Living Architecture Monitor - Green Roofs for Healthy Cities

GREEN ROOFS FOR HEALTHY CITIES 

WINTER 

VOLUMENO 

LIVING 

ARCHITECTURE 

MONITOR 

PLANTSFORHOTCOLD 

ANDDROUGHTS 

ORGANICVS 

INORGANIC? 

CREATINGHABITAT

LIVING 

ARCHITECTURE 

MONITOR 

WINTERVOLUMENO 

Living Architecture Monitor is published four times per year by 

Green Roofs for Healthy Cities* (www.greenroofs.org) 

Steven W. Peck 

Publisher & Founder 

speck@greenroofs.org 

416.971.4494 ext. 233 

Caroline Nolan 

Editor 

cnolan@greenroofs.org 

416.971.4494 ext. 231 

ARTDIRECTION 

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406 King Street East, Toronto, Ontario M5A 1L4 Canada 

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SUBMITNEWSSTORYIDEASORFEEDBACK 

We welcome letters to the editor, feedback and comments, as well as story 

ideas and industry news about people, products and projects for consideration 

in upcoming editions of the Living Architecture Monitor: editor@greenroofs.org. 

Green Roofs for Healthy Cities — North America, Inc. was founded in 1999 as a 

small network of public and private organizations and is now a rapidly growing 

501(c)(6), not-for-profit industry association. Our mission is to increase the 

awareness of the economic, social and environmental benefits of green roofs 

and green walls, and other forms of living architecture through education, 

advocacy, professional development and celebrations of excellence. 

Members of Board 

Peter Lowitt, chair, Devens Enterprise Commission 

Dan Sloan, secretary, McGuire Woods LLP 

Richard J. Buist, Landscource Organixs Ltd. 

Jeffrey Bruce, Jeffery L. Bruce & Co. LLC 

Peter D’Antonio, Sika Sarnafil Inc. 

Karen Moyer, City of Waterloo (Ontario) 

*formerly the Green Roof Infrastructure Monitor 

Disclaimer: Contents are copyrighted and may not be reproduced without written consent. Every effort has 

been made to ensure the information presented is accurate. The reader must evaluate the information in 

light of the unique circumstances of any particular situation and independently determine its applicability.

COLD 

What can we learn from the climate characteristics of 

Nordic green roofs? 

By Kerry Ross 

 

 

 

 

 

FROMTHEFOUNDER 

AVISIONFORTHEFUTURE 

By Steven W. Peck 

STRATA—PEOPLEPRODUCTS&PROJECTS 

ALIVINGLABORATORY 

Students and scientists team up on two green roofs at 

New York City’s Ethical Culture Fieldston School. 

GROUND-BREAKINGSUSTAINABLESITES 

INITIATIVELAUNCHED 

ASLA, Lady Bird Johnson Wildflower Center and 

others developing voluntary standards for sustainable 

land use and landscaping practices. 

REVIEW 

Books: ALSA’s Case Study; Ian McHarg — Conversations 

with Students; Busby: Learning Sustainable 

Design; and Alessandro Rocca’s Natural Architecture 

ONTHEROOFWITH… 

AQ&AWITHTHELEGENDARYLANDSCAPE 

ARCHITECTCORNELIAHAHNOBERLANDER 

By Caroline Nolan 

 

 

 

 

DROUGHT 

Evaluating the performance of green roof plants and 

growing medium. 

By Dr. Bill Retzlaff, Dr. Susan Morgan, Kelly Luckett 

and Vic Jost 

CREATINGHABITAT 

BYDESIGN 

A new process model can help you make the right 

decisions when trying to restore habitats for a specific 

species on green roofs and wall projects. 

By Dr. Reid Coffman and Alison Thurmond 

POLICY 

SEATTLE’S“GREENFACTOR” 

A new urban landscaping policy is creating an incentive 

for more green roofs and walls in this coastal city. 

By Lillian Mason and GRHC staff 

”BUSHTOPS”DOWNUNDER 

South Australian government’s green wall and green 

roof incentive policies are bringing the “bush” back 

into Adelaide. 

By Graeme Hopkins & Christine Goodwin 

 

 

 

PROJECT 

ISLANDPARADISE 

An award-winning Ontario residential project — three 

years later. 

By Flavia Bertram 

BESTPRACTICE 

GROWINGMEDIA—THEORGANICQUESTION 

Rick Buist & Chuck Friedrich face off on how much 

organic — if any — is best for optimal performance. 

NATIVEPLANTRESEARCH 

IMPACTOFGROWINGMEDIAONPRAIRIEGRASSES 

Thinking like a prairie in Lincoln, Nebraska. 

By Richard K. Sutton 

 

 

 

GRHCUPDATE 

GREENWALLTECHNOLOGYCLIMBING 

By Lillian Mason and GRHC staff 

OMAHAWELCOMESOPPORTUNITYTOBUILD 

MOREGREEN ROOFS 

Stormwater management among topics discussed at recent 

Nebraskan-based Local Market Development Symposium. 

By Kent E. Holm 

SYMPOSIUMIGNITESGREENROOF&WALL 

MOMENTUMINATLANTA 

From architects to policymakers — the finest 

professionals gathered to brainstorm an action plan 

for more green roofs in Georgia’s capital city. 

By Lillian Mason & GRHC staff 

 

NATIVESURVIVORS 

Insights from study conducted by the New England Wild 

Flower Society in partnership with the Massachusetts 

College of Art. 

By Ron M. Wik 

 

FROMTHEACCREDITATIONSUB-COMMITTEE 

First Green Roof Professional accreditation exam 

planned for 2009 conference in Atlanta, Georgia. 

By Hazel Farley 

 

EXTREMECONDITIONS 

HOT&HUMID 

What plants work best in tropical and subtropical climates? 

By Steve Skinner 

 

ONSPEC 

FROMWHEREIAGREENROOFERSIT 

The role of the landscaper on green roof projects. 

By Kurt Horvarth

FROMTHEFOUNDER 

AVISIONFOR 

THEFUTURE 

IMAGINEASWEDOOURCOLLECTIVE 

POWERTOCREATEHEALINGRESTORATIVE 

BUILDINGSDESIGNEDWITHLIVING 

ARCHITECTUREPRINCIPLES 

THEEDITTBUILDINGINSINGAPORE 

Image courtesy of TR Hamzah & Yeang Sdn Bhd

THEGROWINGMEDIA&PLANTISSUE 

Welcome to the Living Architecture Monitor. We are dedicated 

to bringing you the best research, policy and practices 

focused on the integration of living and non-living elements 

in and around buildings. Living architecture is the pathway to 

making a more fundamental shift towards the creation of 

healing, restorative high-performance buildings — and by 

extension, healthier, more liveable communities. 

In essence, healing, restorative, high-performance buildings give back 

more than they use over their lifecycles: producing a surplus of renewable 

energy, cleaner water, improved air quality and aesthetics, 

the very foundation for vibrant biological diversity and the greater 

physical and emotional well-being of humans. 

Green roofs and green walls are two key elements of living 

architecture that are gaining more widespread acceptance 

throughout North America. These living architectural forms allow 

for unparalleled benefits at different scales — at the site level 

(aesthetics, stormwater quality and quantity): at the building level 

(energy savings, noise reduction, membrane durability, recreation 

space, urban food production, improved PV efficiency, biodiversity, 

advertising, marketability, improved investment value); at the community 

level (improved aesthetics, air quality benefits, cooling 

urban heat island, noise abatement, educational opportunities, 

community food production, psychological benefits); and the wider 

region (reducing greenhouse gases, supporting ecological diversity) 

— and this list is by no means complete. 

We need to re-imagine buildings as small ecosystems, nestled within 

the larger bioregions of our communities. McDonough and Braungart, 

in Cradle to Cradle, call for a shift toward “eco-effectiveness” and 

suggest we adopt a new design assignment set out to create “buildings, 

that like trees, produce more energy than they consume and purify 

their own wastes.” Restorative buildings won’t add more stress to 

existing infrastructure, such as coal-fired plants and the lengthy 

transmission wires that supply power; or our overtaxed water and 

wastewater treatment plants that regularly discharge vast quantities 

of raw sewage into our lakes, rivers and oceans. 

filtered through a series of ‘John Todd like’ facades and vegetated-terraces. 

The indigenous vegetation areas are designed to be continuous 

and to ramp upwards from the ground plane to the uppermost floor in 

a linked landscaped ramp. The design’s planted-areas constitute 3,841 

sq.m., a ratio 1:0.5 of gross useable area to gross vegetated area. Rainwater 

will be cleansed, stored in the basement and provide water for 

toilets and irrigation for the living architectural features, an amenity to 

building occupants on every floor of the 26-story structure. 

If living architecture is to blossom as a practice this century, we also 

need to understand the full contribution that living systems offer — 

economic, social, psychological and environmental and ensure that 

these are reflected, rather than discounted in the marketplace. 

The vehicle for this change is through policies, regulations, and standards 

and investment. At a city-wide scale, we need to better understand 

the economic benefits of widespread living architecture in order 

to help facilitate the public resources required to fully support these 

developments. As our industry continues to rapidly grow, we can transform 

the building industry into a fundamental force for sustainability. 

Green Roofs for Healthy Cities is dedicated to bringing about the 

rapid shift towards a living architecture and the creation of healing 

restorative buildings. Through this new publication, we will work 

tirelessly to bring you, our members, the latest in research, product 

developments, standards, tools, innovative designs and new policies 

that support your ability to make a lasting life-long contribution 

towards sustainable building. 

Sincerely yours, 

Living architecture is exemplified in Ken Yeang’s remarkable EDITT skyscraper 

in Singapore, designed from an ecological approach (pictured 

left). The building will be 55 per cent water self-sufficient, produce 

renewable energy and process wastewater. Captured rainwater is 

Steven W. Peck 

Founder and President 

LIVING ARCHITECTURE MONITOR WINTER

STRATA 

KUDOS 

PRIZE-WINNINGPROJECTS 

At Green Roofs for Healthy Cities, we love to 

celebrate excellence in green roof and wall 

design — so our hats go off to the following individuals 

and organizations for their recent 

achievements: 

PRESERVINGSTORMWATERINPHILLY 

Pennoni Associates, a consulting engineering 

firm headquartered in Philadelphia, Pennsylvania 

won the award for Stormwater Best Management 

Practices for its green roof design on 

The Radian, located on Walnut Street in 

Philadelphia. The honors came from the 

Philadelphia Water Department, Offices of the 

Watersheds, a statewide program that recognizes 

innovative stormwater best management 

practices. The project, which integrates green 

roof areas into the public terrace level of a 

mixed-use facility that includes lower level 

retail space and a 13-story residential tower 

for student apartments, broke ground in Mary 

2007 and will open this August. The innovative 

strategy for stormwater management drains 

runoff from impervious areas of the roof into 

the green roof structure, maximizing water 

retention on the roof while controlling the 

release rate into two underground stormwater 

management basins. Additionally, the plant 

design of the green roof will serve as a valued 

amenity to residents and the community at 

large. Erdy McHenry Architecture was the 

project architect while Roofscapes, Inc. served 

as subconsultant to Pennoni and provided key 

technical expertise for the green roof design. 

GREENINGCALGARY 

On Nov. 1, 2007, the city of Calgary’s 

Mayor’s Urban Design Awards took place 

with eight winners and four honourable 

mentions in a variety of categories. A 

conceptual entry, Grey to Green: Greening 

Calgary One Roof at a Time, was jointly 

submitted by Kerry Ross, an architectural 

consultant with IBI Group in Calgary and 

Kelly Learned of Cochrane, Alberta, earned 

an honourable mention and special acknowledgement 

by Juror Shannon Nichol 

of the international landscape architecture 

firm, Gustafson Guthrie Nichol. Their 

entry illustrated how a green roof on one 

of Calgary’s landmarks, the Municipal 

Building, could set the tone for the region 

in terms of becoming a green roof 

technology leader. 

BELOWThe award-winning Radian in Philadelphia was recognized for its innovative stormwater management strategy. “This project is an example of how ecology, 

economics and aesthetics can be balanced to satisfy not only the owner and the users of the building, but also broader environmental goals,” says Marc Morfei, 

Philadelphia senior landscape architect. 

Renderings: Erdy McHenry Architecture 

COMINGUP 

The Toronto Botanical Garden will host a green roof conference on Feb. 21, 2008. The event’s 

conference workshops will cover design, plants, biodiversity and technical considerations. Paul 

Kephart of Rana Creek will be a speaker, as well as the instructor for GRHC’s Ecological Design 

Course to be held in the morning of Feb. 22, also at the Botanical Gardens. For information 

about the event, please email greenroof@logistix.com or see their website at www.torontobotanicalgarden.ca/greenroof. 

Further information and registration details about GRHC’s Ecological Design course on Feb. 22 

can be found at www.greenroofs.org 

NEWS 

WANTED! 

We want to hear about your 

announcements (deals and projects 

completed); people moves; awards; 

and books and events. Send us an email 

at editor@greenroofs.org and your 

news may end up in Strata for our next 

issue. Please include photographs or 

images if applicable. 

 

LIVING ARCHITECTURE MONITOR 

WINTER


ALIVINGLABORATORY 

STUDENTSOFALLAGESAREGETTINGANEDUCATION—ANDLEARNINGWHATIT’SLIKE 

TOCONDUCTRESEARCHALONGSIDECOLUMBIAUNIVERSITYSCIENTISTSATOPA NEW 

YORKCITYMIDDLESCHOOL’STWOGREEN ROOFS 

Students at New York City’s Ethical Culture 

Fieldston School will soon be applying their 

science studies towards green roof research. 

The recent $75 million renovation of the middle 

school has incorporated green building 

design and two green roofs. Dr. Stuart Gaffin, 

associate research scientist at The Center for 

Climate Systems Research at Columbia 

University in New York and Dr. Mathew 

Palmer, a lecturer with the Department of 

Ecology, Evolution and Environmental Biology, 

also at Columbia University, spearheaded the 

research and study of the two roofs, both different 

in purpose and design. 

Fieldston made available its two green roofs 

for Columbia’s research, which in turn will 

present unusual opportunities for the 

school’s science teachers from grades 

one through 12. 

