Green Roof at the University of California, Davis - Teaching Green

1. Teaching Green

2. Teaching Green
Environmental, Economical, and Educational Benefits:
Proposal for a Green Roof at the University of California, Davis
University of California, Davis
Department of Environmental Sciences
Landscape Architecture Program
Senior Project: June 2007
Yanet Martinez

3. Teaching Green
Environmental, Economical, and Educational Benefits:
Proposal for a Green Roof at the University of California, Davis
Acceptance and Approval by:
A Senior Project presented to the faculty of the program of
Landscape Architecture at the University of California, Davis
Professor Mark Francis, Senior Project Advisor
in partial fulfillment of the requirements for the degree of
Bachelors of Science of Landscape Architecture.
Assistant Professor Stephen Wheeler, Committee Member
Presented by
Yanet Martinez
Adjunct Assistant Professor Jeff Loux, Committee Member
at
University of California, Davis
on
Steve McNeil, Committee Member
the Fiftheenth day of June, 2007

4. 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-
Abstract 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.

5. Yanet Martinez, a 2007 Landscape Architecture graduating
Biographical Sketch 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.
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6. Since her arrival at the UC Davis campus in 2004, Yanet was Upon her return to Davis, Yanet continued her internship with
intrigued by the community, diversity and environment of the the County of Sacramento Department of Regional Parks, as
campus, which led to her membership to Kappa Kappa Gamma she completed her final courses. After graduation, Yanet will be
where she participated in philanthropic and community events. traveling to South America to see more of the world. Ultimately
In early 2005, Yanet was admitted to the Landscape Architecture Yanet will work to build a professional career in the field of
Program. That same year, she traveled to Japan, where she landscape architecture.
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.
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7. To my loving family that just never stop giving of themselves in
countless ways, both direct and indirect.
Dedications 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!
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8. 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.
Acknowledgements 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!

9. 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
Table of Contents 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
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10. 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 ..............7
2.2. Roof garden at Palazzo Piccolomini ....................................8
2.3. Traditional Scandinavian green roofs in Norway ...............9
3.1. Green Roof Layers ...............................................................11
3.2. Intensive green roof. Layer section ...................................16
3.3. Rockerfeller Center ...............................................................17
3.4. Millennium Park ....................................................................17
3.5. ACROS Prefectural International Hall ..............................17
3.6. Extensive green roof. Layer section ..................................19
3.7. Ocean Houses at Post Ranch Inn ......................................20
List of Figures 3.8. Heinz 57 Center ....................................................................20
3.9. Minneapolis Central Library ................................................20
3.10. Semi-instensive green roof. Layer section ......................22
3.111. The Calhoun School .........................................................23
3.12. The Culver House Residences ..........................................23
3.13. Library Square Building .....................................................23
4.1. Storm Water ...........................................................................25
4.2. Heat Island Profile ................................................................26
4.3. Green roof benefits chart ....................................................27
4.4. Vegetable roof garden at Trent University .......................28
4.5. Green roofs create ecological habitats (1) .........................28
4.6. Green roofs create ecological habitats (2) .........................28
4.7. Solaire building ......................................................................29
5.1. David Beattie and student at Penn State green roof (1) ......33
5.2. David Beattie and student at Penn State green roof (2) ......33
5.3. Ford Motor Company green roof ......................................34
5.4. U of Arkansa students on green roof (1) .........................34
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11. 5.5. U of Arkansa students on green roof (2) .........................34 9.3. Hunt Hall existing site photographs 2 ...............................55
5.6. Rooftops at UC Davis ..........................................................35 9.4. Hunt Hall proposed site .......................................................59
5.7. Green roofs across America ................................................37
6.1. Yerba Buena Gardens. Plan view. ......................................38
6.2. Yerba Buena Gardens ...........................................................39
6.3. YBG. Site Analysis Photograph 1 ......................................40
6.4. YBG. Site Analysis Photograph 2 ......................................40
6.5. YBG. Site Analysis Photograph 3 ......................................40
6.6. YBG. Site Analysis Photograph 4 ......................................40
6.7. Vegetation at YBG .................................................................41
6.8. YBG. Site Analysis Diagram ..............................................42
7.1. Union Square Park. Plan view. ...........................................43
7.2. US. Site Analysis Photograph 1 .........................................44
7.3. US. Site Analysis Photograph 2 .........................................45
7.4. US. Site Analysis Photograph 3 .........................................45
7.5. US. Site Analysis Photograph 4 .........................................45
7.6. Vegetation at US ....................................................................46
7.8. US. Site Analysis Diagram ..................................................47
8.1. YMCA building .....................................................................48
8.2. YMCA. Site Analysis Photograph 1 ..................................49
8.3. YMCA. Site Analysis Photograph 2 ..................................50
8.4. YMCA. Site Analysis Photograph 3 ..................................50
8.5. YMCA. Vegetation at YMCA ............................................51
8.6. YMCA. Site Analysis Diagram ..........................................52
9.1. Hunt Hall vicinity map .........................................................53
9.2. Hunt Hall existing site photographs 1 ...............................54
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12. 1.1. Green Roof.
Introduction 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

