorb the heat radiated
from the sun, which causes this temperature increase. This is
a problem in larger urbanized cities as much of their surface
is made up of this material. “In the United States, buildings
consume six times as much energy and produce six times as
much greenhouse gas emissions as all cars and trucks combined
(Hall 2006).” Green roofs work as a solution in reducing this
problem as they convert some of the surface causing this
problem into green vegetative spaces.
Vegetation important in achieving cooler temperatures. “If all
the roofs in a major city were ‘greened,’ urban temperatures
could be reduced by as much as 12 degrees (Noyes 2006).” This
is because vegetation naturally cool regions and also provides
shade and evapotranspiration. This is created as “heat energy
4.2. Profile of urban heat temperatures.
27
is drawn from the surrounding air to convert the water to water
vapor, which produce a cooling effect (GR-Cooling LA 2006).”
Regions that lack vegetation obviously have higher temperatures,
as illustrated in the Urban Heat Island Profile figure. As larger
cities are lack the space for vegetation, green roofs are now the
alternative. But in order to achieve higher results in temperature
reduction more green roofs need to be constructed.
air PoLLuTion
The cooling effect that is created as a result of vegetation not
only helps to reduce the heat island effect, but it also helps
decrease pollution in the air which is often a result of high
temperatures. As stated by Green Roofs for Healthy Cities, “1
square meter (10.76 sq ft) of grass roof can remove between 0.2
kg of airborne particulates from the air every year (Green Roofs
for Healthy Cities 2007).” Some of these air pollutants include
dust and smog. Cities like Los Angeles where air pollution is a
problem could reduce by green roofs are built. Currently Los
Angeles and many other cities, are following Chicago, the green
roof leader in the United States, by promoting green roofs and
encouraging individuals (GR-Cooling LA 2006).
recreaTionaL, VegeTaTiVe, and MediTaTiVe sPace
In areas where space is limited, green roofs serve as alternative
places for recreation, vegetation, and meditation. Recreational
green roofs provide an opportunity for open space in a
location that would not otherwise exist. Whether these spaces
are public or private, the individuals frequenting the site will
benefit highly as, “green natural environments are places where
humans can recover (Living Green Roofs).” Green roofs can
also help build stronger communities as they provided a space
4.3. Green roofs benefit chart.
28
for neighbors that would typically not have a place to interact,
to interact. In some cases, green roofs have been utilized for
growing vegetables, herbs, and fruits. Growing food on green
roofs is very beneficial as it could produce “fresher produce,
decreased travel time to the market and related environmental
cost, and control soil, fertilizer and pesticides, (Green Roofs
for Healthy Cities 2007).” Using a roof to grow food would
provide economical benefit, as well. An example of this is Trent
University in Canada, whose green roof serves as the growing
grounds that provides the vegetables used by various campus
cafes (Blyth 2006).
Studies have shown that people who live in large cities often
suffer from more health issues as opposed to individuals who
reside in greener environments with more open space. Green
roofs provide a natural environment for individuals to relax and
escape from the city, without having to travel very far. The
“therapeutic benefits that result from caring for plants,” as well
as the “restorative effect of a natural view holds the viewers’
attention, diverts their awareness from themselves and from
worrisome thoughts, thereby improving health (Green Roof for
Healthy Cities 2007).”
reconsTrucTion oF ecoLogicaL habiTaTs
The decline of natural areas as a result of urbanization has
displaced and interrupted ecological habitat for many creatures.
As society becomes more environmentally conscious, the
importance of these creatures and their habitats will have
many organizations throughout the country trying to develop
solutions, in order to fix these problems. For many species that
migrate, like birds, the need for rest-stops may be limited. The
installation of green roofs would build an environment where
these species could create a temporary habitat. In itself, a green 4.4. Vegetable roof garden at Trent University.
29
econoMicaL saVings
Initially, a green roof may seem to be costly, but the long-term
savings that result from having a green roof are greater than the
cost. Some of the initial cost that goes into a green roof project
may qualify under “grants related to energy efficiency and/or
green roofs” depending on the project itself (Green Roof for
Healthy Cities 2007). Although green roofs can be initially
costly, costing twice as much as traditional roofs, in the long term
the savings are greater. Green roofs have shown to last twice as
long as traditional roofs as it “protects the waterproofing from
both the uv-light and the temperature extremes, increasing the
roof could also serve as a habitat for smaller species, such as
butterflies and invertebrates. The extent of how ecologically
sensitive a green roof will be depends on the design and
materials used. For example, ecological benefits are likely to be
higher in extensive and semi-intensive green roofs, as they are
inaccessible, limiting human interaction. Green roofs designed
to be ecologically beneficial differ as they integrate more natural
and organic materials. In Switzerland, for example, often times
to recreate an ecological habitat they “use no particular drainage
layer, but allow the water to drain through the soil, or even be
left standing in puddles, as in nature (Living Green Roofs).”
