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Sky Gardens ~
Travels in Landscape Architecture

By Linda S. Velazquez, ASLA Associate, LEED AP, Publisher

October/November 2004 ~ All photos by Linda S. Velazquez and Kelly Luckett, unless otherwise noted


Stuttgart and Nuertingen Germany.  My husband, Aramis, and I had an opportunity to revisit this beautiful area of southern Germany in September when we attended the International Green Roof Congress in Nuertingen.

Presented by the International Green Roof Association and the DDV - Deutscher Dachgärtner Verband e.V., the two-day event was hosted by the German landscaping, roofing and environmental lobby groups BGL - Bundesverband Garten-, Landschafts- und Sportplatzbau e. V.; ELCA (European Landscape Contractors Association); ZVDH - Zentralverband des deutschen Dachdeckerhandwerks; B.A.U.M. - Bundesdeutscher Arbeitskreis für Umweltbewusstes Management e.V.; and the FLL - Forschungs-gesellschaft Landschaftsentwicklung Landschaftsbau e.V. (Landscape Development and Landscape Construction Research Society).  The first International Green Roof Congress was sponsored by ZinCo International, and by all accounts the International Green Roof Congress (IGRC) was a huge success.

The Congress was presented in German, English and Japanese, and the 200 attendees were all fitted with headpieces for simultaneous translation into the language of our choice, giving the appearance of a green-minded United Nations assembly.  We were all also given a 176-page Conference Transcript for reference. So the Congress was truly international, with representatives from almost 20 countries.  Besides Germany, we made friends from South Korea, Peru, Mexico, Belgium, Singapore, Greece, Macedonia, Ireland, Spain, Japan, the Netherlands, and more.  Fellow attendees from the U.S. and Canada included Janet Faust of JDR; Kelly Luckett of Green Roof Blocks and Green Roof Products; Peter Philippi of Green Roof Service; Bob Berghage of Penn State; Ed Jarger of American Hydrotech; Randy Sharp of Verdir Systems; and Kerry Ross of Studio T. Design.  We encountered several UK people we knew from previous conferences, including Nigel Dunnett from the University of Sheffield and Alun Tarr of Blackdown Horticultural Consultants.

Photo from the International Green Roof Congress website

The state-of-the-art K3N congress facility. Photo: Green Roof World

Everyone in attendance was extremely impressed with the organizers' very professional and informative proceedings, and Heidi Eckert of ZinCo and Wolfgang Ansel of the International Green Roof Association were on hand to make sure everything ran smoothly.  The charming medieval City of Nuertingen's "K3N" offered spacious and generous facilities with courteous staff - the three K's in German stand for Art, Culture and Congress, and N stands for the City of Nuertingen.

Nuertingen's Mayor Otmar Heirich proudly welcomed us to their state of the art Congress facility, serving as a platform for the city's 40,000 citizens to "support volunteerism and community commitment."  The importance of greenroofs were recognized early here, with several thousand square meters constructed within Nuertingen (approximately 8,000 m²).  In fact, the construction plans for all new buildings must include calculations for future greenroofs.

Of course, for us the most fun to be had was found at the two lovely and lively buffet dinner get togethers and the Green Roof Tour (more on that to follow), but the real reason for travelling to Germany was to hear what the speakers had to share about Why Green Roofs, Science and Research, Green Roof Technique, and Green Architecture Worldwide.  Aart Veerman, IGRA President from Holland, Ulrich Schäfer of ZinCo, offered more opening remarks and greetings.  (Skip to photos). Following are only some highlights of the various IGRC presentations, as they were too numerous to list them all here:

Why Greenroofs?

Professor A. Schmidt, President of the FLL - Over the last 25 years, the FLL has promoted greenroofs as sustainable design.  A brief history pursued - in 1979, the FLL started a set of rules and norms for greenroofs; in 1980 the first set was published, revised in 1984; root barrier and resistance testing were added for extensive greenroofs on both flat and sloped roofs; in 1990 the Guidelines for Planning, Construction, Installation and Maintenance was published; by 1995 it was revised and expanded to include information pertaining to drainage layers, and was the first edition available in English; in 2002 the latest release was published, now also available in English and sold at the Congress entitled "Guideline for the Planning, Execution and Upkeep of Green-Roof Sites." (We bought one.)