13. developments have produced a hybrid referred to as a semi- and agricultural issues, that the University of California, Davis
intensive green roof. Although these green roofs can be would consider the idea for a proposal of a green roof for the
beneficial environmentally, economically, and educationally, campus. The addition of such a project to the campus would
each has qualities, which make them distinct from one another. assist in upholding Davis as one of the top universities and
Each type of green roof mentioned will be discussed in further research facilities in the nation and may perhaps even lead to
detail within the following sections. 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
1.2. Installation of a green roof at the University of Central Florida. the construction of green roofs, those that address possible
solutions for air and water pollution, heat island reductions,
As many universities throughout the nation, as well as abroad, additional recreational areas, ecological areas, insulation, and
are already endeavoring into the integration of green roofs as a increase roof life expectancy will all be discussed. A brief
learning tool for students and faculty, it seems only appropriate overview of possible economical benefits will also be covered.
that as a university that is largely dedicated to addressing, Possible disadvantages that may result from green roofs will
educating, and conducting research on environmental, ecological, also be reviewed.

14. 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.
1.3. Hunt Hall. Furture location for the Landscape Architecture Program.
As a result of the data obtained, enough information was By the end of this paper it is intended that the reader gain an
gathered to provide a suggested preliminary conceptual design overall general understanding of green roofs. They should be
for Hunt Hall at the University of California, Davis. The able to define what a green roof is, understand its layers, know
conceptual design consist of the three types of of green roofs, the different types of green roofs, and list the benefits and
in an effort to familiarize possible users with all three. As Hunt possible disadvantages that come with building a green roof.
Hall is proposed to undergo renovation in the next couple It should be noted that the intention of this paper is to get
years and serve as the home for the Department of Landscape the reader acquainted with the concept of green roofs and to
Architecture, it seemed as the ideal location. Aside from a propose the possibility of the University of California, Davis
conceptual design, a suggested plant list for each green roof implementing a green roof on campus. This paper is not to
type was also formulated. The plants selected were based on serve as a primary guide for the construction of green roofs.
what would might possibly be suitable for the site.

15. 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
What is a Green Roof ? 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

16. 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.

17. 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
History of Green Roofs 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

18. creditable individuals such as Strabo and Diodorus Siculus has Early depictions described the construction of these gardens
lead to the belief of their existence. The majestic description upon “stone beams some sixteen feet long and over these were
of these gardens has even listed them as being one of the seven laid first a layer of reed set in thick tar, then two courses of
original World Wonders (Hanging Gardens 2007). baked clay brick bonded by cement, and finally a covering of
lead to prevent the moisture in the soil penetrating the roof
The story behind the creation of these gardens is said to be the (Osmundson 1999).” Plants were then situated on top and
result of king Nebuchadrezzar II, as a way of consoling his wife irrigation was made possible through pumping of the river.
Amytis in her longing for the landscape of her homeland, which As the gardens of Babylonia were described as being elaborate
is described as abundant in vegetations and green hills. These and mainly for aesthetic pleasures it can be said that the first
gardens are said to have been built upon Babylonian ziggurats, historical recorded green roofs were what we refer to today as
pyramid like buildings with large landings that allowed for intensive.
placement of these gardens (Osmundson 1999).
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
2.1. Depiction of the Hanging Gardens of Babylonia. casting molds of their roots (Osmundson 1999).