4.5. & 4.6. Green roofs can provide ecological habitats for various creatures.
4.7. Solaire Building, New York. (photo gallery)
30
life expectancy of the membrane to at least 60 years, according
to studies (Living Green Roofs).”
Green roofs also help cut cost as they serve as insulation for
buildings, which reduces the use of materials, and the use
of heating and cooling systems. Buildings require less air
conditioning during the summer because of their natural way
to retain moisture and cool temperatures. In winter months the
reverse happens as they retain heat, reducing heating cost. This
is especially true with intensive green roofs as they have thicker
layers. Cooling and heating insulation may vary according to the
building size.
Green roofs can also provide other benefits as they allow for
LEED points, the use of recycled material, improved health,
solar panels, and noise reduction among other things.
31
Although the benefits from a green roof are much greater,
disadvantages exist which need considerations prior to starting
any project. The primary disadvantages to constructing a green
roof are almost all directly linked to expenses. Green roofs
can be very expensive, depending on the size of the project.
Often times the cost of installing a green roof can be twice
the cost of traditional roofing. As reported by USA Today,
in 2006 the “cost of green roofs is about $14 to $25 square
foot (Holladay 2006).” Additional expenses may also arise if
structural reinforcement of the building is required. This is
especially true in older building and with intensive green roofs
as intensive green roofs can weigh anywhere between 80 to 150
lbs a square foot (GR-Cooling L.A. 2006). It is important that
the project site be thoroughly studied prior to construction for
potential issues as there have been cases where major repairs
have been required after completion of projects due to things
that may have been fixable during the building stages, such as
cracks and leaks. Disadvantages particular to each green roof
type also exist. For disadvantage on specific green roof types
see the Intensive Green Roofs, Extensive Green Roofs, or
the Semi-Extensive Green Roofs section.
Disadvantages of
Green Roofs
32
As an educational institution, the University of California,
Davis, can expect a great outcome from installing a green roof
as it could join other notable campuses that are leading the
way for environmental awareness. By installing a green roof
at the campus, not only would UC Davis be recognized as
contributing to the research of green roof technology, but the
entire University of California system as well. Investing in a
project of this type would help place the Davis campus amongst
some of the most elite universities currently leading the way in
the research of green roof technology. As of now, some of
the most recognized universities with green roofs on campus
include, Harvard, Carnegie-Melon, Massachusetts Institute of
Technology, University of Georgia, North Carolina-Chapel Hill,
Pennsylvania State, and Michigan State (Colwell 2007).
Despite the fact that green roofs have been around for many
years and countries in Europe and Asia are leaders with its recent
technology, the United States has only recently acknowledged
the potential of green roofs. Currently, government agencies,
businesses, and universities are leaders in the paving the way for
green roofs, but because there is not sufficient knowledge about
Universities & Green Roofs
33
this technology, the people capable of installating green roofs
are limited and the cost for green roofs are high. As Dr. David J.
Beattie and Dr. Robert D. Berghage, who have been advocates for
green roofs at the Pennsylvania State University stated, although
information is abundant in Germany, it is limited and “not
being directed to those who really need it,” in the United States.
“Even landscape architects, the professionals most frequently
called to design a green roof, have little knowledge of soils and
plants. As a result, several projects have been compromised or
have failed (Beattie 2004).”
Educational institutions, especially universities, have the potential
to expand the field of green roofs as we know it within the United
States by developing research which can be applied to projects
and educate individuals in the proper science of green roofs.
In North America alone, “there is potential for a green roof
industry worth several trillion dollars (Beattie 2004).” Because
of the benefits that have already been associated to green roofs,
nationwide and abroad, investing in a green roof as a learning
facility would benefit, educators, students and communities.
Many of the universities which have installed green roofs on
their campuses are already using them to conduct research or
as learning classrooms. Research and topics being discussed
vary from university to university, but one of the main things
that each campus is studying is how green roofs hold up in their
regions and how they may respond differently in different climate
situations. As of now most of the universities conducting this
research are focused primarily in the Northeast, Midwest, and
Southern U.S. states. These part of the nation also have the more
green roofs as shown in the Green Roofs Across America
map. By proposing a green roof for the UC Davis campus, it 5.1. & 5.2. David Beattie and student tending green roof vegetation.
