Advances within the European green roofing industry: Practices, Policy, and Design

Edward L. Ryerson Traveling Fellowship in Landscape Architecture

Final Research ProjectBy: Nellie Mogge

Advances Within the European green roofing Industry: Practices, Policy, and DesignRyerson Traveling Fellowship 2012

by: Nellie Mogge

On May 21, 2012, I embarked on my Ryerson traveling fellowship based on my proposal to study green roofs in Europe. My trip was originally based around questions involving green roof architecture, policy, and the ways in which green roofs could alter the character of a city. Many more questions were answered along the way, though, specifically about construction materials, techniques, and methods. I specifically wanted to go to Germany and Switzerland because of their green roof urban planning strategies. While my six and half week trip through Europe allowed me to see amazing pieces of green roof architecture and learn about new types of construction, it also made me understand the importance of green roof policy in making these projects possible. There are specific reasons why Europe has been able to become a leader in the green roof industry over the past couple of decades. One reason being that increasingly competitive market forces have driven the devel-opment of green roof technology. These forces include years of accumulated research on membrane technology, roof design, and plant performance. Also, social ideals that persist throughout Europe which value environmen-tal protection, stewardship, and the increase of green space in urban areas drive more development of green roof technology. (4) In Germany, “federal environmental laws requires mitigation or compensation for the destruc-tion of natural open space caused by development.” (3) Basel, Switzerland achieved a city wide ordinance that all new flat buildings have a green roof through a series of campaigns which came out of the EU Year of Nature Conservation in 1995. A Building and Construc-tion Law was passed in the late 90’s and today, there are a total of 1929 green roofs present throughout the city. Furthermore, the roof should not only be vegetated, it must also provide some sort of habitat. (1,2). In Munich, Germany, green roofs have been part of the building ordinance since 1984, with a growth of 4.2 million square feet of green roofs over the past 15 years. (3) The city of Stuttgart, Germany has been implementing measures since the 1980s to promote and build more green roofs. Today they even have incentives such as a reduced storm water tax on green roofs with a substrate layer of at least 60 mm. (5) With such promotion of green roofs throughout this region, this means there are a multitude of fantastic projects utilizing new construction materials and techniques. I was able to see many of these at the start of my trip on the green roof 2-day excursion led by Dr. Stephan Brenneisen, the head of the Green Roof Competence Center at the Zurich University of Applied Sciences. After Switzerland, I traveled to Germany to Munich and then Stuttgart,where I was able to meet up with PhD researcher in green roofs & urban ecology at the Univer-sity of Sheffield, Christine Thuring. After this, I headed to Freiburg, Germany with some project recommenda-tions from ZinCo, a company with international acclaim for their green roof projects. I did a bit more traveling through Germany before making my way north to The Netherlands. Paris, France, with its’ beautiful green walls, was my final stop before heading to London for my return journey home.

Travel Itinerary05/22/2012-07/04/2012

Fly into ZurichZurich, Switzerland-Green Roof tour, Lucerne visit, MFO ParkMunich, GermanyStuttgart, GermanyFreiburg, Germany-week stay in Reiselfeld[traveling to Berlin]Berlin, GermanyThe Netherlands - Rotterdam, AmsterdamParis, FranceLondon, United Kingdom Fly home

The green roof tour, which lasted for two days in late May, showcased projects in and around north central Switzerland, all ranging in size, type, but most importantly, intention. Today, there are so many different ways of installing a green roof, whether it be through engineered soil and manufactured trays, or through water-proof matting and local, regional soils. While all are usually successful in achieving their end goal, the intention be it biodiversity, ecology, art, design, or architecture is what makes each interesting.

Travel Route

Switzerland

Green roof 2-day excursion 2012

3rd – 4th May 2012

A trip to Switzerland’s

- most famous green roofs and

- to study sites of the Green roof

Competence centre of the Zurich

University of Applied Sciences

24-25 May 2012

One of the first projects we saw on the tour was the Moos Lake Water Filtration Plant in Wollishofen (Zurich), Switzerland. The roof was originally built in 1914 with a green roof because the planners knew the benefits it would have as a cooling measure for the interior room temperatures. The building itself is a very simple construction employing a great waterproofing material, mastic asphalt.