19. Pompeii wasn’t the only Italian town to have gardens growing purpose of this roof garden was entertainment purposes, this
atop its roofs; Pienza, Lucca and Careggi are towns that had garden was most definitely held intensive qualities. Similar to the
roof gardens as well. In Pienza, a garden constructed atop the garden at Palazzo Piccolomini, this garden was built atop of the
Palazzo Piccolomini during the 1460s, by orders of Pope Pius roof of the building, covered in a layer of soil and vegetation.
II, is one of the most well preserved roof gardens to this date
(Osmundson 1999). The garden is built atop a masonry building On the other side of the world in the island city of Tenochititian
and composed of primarily small manicured plants, making this Mexico, during the same time roof gardens were emerging in
an intensive roof garden. 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
2.2. Roof garden at Palazzo Piccolomini.
the invasion by the Spaniards.
In Careggi, the well-known Medici Family also had a roof
garden. The garden was composed primarily of a collection In the 1600s even more roof gardens emerged throughout Europe
of exotic plants that the Medici family collected and served as a and other parts of the world. Like most gardens documented
representation of their wealth (Osmundson 1999). As the main up to this period, roof gardens built in this era were quite similar.

20. Today we would describe these roof gardens as intensive, as These new versions of roof gardens were usually consisted of
they were quite elaborate and primarily designed for aesthetics a layer of soil, which served as the base for grasses and low
and entertainment. Two gardens in Russia, the Kremlin Palace growing vegetation, to grow. Because these gardens were
in Moscow and the Hermitage in Saint Petersburg are examples generally planted atop smaller dwellings, they weren’t intended
of the gardens built in this era (Osmundson 1999). for larger vegetation or as being accessible hence maintaining
them was less necessary (Dunnett 2004).
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 2.3. Traditional Scandinavian green roofs in Norway.
growing vegetation on the roof of their homes as a method of
insulation for their homes during harsh seasons. During the Middle class in the United States also seemed to have adapted
cooler seasons the vegetation and soil layer helped retain heat this method of insulations, as homes, schools, and other building
in the building and to cool it during warmer seasons. These were being constructed with extensive roofs. Towns within the
new types of roof gardens seemed to share similar building states of Dakota and Nebraska especially demonstrated a liking
approaches as those found in the roof gardens before them. for this technique (Dunnett 2004).