34
would serve as one of the first universities on the west cost to
have a green roof. Since the temperatures on the west coast are
very distinct from other parts in the country, the collection of
information applicable to green roofs in this region is needed if
they are to be successful in this area. By installing a green roof,
plants, soil, and alternative material can be studied by individuals
and communities.
One of the more well-known green roof research programs is
located at Michigan State University and was originally initiated
by Ford Motor Company. This was started in an effort to better
prepare the company with the installation of their own green
roof at the “Dearborn, Michigan assembly plant, a 10.4 acre
project (Colwell 2007).” While the Ford Motor Company did
install their extensive green roofs, the research at Michigan
State University still continues with the objectives “to evaluate
plant species, propagation and establishment methods, plant
succession, water and nutrient requirements, water quality and
quantity of storm water runoff, and energy consumption (The
green roof research).”
At the Penn State Center for Green Roof Research, Dr. Beattie,
director of the program, leads the program in “green roof
research, education, and technology transfer in the Northeastern
US (Penn State Center for GR Research 2006).” Some of the
main objectives for the center include gathering data on storm
water runoff, determining green roof effects on storm water,
and comparison of green roofs vs. traditional roofs.
At the University of Arkansas, professor of landscape
architecture, Mark Boyer, has been in charge of a couple of green
roofs located atop campus building since their construction in
October 2006. As Boyer states, the purpose of the project at the
5.3. Ford Motor Company Green Roof
35
Currently many universities are proposing the adoption of a
green roof for their campus either for educational purposes,
or simply for the benefits that come with installing a green
roof. More recently universities such as Duke University and
Stanford University have joined the other green roof campuses
as they prepare for installation of their own green roof. These
universities along with Massachusetts Institute of Technology,
Virginia Wesleyan and the University of Virginia are among
the few campus to receive grants from the Environmental
Protection Agency to develop and maintain a green roof (The
Leaves are Changing 2005).
Finally the opportunities that can be gained through the
installation of a green roof at the UC Davis campus are
immense. From recognition for the campus, to better-prepared
students in the field, to development of better spaces, green
roofs have much to offer. As Beattie stated, “as educators, one
of our biggest opportunities is to educate those involved in the
extensive green roof industry. Knowledge of plant culture and
the fundamentals of soil science related to green roof media are
of critical importance (Beattie 2004).”
University of Arkansas was “to determine what type of plants
and soil – if any - will survive the Northwest Arkansas climate
(Harris 2007).” Since the installation of the green roofs, Boyer
has stated the success of the green roofs. Their popularity on
campus has resulted in various departments approaching Boye
requesting a green roofs of their own (Harris 2007).
5.4. & 5.5. University of Arkansa students helping with installation of green roof
36
Rooftops at the UC Davis Campus
This aerial illustrates the percentage of the campus that rooftop current make up. The main buildings have been highlighted in green
to show the visual impact green roofs create. Hunt Hall, the proposed site for this project is with the orange outline. (5.6.)
37
Green Roofs Across America
Currently the majority of green roofs in the United States are being built in the east coast. As a result, most green roof information
found is applicable to these regions. In an effort to increase the number of green roofs in the west coast, education and research of
green roofs in this region is needed. (5.7.)
38
“The Yerba Buena Garden is based on the idea that construction of new cultural facilities and public open space can transform a blighted district and bring economic development (boston). “
Yerba Buena Gardens is located in the Central East side of
San Francisco, within the South of Market District. The site is
situated atop the George Moscone Convention Center, covering
5.5 acres on 2-blocks worth of San Francisco real estate.
Surrounded by Mission, Folsom, 3rd, and 4th streets, Yerba Buena
Gardens, marks the center of the larger redevelopment project
Yerba Buena Gardens
6.1. Yerba Buena Garden off Mission and Howe streets. Plan view.
39
effort to minimize the weight on the Moscone’s roof structure
(Osmundson 1999). Applying similar techniques for the
proposed site would help reduce weight, should it be required.
siTe & user anaLysis
Yerba Buena Gardens
has a unique atmosphere
for a fast pace city like
San Francisco. Entering
the gardens, one can
escape from the city.
While observing the
Yerba Buena Gardens
on a Sunday afternoon,
it rapidly became clear
what the demographics for visitors to the site were. Perhaps,
as the result of the children’s garden on the southern block
of the gardens, most of the people frequenting the site were
adults with young children 8 years and younger. Areas of high
user impact versus low user impact are identified in the Yerba
Buena Gardens - Site Analysis.
that transformed this area of San Francisco into one of the city’s
main attractions. Since the beginning of the redevelopment
project, led by the San Francisco Redevelopment Agency
(Yerba Buena Center), back in the 1960s, the project site was
a controversial issue as stadiums and high-rise buildings were
the argued reason for driving low and middle-income residents
out of the area (Osmundson 1999). Actual construction for
the Yerba Buena Gardens did not begin until the 1970s when
the construction of the underground convention center began.