“There are many different technological 

aspects to green building design but none of 

them offers the educational richness of green 

roofs,” says Gaffin, who is in charge of the 

research at the school’s top-level roof. “Green 

roofs can be used to teach physics, climatology, 

hydrology, biology, ecology, chemistry 

and so on. One could never develop such a 

far-reaching curriculum, around say, solar 

panels or energy-efficient windows.” His own 

“ There are many different technological aspects to green building design but none of 

them offers the educational richness of green roofs. Green roofs can be used to 

teach physics, climatology, hydrology, biology, ecology, chemistry and so on.” 

Dr. Stuart Gaffin, research scientist, Columbia University 

research centers on the energy benefits of 

Fieldston’s green roof with New York’s energy 

and water issue needs in mind. 

Columbia’s research on the top-level roof is 

conducted using a weather tower, multiple 

sets of soil moisture and temperature probes, 

an albedometer and plant foliage temperature 

sensors. The albedometer consists of 

two back-to-back pyranometers, a device 

designed to measure natural sunlight radiant 

energy, manufactured by Kipp and Zonen. 

“With the data we are collecting and subsequent 

analysis, much of which will be done by 

the students, I hope we can produce findings 

for an ‘optimal’ green roof design that maximizes 

environmental benefits at the lowest 

cost,” explains Gaffin. “This will help spur 

their adoption by New York City and elsewhere.” 

The lower level roof of the school, planted in 

part by Fieldston’s students last October, was 

designed to be a more interactive site with 

three different types of plant communities. In 

addition to a traditional mix of Sedum 

species, two native, diverse grassland communities 

were planted. One of these communities 

was modeled on the Hempstead Plains, 

a prairie-like grassland from Long Island 

which has been almost completely lost due to 

urban and suburban development. The other 

native community is modeled on grasslands 

native to the Hudson Valley’s rocky hilltops 

with shallow soil, droughts and harsh wind, a 

climate very similar to that on the roof. Students 

will follow the success of the different 

plantings through time and will compare 

ecological processes like pollination and the 

development of the soil between the three 

plant communities. 

“If we can learn how to make native plant 

communities succeed on green roofs, it will 

add immensely to the value of those roofs as 

ecological restoration projects, habitat for 

other species and living laboratories for 

schools,” says Palmer. 

The students at Fieldston created a video 

detailing the building process of the second 

roof which can be viewed at www.ecfs.org 



STRATA 

GROUND-BREAKING 

SUSTAINABLESITES 

INITIATIVELAUNCHED 

ASLALADYBIRDJOHNSONWILDFLOWERCENTERAND 

OTHERSAREDEVELOPINGVOLUNTARYSTANDARDSFOR 

SUSTAINABLELANDUSEANDLANDSCAPINGPRACTICES 

The American Society of Landscape Architects 

(ASLA), the Lady Bird Johnson Wildflower 

Center, the United States Botanic 

Garden, and other stakeholders are working 

under the umbrella of the Sustainable Sites 

Initiative to develop voluntary standards and 

guidelines related to sustainable land use and 

landscaping practices. 

The initiative was established to “identify the 

gold standards in sustainable landscape design 

and marry them to a practical, real-world 

approach so that designers, planners, 

builders, and developers can utilize them,” 

says Nancy Somerville, executive vice president 

and CEO of the ASLA. 

In a preliminary report published in November 

2007, a committee composed of 32 professionals 

practicing across a variety of landscape 

related disciplines identified a series of design 

goals and methods of achieving and monitoring 

a site’s ability to satisfy these objectives. The 

group further recommended integrated design 

strategies as a means to “harness natural 

processes to provide environmental benefits.” 

The guidelines are scheduled for release in 

May 2009 and will be incorporated into the 

USGBC’s LEED® system. 

For more information or to participate in the 

review process visit www.sustainablesites.org. 

GREENGRID 

INSTALLS 

LARGEST 

MODULAR 

ROOFIN 

NORTH 

AMERICA 

A 2.3 acre modular green roof, the largest of 

its kind in North America, covers the new 

court at Upper Providence shopping center 

in Montgomery County, Pennsylvania. The 

GreenGrid® modules were installed in early 

2007 thanks to a joint venture between Gambone 

Development, Inc. and The Highland 

Development Group, Ltd. 

WASHINGTONDCSUPPORTSGREEN 

ROOFDEMONSTRATIONPROJECTS 

Through a grant from the District Department 

of the Environment, Watershed Protection 

Division, DC Greenworks, a 

preeminent green roof organization in the 

area, is subsidizing $3 per square foot of 

green roof demonstration projects. 

“This broadly available subsidy is generating 

a interest from a wider variety of developers 

than other incentives in the DC area. 

It is effectively helping mainstream building 

and land owners test out this progressive 

technology that wouldn’t otherwise have 

access to green roof funding,” says Sheila 

“This broadly available 

subsidy is…effectively 

helping mainstream 

building and land owners 

test out this progressive 

technology that wouldn’t 

otherwise have access to 

green roof funding.” 

Sheila Hogan, DC Greenworks, Washington, DC 

Hogan, executive director of DC 

Greenworks. 

In order to qualify an extensive or intensive 

project must be in D.C., can be new construction 

or retrofit, and on buildings with a 

footprint under 5,000 square feet or larger, 

in cases where the supporting structure 

was built prior to 1988. The program’s next 

deadline is February 15, 2008; others will 

be announced when determined. 

For further information and the application form 

visit: www,dcgreenworks.org. 

 


WINTER

GREENROOFSGO 

EXTREME—ANDPRIMETIME 


It was Tuesday in April 2007 when 

Kelly Luckett got the call. A construction 

manager from the top show, Extreme 

Makeover Home Edition, asked if Luckett’s 

company, St. Louis-based Green Roof 

Blocks, could provide green roof modules 

for a green roof they were planning on a 

fully sustainable house they were building 

for a needy family in Pinon, Arizona on a 

Navaho Reservation. Luckett said he would 

be pleased to help, then came the kicker: 

the construction manager needed fully 

grown-out modules by that Sunday — 

just four days away. 

Under normal circumstances, it would take 

three to four weeks to deliver fully grown out 

modules, but Luckett was undeterred — even 

in the early spring. Saying yes, he quickly 

turned to his team on to the company’s research 

plots. “We could barely scrape together 

the number of square footage they 

needed — 200-modules, about 400 square 

feet in total,” he remembers. With plants 

ready, then came the real challenge — getting 

the modular plants, based in St. Louis, Missouri, 

to Pinon, Arizona — in just days. “No 

commercial freight carriers would commit to 

timelines, so we wound up putting it all into a 

rental truck and a staff member drove it 

across the country,” says Luckett. 

Luckett and his business partner both took 

time off to help out on the rapid installation 

of the green roof, bringing along their children 

for the once-in-a-lifetime experience. 

He was joined by another seasoned green 

roof professional, Dr. Bill Retzlaff, associate 

professor and chair of the Department of 

Biological Sciences Environmental Sciences 

Program at Southern Illinois University Edwardsville 

in Illinois. 

A hectic schedule, but well worth it, says 

Luckett, especially at the moment of the big 

“reveal” when the new house was unveiled 

for the worthy family. “It was a very emotional 

moment,” says Luckett, who, like every 

other contributor to the house, donated all 

his materials and time to make this dream 

house a reality for a very special family.

REVIEW 

TWISTINGNATURE 

Drawing on the works of artists dedicated to 

the use of natural materials — trees, wood, 

bamboo and pebbles — Alessandro Rocca’s 

Natural Architecture locates its readers at the 

intersection of art, architecture and ecology. 

The artists are all linked together by their desire 

to create incredibly complex installations 

while minimizing their effect on the environment 

in which they are created. Most employ 

basic artistic techniques and rely on manual 

labor to create awe-inspiring structures that 

will inevitably disintegrate but which raise lingering 

questions about our ways of inhabiting 

space. (Princeton Architectural Press, 2007) 

STRIKINGTHERIGHTBALANCE 

In an industry as new and multidisciplinary as 

the living architecture field, it is rare to get a 

project’s whole story. Not so anymore, Christian 

Werthmann’s Green Roof — A Case Study 

provides a comprehensive account of the 

American Society of Landscape Architecture’s 

green roof, in which Landscape Architects 

Michael Van Valkenburgh Associates 

and the Conservation Design Forum were 

charged with the task of maximizing both aesthetics 

and environmental performance. For 

the novice, the book demystifies every aspect 

of green roofing; for the seasoned professional, 

it allows for detailed examination of 

the design methodologies, construction techniques 

and maintenance practices employed 

to achieve these lofty goals. In an interview 

between the author and Van Valkenburgh, 

the designer placed emphasized the importance 

of striking the right balance. Hopefully, 

this book will help others do the same. 

(Princeton Architectural Press, 2007) 

ADAPTATION 

Ian McHarg, the author of the ecological design 

classic Design with Nature, has greatly 

transformed the approach to and understanding 

of land-use planning and landscape architecture. 

Ian McHarg — Conversations with 

Students: Dwelling in Nature rearticulates the 

guiding principles of the “McHarg Method,” 

an interdisciplinary approach to land use design 

rooted in the notion that “creativity has 

permeated the evolution of matter and life, 

and actually is indispensable for the survival 

of the system.” He goes on to lay out the tools 

needed for the analysis and execution of 

“creative fitting,” a process driven by the 

theory that “any system is required to find 

of all environments the most fit, to adapt 

that environment, and to adapt itself.” 

(Princeton Architectural Press, 2007) 

BUSBY’SVISION 

Busby and Associates Architects are known 

for buildings that combine a Modernist aesthetic 

with environmentally responsive and 

integrated design strategies. Busby: Learning 

Sustainable Design profiles twelve of the 

firm’s projects (which coincidentally draw 

upon the theoretical framework of Ian 

McHarg’s Design with Nature), highlighting 

their contribution to the development of new 

green building performance standards. The 

book, produced in collaboration with heavyweights 

David Suzuki (foreward) and editors 

Jim Taggart and Kathy Wardle, will serve the 

interests of those interested in the theory, 

practice and direction of the sustainable 

design industry, especially the need for multidisciplinary 

collaboration. As Taggart notes: 

“Optimizing performance depends on a critical 

appreciation of the interdependence of structure, 

form, envelope design and environmental 

systems.” (Janam Publications Inc., 2007) 

By Flavia Bertram

Photos courtesy Elisabeth Whitelaw 


CORNELIAHAHNOBERLANDERCMFCSLAFASLA 

By Caroline Nolan 

Cornelia Hahn Oberlander, born in Germany in 1924, obtained a BA 

from Smith College in 1944 and was one of the first women to 

graduate from Harvard University’s School of Design with a degree in 

landscape architecture in 1947. She worked with Louis I. Kahn and 

Oscar Stonorov in Philadelphia, and landscape architect Dan Kiley in 

Vermont, before moving to Vancouver to establish her own practice in 

1953, Cornelia Hahn Oberlander Landscape Architects. 

Her career is legendary. 

The 84-year-old is well-known for such extraordinary, pioneering works 

including “Robson Square” — the provincial government courthouse 

complex in Vancouver, a three-block green roof designed in collaboration 

with the architect Arthur Erickson (1974–81); the National Gallery 

of Canada, with architect, Moshe Safdie; University of British Columbia’s 

(UBC) Museum of Anthropology, also with Arthur Erickson 

(1975–76); the Canadian Chancery in Washington DC, also with Arthur 

Erickson (1989); the spectacular 28,000 square-foot semi-intensive 

roof on Moshe Safdie’s Vancouver Public Library (1995); and the Northwest 

Territories Legislative Assembly Building in Yellowknife, Canada 

with Matsuzaki Wright Architects and Gino Pin Architects (1995). 

She has received numerous awards including the prestigious Order of 

Canada in 1990; several honorary degrees from University of British 

Columbia (UBC), Simon Fraser University, Ryerson University and 

Smith College; a commemorative Medal for the 125th Anniversary of 

the Confederation of Canada in 1992; the Royal Architectural Institute 

of Canada Allied Medal in 1995; and an honorary membership to the 

Architectural Institute of BC as well as life membership in the British 

Columbia Society of Landscape Architects. 

Cornelia, a true pioneer of socially conscious and sustainable 

landscape design, has collaborated with internationally acclaimed 

architects, including Renzo Piano on public projects in the United 

States and Canada. We caught up with Oberlander in Vancouver 

late last year. 



Q: The Germans have a wonderful sense of stewardship for nature 

and, indeed, created the green roof concept in the first place. 

Do you feel your heritage has influenced your work? 

A: Well, when I was 15, we landed in New York from Germany in 

1939, before the war, because my mother thought it was for us. A 

year and a half later, she came down from breakfast one day and 

said to me and my sister, ‘This place is too materialistic for you girls 

— all you are thinking about is sweaters and skirts. When you come 

new to a country you have to till the soil.’ She then whisked us in 

our wooden-bodied Ford Station wagon up to northern New Hampshire 

and that’s where I grew up. She was trained as a horticulturalist 

and created a Victory Garden to grow vegetables during the war 

and so, that’s how I grew up. 

Q: You have practiced “living architecture” before the term even 

existed — what does the term mean to you now? 

A: Living architecture means that the building is healthy and the land 

is healthy and that you are contributing to the biomass of the city, 

namely to make the air cleaner. I feel that if you have chosen the 

profession of landscape architecture, you have a duty to listen to what 

the times bring. It’s not what I was taught at Harvard way back when, 

necessarily, but all about what we must make of the land today. I’ve 

always looked to the future. 

Q: How has landscape architecture profession changed since you 

established your own practice in 1953? 

A: Well, the industry was non-existent then. You hoped for the best, 

that the building wouldn’t fall down! But I was already at Harvard realizing 

I could not work in a vacuum — that I would have to work in collaboration 

with architects. 

Q: Early in your career, did you ever imagine you would ever see the 

mainstreaming of green roofs as is happening now? 

A: Well, I had hoped it would happen. The municipal bylaws and the 

building bylaws of every city must include green roofs. We have not 

reached this goal yet. 