21. After a project demonstrating the functions of this new roof extensive roof gardens has made it the leader on extensive
technology was revealed at the World Exhibition of 1868 in gardens. Along with Germany, regions in Scandinavia and
Paris, the international launch of the extensive roof garden Kurdistan also developed this technology. Similar to the original
seemed to have taken place as people became fascinated with extensive gardens of the 1800s, the gardens of the twentieth
the concept (Dunnett 2004). At the same time, however, the century were designed for the benefits that they provided to the
intensive roof gardens began to emerge once again, as they buildings and their dwellers. Insulation, extended roof life, and
became a popular entertainment asset especially for theatre and aesthetics were the purposes of the emerging extensive roof
hotels. Again it seemed as if gardens where returning to the gardens (Dunnett 2004).
intensive type gardens. In large developing cities such as New
York, the luxury of open space was limited and so the idea of From the 1950s to today, a stronger emphasis has been put on
converting roofs into an open space began to sprout yet again. studying roof gardens and distinguishing between the two main
The gardens that developed during this era were much like the types, intensive and extensive. As more research is conducted
first roof gardens wherein they were being built for the pleasure on the subject matter, it is becoming apparent that these gardens
of the wealthy (Osmundson 1999). are beneficial to societies on many levels, especially when dealing
with the latter of the two types, the extensive green roof. As
During the twentieth century, technological advancements a result of these recent findings, a third type of roof garden
allowed for improved construction of roof gardens in general. referred to as semi-intensive, which is a mix of intensive and
Roof gardens such as those at the Kensington, Rockefeller Center, extensive, has emerged.
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
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22. I.1. Green Roof Layers.
Green Roof Layers 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
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23. functions will be given. Specific information for each green it is important to study the type of plants which are appropriate
roof type are within Intensive Green Roofs, Extensive Green for a particular type of green roof. Extensive green roofs, for
Roofs, and Semi-Intensive Green Roofs sections. example are designed to support the lightest weight possible,
which limits the plant selections to mainly ground covers,
1. The Vegetation Layer particularly sedum, which are not only light, but whose roots
The vegetation layer, is the part of a green roof individuals are don’t require much depth in the growing medium layer. Intensive
most familiar with as it is the layer that adds the “green” to the green roofs on the other hand, are design to accommodate larger
roof. Depending on the type of green roof and the climatic plants, providing a larger plant selection for this type of green
region where a green roof project is located, the material used roof (Dunnett 2004). In the end, when selecting plant material
within this layer is bound to vary highly, in comparison to for ay green roof, “it is necessary to choose plants suitable for
the other layers. The main objective in creating a successful each climate, whether the conditions are periodically very dry,
vegetation layer for any green roof type, is to use plant material very hot, very cold, or very variable (Living Green Roofs).”
which is typically drought tolerant, able to withstand high
temperatures and wind (Dunnett 2004). Selecting plants with 2. The Growing Medium Layer
these characteristics will help ensure their longevity and the The growing medium or substrate layer is located directed
success of the green roof. Also when selecting plants size and beneath the vegetation layer and above the filter layer. Unlike
root depth of the plants need to be considered especially when most gardens, green roofs can not be planted with the typical
designing an extensive green roof (GR-Cooling L.A. 2006). For “garden soil or topsoil... because it is too heavy and too fertile
these reasons some of the most commonly used vegetation in (Dunnett 2004).” When selecting a growing medium for a green
green roofs include succulents and ground covers. Each green roof it is important to consider weight, especially with extensive
roof type is designed to support particular type of vegetation, green roofs. Instensive green roof may usually use typical garden
12

24. soils, but using a growing medium specialized for green roofs 4. The Drainage Layer
is ideal. A major concern when selecting a growing medium The drainage layer located below the filter and above the
has to do with safety as “soil containing a lot of peat or other protection layer, is one of the most important layer in the
organic substances is liable to shrinking, and can be a fire hazard construction of a green roof. The drainage layer is essential
(Living Green Roofs).” Companies specializing in green roof in determining where water directer toward after it has reached
material often carry specialty growing mediums or substrates. the green roof. “If drainage is inadequate on a flat green
These growing mediums are usually lightweight and contain roof, then damage to the roof membrane may ensue (Dunnett
natural minerals, however artificial soils are also available which 2004).” Other issues that may result from a faulty drainage
usually include “vermiculite and perlite (Dunnett 2004).” “A system include puddles, erosion of growth medium, rotting of
good roof soil is therefore mainly a mineral soil, not containing plants, and unwanted plants (Living Green Roofs). In order
clay, which is too impervious. To make the soil lighter, crushed to achieve a green roof which will be beneficial especially in
brick or lava can be mixed in (Living Green Roofs).” treating storm water it is necessary to install a drainage system,
appropriate for the specific roof type. The drainage layer should
3. The Filter Layer provide the function to store some water which is available to
The filter layer is located between the growing medium and the vegetation layer (Dunnett 2004). The material typically used
the drainage layer. Typically a fabric material is used and is in the drainage layer, is available from all nature to manufactured.
neccessary “to stop the substrate from disturbing the drainage Materials commonly include gravel or crushed rock, crushed
function.” Use of this layer prevents the blockage to the lava, crush leca or crushed bricks, rockwool, foam material, and
drainage layer, which may be caused by possible debris from plastic sheets (Living Green Roofs).
the growing medium and also serves as “an erosion control that
holds the substrate in place (Living Green Roofs).”
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25. 5. The Protection Layer “Unless the roof memebrane is damaged while laying the green
Located under the drainage layer, most green roofs typically roof, the soil and vegetation cover will protect the membrane
include a protection layer. The main purpose of the protection from these types of injuries later (Living Green Roofs).” Three
layer is to create a barrier between the roots of the plants and types of materials which are typically used for this layer include
the waterproofing layer. This layer essential prevent damage the built-up roof, the single-ply membrane, and the fluid-applied
to the roof structure which may result from root penetration. membrane (Osmundson 1999). Each type consist of the
“Root protection membranes are usually composed of rolls of following: built-up roofs consist of “bitumen/asphalt roofing
PVC and laid out over the weatherproofed roof deck or suface felt or bitumized fabrics,” single-ply membranes are “sheets of
(Dunnett 2004).” Other root repellant alternatives also include inorganic plastic or synthetic rubber material” sealed heat or
chemicals, copper sheets, and rubber seals (Living Green Roofs). adhesive, and fluid-applied membranes are liquid “sprayed or
In some cases, especially with extensive green roofs, this layer is painted on the surface of the roof and forms a complete seal
left out as it is believed that the roots of ground covers, such as (Dunnett 2004).”
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.
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26. 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
Intensive Green Roofs 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.
15