Moos lake water filtration plant time series section

Moos lake water filtration plant

The original topsoil, which came from the surrounding farmland, was placed on top of the roof and the vegeta-tion grew out of whatever seeds were either in the soil or transported regionally. It houses 175 species, 9 of which are orchids, including Orchis morio, which is otherwise extinct in the area. Many of the rare and endan-gered species are assumed to have come from the initial planting of topsoil, as seeds from the reservoir, or have since colonized from the surrounding fields. Today the established natural meadow reflects the diverse number of species present in an agricultural region at the beginning of the 20th century. It is also a great example of the potential of a green roof to aid in conservation efforts because it houses a large number of rare and endangered species. The next project we visited was the Earth House Complex in Lättenstrasse (Dietikon) by Peter Vetsch. This roof was constructed in 1993 and answered a question I had prior to my trip, which was how the idea of a green roof from the beginning could drive or alter the rest of the architectural direction. By deconstructing the project as seen here,

it seems as though the green roof guided the construction. All of the materials used came out of the needs of the vegetation. The recycled glass insulation layer provides a level of support and protection for the interior while the root-proof polymer bitumen serves as a water barrier while also ensuring the roots don’t penetrate the roof. The curved house shape itself was achieved by using shotcrete and heat insulation technology. According to the greenroofs.com projects website, Vetsch always designs according to the following two premises: “1) To integrate a building into its environment as much as possible, and to return back to nature a good part of what the constructional encroachment takes away; 2) A living surface on the roof shall arise alone with site-bound growth.” In this case, it seems the end architectural result has arisen out of the needs of the landscape. Rather than a structure with a roof on top, it seems to be a landscape with a house underneath. An interesting project in terms of biodiversity and habitat provision was the Jacob Burckhardt Haus in Basel, Switzerland. Built in 2004 by Morath AG, Tecton AG, it is today incredibly biodiverse with spiders, ants, beetles, and butterflies. Large rocks were added to the roof and are beneficial because they provide microcli-mates by retaining heat and moisture. Also, by mounding rocks in certain areas which have a greater load, plants are able to extend their root depth and create even more biodiversity.

Earth House deconstruction section axon

Jacob Burckhardt Haus closeup-ants, large rocks, sand Jacob Burckhardt Haus mound

More creative construction measures were seen at the BVB tram depot, also located in Basel. The roof greening for this project was done by the Urban Greening department, Institute for environment and natural resources at ZHAW. This project originally posed a challenge because the roof could not support a very high load. This was solved by us-ing chopped china reed for the bottom substrate layer and putting the 5 cm vegetation layer, consisting of lava and pumus material, on top. Such a thin substrate layer ended up being advantageous because it can’t store a lot of water. This in turn means the meadow plants will not be reaching the same heights as they would on the ground and therefore the roof does not need to be mowed.

BVB Tram depot – chopped china reed, lava rock, sedum

Moos Wollishofen construction

BVB Section ZHAW

BVB Truck installation ZHAW

Shotcrete and heat insulation technology ZHAW

The simplest construction I saw on the tour came from 90 years ago with the Moos lake water-filtration plant design. It consists of a strong building construction with slab beams, mastic asphalt, and regional substrate and soils. Mastic asphalt is a material used in roofing, which is effective because of its impermeability.

The Earth House, utilizing shotcrete and heat insulation technol-ogy allows for the curvature of the structure which mimics a mound found in the landscape. Specific materials include root proof poly-mer bitumen, recycled foamed waste glass used as a drainage layer, and the reuse of excavation material found on site.