MOSHESAFDIE’SVANCOUVERPUBLICLIBRARY 

Q: You are retrofitting one of your most important and noted 

projects, Vancouver’s Robson Square — what is being done and why? 

A: Well, after 35 years it was time. In 1976, the waterproofing membrane, 

or EPDM, was guaranteed for 20 years, and it lasted for 35 

years. So that had to be renewed, but on top of that, the province of 

British Columbia demanded seismic upgrading for the whole building, 

and so this is being done at present and with it, came an in-depth 

analysis of the plant materials which were possible to keep. We lifted 

out several 8,000-pound Japanese Maple Trees among others, took 

them to a nursery and brought them back last spring and then planted 

them in exactly the same location as before. 

Q: What were some of the challenges you encountered with your 

design of the green roof on Vancouver’s Library Square Building? 

A: I don’t work with soils, so I knew already in 1976 I knew that I could 

only have a lightweight growing medium for the roofs for the Robson 

Square installation. So for the Library Square, I researched at great 

length how could I get a lightweight growing media and I came upon 

the idea to collect all the vegetable food waste from the restaurants in 

Vancouver and have them process it into compost. The final mix is 

one-third compost from vegetable food waste, one-third pumice and 

one-third sand: it’s called the Library mix — and we will use it at Robson 

Square again, so the challenge was to talk the owners into allowing 

us to use this lightweight material. 

“I feel that if you have chosen the profession 

of landscape architecture you have a duty to 

listen to what the times bring...I’ve always 

looked to the future.”


Q: Looking ahead, what changes do you see? 

A: Well, first of all, we must curb this desire to sprawl. We must limit 

our footprints and employ the principles of ecodensity — that’s number 

one. Number two: we must use every bit of ground for public parks and 

not give it away to developers. Number three: if we want living buildings, 

we must work together as a team of architects, engineers, landscape 

architects. 

Q: As a landscape architect, how do you feel about the emergence of 

green walls? 

A: I think it is very good idea because they insulate the building against 

the cold and heat but they have to be built with drip irrigation. But I 

would like to speak to you about wildlife. 

Q: Please do... 

A: Well, we must build with a holistic approach, for example, it is important 

to include the Canada Geese, and all the other birds that flock 

around. Let them have fun on the roof! 

Q: Canada Geese on a roof? 

A: Yes. On the Library roof, I have two nice Canada Geese couples, 

(you know they mate for life), which come to certain balconies of the 

Court House, for instance, but the judges aren’t too happy with this 

and have asked for them to be removed — so I have not educated 

everyone yet! On the roof of the Vancouver Library, an inaccessible 

roof, I have two more sets of Canada Geese that sit on the roof and 

have their children and then they fly away and return every year. So 

education is necessary for a holistic approach that allows humans and 

geese to be part of the urban landscape. 

Q: If you could impart one kernel of wisdom to other professionals 

in this field, what would it be? 

A: Think about climate change which concerns all of us and what we 

have done to this planet. Learn what we can do and with every project 

to lessen the impact on the environment. Green roofs increase 

biomass, insulate buildings against heat and cold and slow down 

stormwater runoff, if they’re constructed properly. You can do this 

only if you have done your research and if you are working with 

professionals who know how to implement these ideas with working 

drawings and specifications. 

Q: A perfect ending — thank you for your wonderful visions and work. 

Caroline Nolan is the editor of the Living Architecture Monitor.

PROJECT 

ISLANDP 

 


WINTER


PROJECTSPECIFICATIONS 

LOCATION Thousand Islands, Ontario 

PROJECTTYPE New Construction 

GREENROOFSIZE 1,700 square feet 

COMPLETIONDATE 2002-2003 

YEAROFAWARD 2004 

CLIENT/DEVELOPER Carol and Kevin Reilly 

ARCHITECT Shim-Sutcliffe Architects (Winner) 

DESIGNCONSULTANT Mill & Ross Architects 

DESIGNCONSULTANT Donald Chong Studio 

STRUCTURALENGINEERSBlackwell Engineering 

MECHANICALENGINEERSToews Systems Design (Mechanical) 

CONTRACTOR Michael Sheedy and Mark Peabody 

GREENROOFDESIGNER Marie-Ann Boivin, Soprema Canada 

GREENROOFLANDSCAPECONTRACTOR Top Nature, Montreal 

ARADISE 

By Flavia Bertram 


PROJECT 

The majority of green roof projects are located in highly developed 

areas, characterized by limited green space, a searing urban heat 

island effect, stormwater management issues, and as such, often used 

to mitigate these negative effects of urbanization. Not so in the case 

of the 2004 Award of Excellence winning Howe Island home on the 

St. Lawrence River in the Thousand Islands, Ontario. 

The once rural, now semi-suburban island has a history of dairy farming 

and is not subject to the same environmental problems as city 

centers. As a result this green roof project was driven by aesthetics 

rather than the environmental benefits of the technology. 

Shim-Sutcliffe Architects conceived the house with the intent of 

The upper semi-intensive roof transposed the meadow plants from 

the ground to the roof, thereby integrating the building with the 

landscape. This visual effect is facilitated by the omission of parapet 

walls, resulting in roof perimeter details like those usually found 

on sloped rather than flat roofs. Six-inch deep growing medium sits 

on top of a modified bitumen membrane and root repellent layer 

and is contained by borders, which are then surrounded by stone 

vegetation-free zones to prevent the occurrence of plant erosion. 

Prior to construction, and to reinvigorate the large meadow, the 

five-acre site was hydroseeded (a process where a slurry of seeds 

and mulch is sprayed over a targeted area) with clover and a mixture 

of local indigenous flowers. The clover was harvested and 

respecting the region’s agrarian tradition and maintaining the openness 

of the landscape while providing their clients with privacy and a 

splendid view of the river. The green roofs, designed with Soprema 

Canada, were one of many elements that contributed the project 

goals of balancing the landscape, structure and water. On the side 

facing the St. Lawrence River the house opens up to a large water 

garden with indigenous water lilies and bulrushes. 

Initially, the two roofs did not utilize the same vegetation. The 

lower extensive roof was planted with a more traditional sedum 

palette, including Sedum album, Sedum floriferum ‘Weihenstephaner 

Gold’, Sedum kamtschaticum ellacombianum and Sedum 

Spectabile ‘Brilliant’. 

“The green roof is part of 

larger vision for landscape; 

it is one part of a greater 

approach to the agrarian 

context of the island.” 

Brigitte Shim, Shim-Sutcliffe Architects 

 


WINTER


transformed into bales of hay by a local farmer, continuing the 

site’s tradition of contributing to local agriculture. 

This same blend was subsequently used in the field of the upper 

roof of this island paradise, which was then bordered by sedums. 

This connection between the roof and the ground, however, proved 

to be problematic for the semi-intensive roof’s maintenance. The 

original plant-selection (comprised of French hybrids) were quickly 

overrun by native Canadian weeds and wildflowers. Though the area 

was reseeded after the establishment period was complete, the 

maintenance was certainly more than the client had bargained for. 

During the design phase, it became apparent to both the architects 

Both roofs have been annually supplemented with two or three flats 

of sedum to ensure continuous plant coverage. 

Despite this alteration, the striking Howe Island green roof continues 

to be an example of site-specific design that is sensitive to the visual 

and cultural aspects of the surrounding environment. The clover 

meadow and the two green roofs compliment each other, blurring the 

borders of the building roof and the ground plane. 

Flavia Bertram is a research assistant with Green Roofs for Healthy Cities in 

Toronto. She is also a contributor to a new book published by Green Roofs 

for Healthy Cities and Schiffer Publishing called Stretching the Boundaries 

of Green Roof Design and Living Architecture: Five Years of Award-Winning 

“Once we 

got the right 

plants on 

the roof it 

became easy 

to handle.” 

Carol Riley, owner & client 

and manufacturer that the several-hours-by-car distances from the 

nearest centers of green roof knowledge in Canada —Toronto and 

Montreal — were too far for maintenance personnel to travel. As a result, 

the owners and a local gardener were trained in basic maintenance 

procedures and bore the responsibility for them. This capacity 

development is in keeping with the projects goals of respecting the island 

and surrounding area’s existing tradition of agrarian self-reliance. 

However, this independence also necessitated that the labour required 

in its upkeep be limited and resulted in the replanting of the 

upper roof with low maintenance drought resistant sedum species. 

Similarly, plants on the lower roof were redistributed after the establishment 

period was over in order to create a stronger plant palette. 

Projects in the spring. In the book other Green Roof Awards of Excellence 

winning projects and individuals are recognized for demonstrating extraordinary 

leadership and are celebrated for their valuable contribution to the 

green roof industry. This case study is but one of many featured in this exciting 

book, which will be launched at the upcoming annual GRHC conference 

in Baltimore in April. Please see www.greenroofs.org for details. 

INTERESTEDINHAVINGYOURPROJECTPROFILEDHERE? 

We are currently seeking excellent and innovative green roof and green 

wall projects for in-depth case studies for future “Project” consideration. 

Tell us about yours by sending an email to editor@greenroofs.org. 

It would be helpful to include a few photographs. 


BESTPRACTICE 

THEORGANIC 

QUESTION 

WHENITCOMESTOGROWINGMEDIATHEREISCONSID- 

ERABLEDEBATEASTOWHATEXACTLYCONSTITUTESTHE 

BESTMIXFORSUPERIORPERFORMANCE 

On any green roof project, there inevitably comes a time when 

professionals must answer a crucial question: Exactly what kind of 

growing media is best for the roof’s long-term performance? 

In North America, much research is still required to determine the 

optimal composition of growing media and a wide variety of opinions. 

Currently, many green roof professionals are grappling with 

the issue of organics versus non-organic materials in growing media. 

Here, we present just two of those opinions from two, respected 

industry professionals, both members of Green Roofs for Healthy 

Cities’ Growing Media Sub-Committee which is developing performance 

standards for growing media: Chuck Friedrich and Rick Buist. 

Rick Buist is a horticulturalist and president of BioRoof Systems 

Inc. and chair of the GRHC Growing Media Sub-Committee. 

Chuck Friedrich is also a horticulturist — and landscape architect — 

and is the director of horticulture research and product development 

for Carolina Stalite Company in Salisbury, North Carolina. He is 

also a member of the American Society of Landscape Architects, NC 

Landscape Contractors Association, and ASTM Green Roof Subcommittee. 

He also sits on the ASTM Green Roof Task Committee. 

 


WINTER


“DON’TCALLITDIRT!” 

By Chuck Friedrich, RLA, ASLA 

My college soil science professor always reprimanded the class 

for referring to soil as “dirt.” He would always say: “dirt is 

something that is tracked in onto the carpet.” Actually the ideal 

green roof growing media should NOT contain any natural soil; 

therefore, we should not even call it soil. Most green roof professionals 

prefer the term growing media or medium, substrate, or 

planting media. My definition for green roof media is: “the particulate 

matter or substrate that anchors the plant roots to sustain plant 

growth.” Sounds simple, but it can get very complicated. 

For proper terminology, we should refer to the growing media as 

intensive or extensive green roof media. The media should be designed 

for the physiology of the plant material growing in the media. 

Sedums require an extensive media that has a coarser gradation than 

those used for grasses or other non-succulents. In addition to plant 

material, other factors affecting media selection are climate, weight, 

fertility, depth, location, microclimate, and irrigation. With all these 

factors to contend with we can then add a bunch of engineers to the 

equation. Over the past 15 years I have supplied green roof media on 

over 140 green roofs. It has been a learning experience offering much 

success. (Having a German last name didn’t hurt.) 

LOSINGORGANICMEDIA 

Trees, shrubs, lawns and flowers need water, air, space for the roots, 

and nutrients. Within the proper microclimate, many plants can 

grow better on the roof than on the ground. Why? With a green roof 

we can create a very big pot filled with the perfect growing media 

that is fertilized, irrigated, and most important, well drained. What 

we don’t want is a natural soil or a 100 per cent organic mixture 

GOINGFORORGANICS 

By Rick Buist 

When considering the writing of this best-practices article on 

using organics in growing medium, I reflected on the experiences 

I have had in the green roof marketplace to date. Since first becoming 

aware of the green roof industry, I had numerous people tell 

me how you shouldn’t use more than a certain percentage of organics 

in the growing medium. One says five per cent, another 20 per cent, 

and yet others argue it would be best if there were no organics at all! 

Now at the time, I found this all rather odd. Our company has many 

successful installations (over 80 to date) with few observed problems, 

and our sister company has been producing millions of cubic meters of 

organic-based growing mediums for decades to the nursery industry. 

Then I was told that our organic growing medium projects we installed 

did not have a long enough track record to be sufficiently evaluated. 

“Just you wait,” they ominously warned, ‘eventually the organic growing 

medium will disappear — it’ll be a disaster.” One person even 

claimed they had pictures of a green roof we installed showing exposed 

roots — impending doom was just around the corner! 

So I took all of this great advice to heart and also personally visited the 

site in question, only to discover the growing medium depth had not 

changed in four years. The roots were not exposed (although clumping 

fescues could give that appearance) and the owners were very happy. 

Naturally I had to ask myself: Why the strident accusations against organics 

in growing mediums?” Is it because some have invested in proprietary 

products associated with growing mediums? Is it because of the European 

experience? Or do they really have a sound scientific argument? 


BESTPRACTICE 

contained up on a giant frying pan in the sky. Natural soils are 

cohesive and can change over a long period of time or simply get 

“damaged” if installed when wet. The same is true with organic 

matter; though it is a very important component, too much organic 

can be problematic depending on the circumstances. 

Organic matter breaks down and is washed out of the system due to 

rain or irrigation; to replace lost material could require many trips 

with heavy bags up steps or an elevator. The use of natural soil or too 

much of the wrong type of organic amendment may produce finer 

particles. Fine particles can move down and accumulate on the filter 

fabric, slowing down drainage. I have not been a big fan of sewage 

sludge compost for this reason. Runoff from green roofs containing 

levels of nutrients is a topic of current discussion with water quality 

researchers. 

The best practice is to use a media that will provide enough air 

throughout the profile to promote the roots to go down instead of 

up. If the bulk of roots are down deeper in the media where it is 

cool and moist, the better the plant can sustain itself during periods 

of extreme temperature. 