27. Advantages and Disadvantages exceed over 1 foot in depth, will help determine that a green
The following is a list of the positive and negative factors that roof is indeed intensive (Dunnett). Plant material used is usually
may result from an intensive green roof. enough, however to identify the type of green roof. Instensive
green roofs are the only capable of supporting trees and large
Pros Cons
shrubs in it vegetation layer, and contains the largest plant
Accessibility High maintenance
Good use of otherwise non Heavy weight load selection of all three types, and as a result bear more weight.
used space
The figure below shows two sections illustrating the layers of an
Allows for recreational uses High cost/Expensive
and multi-purpose activities intensive green roof. Intensive green roofs may also require an
Wider vegetative selection May require additional
structural support additional irrigation layer, not shown in the figure below.
Provides the best insulation Usually requires profes-
sional installation Intensive Green Roof Layers
Aesthetically appealing Requires irrigation
1. Waterproofing
Components Layer
Green roofs of all types usually consist of similar layers. The 2. Protection Layer
difference for each usually seen in the thickness of each layer,
3. Drainage Layer
plant selection, and weight. Because intensive green roofs are
4. Filter Layer
more elaborate and require more support its layers are thicker
5. Growing Medium
than extensive are semi-intensive. According to the specific Layer
project, the layer thickness will vary. Often the thickness of
6. Vegetation Layer
the growing medium layer, which is minimally 6 inches and can
3.2. Intensive green roof. Example of two layer types.
16

28. Examples
The following are examples of Intensive Green Roofs:
1. Rockefeller Center, New York, New York (3.3.) 3. ACROS Prefectural Int’l Hall, Fukuoka, Japan (3.5.)
2. Millennium Park, Chicago, Illinois (3.4.) 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
17

29. 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
Extensive Green Roofs 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.
18

30. Advantages and Disadvantages layer is limited to mostly low growing grasses and groudcovers,
The following is a list of the positives and negatives factors that such as sedum. Extensive green roofs are not designed to
may result from an extensive green roof. support shrubs or larger plants. Finally the combined system
of an extensive green roof typically has a “saturated weight of
Pros Cons
15-30 lbs/sq ft (Green Roof Types 2005).”
Light weight Limited plant selection
Low maintenance Inaccessible
Yields high percentage of Less aesthetically pleasing Extensive Green Roof Layers
ecological benefits
Less expensive 1. Waterproofing Layer
Can be placed on smaller
2. Protection Layer
structures
3. Drainage Layer
4. Filter Layer
Components
5. Growing Medium Layer
Extensive green roofs are composed of the similar layers as the
6. Vegetation Layer
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
3.6. Extensive green roof. Exampe of two layer types.
19