In the case of the BVB tram depot, it was too expensive to pump gravel onto the roof, so here the team used Miscanthus (chopped china reed) and a lighter lava, pumus material for the substrate. The china reed was trucked in and placed as a first layer, then 5 cm of soil, then the local pumus, lava rock was placed on top. Over time, the layers biodegrade to combine 8 cm of soil.

Installation technique (Miscanthus)

Overall, the tour helped me gain a lot of information about the sorts of construction techniques being used in the green roof industry and how they aid in the lifespan and quality of a green roof.

Small scale elements can be added to a green roof which prove to enhance the biodiversity and provide more habitat.

dead wood

humus large rocks chopped china reed

variable substrate levelsmounds of local gravel

Water local material-lava, pumus rock variability in plantings

Following the Swiss tour, my green roof pursuits, with helpful tips from Green Roof Safari, led me to Munich and then Stuttgart, Germany. In Stuttgart, I was delighted at the way the landscape itself aided in the apprecia-tion of the many green roofs throughout the city. The rolling hills covered in vineyards and the many lookouts allow for a clear view of the city’s green direction.

View from Chinese Gardens, Stuttgart, Germany

Stuttgart, Germany

Observation Tower

View from Observation Tower- Chinese Gardens & Vineyards

View from ascent to Chinese Gardens and vineyards

View from vineyards

Stuttgart green roof examples

It was not difficult to stumble upon numerous green roof projects while simply navigating the newer parts of the city. Also, Stuttgart is in the middle of a massive railway and urban redevelopment effort, Stuttgart 21. It is highly controversial as well as expensive, costing roughly 4.1 billion euros. However, this as well as the city’s general green attitude explains the great amount of green roof projects throughout the area.

Green roof zoo

Through the use of the various lookouts throughout the city, I was able to analyze some projects through a birds eye perspective. This project, for example, shows how certain areas of the roof were predetermined for accessi-bility in the architectural design stage. Thinking of a green roof from the beginning allows for a more symbiotic relationship between roof and structure, outside and inside, landscape and interior. The intensive roof garden seen in the middle photo was obviously a forethought prior to architectural decisions and construction. The needs of the landscape coincided with the needs of the structure and a much more integrated design emerged. Also, more subtle green roofing was possible as seen in the image on the right, in which a slight repose into the landscape from the fifth floor would be a possibility.

Residential

This photo clearly shows the old part of the city in the background alongside the new developments which are dominated by green roofing projects.

Signage about Stuttgart 21 project displayed on one level of the lookout tower

A particularly interesting roof in Stuttgart, which I was pleased to gain access to from Christine, is the green roof atop the Rathausgarage (city hall parking garage).

Rathausgaragegreen roof

Rathausgarage, Stuttgart, Germany

Front of rathausgarage Rathaus - front of building

This roof is about 21 years old and quite diverse in terms of flora. Through quadrat sampling and analysis, this roof is one of 9 sites for Christine Thuring's PhD research at the University of Sheffield. By sampling old ex-tensive green roofs, this work could reveal some of the key factors determining long-term species diversity over time on such systems. It's quite a unique study, because the roofs sampled are among the oldest extensive green roofs in the world. Some were prototypes at the time of their installation. It was a treat to get access to these, as access if often a major barrier for any kind of roof.

quadrat diverse flora

Christine on the roof Me on the roof

KönigstraßeGermany’s longest pedestrian street

Stuttgart left me with an image of a city where green roofs are a normal element in new construction as well as reconstruction efforts. In the case of the Rathausgarage, this roof is incredibly visible to the city hall workers in the adjacent Rathaus Stuttgart building. The city’s direction and commitment to green design is visible right outside their windows. This roof made me question how a city responds to the existence of a large number of green roofs within its’ boundaries. The response may not be quite as complicated or dramatic as I had originally envisioned. In fact, while walking down the Königstraße (Germany’s longest pedestrian street) on my way to the train station observation deck, I had no clue that almost every building I was walking by had a green roof on top. The response of a city lies in public appreciation and understanding and I do think Stuttgart is at an advan-tage here because of its’ topography and lookouts. Aside from their appreciation, a transparent dialogue between professionals and the public concerning their benefits and construction techniques is also important in their promotion. With more understanding through research and proliferation, that’s one step closer to getting them into more cities.