When proportionally blended, a mixture of lightweight aggregate, 

quality sand and organic compost makes a good media for intensive 

green roofs. 3/8" and finer lightweight aggregate has pore spaces in 

Throughout the horticultural and landscape industry, organics are the 

overwhelming trend. The industry has embraced organics’ role in sustaining 

biological functions in the soil. Research is abundant, covering 

actinomycetes, nematodes, micchorhizal fungi and various other microand 

macro-organisms (let’s not forget the lowly earthworm) — all of 

which bind contaminants, cycle nutrients, suppress disease and more. 

So once again, I asked myself: With this track record and research going 

on, why are many in the green roof world so opposed to using organics? 

If I were to ignore the obvious implications for those who have 

invested in distribution rights for European based systems, I would 

have to turn to the science behind the German Standards developed 

by the nonprofit known as Forschungsgesellschaft Landschaftsentwicklung 

Landschaftsbau (or FLL). I spent considerable time reviewing the 

FLL Standard and the research that led to its’ very conclusions. 

I also considered it imperative to understand the initial terms of reference 

and historical context by which the need for the standards 

came about. The terms of reference weighed very heavily on avoidance 

of problems, which given some of the failures in the German 

marketplace at the time, seemed to make sense. Unfortunately, I do 

not have enough article space to get into everything that I found; 

however, there are some serious holes. 

The first of which is the way the Standard does not adequately 

distinguish between organics (this may be because the science of soil 

biology was out of fashion at the time, research focused instead on 

the science of chemistry — much better funding opportunities). 

When referring to organics, there must be awareness that there is a 

huge array of source stock, composting processes, characteristics, 

etc…which makes it impossible to generalize. No one would suggest 

that we should refer to the entire automotive world as being all the 

same. Is a skateboard the same as an F1 racing car? That’s absurd. It is


“Organic matter breaks 

down and goes away; to 

replace lost material could 

require many trips with 

heavy bags up steps or 

an elevator.” 

Chuck Friedrich 

the particles which lighten the load, retain nutrients and water, and 

best of all it is permanent. A good quality graded sand as filler is 

good for stability, and a measured amount of the proper organic 

compost provides microbial activity that is beneficial to the biology 

of the media. Currently, there are no standards related to the use of 

compost on green roofs. 

What about fertilizer? Save it for planting time. There is absolutely 

no reason to add fertilizer to a green roof media during the blending 

process. For good reason, in most cases the media is installed 

months before the first plant is installed. Therefore, why spend 

money on fertilizer that will only end up leaching out and down the 

drain before the plants show up on the job? The best method is to 

blend a good slow release fertilizer into the top layer of the media 

during the planting operation. 

Once planted, provide lots of maintenance and irrigation; with that 

it can be beautiful and last for several decades. I forgot to mention, 

also add lots of money, you get what you pay for. If you can keep the 

general contractor and schedule in check, the process can actually 

go smooth, right? Wrong. Don’t forget about the engineer. 

AWEIGHTYSUBJECT 

I am amazed how the specification on the weight of the media can 

be so tight, while in the same specification, the plan calls for 14 

Oak trees to be planted. It tickles me when I am asked at least 

twice per month by designers, “how much does a full grown tree 

weigh?” What? Dogwood or Sequoia? Does an additional pound or 

two per cubic foot of media, one way or another, make that much 

of a difference? I guess it will when 350-pound Aunt Bertha and 

the twins decide to have lunch up on the roof. 

All kidding aside, weight is an issue, especially on retrofitted extensive 

roofs. It is important to design using the saturated weight of the 

media. The ASTM Sub-committee for Green Roofs has developed 

standards for the practice and test methods for the determination 

almost as absurd to consider all organics to be the same. There are 

some organics that I would never use on a green roof (some of which 

were used in the research behind the FLL Standard). From cellular 

structure to composting process and beyond, organics are far too complex 

to generalize within a Standard. 

Secondly, the FLL Standard dictates organic content by mass. I can 

understand why, since the dominant testing method for organic content 

is the burn method, which can only measure by mass. However, by doing 

so, the Standard leaves a lot open to interpretation. For instance, one 

can use an extremely heavy inorganic material to achieve a high percentage 

of organic content since organics are generally much lighter. I was 

able to achieve organic content of over 60 per cent by volume in the 

growing medium but only eight per cent by mass. Was this ambiguity 

intended by the Standard? 

Interestingly, contrary to what I heard in the industry, the FLL Standard 

did allow for higher levels of organics. Section 9.2.2 states: “A greater 

proportion of organic matter may be required where special forms of 

vegetation, such as humus rooting plants, are used.” This shows the 

importance of matching the growing medium to the physiological 

needs of the plants, another area largely uninitiated by many suppliers 

in our industry. 

Thirdly, the Standard focused on material specifications instead of 

performance specifications and by doing so, essentially closed the 

door on innovation. (It seems the lowly sedum is the order of the day, 

matched to equally low performance mediums). This caused companies 

to scramble to find similar products in North America with the 

prize going to those who could quickly identify and corner the market 

on certain products. As most of the construction industry in North 

America makes the change to performance-based specifications, the 

FLL Standard represents a step backward. 

Lastly, I concluded the Standard itself was not as much a problem 

as people’s interpretation of it. For example; there seems to be much 

misunderstanding of what organic content is. One hundred per cent 

FORMULATING, TESTING, PLANT 

GROWTH TRIALS, PROBLEM SOLVING 

“SEND US YOUR 

EXTENSIVE/INTENSIVE 5 

GALLON PAIL PLEASE!” 

SOIL CONTROL LAB 

42 HANGAR WAY 

WATSONVILLE, CA 95076 

(831) 724-5422 PHONE, 

(831) 724-3188 FAX, 

WWW.GREENROOFLAB.COM 

FRANK@COMPOSTLAB.COM 

CONTACT: FRANK SHIELDS

“Why the strident 

accusations against 

organics in growing 

mediums? Is it because 

some have invested in 

proprietary products 

associated with growing 

mediums? Is it because 

of the European experience? 

Or do they really 

have a sound scientific 

argument?” 

Rick Buist 

organic material may only have an end organic content of 20 per cent. 

The remaining 80 per cent may be inorganic or mineral based. This is 

largely lost in the language of the industry. 

The performance which organic matter brings to stormwater retention, 

pollutant degradation, plant variety, cooling benefits, sustainable materials, 

etc. is too great to ignore. 

Organic-based growing media can hold far more water than mineralbased 

growing mediums while maintaining porosity; this is because of 

the way in which they hold water through particle swelling instead of just 

void filling and capillary forces. Biology can be customized to degrade


of dead loads and live loads associated with green roof systems. If 

flooded, the media weight could increase up to 20 pounds over the 

drained weight. This could be catastrophic when a heavy snow load 

is added to roof during the same event. 

MEDIAFORSEDUMS 

Most extensive growing media is used in a thin profile of three to six 

inches. If weight restrictions allow; go deeper, just keep Aunt Bertha 

off the roof. 

Sedums do well in aerated media. Most extensive media is at least 

80 per cent lightweight aggregate (for porosity and nutrient retention). 

Care must be taken not to design a growing media that is too 

fine. If the media does not routinely dry out, excessive water may 

cause weed promotion and some sedum roots to rot. 

Sedums will die quicker if the media stays too wet rather than 

too dry. In my view, it is better to provide a well-drained material 

with supplemental irrigation then to have plant loss during the 

rainy season. 

SPEAKINGOFIRRIGATION 

Those who think extensive green roof systems do not need, at least 

temporary irrigation ought to camp out on a green roof in North 

Carolina during an August heat wave. I have run several studies in 

NC and have been able to just get by without automatic watering. 

That success ended with this year’s record drought. No matter how 

fine the media was or the amount of organic content in the mix, the 

sedums still died from lack of moisture. Without the morning mist 

experienced daily in Germany and the Pacific Northwest, sedums 

have a tough time in hotter and drier climates. Though sedums may 

go dormant and survive a green roof that looks like dead weeds is 

bad for business. Find a water source, reclaimed if you must, and 

find a way to get it up on the roof. Do not over water; monitoring irrigation 

after the establishment period is essential. The controversy 

over irrigation will continue; occasional drip irrigation as needed 

works. The holdouts need to quit bellyaching and just do it. 

In conclusion, controversy between schools of thought over green 

roof media will continue within the United States. Being in its infancy 

compared to Europe, whether intensive or extensive, communications 

between the parties involved do tend to drift. When everyone 

with professional integrity and the proper knowledge work together 

and stay current with the latest technology, the long-term results will 

benefit everyone. 

specific and non-specific pollutants. Plants that provide evaporative 

cooling can be used more frequently with success. Fertilization can 

occur naturally through nutrient cycling. Materials can be sourced 

locally. And the list of benefits goes on. 

Practically every argument I have heard against the use of organics 

comes with a relatively easy solution: 

• Lost depth because of organic cycling is easily addressed through 

inputs such as biomass created by the plant choice through roots 

or refuse, or annual (if required at all) top-dressing with a 

pelletized product such as compost or alfalfa (readily available 

in dry, bagged form). 

• Fines clogging drains or water-logging can be averted by careful 

selection of organic materials. Organics with crystalline structures, 

such as certain bark-based products, will behave much like sand for 

free drainage, while organics with strand characteristics will hold 

structure together. Careful selection and installation of components 

such as filter cloth are also helpful. 

• Wind erosion is averted by using biodegradable netting until plants 

are established, thereby providing continuous cover. 

• Fire prevention can be improved by avoiding certain substances 

(i.e. peat moss — a limited resource) and by using organics with 

high ignition-thresholds and large moisture-retention capacities. 

Although any biomass on a roof can burn, it is easy to mitigate the 

risk by paying attention to the details. 

My intention in promoting the use of organics is not to replace 

the good work already achieved by the FLL Standard (the bulk of 

which I strongly endorse), but to expand its terms of reference. We 

should not be afraid of opening the door to creativity. Let’s set 

performance objectives that will not only serve to reduce risk but 

also allow for innovation. 

We should also practice what we preach. If we as an industry are 

promoting stormwater retention or cooling benefits, we must prescribe 

a high level of performance to justify the cost of our product. If 

not, we risk being passed off as a fad, as eco-chic. Are we environmental 

stewards? Don’t we appear hypocritical by using mined products 

for the bulk of our material? If we’re pushing the idea of biodiversity, 

we must use plantings that give entomological teeth to our argument. 

An immature marketplace is always better served by collaboration 

than by competition. We risk alienating an extremely large demographic 

in the landscape, horticultural and composting industries who 

could help our industry immensely if we continue to promote against 

the use of organics. 



IMPACTOFGROWINGMEDIA 

ON PRAIRIEGRASSES 

RESEARCHFROMLINCOLNNEBRASKAPROVIDESINSIGHTONTHEPERFORMANCEOF 

GROWINGMEDIAINTHEESTABLISHMENTOFTALLNATIVEGRASSESONEXTENSIVEROOFS 

By Richard K. Sutton 

American conservationist, Aldo Leopold asked us to “Think like a 

mountain.” When it comes to extensive green roofs in drier climates, 

however, we need to think like a prairie. 

Selected research on tall grass prairie species questions their use, 

but sedum now used on too many extensive green roofs is a monoculture 

inherited from Northwest European countries including 

Germany — and nature rewards diversity. 

In the Great Plains’ climate, short- and mid-grass prairies have 

evolved diverse communities of grasses, forbs and sedges in shallow 

soil with hot summers, cold winters, high winds, low humidity 

and little rainfall. While sedum grows well in Germany’s effective 15 

to 18 inches of net precipitation (accounting for potential evapotranspiration), 

the Great Plains prairie can flourish on net precipitation 

that has a 0- to 15-inch deficit. 

Thinking like a prairie in 2006, Architectural Partnership, an architectural 

firm in Lincoln, Nebraska, designed the state’s first public 

building, the Pioneers Park Nature Center (PPNC) Prairie Building 

addition, to incorporate a 900-square-foot extensive green roof. 

The green roof uses Hydro-tek Gardendrain system covered by 

three and one-half inches of Rooflite’s 95 per cent heat expanded 

shale and five per cent compost by volume. 

Given where the building was situated, it was only logical to take 

note of the mission of the Pioneers Park Nature Center (PPNC) — 

that is, to teach the public about the importance of native plants 

and animals — and use prairie plants on the green roof. 

As a landscape architect doing research at UN-Lincoln, I worked 

with the PPNC staff to design an assemblage of green roof prairie 

plants that included grasses, sedges and forbs. Plantings were 

placed to be ongoing three- to five-year (or longer) experimental 

plots and a roof-top prairie. 

Our first studies look at the establishment of the selected prairie 

plants especially their growth under two simple treatment additions 

to the Rooflite media. 

Though the first treatment (supplementing available moisture with 

super-absorbent polymer gels such as Horta-sorb) has been 

around the horticulture industry for years it has not, to my knowledge, 

yet found its’ way onto green roofs. 

The second treatment (adding soil microbes gleaned from prairie 

soils) has gained use in landscape plantings on low-nutrients soils and 

hypothesized to help activate the compost fraction in the media, thus 

making nutrients and water more readily available to plants. 

A dozen six-by-six foot plots were randomly planted eight inches on 

center to a mixture of native species consisting of six grasses, one 

sedge and five forbs as # 72 plugs. Three plots each were randomly 

assigned to: 

“American conservationist, Aldo 

Leopold asked us to ‘Think like 

a mountain.’ When it comes to 

extensive green roofs in drier 

climates, however, we need to 

think like a prairie.” 

LEFTBecky Seth, a Pioneers Park Nature Center naturalist, assists Dr. 

Richard Sutton in recording prairie plant growth ratings on the nature 

center’s new extensive green roof.