31. Examples
The following are examples of Extensive Green Roofs:
1. Ocean Houses at Post Ranch Inn, Big Sur, California (3.7.) 3. Minneapolis Central Library, Minneapolis, Minnesota (3.9.)
2. Heinz 57 Center, Pittsburgh, Pennsylvania (3.8.) 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
20

32. 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/
Semi-Intensive Green Roofs 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
21

33. qualities are moderate. When studying all three green roof types roof system has a “saturated weight of 30-50 lb/square feet.
together, factors such as cost, maintenance, weight, all appear (Green Roof Types 2005).” Because semi-intensive green roofs
to be moderate for semi-intensive green roofs. Advantages combine the benefits of extensive and intensive green roofs,
and disadvantages for this green roof can be made only when they are becoming more appealing.
compared one-on-one with another type. The following is a list
of some of the more obvious positives and negatives that may Semi-Intensive Green Roof Layers
result from semi-intensive green roofs: 1. Waterproofing Layer
2. Protection Layer
Pros Cons
3. Drainage Layer
Accessible Partly limited plant selection
Aesthetically pleasing May require irrigation 4. Filter Layer
Provides moderate recre- Require regular mainte-
5. Growing Medium Layer
ational space nance
6. Vegetation Layer
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.
22

34. green Examples
The following are examples of Semi-Intensive Green Roofs:
1. The Calhoun School, New York, New York (3.11.) 3. Library Square Building, Vancouver, British Colombia (3.13.)
2. Culver House Residences, Chicago, Illinois (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
23

35. 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
Benefits of Green Roofs 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.
24

36. 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). 4.1. Storm water from residential and urban areas collect pollutants that
eventually make their way into natural bodies of water.
Green roofs would not only be beneficial in reducing the to around 5 percent for a forested area.” This extra surface
amount of pollutants that storm water collects, but also in the runoff is water that eventually finds its way to natural bodies
prevention of storm water flow in sewage systems and natural of water and sewage systems. Natural bodies of waters such as
bodies of water, in erosion, and in lowing temperatures by rivers and lakes are effected “not only by the quality of runoff
retention of water. As Dunnett states, “75 percent of rainfall but also by its quantity, as a high volume of flow contributes to
on towns and cities is lost directly as surface runoff compared erosion and sedimentation, and impacts aquatic habitats (Storm
25

37. Water Pollution Prevention 2006).” In a similar way, sewage is made up of this material. “In the United States, buildings
systems and water treatment facilities become overloaded when consume six times as much energy and produce six times as
dealing with large amounts of surface runoff. much greenhouse gas emissions as all cars and trucks combined
(Hall 2006).” Green roofs work as a solution in reducing this
By installing green roofs on building especially in large urban problem as they convert some of the surface causing this
cities, storm water pollution would be reduced, as water problem into green vegetative spaces.
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 4.2. Profile of urban heat temperatures.
by the Environmental Protection Agency, “’heat island’ refers
to urban temperatures that are higher than nearby rural areas Vegetation important in achieving cooler temperatures. “If all
(Chang 2000).” Heat islands result from surfaces such as asphalt, the roofs in a major city were ‘greened,’ urban temperatures
concrete, and roof materials that absorb the heat radiated could be reduced by as much as 12 degrees (Noyes 2006).” This
from the sun, which causes this temperature increase. This is is because vegetation naturally cool regions and also provides
a problem in larger urbanized cities as much of their surface shade and evapotranspiration. This is created as “heat energy
26

38. 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 4.3. Green roofs benefit chart.
decrease pollution in the air which is often a result of high
temperatures. As stated by Green Roofs for Healthy Cities, “1 Recreational, Vegetative, and Meditative Space
square meter (10.76 sq ft) of grass roof can remove between 0.2 In areas where space is limited, green roofs serve as alternative
kg of airborne particulates from the air every year (Green Roofs places for recreation, vegetation, and meditation. Recreational
for Healthy Cities 2007).” Some of these air pollutants include green roofs provide an opportunity for open space in a
dust and smog. Cities like Los Angeles where air pollution is a location that would not otherwise exist. Whether these spaces
problem could reduce by green roofs are built. Currently Los are public or private, the individuals frequenting the site will
Angeles and many other cities, are following Chicago, the green benefit highly as, “green natural environments are places where
roof leader in the United States, by promoting green roofs and humans can recover (Living Green Roofs).” Green roofs can
encouraging individuals (GR-Cooling LA 2006). also help build stronger communities as they provided a space
27