Freiburg - Rieselfeld

My next stop on my journey was to the small new village of Rieselfeld, located just outside of Freiburg, Ger-many. Freiburg, a city well-renowned for its status as the German green capital, founded the new district in 1992. It was originally aimed at young people in an effort to discourage suburban sprawl. Development started in 1993 and all of the houses are low energy, equipped with green roofs, photovoltaics and solar heating. It is an interesting urban design case study in its’ own right but in terms of green roofs, it is an interesting display of the types of architecture that are following green roof mandates. (7,8)I was originally curious as to how green roofs were altering or directing architecture. By including green roofs in the building design from the beginning, how does this alter the rest of the architectrual direction? The struc-tures in Rieselfeld all have a similar goal and therefore they all end up with a somewhat similar appearance. Also, since the district is composed almost entirely of extensive green roofs, the structural image based on load bearing capability will be similar throughout.

Architecture examples-Rieselfeld

The architecture ends up being representative of the time we are living in where less is more and the environ-ment comes first. The “quality” or aesthetic appeal of the building ends up being defined by how sustainable it is. This is not to say these structures aren’t attractive, but they are attractive in a historically different way which reflects what we, as human beings, see as being important today.

freiburg.de (original photo)Identified green roofsaerial view Rieselfeld

Aside from all of the rowhouses with basic flat extensive green roofs on top, there is an especially no-table project in Rieselfeld, the Clara Grunwald school sports hall done by architect Lorenz Wehrle with green roof build up by ZinCo. I received very helpful instruction from the company ZinCo throughout my travels, to include direction to visit this green roof project. Most of the structure is located underground with the green roof being the most visible from street level. The barrel-shaped roof is intended to serve as a bridge between the central square and surrounding green areas. (6) Having the majority of the sports hall underground as well as insulated is going to significantly reduce heating and cooling costs, which is important for a sports hall which generates a lot of heat. The roof is acces-sible, leading to social and recreational advantages for school children. Here, it appears the architect thought of the sports hall as an extension of the landscape from the very beginning, which then created an interesting and more ecological structure.

Clara-Grunwald Schule Sports Hall - Rieselfeld

Zinco project report

Project Report Sports hall Clara-Grunwald-School, FreiburgProject Data

Concept

System Build-up

Development

Area: 960 m² Construction Year: 2006 Architect/ Dipl.-ArchitektDesign: Lorenz Wehrle, FreiburgContractor: Gründach Technik, Unterensingen System Floratherm®

build-up: WD 65-H with 150 mm System Substrate Roof Garden Coordinates: 48°00'01.52"N 7°47'30.97"E

Near the Clara-Grunwald School in Freiburg, a sports hall with a barrel shaped roof was built in the adjacent municipal park. This form was cho-sen because the roof also needed to serve as a connecting bridge be-tween a central square and the adjacent park. The roof was greened with lawn in order to obtain a continuously accessi-ble area. A thermally insulating drainage element Floratherm® WD 65-H was chosen as the system build-up and was installed on a basic thermal insulation made of Foamglas®. Due to the installation of the Floratherm®-elements, the thickness of the comparative expensive basic thermal insu-lation could be minimised. Because the roof waterproofing is situated in a roof area which is protected against influences of temperature, a longer roof life cycle can be expected.

The walkable barrel-shaped roof of the Sports hall in Freiburg.

Railing system as fall protection.

The big barrel-shaped roof is also used in summer as staying surface.

Roof with waterproofing, prior to the green roof installation.

Installation of the Floratherm® WD 65-H elements.

The substrate is blown onto the roof.