FIRSTGROWINGSEASONPLOTGROWTHRATINGSFOR 

TREATMENTSWITHMICROBESHORTA-SORBHEIR 

INTERACTIONANDROOFLITECONTROL 

GROWTHRATINGSANDAVERAGEFORTREATMENTS 

TREATMENTS TOTALPERBLOCK AVERAGETREATMENT AVERAGEPERPLANT 

GROWTHRATING GROWTHRATING GROWTHRATING 

Blk 4 A Control 169 



474 158 2.63 

Blk 1 B Microbes 168 



503 168 2.80 

Blk 6 C Horta-Sorb 183 



541 180 3.00 

Blk 2 D Microbes + Horta-Sorb 202 



582 194 3.23 

1) A treatment of: Horta-sorb; 

2) A slurry of prairie microbes; 

3) A combination of Horta-sorb and microbes; and 

4) A control consisting of straight Rooflite. 

6 = Roots well established and exceptional growth and vigor and establishment 

of plant crown greater than 6 cm but less than 10 cm; 

7 = Plant expanding beyond 10 cm but less than 16 cm; and 

8 = Plant expanding to greater than 16 cm. 

In addition, 95-hundredths of an inch of water was applied by irrigation 

per week from June to September. 

The plants were examined monthly from July to October and rated for 

growth and establishment, using the following system: 

PLANTGROWTHRATINGSYSTEM 

0 =Dead or missing plant; 

1= Live plant in poor condition; less crown or stem growth than when 

planted plant loose; no rooting beyond initial plug; 

2 = Plant established but crown not expanding or top growth stagnant, 

beyond areas of plug; 

3 = Plant with roots established and crown expanding up to 1 cm 

beyond; or vigorous top growth; 

4 = Plant roots established and plant crown expanded up to 2 cm 

beyond; additional stems; 

5 = Roots well established and vigorous; plant crown expanded beyond 

original plug area by greater than 2 cm but less than 6 cm; 

Data from the end of the first growing season (October) is just being 

analyzed. Raw plot totals for plant growth ratings are greatest (above) 

for the interaction of Horta-Sorb and the slurry of microbes, next 

for the Horta-Sorb alone, then next for the slurry of microbes alone 

and finally lowest for the Rooflite media alone. This data has not 

been checked for homogeneity of variance or significant differences, 

however the visual difference between the treatments and the control 

are readily apparent when one sees the green roof plots for the 

plants in treatments are greener and appear more robust. The implications 

are that media manipulation may make short and mid-grass 

prairie plantings a viable alternative to sedum for extensive green 

roofs in the Great Plains. 

Richard K. Sutton, ASLA, Ph.D, is a Lincoln, Nebraska-based associate 

professor of Agronomy and Horticulture and Horticulture and Landscape 

Architecture at the University of Nebraska-Lincoln. He is a 

featured presenter at Green Roofs For Healthy Cities’ upcoming annual 

conference — www.greenroofs.org/baltimore. 



NATIVESURVIVORS 

Ron Wik 

THENEWENGLANDWILDFLOWERSOCIETYINPARTNERSHIPWITHTHEMASSACHUSETTS 

COLLEGEOFARTISTRIALINGNATIVEPLANTSHEREISWHATTHEY’VELEARNEDSOFAR 

ABOUTCERTAINSUN-ANDDROUGHT-TOLERANTSPECIES 

By Ron M. Wik 

The use of native plant species on green roofs is a topic of 

increasing interest, especially in the Northeast where architects 

want to make buildings that are both “green” and sustainable. 

To meet that demand, designers are requesting a palette of plant 

material of North American origin. These installations can represent 

entire ecosystems by providing food sources and shelter for 

birds and insects. 

Many North American indigenous plant species are suitable for 

green roof installations. These are typically plants that have 

evolved in exposed areas, such as mountainous regions. Others 

originate in sandy or xeric conditions, where they have developed 

strategies to cope with lack of water. In both habitats, survival involves 

morphology devoted to water storage or reduction of water 

loss. Fleshy leaves and stems are especially useful for plants needing 

to cope with drought and high temperatures. 

New England Wild Flower Society has partnered with the Massachusetts 

College of Art to test the stamina of native plants on the 11th 

floor of a building in southwest Boston, Massachusetts. These 

sun- and drought-tolerant species were selected primarily from sand 

prairie and alpine biomes to cope with the site’s southern exposure 

and the sandy media (89 per cent sand; six to nine inches deep). 

The plants were watered twice weekly for one-month after planting, 

with no further irrigation since. The study began in October 2005. 

Antenarria parlinii ssp. fallax (Plantain Pussytoes) and A. rosea 

(Rosy Pussytoes) are both low growing (two to four inches) species, 

 


WINTER


Ron Wik William Cullina William Cullina 

OPPOSITEPAGETest Site: The 11th floor MassArt Green Roof at Boston’s Massachusetts College of Art. The 1,000-square foot semi-intensive research roof has 

a one-per cent slope and was designed by Somerville, MA-based Heimarck & Foglia, LLC. LEFTAntenarria rosea (Rosy Pussytoes) CENTRESedum nevii (Nevius’ 

Stonecrop) RIGHTSibbaldiopsis tridentata (Three-Toothed Cinquefoil) 

flowering in spring. The dense silver/grey foliage provides substantial 

textural interest and excellent coverage. Remarkably, we found 

a brood of painted lady butterfly larvae foraging in these plants — 

110 feet above ground level. 

Aster ericoides f. prostratus (Heath Aster) and A. spectabilis 

(Showy Aster) have had no difficulty flourishing in the xeric rooftop 

conditions. They establish quickly and extend the floral interest 

well into frost. A. ericoides is a prostrate species achieving a maximum 

height of six inches and forming a dense mat covered in tiny 

white flowers from late July to October. A. spectabilis produces 

dense basal foliage with stalks reaching 18 inches and bearing large 

purple flowers. 

Houstonia caerulea (bluets) form low (one inch) mats of tiny dark 

green leaves. Stalks of pale blue flowers, produced from spring 

until frost, reach four inches in height. This species reseeds readily 

and tends to wander around the planting area. It quickly fills in the 

nooks and crannies left by other establishing plants. 

Schizachyrium scoparium (Little Bluestem) is a grass species known 

for being extremely adaptable. It establishes very quickly, forming 

tufts of silver/green foliage. Fuzzy purple inflorescences (18—24 

inches) are produced in the fall and persist through the winter. 

Sedum nevii (Nevius’ Stonecrop) is one of several North American 

stonecrops. It is especially drought-tolerant, producing a thick mat 

(three inches) of burgundy-tinged, mint green foliage. White flowers 

in early summer produce seed that speeds coverage. 

Sibbaldiopsis tridentata (Three-Toothed Cinquefoil) forms an extremely 

dense mat (three to four inches) of shiny dark green leaves. 

It has proven to be especially resilient, colonizing rapidly and producing 

small white flowers sporadically throughout the summer. 

This is just a small selection of the species that have proven successful 

under these challenging conditions. All of them are showing 

excellent promise for lesser soil depths. New England Wild Flower 

Society will continue to assess native plants to promote the implementation 

of sustainable green roofs and intends to carry on this 

study indefinitely. 

Ron M. Wik, nursery business director, Nasami Farm Native Plant 

Nursery in Whately, MA. The nursery is operated by the New 

England Wild Flower Society, America’s oldest plant conservation 

group. Its botanical and horticultural living museum, Garden in 

the Woods in Framingham, Massachusetts displays 1,500 mature 

native plant species and cultivars including 200 rare species. 

www.newenglandwild.org. 



HOTANDHUMID 

WHATPLANTSWORKBESTINTROPICALANDSUBTROPICALSITUATIONS? 

By Steve Skinner 

The vast majority of extensive green roofs in Europe and North 

America have been based on traditional plantings of sedums 

and other highly drought-tolerant plants on non-irrigated roofs in 

relatively mild climates. In the last few years, however, innovative 

designers have demonstrated that the benefits of extensive green 

roofs — including stormwater management, energy savings and 

bringing nature to the built environment — can be enjoyed in 

almost any climate. 

In North America, successful extensive green roofs have been 

established from Alaska to Mexico and from Nova Scotia to the 

Caribbean. To succeed in more extreme climates designers must 

recognize the limitations of traditional extensive green roofs 

and adjust plant choices, growing media and system build-up to 

account for the climate extremes that will be encountered. 

The hot and humid climates found in the tropics and subtropics, for 

instance, simply will not sustain traditional green roof plants such as 

sedums. In these areas, daily precipitation with persistent high temperatures 

and humidity commonly occurs in the spring and summer. 

Alternately, during the fall and winter, extended periods of water 

deficits are not uncommon. Sedums and other traditional green roof 

plants cannot withstand the humidity and constant high temperatures 

in the summer in these areas and will likely perish. 

So what is necessary for extensive green roofs to succeed in tropical 

and subtropical areas? First, designers must select plants that can 

cope with the very wet and hot spring/summer conditions and then 

plan to irrigate during the extended drier periods in the fall and winter. 

Many native groundcovers and vines possess the ability to cope 

with constant heat and very wet conditions and yet survive with little 

extra water during dry periods. Many of these plants naturally occur 

in sandy coastal soils that are low in nutrients due to frequent leaching 

and have evolved shallow fibrous root systems that can anchor 

them during the frequent strong winds experienced in these areas. 

Plants such as Muhly Grass (Muhlenbergia, various species), Coral 

Honeysuckle (Lonicera sempervirens), Dune Sunflower (Helianthus 

debilis) and other associated species can thrive in as little as five to 

six inches of growing media, and once established, need supplemental 

water only during extended periods of drought. 

Secondly, for hot and humid climates, a growing media with the dual 

properties of a) good water holding and b) easy drainage of excess 

water, are even more critical than for most green roofs. The heat, 

 


WINTER

THRIVINGCONDITIONS 

Tips for sustaining growth on extensive green roofs in tropical and 

subtropical areas. 

• Select native plants that can cope with wet and hot spring/summer 

conditions. 

• Plan to irrigate during drier periods in the fall and winter. 

• Select plants from well-drained, sandy coastal environments that 

spread quickly. 

• Select low-growing species with fibrous root systems to 

withstand wind. 

• Use high-quality growing media with great water holding capacity 

that still drains well when saturated. 

Even the best possible plants will need a green roof system that can 

provide three critical elements to sustain growth. 

1. A method for keeping subsurface water in reserve that can be 

accessed when evapotranspiration exceeds available water in the 

growing media. This can be achieved efficiently with drainage mats 

with built in water reservoirs or with moisture mats. 

2. A means to provide good aeration even when the growing media 

is saturated. 

3. An excellent drainage capacity to deal with frequent intense 

rainfal events. 

THRIVINGCONDITIONSFORTHISEXTENSIVEROOFATPERRY 

YARDATTHEUNIVERSITYOFFLORIDA’SRINKERHALLINHOT 

ANDHUMIDGAINESVILLEFLORIDA 

Tropical and subtropical climates pose a challenge to green roof 

designers but thoughtful application of high quality systems can 

produce outstanding results. 

wind and high solar energy levels in these areas create very high 

evapotranspiration rates and the thin growing media of extensive 

roofs means that water delivery to the plants must be highly efficient. 

At the same time, intense rainfall requires a media that has 

high hydraulic conductivity to allow excess water to rapidly drain. 

“Many native groundcovers 

and vines possess the 

ability to cope with 

constant heat and very 

wet conditions and yet 

survive with little extra 

water during dry periods.” 

The third most critical criterion for success in hot and humid areas 

is to have a green roof system that provides the ability to retain 

water in reserve that can be accessed by the plant root systems 

when high evapotranspiration rates rapidly deplete the moisture in 

the growing media. A water reserve provided by drainage mats that 

have built-in water reservoirs and the use of moisture retention 

mats can reduce, but not eliminate, the need for supplemental 

irrigation when evapotranspiration exceeds precipitation. 

Recently, recognition and planning for the special set of 

conditions found in hot, wet climates in Florida (University of 

Florida in Gainesville, University of Central Florida in Orlando 

and the Nancy Foster Environmental Center in Key West), Texas 

(University of Houston) and on Necker Island, BVI (Virgin Resorts) 

have resulted in extensive green roofs that adhere to the principles 

of low weight, low maintenance and an aesthetically pleasing 

appearance that have fostered a booming green roof market in 

other parts of the world. 

Steve Skinner joined American Hydrotech, Inc. as garden roof product 

manager in 2003 after a 20-plus year career as a soil scientist 

and environmental manager. He has served on the board and in 

numerous committees with Green Roofs for Healthy Cities and on 

several green roof industry task groups. 



COLD 

ATOUROFTHENORDICCOUNTRIESREVEALSATHRIVINGGREENROOFINDUSTRY 

By Kerry Ross 

In the summer of 2007 the Royal Architectural Institute of 

Canada sponsored a tour of Nordic green roofs through the 

Burwell Coon Travel Scholarship. For most of a month, my husband, 

Bob and I toured a variety of cold climate green roof projects 

where we photographed and documented different green roof 

solutions and met with a number of individuals involved in green 

roofing. The purpose of the study was to gain a better understanding 

of contemporary green roofs from northern regions where the 

technology was more advanced; areas which share climatic characteristics 

similar to regions of Canada such as long, cold winters, 

short growing seasons, extreme sun paths and reduced numbers of 

suitable plant species. 

The excursion included stops in Iceland, Denmark, Norway and Sweden. 

In many of the areas we visited, we found that while general 

awareness of green roof technology seemed surprisingly modest, we 

nevertheless discovered that there were both new traditional style 

green roofs as well as contemporary green roof applications. 

In Scandinavia, we were struck by how significant the influence of 

the Gulf stream on the climate and vegetation of the region even at 

the most northern latitudes of our visit (Selfoss, Iceland at 63.94° N 

and Trondheim, Norway at 63° 36’) both destinations several hundreds 

of kilometers north of my adopted hometown of Calgary (51° 6’ 

N). We observed that many plant species, incapable of growing in 

Calgary, seem to grow vigorously in the Northern regions of Scandinavia. 

As we climbed in elevation and travelled inland, however, the 

effect of the Gulf Stream fell away. 

One of our stops included a visit to the Have og Landscab (Garden 

& Landscape) Expo in Slagelse, Denmark, an annual event held in 

August attracting hundreds of companies involved in the landscape 

industry from all over Scandinavia. It was there that I met representatives 

from Veg Tech AB, the largest green roof supplier in Scandinavia. 