It wasn’t until over twenty years after construction on the site
began that the lower portion bounded by Mission and Howe
streets opened to the public in October 11, 1993 (Yerba Buena
Gardens). In 1998, the upper portion of the garden referred to
as the children’s garden opened (Yerba Buena Gardens-Wiki).
Yerba Buena Gardens, much like any public garden, is composed
of a variety of garden elements such a multi-purpose lawn
area, amphitheater seats, children’s playground, and more. The
Esplanade area of the Yerba Buena Gardens serves as the
largest open space and is unique as its “grassy slopes” were
constructed with of 2-feet of Styrofoam and 2-feet soil in an
6.2. Yerba Buena Gardens.
40
departments for the purpose of education and research, input
from these departments is ideal in developing a site that would be
suitable to all. Spaces should also be designed to serve multiple
functions suitable for an array of events such as lectures, labs,
and special exhibits. Elements such as amphitheater seating
and shade structure could possibly be integrated into the site, in
order to accommodate all uses.
The northern block of the gardens in the areas referred to
as The Esplanade and the Sister City Gardens, were also well
occupied, although the demographics differed much from those
found in the block located just south of it. Here you will find
young adults relaxing and lost in there own world, senior citizens
practicing yoga, and business people glancing at the daily news.
generaL FeaTures & Lessons
General elements that can be borrowed from the Yerba Buena
Gardens include community planning, multi-purpose open
space, amphitheater style seating, shade structures, art sculptures,
walkways and materials. Lessons learned from the Yerba Buena
Gardens will allow for a more successful design for the proposed
university site. If this green roof is to shared amongst different
6.5. & 6.6. Yerba Buena Garden. Users on the Esplanade side of the gar-den. View toward Mission Street and of the stage.
6.3. & 6.4. Yerba Buena Gardens. Users on the amphitheatre seating area located in the children’s garden.
41
VegeTaTion
Plants at the Yerba Buena Gardens included, but were not
limited to, the following plants:
• Agapanthus spp. – Lily of the Nile
• Lagerstroemia indica – Crape Myrtle
• Leptospermum spp. – New Zealand Tea Plant
• Liriope muscari – Liriope
• Loropetalum chinese – Chinese Fringe Bush
• Nandina domestica – Heavenly Bamboo
• Pelargonium spp. – Geranium
• Prunus cerasifera – Purple Cherry Plum Tree
• Rhaphiolepis indica – Indian Hawthorn
• Rhododendron spp. – Azalea
• Sultera corda. – Bacopa
PLanT PaLeTTe
6.7. Vegetation at Yerba Buena Gardens.
42
Building/Structure
High Impact Area
Low Impact Area
Open Space/Multi-Purpose
Vegetation/ Planting Area
Seating Area
Water Feature
Entry Access
Roof Limit
yerba buena gardens - siTe anaLysis
Green Roof Limit
(6.8.)
43
“Planted rooftops are still a rarity in the central downtown areas of our cities. That must change, or our cities will continue to become more crowded, sterile, and unattractive places to live and work (osmundson).”
Union Square Park is located in the North East side of San
Francisco, within the Union Square District. The site is situated
atop an underground parking garage, surrounded by Powell,
Post, Geary, and Stockton streets.
The history of this park dates back to 1850 when this land was
first contributed and reserved by John Geary, San Francisco’s
first mayor, for the development of a park (Osmundson 1999).
Union Square Park
7.1. Union Square Park. Plan view.
44
The park was given its name as a result of the demonstrations for
troop support during the Civil War (Union Square). No official
park planning was done during this time, other than community
contributions. It wasn’t until the 1940s that the development
of the underground parking structure came about to become
the first of its kind in the United States. In the 1990s, not
long after its first official design, Union Square, was redesigned
after complaints that the original design was no longer up to
standards (US, San Francisco 2007). In 2000, the new design,
which had been the result of a design competition was selected.
In 2002, Union Sqaure as we now know it, was completed (US
Past & Present).