Pre-cultivated lawn

System Substrate ‘Roof Garden’

Filter Sheet SF

Floratherm® WD 65-H

Protection Mat SSM 45

Roof construction with Foamglas®

basic thermal insulation and root resistant waterproofing

ZinCo Green Roofs Australia • 56 O´Dea Avenue, Waterloo NSW 2017 Phone: 02 9125 0900 • www.zincoaustralia.com.au • info@zincoaustralia.com.au

Authorized by ZinCo GmbH

After leaving Freiburg, I traveled north through Germany to Berlin and The Netherlands. En route, I encountered dozens of green roofs throughout Germany on the train and in stopover cities. In Rotterdam, I visited the Nether-lands Architecture Institute where green roofs are one component of their sustainable city direction.

Rotterdam, like Stuttgart, is a city undergoing massive redevelopment, which is where green roofs again enter the picture. I find this to be a good way to think about green roofs, as a component of a larger system as well as a new component of architectural design. Before I left, I had these grandiose top down visions of entire cities in which the plan view appeared totally green. There are many ways to green a city, though, and unless you want to end up with an entire city full of identical structures, it’s important to also include other types of sustainable infrastructure. There are also historical and site specific restrictions which limit their prolific spreading.

Rotterdam, The Netherlands

“Making of a City” exhibit - Netherlands Architecture Institute

While historical architecture can be a limiting factor in green roof development because of structural limita-tions, utilizing the past as an indicator for the future can be a good way to maintain the character of a region. I found an interesting take on historic architecture in Amsterdam, The Netherlands. The Borneo-Sporenburg housing development by West 8 is an excellent way to integrate the past with the present. “West 8 suggested new types of three-storey, ground-accessed houses deviating from the usual terraced house in being strongly oriented to the private realm by incorporating patios and roof gardens.” (9)Their design references the past traditional Dutch canal houses which are preserved and still in use thoughout Amsterdam, while bringing them into the 21st century and making them more sustainable through the use of more passive housing, green roof gardens, and natural lighting.

Traditional dutch canal houses - Amsterdam, The Netherlands

Borneo-Sporenburg - Amsterdam, The Netherlands

Christine’s Ramblings Archives

My last green roof stop was Paris, France and with much help from Christine Thuring’s previous article on green walls in Paris from greenroofs.com, I was able visit some of the projects she outlined.

I returned on multiple occasions to see Patrick Blanc’s Vertical Garden at the Musée de Quai Branly. Although beautiful even in photograph, this living wall is even more interesting in person because of people’s reactions, both mine and passerby. Its’ presence is unexpected and also quite close to the Eiffel Tower so it draws a lot of tourists en route to and from the train. Not only are people perplexed as to how there are plants growing on the wall, they are also impressed aesthetically. The composition itself is pristine and well maintained so that it is almost like a painting. It’s not until one gets up close that they actually notice the “dis-crepancies,” which are unavoidable because no matter how much we try, we can never actually tame the landscape.

“Designed by Patrick Blanc using his hy-droponic Mur Végtal system, the Musée du quai Branly greenwall is one of Blanc’s most famous vertical gardens, and one of the most highly photographed in the world. Facing the River Seine with a park and small streets in between, the micro-climate creates a good environment for a large variety of plants. A range of species were selected from the world’s main temperate zones, including North America, Europe, the Himalayas, Chi-na, Japan, Chile, and South Africa. Patrick insisted that the biodiversity represented in this vertical garden echo the cultural diver-sity of artists the world over, whose works were on exhibit in that very museum.”(10)

Patrick Blanc’s Vertical Garden at the Musée de Quai Branly.

Christine’s Ramblings Archives

Closeup images of wall - details

The wall contains over 15,000 plants and 150 different species from around the world. (9)

My final stop in Paris was to La Floral Promenade, or La Promenade Plantée, designed by architect Phillippe Mathieux and landscaped by Jacques Vergeley. This proved to be an excellent and beautiful escape from the city life below. The rail line was discontinued in the 70’s and the idea to preserve the viaduc rather than demolish it arose in 1979. (11)

It is a highly accessible, intensive green “roof,” or in better terms, “corridor” throughout the city.