While sedum mats are one of their best-selling systems, 

another that is particularly interesting consists of pre-grown “herb 

and sedum” mats that use a mixture of perennial grasses and flowering 

forbs and resembles a meadow or the forest floor. This product 

provides immediate coverage, excellent cold and drought hardiness 

as well as greater biodiversity. 

While in Denmark, I had a chance to see an installation of the 

herb and sedum mat on a rooftop of a new multi-family residential 

building in the emerging district of Ørestad in South Copenhagen. 

Historic urban housing in Copenhagen is characterized by four to six 

storey apartment blocks built around a common courtyard which are 

frequently used for gardening, barbecuing, outdoor play and picnics. 

With the urban renewal of the historic center, Copenhagen is going 

through a building boom. Along with a number of key cultural commissions, 

significant growth in the development of urban housing can 

be seen. This building boom is characterized by more varied housing 

stock and often larger scaled buildings. In place of the historical 

courtyard amenity, rooftop amenities including green roofs are 

starting to emerge. 

Kerry Ross is an architectural consultant with IBI Group Architects 

Engineers in Calgary, Alberta. 

LEFTPre-grown mats installed on upper roof deck of multi-family housing project. CENTRETOP Green wall on Reykavik City Hall 

CENTREBOTTOMGreen roofs on Solheimar Ecovillage main hall in Selfoss, Iceland RIGHTPre-grown herb & sedum mats from Veg Tech AB in Scandinavia.


DROUGHT 

EVALUATINGTHEPERFORMANCEOFGREENROOFPLANTSANDGROWINGMEDIUM 

By Dr. Bill Retzlaff, Dr. Susan Morgan, Kelly Luckett and Vic Jost 

Two of the most critical decisions facing those wishing to place 

a green roof are plant and growth media selections. Choose the 

wrong species mixture or the wrong growth-media formulation and 

a failed green roof project will usually result. 

The Green Roof Environmental Evaluation Network (G.R.E.E.N.) at 

Southern Illinois University Edwardsville (SIUE) has evaluated 40+ plant 

species and more than a dozen growing mediums for use in extensive 

green roof systems since spring 2005. We have made a number of significant 

discoveries in these areas that have implications for the green 

roof industry — and this article highlights some of our initial discoveries. 

Some sedum species will not tolerate winter shade while others 

do quite well (See “Winter Shading” next page). In a fully replicated 

species/media/fertilizer experiment on the Engineering Building roof 

at SIUE, 100 per cent of Sedum hybridum immergrunchen was lost 

when the roof was in full winter shade (no direct sunlight) while other 

species, like S. sexangulare, experienced 100 per cent winter survival. 

Similarly, some sedum species will not tolerate heat-released fertilizers 

while others have no fertilizer preference (See “Heat & Release,” 

next page). Sedum floriferum ‘Weihenstephaner Gold’ suffered fertilizer 

injury from a commercial slow-release fertilizer following a minimal 

rainfall event while other species, like S. sichotense, experienced 

no injury. We now use and recommend a fertilizer blend of Osmocote-Nutricote-IBDU 

to avoid this injury issue. 

Unsurprisingly, mixed sedum plugs are a better option than monocultures 

of single sedum species (see “Biodiversity Works,” next page). 

We have lost many plant species due to heat, cold, fertilizer, 

drought, growth media over-saturation, and shading. The use of a 

single species in a green roof project and the loss of that species has 

resulted in green roof project failures. As a consequence, we are 

now evaluating mixed species plugs containing as many as five different 

sedums. The mixed species plugs were planted on our research 

green roof in Green Roof Blocks and Green Paks in March 2007. 

Plant growth and roof coverage are excellent at the end of the first 

growing season (November 2007). 

One recycled growing medium that we are evaluating consisting of 80 

per cent spun-glass aggregate and 20 per cent composted pine bark 

remains saturated even during periods of drought. While promising in 

that it retains high-moisture content, it stays too wet for sedum (see 

“Saturated Green Roof,” next page). The saturated root-zone reduces 

growth and results in plant losses. Because the moisture-holding capacity 

of growing mediums is critical, in the lab we determined the 

maximum moisture retention of various growth media blends, consisting 

of 20 per cent organic material and 80 per cent aggregate (see 

“20-80 Best” next page). 

Our results demonstrate that lava rock, a natural aggregate, has a 

similar moisture retention to Arkalyte, a heat-expanded aggregate 

“One recycled growing medium that 

we are evaluating consisting of 80 

per cent spun-glass aggregate and 

20 per cent composted pine bark 

remains saturated even during 

periods of drought.” 


FIGURE//WINTERSHADING 

FIGURE//HEAT&RELEASE 

FIGURE//BIODIVERSITYWORKS 

FIGURE//SATURATEDGREENROOF 

FIGURE//-BEST


LEFTFIGURE//WINTERSHADINGEffect of full, winter shading on survival of Sedum hybridum immergrunchen (left picture — no survival) and S. sexangulare 

(right picture — 100 per cent survival). FIGURE//HEAT&RELEASEEffect of fertilizer injury under low rainfall conditions on Sedum floriferum ‘Weihenstephaner 

Gold’ (left picture — foliage burning) and S. sichotense (right picture) FIGURE//BIODIVERSITYWORKSEvaluation of mixed species plugs in 

green roof applications — exceptional growth and roof coverage after one growing season. FIGURE//SATURATEDGREENROOFEffect of growth media 

water-holding capacity on performance of Sedum hybridum immergrunchen. On the left, 80 per cent spun-glass aggregate and 20 per cent composted pine bark. 

On the right, results with 80 per cent Arkalyte and 20 per cent composted pine bark. FIGURE//-BESTEvaluation of the performance of various commercially 

and specially blended growth media: lava, Arkalyte, bottom ash and Haydite, respectively. 

(32 vs. 30 per cent, respectively), but is significantly greater than 

Hadite, another heat-expanded aggregate (23 per cent) and bottom 

ash (20 per cent) recycled from a coal-power facility. 

G.R.E.E.N.’s experimental results are designed to aid those wishing 

to implement green roof systems by developing a “prescription” for 

each green roof application. It is our goal that a series of questions 

about each green roof installation can be addressed and a prescription 

containing the proper green roof plant list and growing medium 

be developed for use in each commercial green roof installation 

plan. We invite you to visit our website for more results at 

www.green-siue.com/researchresults.html. 

Dr. Bill Retzlaff chair of the Department of Biological Sciences, 

Southern Illinois University Edwardsville and research coordinator of 

the St. Louis metropolitan area research collaboration (G.R.E.E.N.). 

Dr. Susan Morgan is chair of the Civil Engineering Department, Southern 

Illinois University Edwardsville and research member of G.R.E.E.N. 

Kelly Luckett is president of Green Roof Blocks, Florissant, Missouri 

and industry-collaborator member of G.R.E.E.N. 

Mr. Vic Jost is co-owner of Jost Greenhouses, Des Peres, Missouri 

and industry-collaborator member of G.R.E.E.N.

CREATINGHABITAT 

BYDESIGN 

RESEARCHERSHAVEDEVELOPEDANEWPROCESSMODEL—USINGTHEDICKCISSELSPIZA 

AMERICANAATHREATENEDGRASSLANDBIRDASANEXAMPLE—TOHELPGREENROOFERS 

MAKETHERIGHTDECISIONSWHENTRYINGTORESTOREHABITATFORASPECIFICSPECIES 

By Dr. Reid Coffman and Allison Thurmond 

Great Plains grassland bird populations have plummeted in 

response to fragmented grasslands and a growing presence of 

agricultural chemicals in surviving habitat. In addition to the restoration 

and conservation needed to protect grasslands, Michael Rozenweig’s 

idea of “reconciliation ecology” seeks to pick up where the two leave 

off, at the edges of development. 

Preliminary studies indicate strong potential for reconciling habitat on 

urban rooftops. To further advance the idea, a green roof was proposed 

as nesting habitat for the Dickcissel (Spiza Americana), a migratory 

ground-nester (pictured above). The species was chosen for its adaptability, 

height threshold, and threatened status. From this we designed a 

new habitat based on the Dickcissel’s environmental needs to demonstrate 

the ease of applying a habitat template approach to green roof 

ecological design. 

Our green roof habitat design is a template which is intended to mimic 

the environment based on the species-specific information such as soil 

needs, prey population and nesting behaviors — and provides a model for 

other designers to consider when designing for ecological restoration. 

The design process is organized into seven explicit steps, which aid in 

matching appropriate wildlife species to a functional green roof system. 

The contextual information is directed to suburbanizing communities 

practicing bird conservation in the southern Great Plains, while the 

template concept holds a universal application in ecoroof habitat design. 

Several constants are locally available materials, and appropriate 

indigenous species and creation of diverse habitat. 

One key variable to habitat establishment is matching plant 

species to substrate mixes. For central Oklahoma, the Permian 

shale outcroppings found to our west are an ideal example of 

the drier, windier, hotter, and rockier conditions that a rooftop 

condition imposes. The Dickcissel’s need for tall vegetation led to 

a projected substrate depth of 15" to 24": deep enough to support 

a selection of shallow-rooted native plants with a structure that 

mimics the archetypical deep-rooted prairie species. Materials 

like crushed brick, lightweight expanded clay, and cottonseed 

hulls (lightweight, water-retaining agricultural byproduct) mixed 

with clean topsoil, sand and gravel are used in different proportions 

to maintain a diverse environment and lower the overall 

weight of the roof. 

Plants are then selected based on several key factors, found in the 

Plant Rationale Key (see next page). The rational underscore the most 

important needs of the nesting pair, but may vary by keystone species. 

 


WINTER

“The design process is 

organized into seven 

explicit steps, which aid 

in matching appropriate 

wildlife species to a functional 

green roof system.” 

In this case, Elbowbush (Forestiera pubescens), a shallow rooted Plains 

bush provided structure while Sand Dropseed (Sporobolus cryptandrus) 

and Idaho Fescue (Festuca idahoensis) served as grassy height and forage. 

Shale adapted Blue Grama (Bouteloua gracilis) holds soil and native 

forbs like Evening Primrose (Oenothera speciosa) and Beebalm 

(Monarda fistulosa) sustain insect populations. Finally, edging the building 

with trees supplements woody height and eases transition to the roof. 

The project information is currently being used to educate local officials 

and designers on the use of a template approach to green roof 

habitat. It is our hope this step-by-step model will assist you in creating 

restorative habitats on green roofs and walls. 

THESEVENDESIGNSTEPS 

FROMIDENTIFICATIONTOFINALHABITAT 

STEP 

identify a threatened bird species in need of nesting habitat 

STEP 

locate under-utilized, low slope roof 

STEP 

confirm that your roof is adjacent to open land 

STEP 

be creative with locally available materials for the growing 

substrate 

STEP 

calculate the substrate’s weight and the structure you’ll need to 

support it 

STEP 

design your base substrate 

STEP 

design the nesting habitat, focusing on indigenous plants and 

biodiversity 

RECOMMENDEDREADINGS 

Brenneisen, S. (2003). Biodiversity of European Greenroofs. In conference 

proceedings of Greening Rooftops for Sustainable Communities 

Chicago, Illinois. Green Roofs for Healthy Cities. 

Coffman, R. (2007). Comparing Wildlife Habitat and Biodiversity 

Across Green Roof Type. In the conference proceedings of Greening 

Rooftops for Sustainable Conference, Minneapolis, Minnesota, 

Green Roofs for Healthy Cities. 

Lundholm, J. (2006). Green Roofs and Facades: A Habitat Template 

Approach. Urban Habitats Dec. Vol 4, Issue 1, pages 87 — 101. 

Rozenweig, M. L. (2003) Win-Win Ecology: How the Earth’s Species Can 

Survive in the Midst of Human Enterprise. Oxford University Press. 

Dr. Reid Coffman, Ph.D. is an assistant professor of landscape architecture 

at the University of Oklahoma. He is a founding member of the International 

Research Committee for Green Roofs for Healthy Cities and 

a past fellow with the National Wildlife Federation. He holds degrees in 

urban ecology, environmental horticulture and landscape architecture. 

Allison Thurmond is a fifth year architecture student at the 

University of Oklahoma based in Norman, Oklahoma, with a focus 

on Environmental Studies and Anthropology. She is also a LEED® 

accredited professional and a National Merit Scholar. 

PLANTRATIONALEKEY 

USETHISGUIDETODETERMINEPLANSUITABILITY 

F/FORAGE 

produce seeds eaten by the Dickcissel 

N/NESTING 

locate under-utilized, low slope roof 

C/COVER 

provides height and protection for the Dickcissel and its insects 

I/INSECTATTRACTOR 

sustains invertabrate communities needed as a for source for 

nesting Dickcissel pairs 

W/EVERGREEN 

maintains evapotranspiration and insulating plant material year 

round, improving the performance of the roof 

E/EROSIONCONTROL 

helps hold substrate in place, a concern with the additional wind 

and runoff erosion stresses on an elevated habitat 

S/SOILFIXER 

maintains or replaces nitrogen and organic matter in the soil, critical 

for long-term success for the roof

POLICY 

SEATTLE’SGREENFACTOR 

ANEWURBANLANDSCAPINGPOLICYISPUTTINGMOREGREENROOFSANDWALLS 

PROJECTSONTHEBOOKSINTHISCOASTALCITY 


Seattle’s vision to increase green space in its urban areas through the 

implementation of a new landscaping requirement is starting to pay 

off with steady growth in green roofs and green wall projects. 

Since January of last year, developers and designers of new construction 

projects planned for either Seattle’s neighborhood business districts 

or commercially zoned areas must demonstrate how they intend 

to meet the city’s new landscaping requirement — or no building permit 

will be issued by its Department of Planning and Development. It’s 

called “Seattle Green Factor” and builds on the “Biotope Area Factor” 

developed by Carlo Becker and already being applied in Germany 

and parts of Sweden. 