39. for neighbors that would typically not have a place to interact, Studies have shown that people who live in large cities often
to interact. In some cases, green roofs have been utilized for suffer from more health issues as opposed to individuals who
growing vegetables, herbs, and fruits. Growing food on green reside in greener environments with more open space. Green
roofs is very beneficial as it could produce “fresher produce, roofs provide a natural environment for individuals to relax and
decreased travel time to the market and related environmental escape from the city, without having to travel very far. The
cost, and control soil, fertilizer and pesticides, (Green Roofs “therapeutic benefits that result from caring for plants,” as well
for Healthy Cities 2007).” Using a roof to grow food would as the “restorative effect of a natural view holds the viewers’
provide economical benefit, as well. An example of this is Trent attention, diverts their awareness from themselves and from
University in Canada, whose green roof serves as the growing worrisome thoughts, thereby improving health (Green Roof for
grounds that provides the vegetables used by various campus Healthy Cities 2007).”
cafes (Blyth 2006).
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
4.4. Vegetable roof garden at Trent University. these species could create a temporary habitat. In itself, a green
28

40. roof could also serve as a habitat for smaller species, such as Economical Savings
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
4.7. Solaire Building, New York. (photo gallery)
left standing in puddles, as in nature (Living Green Roofs).”
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
4.5. 4.6. Green roofs can provide ecological habitats for various creatures. both the uv-light and the temperature extremes, increasing the
29

41. 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.
30

42. 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
Disadvantages structural reinforcement of the building is required. This is
especially true in older building and with intensive green roofs
of as intensive green roofs can weigh anywhere between 80 to 150
Green Roofs 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.
31

43. 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
Universities Green Roofs 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
32

44. this technology, the people capable of installating green roofs Educational institutions, especially universities, have the potential
are limited and the cost for green roofs are high. As Dr. David J. to expand the field of green roofs as we know it within the United
Beattie and Dr. Robert D. Berghage, who have been advocates for States by developing research which can be applied to projects
green roofs at the Pennsylvania State University stated, although and educate individuals in the proper science of green roofs.
information is abundant in Germany, it is limited and “not In North America alone, “there is potential for a green roof
being directed to those who really need it,” in the United States. industry worth several trillion dollars (Beattie 2004).” Because
“Even landscape architects, the professionals most frequently of the benefits that have already been associated to green roofs,
called to design a green roof, have little knowledge of soils and nationwide and abroad, investing in a green roof as a learning
plants. As a result, several projects have been compromised or facility would benefit, educators, students and communities.
have failed (Beattie 2004).”
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
5.1. 5.2. David Beattie and student tending green roof vegetation. map. By proposing a green roof for the UC Davis campus, it
33

45. would serve as one of the first universities on the west cost to roof at the “Dearborn, Michigan assembly plant, a 10.4 acre
have a green roof. Since the temperatures on the west coast are project (Colwell 2007).” While the Ford Motor Company did
very distinct from other parts in the country, the collection of install their extensive green roofs, the research at Michigan
information applicable to green roofs in this region is needed if State University still continues with the objectives “to evaluate
they are to be successful in this area. By installing a green roof, plant species, propagation and establishment methods, plant
plants, soil, and alternative material can be studied by individuals succession, water and nutrient requirements, water quality and
and communities. 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.
5.3. Ford Motor Company Green Roof
One of the more well-known green roof research programs is At the University of Arkansas, professor of landscape
located at Michigan State University and was originally initiated architecture, Mark Boyer, has been in charge of a couple of green
by Ford Motor Company. This was started in an effort to better roofs located atop campus building since their construction in
prepare the company with the installation of their own green October 2006. As Boyer states, the purpose of the project at the
34