Provides an escape from the city life below

Provides enjoyable views for nearby buildings

Types of green roofs

Potentials of green roofs

How cities are promoting more green roofs

extensive-thin growing medium, most suitable for roofs with a low load-bearing capacity

While the types of green roofs I saw during my travels varied from extensive to intensive, accessible to non-accessible, I found there are also more unconvential uses and potentials for this living architectural component.

extensive-Stuttgart, Germany

suggestive qualityvisible from street- Zurich

extensive-Rieselfeld, Freiburg, Germany

many levels of applicationcar garage green roof-Stuttgart

semi-extensive-Gemperle AG Company, Sins (Aargau)

integration with surrounding landscapeplayground feature-near Lucerne

semi-extensive-Stuttgart, Germany

integration and visibility in urban settingsLegoland visible from street - Berlin

semi - extensive- between extensive and intensive, has the ability to hold a slightly higher load

Germany Zoning certain districts that require green roofs on all flat roofs Collect taxes on anticipated storm water control or usage fees - taxes used to cover constructing, maintaining, and replacing stormwater management facilities Levy a 100% utility surcharge against owners of impervious roof covers - 13 German cities allow a reduction between 50% and 80% of the utility fee for using a green roof. 3

intensive-Stuttgart, Germany

accessibilityPromenade Plantee - Paris

accessible-Stuttgart, Germany

variability in material usagewater roof vehicle garage - Rotterdam

accessible-Rieselfeld, Freiburg, Germany

sustaianable city design ele-ment“Making of a city” exhibit - Rotterdam

inaccessible-Stuttgart, Germany

multiple uses- public square/garage roofTheatre Square - Rotterdam

intensive (roof garden)- has a very high load-bearing capacity and the deepest substrate level

accessible-designed for public access, has various features for public interaction

inaccessible-soley serves the purpose of roof greening, public interaction not considered in design

Basel, Switzerland Include green roofs in the city building ordinance

Stuttgart, Germany Reduced storm water taxes

Munich, Germany Subsidy program pays a portion of the costs

4

As my trip came to a close, I began to think about how one might define “quality” in terms of green roof design. With so many ways to green a roof, which way is best? On the one hand, there is the manufactured ap-proach utilizing various technologies versus the totally natural approach using local soil and substrate. In cities, though, nothing is natural or local anymore with all of the construction and transportation of materials. There-fore an approach using local soils would not be appropriate. For this reason, I hesitate to classify each project as good or bad, or rank it on a scale from 1 to 10 because each project is unique and as I stated previously, comes with its’ own intention. Through research, though, I think it is possible to find out what Best Practices are in this industry. From the tour, research, and travel contemplation, I developed a set of criteria for defining Best Prac-tices within the Green Roofing Industry.

Firstly, a change in the terminology based on a green roof’s achievement of the above Best Practices would separate some of the “greenwashed” projects from those that actually provide some sort of ecological advantages. Greenwashing occurs when the only aim of the project is to provide a green roof for the idea of having a green roof. The goal is to have some sort of vegetation growing on the roof but only for aesthetic and subliminal purposes. An ecoroof would meet all of the above criteria as well as having those basic benefits of most green roofs in general. The separation of the terms would allow for there to be incentives for the design and installation of these ecoroofs, thereby encouraging their promotion and proliferation. The next set of criteria come into play because there is a lot more to a green roof than the finished product. Sustainable installation and maintenance practices are important as well. An example of a sustainable installation practice would be like in the case of the BVB tram depot where they trucked in bales of miscanthus and simply layed it down on the roof as a layer of substrate. Sustainable maintenance practices would be those roofs which require little to no irrigation or do not require annual mowing. In the case of the Rathausgarage in Stuttgart, the cuttings that are trimmed from the vegetated roof are then returned to the company manufacturer (such as Zinco) and later recycled as fresh cuttings on a new roof. Local material usage is an especially impor-tant factor and also ties in with a decreased carbon footprint from installation. The final factor, having to do with ecology, is already being required in new green roofs in Basel, Switzerland. There are many simple ways as outlined previously of designing for an increased amount of habitat and biodiversity. Can a green roof be the impetus for subsequent creative ecological design? Through the separation of terminology, I think it is entirely possible in the case of ecoroofs. An ecoroof as defined by the above criteria re-quires more creativity at the architectural design phase. If the design of ecoroofs came with more incentives, we could see a lot more ecoroofs as well as much more interesting pieces of ecological architecture. In the future the importance of providing a habitat has the potential to override and alter certain architectural decisions. The architecture we will see coming out of this time period will be representative of green roof mandates and eco-logical consciousness. The emergent architectural style of this time will therefore be representative of people’s eco-minded values and beliefs.