Professor Schmidt added that 30% of all German municipalities support greenroofs.   Many municipalities in Germany use greenroofs as "compensational greenspace," with 70% currently offering direct subsidies.  He stated that we need a set of international guidelines and measures and new strategies to convince more governments.

Dr. Franz Alt, Editor and Solar Expert - This particular presentation was the most "eco-politically" charged, but still offered a great perspective on the necessity and opportunities to combine the technologies of greenroofs and solar energy.

Prof. Dr. Maximilian Gege, CEO of B.A.U.M. - Serious global climatic changes can only be avoided by stringently reducing greenhouse gas emissions and utilizing renewal energy strategies, including solar and wind power. Innovative energy savings technologies should involve "the thermally insulating green roof build-up."

Dr. Bettina Menne, WHO (World Health Organisation) Europe, European Centre for Environment and Health Medical Officer - The medical doctor explained some of the reasons why 14,800 died during the horrific 2003 French heat wave and over 25,000 more in other parts of Europe, and other health impacts. Dr. Menne cited preventative measures and a need for international collaboration for design solutions to combat the heat as well as economic and political changes.

Klaus-Jürgen Evert, Dept. of Garden and Cemetery, City of Stuttgart - Greenroofs should be realized as the architectural response to the managing and harvesting of rainwater. Aesthetically, The City of Stuttgart has established pioneering efforts to support municipal programs to implement a large number of greenroofs. Measures have been in place since the mid-eighties to firmly promote greenroofs, including code requirements, direct financial support, greenroof awards, and landscaping of municipal buildings.

For example, the "Weiler Park" industrial area, about 24 ha northwest of Stuttgart, made greenroofs required on all flat roofs. The private sector produced 358 green roof projects with approximately 50,000 m² receiving local authority grants within the last few years.

Presenting but but not cited here:  Dr. Paolo Abram, Italian Green Roof Association (A.I.VE.P.); Klaus W. König, Architect, member of the "fbr" board (German Association of Rainwater and Grey Water Reuse); James Van Zee of the Northern Virginia Regional Commission.

Science and Research

Prof. Gilbert Lösken, Department of Landscape Architecture and Environmental Development, University of Hannover, and head of the FLL Green Roof Task Force - The FLL has been the neutral platform for lively discussions for the past 25 years and has played a decisive role in fixing standards for greenroof technology in Germany. The FLL offers guidelines, not norms such as ISO or DIN and therefore these can be changed quickly as research dictates.

Werner Küsters, BGL and ELCA - Mr. Küsters quotes the architect Hundertwasser as saying "It is your duty to do justice to Nature." Interdisciplinary efforts are needed to build well planned greenroofs, and the best way to promote them is with high quality projects. Greenroof design, therefore, is not for amateurs. We should be specialists to design greenroofs, and the field should not be wide open. Which profession can carry out this work? Landscape Architects.

Tassilo Schwarz, Bavarian Institute for Viticulture and Horticulture, Veitshöchheim - Successful plant communities for greenroofs are those that must face extreme environmental conditions, especially for those with very thin substrates, like those found in crevices and rocks, dry meadows, edges of woods, and steppes. Bavaria has had over 25 years of experience with extensive greenroofs regarding plant material and has found many natural plants and plant communities within Germany to provide a rich selection pool. For example, Carex humilus has 180 different species tested there.

Dr. Nigel Dunnett, University of Sheffield -
Nigel described "Options and Constraints for Plant Use on Green Roofs in the UK." Most recent greenroofs here have not only been extensive, but the imported German-style sedum greenroofs, and he believes there is much opportunity to further promote different systems to satisfy a larger ecological need. The unique climatic conditions within the UK was examined, and a call was made to diversify both in the greenroof systems chosen and the plant communities offered. Dr. Dunnett also stated that moderate stress promotes greater plant diversity, with the stress related to the substrate depth.