As a result of its redesign, Union Square Park gained attributes
which make it a popular place for all types of visitors that frequent
the site. It is composed largely of granite pavement, which
allows for accessibility of multi-purpose uses, easy maintenance,
and control of the site. Terracing lawn areas were also added as
a new design feature, which are in the direction of Geary Street,
giving viewers a front row seat to observe shoppers.
siTe & user anaLysis
As the center of the major shopping district, Union Square Park
serves as a place to sit and take a break. Like the district to which
it is a part of, Union Square Park is constantly busy with people
moving in and out. While visiting the site, it accommodated a
variety of people each engaging in very distinct activities. The
eastern side of the site was utilized as an art gallery where local
artists and art enthusiasts mingled. A café located in the park
accommodated the espresso and cappuccino lovers. On the
northern and southern ends of the site, individuals relax on
lawn areas, while a few sun bathed, napped, walked their dogs.
7.2. Union Square Park provides people with a place to relax and people watch.
45
generaL FeaTures & Lessons
General elements that can be borrowed from Union Square
Park include multi-purpose open space, seating, and planters.
Lessons learned form Union Square Park will allow for a more
successful development at the proposed university site. One
of the main ideas that Union Square inspired was the idea
of allowing other departments to access the facility for their
uses. For example, the art department could use the site for
7.3. Union Square. Art gallery of local artist held in the center of the park.
7.4. Union Square. High rise buildings surround this park.
7.5. Union Square. People enjoying terrace seating, which also funtions as access way into the park.
46
art exhibits. Asking for donations from events could help with
upholding the green roof. Providing some sort of informal
seating would also be a good idea so people could feel engaged
with the site.
VegeTaTion
A list of plants located at the site was developed. Plants at Union
Square Park included, but were not limited to the following
plants:
• Agapanthus spp. – Lily of the Nile
• Brugmansia versicolor – Angel’s Trumpet
• Penstemon spp. – Penstemon
• Phoenix canariensis – Canary Island Date Palm
• Phormium tenax – New Zealand Flax
• Prunus spp.
• Rhododendron spp. – Azalea
PLanT PaLeTTe
7.6. Vegetation at Union Square Park.
47
Building/Structure
High Impact Area
Low Impact Area
Open Space/Multi-Purpose
Vegetation/ Planting Area
Seating Area
Storage
Entry Access
Roof Limit
yMca rooFToP garden - siTe anaLysis
No Access
(7.7.)
48
“Perhaps the best part of this old building is its rooftop garden, where members can sunbathe in a quiet, serene and sheltered environment. Up there, high above the Tenderloin streets, you can close our eyes and pretend you’re in your own backyard without worrying about what your neighbor thinks (Tenderloin).“
The rooftop garden atop the Central YMCA is located in the
North East side of San Francisco within the Tenderloin District.
The roof garden is located atop the eastern most side of the
building that looks over Leavenworth Street and Golden Gate
Avenue.
Central YMCA Rooftop
8.1. YMCA building located on the corner of Leavenworth and Golden Gate streets.
49
This roof garden has been in existence for approximately 25
years now. It was first started through the dedicated work
of YMCA volunteer Peter Hayman (Peck 2002).” Hayman
who put in a lot of initial work to create this rooftop garden,
established most of the larger trees that are still in existance on
the site. Much of the other vegetation on the site has resulted
as a collection of volunteers maintaining the garden.
The roof garden is set up so that most of the vegetation is on
the edge of the roof limit. This vegetation is mainly planted
on containers, and the plant variety varies from pine trees to
the tiniest ground cover hanging aside a pot. Most of the inner
part of the roof is left open for accessibility as a walkway. The
northern part of the roof attracted an informal picnic area,
while the center west part of it resembled an informal stage.
A small area at the southern left corner of the garden was also
dedicated as a storage space for maintenance supplies of the
garden.
Currently, the Central YMCA is looking to relocate a couple of
blocks down from its current location as the result of a need for
an improved facility and general building upgrade. However, as
part of the new facility plan, a green roof is being purposed as
there is talk to “retain sustainability and green roof consultants
including Donald Aiken Associates and Simons and Simon &
Associates (Welcome to YMCA).”
siTe & user anaLysis
Unlike the Yerba Buena Gardens or Union Square Park, the
rooftop garden located at the central YMCA is reserved for a
more serene and private space. The number of individuals at
the time of the site visit was very minimal, never having more
8.2. YMCA. Volunteer assist with upholding the rooftop garden.
50
than three individual up at once. The area was used primarily
as a place to relax, as these individuals just hung out, came to
take a break, and/or mediated yoga. Through speaking with
one of the assistants of the center, it was informed that people
(primarily members) utilize the facility for personal purposes
or group activities. Members who utilize it, also volunteer in
helping maintain the garden and provide its up-keeping. For
the members that tender the garden, they find their time
volunteering on the rooftop as a way to relax, hence making this
garden functional as a healing garden.
generaL FeaTures & Lessons
General elements that can be borrowed from the Central
YMCA rooftop gardens include community planning, active
involvement with maintenance participation, Multi-purpose
open space, access way, and storage facility. Because funding
for the Central YMCA is limited, most of the effort that goes
into the rooftop garden is the result of involved members and
volunteers. The proposal of something similar for a green
roof at UC Davis would help finance maintenance expenses
if students occupying the facility were involved in its upkeep.