The Seattle idea stems back to a talk by Melissa Keeley, who received 

her doctorate from the Institute of Landscape Architecture and Environmental 

Planning at the Technical University of Berlin. Her presentation 

on “The Green Area Ratio,” at a GRHC meeting in Denver, was heard by 

an interested engineer who passed the info over to the city of Seattle 

LANDSCAPINGMENU 

The Seattle Green Factor is a menu of landscaping strategies, each with 

an assigned point value. Landscaping strategies incorporating asphalt, 

concrete and conventional roofs, for instance, have no value. Permeable 

paving, green roofs and green walls, on the other hand, are among the 

highest-value landscaping options (see “The Green Factors,” next page). 

Bonuses are given for rainwater harvesting and or low-water-use plantings. 

The ultimate idea is to encourage the planting of layers of vegetation and 

larger trees in areas visible to the public and in public rights-of-way. 

Projects must meet minimum landscaping scores — the so-called “green 

factor” — and submit those scores along with their other planning documents, 

including a plan, worksheet and a chart explaining how the score 

was achieved. The minimum score for any commercially zoned land is 

0.3, which means a project must plan for the equivalent of 30 per cent 

of the parcel area committed to urban landscaping. In practice, however, 

it takes up much less than that of the footprint, through the layering 

and bonus options. For buildings that entirely cover their lot you can 

meet the minimum requirement by simply covering half of your roof. 

The factors were originally developed by Mr. Becker to reflect the watershed 

value of these various landscape treatments. Seattle started 

with the Biotope Area Factors and then nudged up or down to better 

reflect local conditions. 

Seattle’s Department of Planning and Development created a worksheet 

that helps applicants calculate their projects score, enabling 

them to use different combinations of green features to reach the 

minimum requirement. 

For example, one small mixed-use development in a neighborhood business 

district was able to meet the Seattle Green Factor score by adding 

a small green roof, cascading vegetation across a portion of the façade, 

and a vegetated wall along the back alley. 

Since implementation of the Seattle Green Factor on Jan. 20, 2006, 

over 50 projects have used the online worksheet to calculate their 

options, with many choosing green roofs and walls to raise their 

scores. In fact, says Steve Moddemeyer, senior strategic advisor at 

the Seattle Department of Planning and Development, judging from 

the plans they are seeing, green walls are proving to be very popular 

urban landscaping choices. 

“The vegetative walls really don’t take up much of the overall building 

footprint, but have the highest credit value,” he explains. “What we’re 

“What we’re seeing is that 

green walls are becoming a 

very strong element of the 

overall design, sometimes 

even the focal point.” 

Steve Moddemeyer, Seattle Department of Planning & Development 

(pictured left)

seeing is that green walls are becoming a very strong element of the 

overall design, sometimes even the focal point. It appears more designers 

and developers are asking themselves, ‘How do we integrate a 

green wall into our project in a way that is both functional and aesthetically 

pleasing?’ It’s what we hoped would happen.” 

Like any new public policy, however, Seattle’s Green Factor is not 

without the odd challenge. Public utilities must review and approve 

any landscaping plans that cover a public-right of way such as a 

sidewalk. So developers and designers original plans may not always 

get approved if such things as trees and shrubs are conflicting 

with a planned or existing public utility such as an electrical 

box. Also, public utilities may or may not allow alternative methods 

for dealing with stormwater runoff from development so that could 

potentially constrain opportunities. At the same time, says Moddemeyer, 

it will also highlight the need for public utilities to better 

understand innovative new urban landscaping opportunities and 

their public benefits. 

The Seattle Green Factor has been working so well that the city is 

now proposing the expansion of its application to multi-family zones, 

where green spaces are larger and would require higher standards. 

“In these areas, where there can be side-yard setbacks and openspace 

requirements we are considering a required score of 0.75,” explains 

Moddemeyer. “We are just beginning our public process, so it 

will be interesting to see how that level fares in the debate.” 

Incidentally, Keely who is a fellow at The Earth Institute at Columbia 

University in New York, has received two federal grants in order to 

research how to implement “The Green Area Ratio” in Philadelphia 

and Washington D.C 

Green Roof for Healthy Cities’ staff with files from Lillian Mason, a freelance 

writer based in Toronto, Canada with an interest in green building. 

RESOURCES 

To see the Seattle Green Factor online worksheet, visit 

www.seattle.gov/dpd/permits/greenfactor. 

Graphic by Liz Martini; illustrations by Jeff Benesi. Image courtesy of Seattle’s Department of Planning and Development.

POLICY 

“BUSHTOPS”DOWNUNDER 

ADELAIDE'SINNOVATIVEGREENWALLANDROOFINCENTIVEPOLICYSETTOBEA 

MODELFOROTHERAUSTRALIANCITIES 

By Graeme Hopkins & Christine Goodwin 

The South Australian Government is leading the development of an 

innovative green roof and living wall incentive policy structure to 

bring the Australian “bush” into the city of Adelaide — and the program 

could be a model for other cities. 

A series of living walls and green rooftops or “bushtops” that mimic 

the endemic ecosystems of the original landscape of the city of 

Adelaide are planned. Individual projects will be linked together to 

form stepping-stone wildlife corridors across the central business 

district to restore the original migration patterns of birds, insects 

and certain animals. 

Green walls will connect the bushtops to the ground and allow the 

passage of animals and insects between the vertical and horizontal 

planes. The projects will be carefully integrated with current research 

at the School of Urban Ecology at the University of South 

Australia and it’s expected that Planning SA’s program will be a 

major platform for the reintroduction of species back into Adelaide’s 

urban environment. 

Planning SA’s program, Bushtops for Green Roofs and Walls, will 

include a unique green roof and living wall incentive program for 

government buildings and projects. Often with many government 

agencies, monies for incentive programs are limited and very competitive, 

so a pioneering idea may have very little leverage to attract 

funding. However, under this new incentive program, government 

projects can now access design and development services via 

Planning SA’s principal urban designer’s expertise in green roof and 

living wall design. This is a free service for government projects to 

encourage the inclusion of green roofs and walls into their sustainable 

projects. This is an effective way to incorporate this green 

technology into new buildings or revitalisation projects in Adelaide. 

The City of Adelaide is also actively promoting green roofs on 

residential buildings through its Rooftop Gardens Fact Sheet — a 

document that provides homeowners with examples of rooftop 

garden layouts and suggested planting lists to achieve a sustainable 

green roof. The Fact Sheet also explains benefits to city residents 

of living architecture: improved lifestyle, reduced costs, improved 

property values, residents comfort, natural attraction, water 

conservation, improved air quality and reduced air temperatures. 

Fifth Creek Studio’s first bushtop project on the fourth floor of a 

community housing development at Hocking Place (see above) in 

Adelaide was supported by government and recently won the Australian 

Institute of Landscape Architects SA Award for Residential 

 


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Fifth Creek Studio 

PREVIOUSPAGEColorful "Kangaroo Paw" plants attract birds and insects to a residential high-rise rooftop in Australia. THISPAGELEFTA bat box creates 

an attractive habitat for microbats on the green roof at Hocking Place in Adelaide — and the residential buildings tenants are grateful for fewer mosquitoes and 

Australia’s pesky flying ants. THISPAGERIGHTClimbing native plants provide shade for residents of Adelaide’s Hocking Place’s award-winning “bushtop” 

designed by Fifth Creek Studio. 

“Several city-wide projects are 

in the conceptual development stage, 

including a new state government 

hospital featuring green roofs.” 

Design, and a Special Citation for Future Directions for Cities. The 

bushtop is an accessible intensive green roof, combining animal and 

insect habitat with passive recreational access by the residents of the 

building’s 15 apartments. 

Particular species of small birds that were once common in the Adelaide 

Plains were targeted by planting selected native grasses and 

sedges, and flowering plants to attract butterflies and other insects. A 

bat box attracts microbats, useful in the control of mosquitoes and flying 

ants. The bat box is being monitored during summer months as part 

of Adelaide City Council’s Bat Track program. If this box is successfully 

colonized other boxes may be added. 

The Hocking Place project is now a demonstration project for promotion 

of the bushtop concept within state and local government authorities. By 

combining the success of this first project with Planning SA’s attractive incentive 

program, the concept of stepping-stone corridors can be realised. 

Several city-wide projects are in the conceptual development stage, 

including a new state government hospital featuring green roofs at 

various levels, and proposed redevelopment infill residential projects 

with green roofs and walls as part of the open space recreation 

requirements. These projects are forming elements within the stepping-stone 

corridors throughout the city. 

Graeme Hopkins and Christine Goodwin are landscape architects and 

directors of Fifth Creek Studio located in Adelaide, Australia. Together, 

they have researched bushtops in cities for more than five years. 

Additionally, Graeme is the government’s Planning SA’s Principal Urban 

Designer with a role to focus on environmental sustainability and 

intensified population density in the metropolitan context including the 

bushtop policy project in Adelaide. 

RESOURCES 

Fifth Creek helped develop the Rooftop Gardens Fact Sheet for the 

City of Adelaide (to be on the Adelaide City Council website soon: 

www.adelaidecitycouncil.com 

To learn more, please also see Green Roofs for Healthy Australian 

Cities, a new industry association developing green roofs and walls in 

Australia at www.greenroofs.org/au 


GRHCUPDATE 

AVERTICALOASIS—MFOPARKINZURICHSWITZERLAND 

GREENWALL 

TECHNOLOGYCLIMBING 

Green Roofs Healthy Cities is branching 

out beyond green roofs and into green 

walls that involve the use of a variety of 

exciting new technologies that integrate 

plants with the facades of buildings for 

multiple benefits and integration potential. 

In early fall of 2006 Steven Peck, president of 

GRHC brought together various green 

wall system manufacturers and together they 

struck a Green Wall Sub-Committee. Their 

first order of business was to combine 

resources and expertise to develop a new 

training course for green walls with expert 

assistance from Randy Sharp, principal of 

Sharp and Diamond, and a long time advocate 

and designer of green walls. This effort led to 

the development of Green Walls 101: Introduction 

to Systems and Design, launched at the 

Greening Rooftops for Sustainable Communities 

conference in Minneapolis last May. 

The new Green Wall course, the first in North 

America, provides an overview of the many 

tools and techniques needed to satisfy greenwall 

project objectives, the major functions and 

characteristics of components and systems 

available in the marketplace, as well as benefits 

and policy programs driving this industry forward. 

Since its launch the course has been delivered 

in San Francisco, Boston, Chicago, New 

York, Washington, Vancouver and Toronto to 

over 300 professionals. 

The upcoming 6th Annual Greening 

Rooftops for Sustainable Communities Conference 

in Baltimore will mark another first 

for the Green Walls Sub-Committee, with 

the introduction of a green walls category in 

the Green Roof Awards of Excellence program. 

The new award will recognize green 

wall projects that exhibit extraordinary leadership 

in integrated design and implementation 

of green walls. It will also help increase 

general awareness of green wall infrastructure 

and its associated public and private 

benefits, while recognizing the valuable contributions 

of green wall design professionals. 

The Green Wall Sub-Committee, chaired 

by Reuben Freed, greenscreen®, is also 

beginning to develop a green wall research 

program. It will establish a research fund and 

is exploring strategies to stimulate research 

that will fall in line with the USGBC and 

CanGBC LEED® rating systems. 

The six LEED® categories (taken from the 

LEED® 2.1 for Non-Commercial buildings 

checklist) which will guide the scope of the 

project include are: Sustainable Sites; Water 

Efficiency; Energy & Atmosphere; Materials 

and Resources; Indoor Environmental Quality; 

and, Innovation & Design Process. It is the 

sub-committee’s hope that this information 

will facilitate the explicit inclusion of green 

walls in the LEED® rating system and increase 

the rates of green wall construction throughout 

North America. 

The sub-committee is also is working to 

establish a green wall image, project information 

and incentive database, which will 

Photo courtesy of Jakob 

 


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profile different green wall systems and 

applications on various building types across 

the continent. The database will act as a 

tool to support LEED® efforts and project 

specific research for building owners and 

designers. 

Reuben Freed, attributes the early success of 

green walls thus far to the technology’s “intuitive 

and visceral appeal; green walls bring a 

natural exuberance to designed structures, 

and deliver a maximum of beauty from a minimum 

requirement of space, providing shade, 

privacy, comfort and vital, visual relief from 

the hardscape surrounding us.” 

LEARNMOREABOUT 

GREENROOFSANDWALLS 

GRHC’SPROFESSIONALCOURSECALENDARISNOW 

ONLINE—ANDTHEREAREMORECOURSESTHANEVER 

INNORTHAMERICANCITIES 

The 2008 Course Calendar is now available online and is sorted by city and date. Over 100 

green roof and wall courses will be delivered in over 30 North American cities throughout 

the year. Visit www.greenroofs.org to view the schedule or to register for any one of these 

popular daylong courses. 

The sub-committee’s four-part approach 

promises to lay solid foundations for rapid 

growth and development of green walls, 

an exciting new approach to implementing 

living architecture and restorative and 

healing buildings. www.greenroofs.org 

GREENWALLDESIGNERS 

Visit the web site for Awards of Excellence contest details or contact the awards administrator 

at awards@greenroofs.org for more information. Green Wall courses in 2008 

will be posted on www.greenroofs.org regularly 

By Flavia Bertram

GRHCUPDATE 

OMAHAWELCOMESOPPORTUNITY 

TOBUILDMOREGREENROOFS 

STORMWATERMANAGEMENTAMONGTHETOPICSATRECENTNEBRASKAN-BASEDLOCAL 

MARKETDEVELOPMENTSYMPOSIUM 

Over 60 participants attended the Oct. 25, 

2007 Omaha-GRHC Green Roofs Symposium, 

hosted by Douglas County and the 

City of Omaha, Nebraska and co-sponsored 

by Omaha’s Metropolitan Community College. 

The Nebraska Department of Environmental 

Quality’s Stormwater Management 

Plan Program provided partial funding for 

the symposium. 

Omaha Mayor Mike Fahey and Douglas 

County Commissioner Pam Tusa kicked off 

the symposium with welcoming remarks. 

“In 2006, I signed the U.S. Mayor’s Climate 

Protection Agreement joining the now 600 

United States mayors committed to helping 

stop the advancement of global warming,” 

said Omaha Mayor Mike Fahey in a statement 

about why green roofs are important. “By encouraging 

more green roofs and walls in and 

around Omaha, we have the opportunity to 

reduce greenhouse gas emissions and create 

a healthier city for generations to come.” 