Prof. Dr. Manfred Köhler, Landscape Architect, BDLA, University of Applied Sciences, Neubrandenburg - "Green Roofs are relevant to cool down inner city surfaces. This effect shall be explained by the measurements of the storage capacity, run-off, evaporation, interception rates and climate parameters," (2004 International Green Roof Congress Transcript).

Dr. David J. Beattie, Director of the Center for Green Roof Research at the Pennsylvania State University -  Dave started off with his famous Rotweiler joke, and proceeded from there to present a very lively and informative talk. Dr. Dave stated that in Germany greenroofs cost approximately $40-60/m² while in the u.s. the range is closer to $100-300/m². He advocates educating greenroof professionals and developing standards for greenroof installation in North America.

Presenting but but not cited in this session: Prof. Dr. Stephan Roth-Kleyer, Director of the Institute for Landscape Construction at the Geisenheim Research Facility and lecturer at the University of Applied Sciences in Wiesbaden; Prof. Dr. Klaus Neumann, Associate Professor for Landscape Conservation at the University of Applied Sciences in Berlin, Landscape Architect, BDLA and Vice President of the FLL; Martin Jauch, Scientific Assistant at the Research Institute for Horticulture in Weihenstephan.

Green Roof Techniques

Kurt Michels, Lecturer at the Roofing Vocational School in Mayen, member of the FLL Green Roof Task Force - Mr. Michels spoke about the various stress of waterproofing, root resistant waterproofing and the technical features necessary for professional installation. FLL by-laws and rules address issues of fire, wind, and uplift as well as energy savings and the prevention of accidents.

Roland Appl, Technical Director of ZinCo GmbH

Roland Appl, Technical Director of ZinCo GmbH, member of the FLL Green Roof Task Force - Mr. Appl spoke about the importance of adhering to the time tested recommendations of the FLL, and that although each project is unique, certain layers are always required. General layering was discussed as well as specifics.

For example, he added that 90% of German waterproofing contains root resistance. Quality bonding of seams is essential to prevent lateral root growth. A separation layer is important for physical stress, at a minimum of 300 g.

Hans-Jörg Kiesewetter, Green roof Contractor, Pro-Natur
- As a hands-on greenroof designer and contractor, Hans-Jörg eloquently addressed many questions of scheduling and logistics during the planning and installation stages. He talked about the transfer of materials to the site and the roof, including substrate delivery methods and costs.

Bernd W. Krupka, Landscape Architect and Green Roof Surveyor, former leader of the FLL working group "green roofs," author - Mr. Krupka is dedicated to the research and development of greenroofs and is a professional expert court witness in this field. "The knowledge of the potential sources of failure and the consequent observances of guidelines and instruction helps to avoid defects and damages on green roofs" (2004 International Green Roof Congress Transcript). Since 1992 we can analyze the past mistakes in terms of loads, material handling, wind uplift, root and rhizome resistance and protection, wind/water erosion, insufficient planting, poor maintenance and much more.

Green Architecture Worldwide

Daniel Roehr, Landscape Architect - Mr. Roehr spoke about The DaimlerChrysler Project at the Potsdamer Platz in Berlin, and how greenroofs and modern rainwater recycling systems are no longer mutually exclusive technologies. The office Dreiseitl and its involvement with the masterplan and layout was greatly discussed.

Maria José Barrio, Product Manager Green Roofs, Madrid - Soon to be the largest greenroof in the world, the "Banco Santander Central Hispano" Financial District in Madrid, the extensive area will cover 165 hectares and offer 100,000 m² of office space. The live, play, work development is designed to create a welcoming atmosphere and to become an asset for employees and clients alike.

Susan K. Weiler, ASLA, Landscape Architect with Olin Partnership, lecturer at the Temple University and the University of Pennsylvania - Susan stated that her company, Olin Partnership, strived not to recreate natural landscapes, but evoke them in their designs. Such was the case with the Church of Latter-Day Saints Conference Center in Salt Lake City, UT, a massive, exciting and highly intensive greenroof. Nearly 1,300 trees, 27,000 shrubs, 36,000 bulbs and 800 vines were planted by over a thousand volunteers.