Designing areas that are versatile and multifunctional are ideal if
8.3. YMCA. Entry way and storage area of the rooftop garden.
8.3. YMCA. The rooftop garden provides members with a place to relax.
51
considering the green roof design as a learning facility, so long
as it doesn’t take away from the main purpose of the facility. As
access to the rooftop of Hunt Hall would be a primary issue to
address in the considering for such a project, the Central YMCA
serves as an example of a simple, minimal, yet functional access
way. When designating areas for specific purposes, other
possible uses should be considered as well. As the purposed site
at the UC Davis campus would probably restrict access to such a
project, especially during later times of the day, a storage similar
to the one at the Central YMCA rooftop would be functional to
store tools that would be used on a regular basis.
VegeTaTion
Plants at the Central YMCA rooftop varied from trees, to
shrubs, to succulents, and grasses. The following is a list of
plants that were present and thriving on the rooftop:
• Bougainvillea spp. – Bougainvillea
• Iris spp. – Iris
• Pelargonium spp. – Geranium
• Phyllostachys aurea – Golden Bamboo
• Pinus canariensis – Canary Island Pine
PLanT PaLeTTe
8.5. Vegetation at YMCA roof garden.
52
Building/Structure
High Impact Area
Low Impact Area
Open Space/Multi-Purpose
Vegetation/ Planting Area
Seating Area
Storage
Entry Access
Roof Limit
yMca rooFToP garden - siTe anaLysis
No Access
(8.6.)
53
LocaTion
The site for the proposed green roof is located on the rooftop of
the Hunt Hall building located on the north east side of the UC
Davis campus. Hunt Hall is on the corner of Howard Way and
North Quad and is surrounded by the Plant and Environmental
Science Building, Freeborn Hall, Hickey Gym, and the Marya
Welch Tennis Courts.
Hunt Hall Site Analysis
9.1. Hunt Hall vicinity map
54
rooFToP access
Currently, Hunt Hall has access to its rooftop at three different
locations the north wing, the south wing and the center.
However, these access ways are not accessible to students or
faculty and are primarily used for maintenance purposes. Also
at the center part of the building there is an elevator which may
have potential access to the roof. Access on the exterior of the
building through built-in ladders is also present.
sTrucTuraL coMPonenTs
The rooftop of Hunt Hall currently is made-up of a flat roof
with ventilation and heating system structures. The roof
appears to be of a concrete or similar impermeable material,
which is a cause of storm water runoff. The is no barrier at the
edge of the roof, so the roof is flat all around. The fact that
there is no barrier at the edges of the roof-line, should also be
considered as it may lead to a potential safety issue. The roof
does however contain many large structures of various size and
shapes, many of which will be removed after the completion of
Hunt Hall’s renovation.
sunLighT exPosure
Due to the location of the green roof, the site will get full sun
exposure throughout the day. Micro shade areas may exist on
the around of the existing structures. Minimal shade may also
be produced by trees surrounding the building.
9.2. & 9.3. Hunt Hall existing site. North (above) and South(below) sections.
55
Hunt Hall Site Analysis - NORTH SECTION
56
Hunt Hall Site Analysis - CENTER SECTION
57
Hunt Hall Site Analysis - SOUTH SECTION
58
Designing a Green Roof
Through the information attained from the research of this
projects a conceptual design of a green roof for Hunt Hall
was designed. The design is a combination of the information
gathered on the topic of green roofs in general, including the
case studies. By creating a conceptual design for Hunt Hall, I
expected to show the difference that a green roof could make
visually. As Hunt Hall is proposed as the future home for the
Landscape Architecture program, this building seemed ideal as
the students educated in this field will become the leaders in
this technology for years to come. This green roof, however, is
also intended for the use of students within other departments
such as Environmental Horticulture, Hydrology, Soil Science,
Environmental Sciences, among others.