46. University of Arkansas was “to determine what type of plants Currently many universities are proposing the adoption of a
and soil – if any - will survive the Northwest Arkansas climate green roof for their campus either for educational purposes,
(Harris 2007).” Since the installation of the green roofs, Boyer or simply for the benefits that come with installing a green
has stated the success of the green roofs. Their popularity on roof. More recently universities such as Duke University and
campus has resulted in various departments approaching Boye Stanford University have joined the other green roof campuses
requesting a green roofs of their own (Harris 2007). 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
5.4. 5.5. University of Arkansa students helping with installation of green roof of critical importance (Beattie 2004).”
35

47. 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.)
36

48. 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.)
37

49. “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
6.1. Yerba Buena Garden off Mission and Howe streets. Plan view.
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
38

50. that transformed this area of San Francisco into one of the city’s effort to minimize the weight on the Moscone’s roof structure
main attractions. Since the beginning of the redevelopment (Osmundson 1999). Applying similar techniques for the
project, led by the San Francisco Redevelopment Agency proposed site would help reduce weight, should it be required.
(Yerba Buena Center), back in the 1960s, the project site was
a controversial issue as stadiums and high-rise buildings were Site User Analysis
the argued reason for driving low and middle-income residents Yerba Buena Gardens
out of the area (Osmundson 1999). Actual construction for has a unique atmosphere
the Yerba Buena Gardens did not begin until the 1970s when for a fast pace city like
the construction of the underground convention center began. San Francisco. Entering
It wasn’t until over twenty years after construction on the site the gardens, one can
began that the lower portion bounded by Mission and Howe escape from the city.
streets opened to the public in October 11, 1993 (Yerba Buena While observing the
Gardens). In 1998, the upper portion of the garden referred to Yerba Buena Gardens
as the children’s garden opened (Yerba Buena Gardens-Wiki). on a Sunday afternoon,
6.2. Yerba Buena Gardens.
it rapidly became clear
Yerba Buena Gardens, much like any public garden, is composed what the demographics for visitors to the site were. Perhaps,
of a variety of garden elements such a multi-purpose lawn as the result of the children’s garden on the southern block
area, amphitheater seats, children’s playground, and more. The of the gardens, most of the people frequenting the site were
Esplanade area of the Yerba Buena Gardens serves as the adults with young children 8 years and younger. Areas of high
largest open space and is unique as its “grassy slopes” were user impact versus low user impact are identified in the Yerba
constructed with of 2-feet of Styrofoam and 2-feet soil in an Buena Gardens - Site Analysis.
39

51. The northern block of the gardens in the areas referred to departments for the purpose of education and research, input
as The Esplanade and the Sister City Gardens, were also well from these departments is ideal in developing a site that would be
occupied, although the demographics differed much from those suitable to all. Spaces should also be designed to serve multiple
found in the block located just south of it. Here you will find functions suitable for an array of events such as lectures, labs,
young adults relaxing and lost in there own world, senior citizens and special exhibits. Elements such as amphitheater seating
practicing yoga, and business people glancing at the daily news. and shade structure could possibly be integrated into the site, in
order to accommodate all uses.
6.3. 6.4. Yerba Buena Gardens. Users on the amphitheatre seating area
located in the children’s garden.
General Features Lessons
General elements that can be borrowed from the Yerba Buena
Gardens include community planning, multi-purpose open 6.5. 6.6. Yerba Buena Garden. Users on the Esplanade side of the gar-
den. View toward Mission Street and of the stage.
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
40

52. Vegetation Plant Palette
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
6.7. Vegetation at Yerba Buena
Gardens.
41

53. Yerba Buena Gardens - Site Analysis
Building/
Structure
High Impact
Area
Green Roof Limit Low Impact
Area
Open Space/
Multi-Purpose
Vegetation/
Planting Area
Seating Area
Water Feature
Roof Limit
Entry Access
(6.8.)
42

54. “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
7.1. Union Square Park. Plan view.
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).
43