Tsuneo Tajima, Tajima Roofing - This was one of the most lively presentations as Mr. Tajima spoke in Japanese, which was translated into German by his associate, and then into English via the headphones.  So his jokes had a distinct delayed reaction from the crowd, which made it even more humorous! Since 1990 Tajima Roofing has been designing greenroofs in Japan, and the evolution of concepts, systems and designs was presented.

Steve Skinner, American Hydrotech - Steve spoke about the intensive greenroof at the Schwab Rehabilitation Hospital in Chicago, IL, and how it creates an oasis of wellness for its patients. Horticultural therapy was discussed at length, and how the design of this hospital offers a respite to severe victims, helping to heal physical, spiritual and emotional trauma.

Ho Wan Weng, Managing Director, ZinCo Singapore -
Increasing emphasis on greenspaces, including rooftops, is becoming more important in Singapore, and insights were offered regarding experiences gained and lessons learned with the first government extensive greenroof project, or "Skyrise Garden" here.

Presenting but but not cited in this session: Aart Veerman, Commercial Director of Van der Tol b.v., President of the Dutch Green Roofs and Facades Association (DGS) (greenroofs in the Netherlands); Behnisch, Behnisch & Partner Architecture Firm (Genzyme Center in Cambridge, MA); Angela Beck-Møller, author (greenroofs in Denmark); Ian Johnston, Alumasc National Business Manager (greenroofs in the UK).

Time for Interacting with Each Other

All the food and beverages were great, with a wide selection of both, including appetizers and snacks.  Here was a great opportunity to relax and have some fun interacting with other greenroof people.  I didn't make it all around the room to take pictures of everyone, but below are some photos of various tables.

Dining Gallery:

The ZinCo Green Roof Tour

On September 16 we opted for the ZinCo Green Roof Tour, while many associates went to the GaLaBau - the International Trade Show for Urban Green and Open Spaces - in Nuremberg.  Around 850 exhibitors presented their latest products and services for the horticulture and landscape gardening sector as well as for the design of greenroofs - see Janet Faust's Guest Feature contribution this month about the GaLaBau 2004 here.

There was not a single empty seat on the huge comfortable tour bus, and in fact some people said they had traveled half way around the world specifically for this tour of exciting projects.  Our host for the day was Roland Appl of ZinCo, and a hearty German lunch was included, along with our selection of beer.

First stop:  "Hundertwasserhaus Plochingen" - the Hundertwasser Multi-Family Development - Situated within a lovely southern Germany-style live-work-play development, the architect Hundertwasser designed this 10-year old Gaudi-inspired private lush green courtyard intensive greenroof located over a supermarket.  Approximately 50 greenroofs occupy the colorful, wavy, very organically designed and tiled wavy buildings and interior spaces, including the smallest over a doorway at just two m².

The charming pedestrian-friendly village itself is a mixture of architectural styles, and just as "green" as the Hundertwasserhaus, but in different ways, including innovative drainage channels, fountains, green poles, green walls and flowering baskets and containers everywhere. The Hundertwasserhaus was definitely a "must see" experience.

"Hundertwasserhaus Plochingen" Gallery:

"MAG-Galerien" in Geislingen -  This three-year old 8,000 m² green rooftop over a private shopping mall or gallery has been transformed into a public park open to all the adjoining neighbors. The MAG contains a playground with sandbox, a basketball court, walkways and trellises, On the top level, approximately 5,400 m² are intensive greenroof areas and 2,600 m² are extensive, and the two are separated by a chain link fence. Two more separate extensive greenroofs wind down the ramp to access the shopping area below.

The original idea for the top level extensive area was for it to be a test area of sorts, but it has actually received no monitoring nor maintenance. In fact, it had to be hydroseeded twice because initially it did not receive any irrigation. The intensive area, on the other hand, is highly maintained with its plush lawn and beautiful perennial beds, and is irrigated. Although city residents use the new "city park," it does not receive any public assistance for its maintenance.