For the purpose of this project, the information found in this
section will not go beyond a conceptual design and suggested
plant listed, and therefore will not specify how each green roof
layer applies to the proposed site. For a general understanding
of each layer including waterproofing, drainage, root barrier,
and soil, please see the Green Roof Layers section. In trying
to provide a green roof design that educates individuals on
59
how each green roof type (i.e. intensive, extensive, and semi-
intensive) differs from each other, a design divided into the
three types was created. The green roof gardens were divided
so that the northern wing would represent an extensive green
roof, the center would represent a semi-intensive green roof,
and the southern wing would represent an intensive green roof.
This section will provide plan view drawings on each of the
green roof types, along with its specific plant list. Each green
roof type will be visually distinct by design and plant selection.
Each section was designated with the green roof type that was
deemed most suitable for that part of the roof on account of
access, existing structures, space and visual interest. Design
components that can not be represented in the concept plan,
but played an important role in design decisions, will also be
discussed in this section
iMPorTanT oVeraLL design coMPonenTs
Potential access Way
Since Hunt Hall already has access ways to its rooftop, the
conceptual design has kept these locations the same. However,
because these access ways are currently used primarily for
maintenance purposes, it is being proposed that these access
ways be expanded and made suitable for access by students and
faculty. The center portion of the building where an elevator
is located is proposed that the elevator access be extended
to the rooftop for purposed of making the green roof ADA
accessible. The elevator would function as the main entry to the
center portions, while the north and south wings of the building
would have a staircase.
9.4. Hunt Hall. Proposed site for a green roof.
60
Dealing With existing conDitions
One of the main issues in designing a green roof for Hunt
Hall was working around the existing ventilation and heating
structures. Because these structures are quite large, coming up
with a design was difficult at first. Eventually the decision was
made to have vegetation growing up to were these structures are
as is often done in many green roof designs. By surrounding
these structures with vegetation and maintaining paths at a
decent distance away from them, potential safety concerns could
be eliminated. Also for the purpose of making these structures
more aesthetically appealing, it is also proposed that they be re-
painted.
aDDressing Potential safety concerns
Currently the proposed rooftop of Hunt Hall has no barrier
on the edge of the roof line, which may be viewed as a safety
issue, especially with large groups of people interacting on the
roof. The conceptual design proposes a three-foot high wall to
address this concern. Another potential safety issue may be the
ventilation and heating structures, which would be separated by
vegetation as stated in the previous subsection.
suitable for Vegetation
Because the proposed site is on a rooftop, all vegetation will have
full sun exposure, except for minimal areas where shade may be
produced by trees surrounding the building. For this reason
all of the suggested plant material is tolerant of full exposure
to the sun and even drought tolerant. Where a concern may
have existed for the intensive green roof, trees were provided
to create partial shade. Due to the fact that the weather in
Davis is extreme, with very dry summers, it is also proposed
that irrigation be installed, with drip irrigation being the main
system used.
The idea behind The concePT
the intensiVe green roof Design
For the design of the Intensive Green Roof, one of the main
ideas was to try and keep it as garden-like as possible. Many
of the plants selected in the suggested list are plants that are
commonly seen throughout landscapes in the city of Davis.
This was the only green roof type with trees in the design, as
it is intensive, and trees are typical. Because intensive green
61
roofs are designed to be accessible, this design has the largest
amount of non-vegetative space in order to provide individuals
with enough room to move around in. Built in seating was also
incorporated in the design to accommodate large groups for
lectures or discussions on the rooftop. The curvy planters were
the result of an effort to separate visitors away from the existing
structure, as well as to break the edges of the roof. The idea
for the ground is for the combination of large tile and ground
cover to collect water that would not be collected otherwise.
Also, having this green roof on the south wing should provide
more of a visual interest for as it is the only side of Hunt Hall
facing campus.
the semi-intensiVe green roof Design
The Semi-Intensive Green Roof was limited to a space, partly
because it joins the other two types together and because this
part of the Hunt Hall is the shortest. The idea behind this
green roof was to incorporate many medium size vegetation, as
semi-intensive green roofs are comprised of just that. In order
to make it more interesting and distinct from the other two
types, a large selection of succulents and grasses were suggested
in the plant list, in an effort to use drought tolerant plants and
to create a desert-like theme green roof. Within this part of the
roof, two storage units were also proposed for the purpose of
easy access of accommodating users.
the extensiVe green roof Design
The Extensive Green Roof was design so that it would have
rolls of different ground covers lined up. All of the plants
suggested in this sections, are ground cover, with the majority
consisting of sedums, as these are the plants most commonly
used in extensive green roofs. In order to maintain minimal
activity on this green roof type, as is commonly typical, only a
small path to allow for occasional access was incorporated.