Green roof case studies were presented by 

Richard Sutton of the University of Nebraska- 

Lincoln on a new green roof project in Lincoln, 

Nebraska at the Pioneer’s Park Nature 

Center and then by Kevin Schluckebier of the 

architectural firm Berringer, Ciaccio, Dennel 

and Mabrey on the proposed Saddlebrook 

joint-use facility in Omaha. 

Keynote speaker Jeffrey L. Bruce of the Jeffrey 

Bruce Company of Kansas City gave an 

in-depth presentation on key aspects of green 

roofs along with examples of some of his firm’s 

outstanding projects. 

Afternoon focus groups on stormwater management 

and retrofitting buildings rounded 

out the symposium. Input from these focus 

groups will inform the development of an action 

plan to promote the use of green roofs in 

the Omaha metropolitan area. 

The University of Nebraska-Lincoln’s Sutton 

says he was impressed with the turn-out for 

“ By encouraging more green 

roofs and walls in and 

around Omaha, we have the 

opportunity to reduce 

greenhouse gas emissions 

and create a healthier city 

for generations to come.” 

Mike Fahey, Mayor of Omaha, Nebraska 

the meeting. “Just before I gave my talk, I 

surveyed the audience and was pleased to 

find it pretty evenly split into four groups: engineers, 

architects, landscape architects and 

green industry professionals,” he observed. 

“Green roofs have truly become a vehicle for 

interdisciplinary collaboration.” He hopes a 

support group to continue the dialogue 

between various groups will move forward. 

By Kent E. Holm 

Kent E. Holm is the Environmental Services 

Director for Douglas County, Nebraska. 

RESEARCH 

COMMITTEEREPORT 

The Green Roof Research Committee has had 

an active summer and fall. Brad Rowe has 

passed the duties of the Chair to Dr. Brad Bass 

from Environment Canada. The committee approved 

the creation of a Data Repository for 

green roof data that has been collected at different 

sites across North America. The committee 

is now accepting nominations for two 

awards to be presented at the annual conference 

in Baltimore. One for best research 

paper, the second, recognition of a long-term 

achievement in green roof research. Details 

and submission forms are available at 

www.greenroofs.org or contact the awards 

administrator at awards@greenroofs.org. 

Update by Dr. Brad Bass, co-chair, GRHC 

Research Committee 

LOCAL 

CHAMPIONS 

WANTED! 

Want to see what other local champions 

are doing to promote the green roof and 

green wall industry across North America? 

Check out www.greenroofs.org and 

click on the Symposia button to connect 

to local champion materials by city including 

the action plans developed during 

the symposiums. They could be a 

blueprint for your city! 

 


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SCIENTIFIC 

INTEREST 

GREENROOFSDEBUTIN 

INFLUENTIALJOURNALS 

Two prestigious, internationally profiled peer 

reviewed magazines are publishing green roof 

research developed by GRHC members. 

BioScience which was published last November 

features a multidisciplinary synthesis on green 

roof research co-authored by GRHC members 

including Jeremy Lundholm Ph.D, assistant 

professor of Biology and Environmental Studies 

at Saint Mary’s University in Halifax; Dr. 

Brad Bass, with the Institute for Environmental 

Studies, Environment Canada at the University 

of Toronto; and Bradley Rowe, professor of 

Horticulture at Michigan State University. 

Urban Ecosystems journal will be publishing a 

special edition on green roof research. The 

idea originated from a GRHC research committee 

meeting and will have a special emphasis 

on urban ecology. 

Lundholm, who will be guest editing the Urban 

Ecosystems issue, is pleased green roof 

research is branching into different areas. He 

explains that not many biologists are working 

with green roof systems — mostly it has been 

engineers, urban planners and horticulturalists. 

Calculating habitat value and promoting biodiversity 

on green roofs is expanding. Other 

areas of research that may be featured are 

psychology, social sciences and health. 

By Lillian Mason 

WANTAGREENROOF 

SYMPOSIUMINYOURCITY? 

Are you interested in co-hosting a 

GRHC sponsored symposium in your city? 

If so, please contact Jennifer Sprout at 

416.971.4494 ext. 229 or 

jsprout@greenroofs.org

GRHCUPDATE 

SYMPOSIUMIGNITESGREENROOF 

ANDWALLMOMENTUMINATLANTA 

FROMARCHITECTSTOPUBLICPOLICYMAKERS—THEFINESTPROFESSIONALSGATHERED 

TOBRAINSTORMANACTIONPLANFORMOREGREENROOFSANDWALLSINGEORGIA’S 

CAPITALCITY 


GRHC Symposiums' continue in cities 

across North America, developing the 

sector and kick-starting projects that engage 

professionals throughout the green 

roof and wall industry. One of the organization’s 

latest symposium stops was Atlanta — 

sparking excitement, energy and cooperation 

among Georgia-based professionals 

and policymakers interested in green roofs. 

The event, held in September 2007, was attended 

by a wide array of architects, students, 

planners, non-profits, engineers and 

landscape architects. Kelly Caffarelli of the 

Home Depot Foundation, a lead sponsor of 

the event, welcomed participants with her 

opening remarks, followed by Clair Muller, an 

Atlanta City council member for District 8. 

Participants then heard from several Georgia 

designers, advocates and researchers who 

presented case studies of several existing 

green roofs projects in the Atlanta-area. 

Dan Gerding, AIA, of Gerding Collaborative 

shared his involvement with several regional 

projects including: Georgia’s Sweetwater 

Creek State Park Visitor Center, a LEED®platinum 

certified building opened in July 

2006 (see images above and right); and the 

recently completed NeoTerra Townhomes in 

Atlanta featuring a half-an-acre extensive 

residential green roof with underground 

rainwater cisterns for site irrigation and 

stormwater management. Other presenters 

included Meg Needle from architect firm 

Lord, Aeck, Sargent sharing details of one of 

their exciting projects, the Gwinett Environmental 

and Heritage Center in Gwinnett 

County, GA, a site with an extensive green 

roof, rain chains and native plants. 

As with every GRHC-sponsored Symposium, 

part of the agenda was devoted to 

identifying barriers to green roof implementation 

— and Atlanta was no exception. 

Here, Art Gibert, a planner from the GA Department 

of Community Affairs and other 

participants expressed their concerns about 

what they felt were the major issues including 

costs associated with green roofs, lack 

of incentives, potential leaks and liability issues, 

as well as maintenance and a general 

apathy towards energy conservation. 

But problem identification is only the beginning; 

the next step is a brainstorming 

“The symposium 

and training 

provided 

inspiration 

and hope for 

Atlanta — not to 

mention vital 

information — 

for the future 

of society and 

our world.” 

Art Gibert, planner for the State of Georgia & 

Atlanta Symposium participant 

 


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FROMTHE 

ACCREDITATION 

SUB-COMMITTEE 

session leading to the development of an 

Action Plan, which in the case of Atlanta’s 

Symposium included the establishment of 

an Atlanta Green Roof Steering Committee 

and “smart growth” strategies. 

Other action items included the 

exploration of potential partnerships and 

a proposal for providing incentives for 

green roofs in Chamblee, a smaller city 

outside Atlanta, also emerged from the 

event and will be discussed by the new 

Atlanta Green Roof Steering Committee 

after newly elected officials take office in 

early 2008. 

Also, the city of Atlanta is considering an 

ordinance to require LEED® certification 

for all public projects and any private development 

over 50,000 square feet. This is 

a first in Georgia, therefore an important 

prospect, being that green roofs can be 

used to achieve many LEED® points. 

The long-term impact of the symposium is 

likely to include a more directed effort toward 

getting green roofs and green walls 

recognized as solutions that can mitigate 

and reduce many of the Atlanta’s pressing 

energy and water conservation challenges. 

“Green roofs offer a magnificent opportunity 

to improve humankind’s relationship to 

the environment and the problems of shelter 

and lifesupport,” noted Gibert after the 

event. “The symposium and trainings offered 

by Green Roofs for Healthy Cities 

provided inspiration and hope for Atlanta — 

not to mention vital information — for the 

future of society and our world.” 

FIRSTGREENROOFPROFESSIONALACCREDITATION 

EXAMPLANNEDFORCONFERENCEIN 

ATLANTAGEORGIA 

Behind the scenes at GRHC, the organization 

continues to develop an industry-wide 

Accreditation Program. To this end, we are 

working with a dedicated team of subjectmatter 

experts to develop the final course 

in our program — Plants and Growing 

Medium 401. Simultaneously, we have been 

working on the development of the Accreditation 

Model that would be most appropriate 

to establish the Accredited Green Roof 

Professional designation. 

To accomplish this goal, we formed an Accreditation 

Sub-Committee, chaired by Professor 

Virginia Russell of the University of 

Cincinnati in Ohio. The main focus for this 

sub-committee was the review of a variety of 

other accreditation/certification models currently 

used by organizations such as the U.S. 

Green Building Council, RCI, and ANLA etc. 

To date, the sub-committee has concluded 

that the most appropriate model for GRHC 

would be one similar to the LEED® accreditation 

model. This would mean an accreditation 

exam would be available to a broad range of 

potential candidates without any prerequisites. 

The test itself will be based on the 

multi-disciplinary material in our Occupational 

Standards, completed over a year ago. 

This knowledge is covered in GRHC courses, 

which while highly recommended, will not be 

a requirement prior to taking the test. 

Although we have made significant progress, 

there is still much work to be done. First we 

must complete the development of the 401 

Course for delivery at GRHC’s Sixth Annual 

International Greening Rooftops for Sustainable 

Cities Conference in Baltimore this 

spring (April 30–May 2, 2008). Second, we 

need to develop the written test and make 

critical decisions regarding the maintenance 

of the Accreditation designation through such 

mechanisms as continuing education credits. 

To assist us with the test development, we will 

be working with Prometric, a company with 

20 years of experience as a provider of valid 

and legally defensible accreditation and certification 

examinations for professional trade 

associations worldwide. We will also forge 

long-term relationships with a strong group of 

subject matter experts, some of who were 

also involved in developing the Occupational 

Standards for the Accreditation program 

earlier this year. This next step promises to be 

a lengthy, challenging and yet fulfilling process 

— the one we must take to help us reach the 

critical milestone to deliver the first GRHC 

Accreditation test at our annual conference in 

spring of 2009. 

SUB-COMMITTEEMEMBERS 

Kelly Luckett, St. Louis Metalworks 

Roger Schickedantz, William McDonough & 

Partners 

Jeffrey Bruce, Jeffrey L. Bruce & Company 

Stephen Teal, Flynn Canada 

Bruce McTavish, McTavish Resource & 

Management Consultants 

Update by Hazel Farley 

Hazel Farley is director, training and accreditation, 

for Green Roofs for Healthy Cities. 


SECTION 

ONSPEC 

FROMWHEREI 

AGREENROOFERSIT 

THEROLEOFTHELANDSCAPERONGREENROOFPROJECTS 

By Kurt Horvath 

On commercial projects it is rare for landscapers to participate in 

the design process — and that might be OK because not every 

landscaper should be a green roof installer. 

I have been called in to assess the condition of some green roofs 

and have found simple mistakes that have had a huge impact on the 

performance of the green roof. 

For instance, on one green roof project we were called into assess, we 

found the drainage core was installed upside-down and did not provide 

for any water retention. For two years this green roof had struggled, 

but once the problem was corrected, the roof progressed more in a 

single season than it had in the two prior. 

A true green roofer is familiar with membrane types, appropriate 

assemblies by membrane, plant materials, details, media weights and 

general construction practices. 

A more complex concern lies in the newness of domestic green 

roof design / builds. Many US architects and landscapers lack 

experience in specifying green roofs or delivering the best possible 

green roof installations. This is why I distinguish myself as a “green 

roofer.” The Construction Specifications Institute (CSI) also recognizes 

this distinction and even recently assigned green roofs its own 

industry code. 

Whether you are a landscaper with a growing interest in green roofs, 

or another professional part of a green roof team, there is lots to 

consider when it comes to the role of the green roof landscaping professional. 

Although some of the information I have listed below may 

be simple and straightforward I still feel it is worth to note: 

Number 1, you are on a roof! So it’s safety first. No job is a good job if 

someone on your team gets hurt. 

Number 2, get educated. Take advantage of the green roof education 

courses provided by GRHC and the roofing and waterproofing companies 

Number 3, consider and recommend alternatives. Budget constraints 

can engineer green roofs out of projects. A true green roofer always 

looks for ways to conserve. Alternate / hybridized systems can provide 

needed savings. Attainability leads to sustainability. 

Number 4, manage logistics and think strategically. Installation is the 

nitty-gritty, hands-on aspect of the landscaper’s role. Know your systems, 

your components, your media and, especially, your plants. 

Number 5, follow up. Maintenance, unless otherwise contracted, is the 

primary responsibility of the owner who will want to see their green 

roofs thriving within the first year of installation. This goal is best 

achieved when: the green roof landscaper consults during the design 

phase; keeps job costs in line with objectives; respects other trades; 

and maintains efficient and safe practices during mobilization and construction 

with post-installation follow-up to promote successful growth. 

Number 6, help develop your industry and promote green roofs. At 

our company, we’re committed to successful outcomes and have a 

true passion to build as many green roofs, as cost-effectively, as 

green and as fast as possible. 

As a landscaper/green roofer, I invite others to envision the same. 

The success of each green roof installed will promote the green roof 

industry at large — and in this way, we all win. 

Kurt Horvath is a Green Roofer and the President of Glenview, IL-based 

Intrinsic Landscaping, Inc. (www.intrinsiclandscaping.com). Intrinsic has 

installed over 100 Green Roofs in the Midwest. He helped develop 

the occupational analysis for the Accredited Green Roof Professional 

designation being developed by GRHC with industry stakeholders. 

GOTSOMETHINGTOSAY? 

Do you feel strongly about something that is going on in the green roof or wall industry? Do you have a vision for how things could be different or 

better? Well, stop stewing and start sharing here in our new back-page guest editorial. Send us a 150-word description of what you would like to 

write about and you could be featured in an upcoming On Spec. Write to us at editor@greenroofs.org. 

 


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