"MAG-Galerien" Gallery:


Green Roofs& Photovoltaic Panels atop Schule Unterensingen, Germany; Photo Source:  ZinCo

Schule Unterensingen -  200 solar panels and an extensive greenroof grace the top roof of this large school in Unterensingen.  This is ZinCo's first project combining the two green technologies, completed in 2002.

The panels power enough electricity for the entire school. The panel bases are secured directly to the specially designed drainage board.

The school was quite impressive in that every building and covered walkway was covered in extensive greenroofs - easily over ten separate ones.

"Schule Unterensingen" Gallery:

ZinCo Dachgarten - ZinCo International's headquarters is quite impressive in that it covers a very large area, and every single building on the campus is greened, with approximately 12 extensive greenroofs dating from the 1970's and the one new highly stylized intensive greenroof.

Completed a year ago in September 2003, the intensive greenroof atop the headquarter penthouse conference room did not require a new membrane for the green installation; ZinCo only replaced the previous greenroof build-up to accommodate the new design. Lighted wood walkways meander around turf, lovely evergreen and flowering shrub and perennial beds (irrigated, of course), a water fountain, and a covered seating area offers a cool place to sit outside and chat with clients or just enjoy the view.

A very large extensive test garden greenroof abuts this new expansive space. Consisting of two separate areas, these roofs are about 20 and 27 years old, and ZinCo uses these roofs to test for plant material, different growth media types and depths, and waterproofing and other system components.

"ZinCo Dachgarten" Gallery:


"Römerpark-Museum" in Köngen - The futuristic design of this museum housing information and artifacts of Roman influence in the area has a feeling of both grounding itself to Earth and positioning itself to take off. Incredibly, the roofs also sport a 20° slope. Cables run the length of the roof line so that workmen can attach themselves during periodic maintenance checks, and the edges are weighted down with medium sized pebbles.

"Römerpark-Museum" Gallery:

Although we were in Stuttgart specifically to hear all about German and other European industry happenings and participate in the Green Roof Tour or the GaLaBau 2004, I especially delighted at all the "random" or accidental sightings of greenroofs and green walls at every turn on our way to the Congress or on the bus tour. For example, along the Green Roof Tour Roland pointed out the highly visible 30-year old grass roofs in Überkinger, situated in a valley; the one-year old "Rasthause Gruibingen" barrel-shaped restaurant greenroof; and an 8,000 m² sedum and grass greenroof atop the "Kompostwerk" - the local compost factory. Unfortunately, we were going too fast to take any photos!

"Random" Greenery Gallery:

We also had a chance to spend a day in lovely Stuttgart and do some sightseeing;  if you are interested in photos, see the Stuttgart Gallery below.

Stuttgart Gallery:


I'll bet Stuttgart area residents take these light poles, carports, garages, factories, restaurants, marketplaces and the like for granted, with greenroof architecture pretty much being ensconced here in everyday life.  Wouldn't it be great if we could all say the same?  International venues such as the International Green Roof Congress can only help to accomplish this by inspiring the rest of the world to visit new places and new ways of looking at things, and then coming home to promote the same type of sustainable development in our own cities and neighborhoods.  I think information sharing and collaboration is the key to a true healthy community of design, respect, and understanding. In 1989, the real first Green Roof Congress was held here, and 15 years later in 2004 this International Congress was held - talks are underway to consider holding the second International Green Roof Congress in Basel, Switzerland.

If you are interested in reading more about Stuttgart area greenroof activity, read my
October 2003 - Sky Gardens column about Stuttgart, Germany. To learn more about the International Green Roof Congress, please visit; to read more about ZinCo International, visit

Linda is founder and publisher of, a greenroof design consultant, and has been a Delta Air Lines international flight attendant since 1979.  She went back to school and received her Bachelor’s of Landscape Architecture degree from the University of Georgia in 2000.   Linda recently received her LEED™ Accredited Professional designation, and welcomes your comments; contact her at:

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