62
Hunt Hall Conceptual Design - EXTENSIVE GREEN ROOF
ROOF ENTRY ACCESS
UTILITY STRUCTURES (PAINTED)
COREOPSIS GRANDIFLORA - COREOPSIS
STACHYS BYZANTINA - LAMB’S EAR
DELOSPERMA COOPERII - COOPER’S ICE PLANT
SEDUM ACRE - GOLDMOSS SEDUM
SEDUM AIZOON - STONECROP
SEDUM CAUTICOLA - WHITE STONECROP
DENDRANTHEMA PACIFICUM - GOLD CHRYSANTHEMUM
63
Hunt Hall Conceptual Design - SEMI-INSTESIVE GREEN ROOF
ROOF ENTRY ACCESS
UTILITY STRUCTURES (PAINTED)
STORAGE
PENNISETUM ALOPECUROIDES ‘HAMELN’ - DWARF FOUNTAIN GRASS
OPUNTIA VIOLACEA SANTA-RITA - PURPLE PRICKLY PEAR
KNIPHOFIA UVARIA - RED HOT POKER PLANT
CAREX TESTACEA - ORANGE SEDGE
GAZANIA RIGENS - GAZANIA
64
Hunt Hall Conceptual Design - INTENSIVE GREEN ROOF
ROOF ENTRY ACCESS
UTILITY STRUCTURES (PAINTED)
PERSON
LAGERSTROEMIA INDICA - CRAPE MYRTLE
PRUNUS CERASIFERA - PURPLE PLUM TREE
ACER TRUNCATUM - SHANTUNG MAPLE
RHODODENDRON SP. - AZALEA
LAVANDULA ANGUSTIFOLIA - LAVENDER
EUONYMUS FORTUNEI - WINTERCREEPER
PELARGONIUM GRAVEOLENS - GERANIUM
OPHIOPOGON JAPONICUS - MONDO GRASS
ABELIA X GRANDIFLORA - WHITE ABELIA
ROSMARINUS OFFICINALIS - ROSEMARY
Conceptual Design Perspectives
66
Suggested Plant List
exTensiVe PLanT LisT
Achillea spp. - Yarrow
Coreopsis grandiflora - Coreopsis
Delosperma cooperii - Cooper’s Ice Plant
Delosperma nubigena - Hardy Ice Plant
Dendranthema pacificum - Gold Chrysanthemum
Iberis sempervirens - Evergreen Candytuft
Oenothera speciosa - Pink Primrose
Phlox subulata - Moss Pink
Santolina chamaecyparissus - Lavender Cotton
Sedum acre - Goldmoss Sedum
Sedum aizoon - Stonecrop
Sedum cauticola - White Stonecrop
Sedum cauticolum ‘Lidakense’ - Stonecrop
Sedum ochroleucum - European Stonecrop
Sedum sieboldii - October Daphne
Sedum tetractinum - Chinese Sedum
Stachys byzantina - Lamb’s Ear
67
seMi-inTensiVe PLanTing LisT
Agave americana - Century Plant
Agave attenuata - Foxtail Agave
Aloe nobilis - Gold Tooth Aloe
Aptenia cordifolia - Red Apple
Baccharis pilularis - Coyote Brush
Carex testacea - Orange Sedge
Ferocactus sp. - Barrel Cactuses
Festuca brachyphylla - Alpine Fescue
Festuca glauca - Blue Fescue
Gaura lindheimeri - White Gaura
Gazania rigens - Gazania
Kniphofia uvaria - Red Hot Poker Plant
Muhlenbergia rigens - Deer Grass
Opuntia basilaris - Beaver Tail Cactus
Opuntia ficus-indica - Prickly Pear
Opuntia violacea santa-rita - Purple Prickly Pear
Pennisetum alopecuroides ‘Hameln’ - Dwarf Fountain Grass
inTensiVe PLanT LisT
Abelia x grandiflora - White Abelia
Acer palmatum - Japanese Maple
Acer truncatum - Shantung Maple
Caesalpinia gilliesii - Bird-of-Paradise Shrub
Euonymus fortunei - Wintercreeper Euonymus
Lagerstroemia indica - Crape Myrtle
Lavandula angustifolia - Common Lavender
Lavandula stoechas - Spanish Laverder
Leptospermum sp. - New Zealand Tea Plant
Nandina domestica - Heavenly Bamboo
Ophiopogon japonicus - Mondo Grass
Pelargonium graveolens - Geranium
Phormium tenax - New Zealand Flax
Pittosporum tobira ‘Wheeler’s Dwarf ’ - Wheeler’s Dwarf Pitto.
Prunus cerasifera - Purple Plum Tree
Rhododendron sp. - Azalea
Rosmarinus officinalis - Rosemary
68
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