Works cited

1. Brenneisen, S. Busse, H. From Pilot to Mainstream: Green roofs in Basel, Switzerland Abstract. http://pd.zhaw.ch/wbdb/downloads/N44155_190639357.pdf

2. Brenneisen, S. Space for Urban Wildlife: Designing Green Roofs as Habitats in Switzerland. 2010. http://ur-banhabitats.org/v04n01/wildlife_full.html

3. Greenroofs.com. “Industry Support.” 2011 http://www.greenroofs.com/Greenroofs101/industry_support.htm

4. Currie, Beth Anne; Lawlor, Gail; Doshi, Hitesh; Wieditz, Ireen. “Green Roofs: A Resource Manual for Mu-nicipal Policy Makers.” Canada Mortgage and Housing Corporation (CMHC). 2006. http://www.cmhc-schl.gc.ca/odpub/pdf/65255.pdf?lang=en

5. International Green Roof Association. “Green Roof News 1/2012.” Ed. Wolfgang Ansel/Sabine Früh.http://www.igra-world.com/links_and_downloads/images_dynamic/IGRA_Green_Roof_News_1_2012.pdf

6. ZinCo Green Roofs Australia. “Project Report Sports hall Clara-Grunwald-School, Freiburg.” Authorized by ZinCo GmbH.http://www.zincoaustralia.com.au/references/images/ppd/ZinCo_DE_Clara_Grunwald_School.pdf

7. Projektgruppe Rieselfeld. “The new district of Freiburg-Rieselfeld: a case study of successful, sustainable urban development” January 2007. www.energycities.eu/IMG/pdf/freiburg_sustainable_urban_dvt.pdf

8. “Freiburg Wulf Daseking” video. Mar 9, 2011. accessed Oct. 1, 2012. http://www.youtube.com/watch?v=RaCmIEcplKg&feature=related

9. West 8. “Borneo-Sporenburg.” Accessed Oct. 1, 2012. http://www.west8.nl/projects/borneo_sporenburg/

10. Velazquez, Linda. “GPW: Musée du quai Branly.” Sep. 26, 2011. Accessed Oct. 1, 2012. http://www.green-roofs.com/blog/2011/09/26/gpw-musee-du-quai-branly/

11. Thuring, Christine. “Christine's ramblings archives.” Greener Impressions of Paris, 2010. Sep. 6, 2010. Ac-cessed Oct. 1, 2011. http://www.greenroofs.com/archives/christines_ramblings.htm

Photos-Moos Wollishofen lake water-treatment plant constructionhttp://www.greenroofs.com/projects/pview.php?id=680 -aerial view Rieselfeld http://www.fwtm.freiburg.de/servlet/PB/menu/1174687_l2/index.html -identified green roofs Rieselfeld http://www.freiburg.de/pb/,Lde/208560.html-Zinco project reporthttp://www.zincoaustralia.com.au/references/images/ppd/ZinCo_DE_Clara_Grunwald_School.pdf-West8 Borneo Sporenburghttp://www.west8.nl/projects/borneo_sporenburg/ -Christine's Ramblings Archiveshttp://www.greenroofs.com/archives/christines_ramblings.htm