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Students on Green Roofs

What is the Students Page?  A place where the Student Editor and all students can post Student Guest Feature Articles about projects, research, and other happenings.  Make contacts with other students and companies - all free of charge.

Christine Thuring is the Student Editor and writes a biannual newsletter entitled "Green roofs on the curve" see below.  Read more about her here, and contact her at:  christine (at)

We are currently Under Construction, so send us your ideas as we continue to develop the following sections exclusively for you:

  • Student Projects
    (Research, Design, Design/Build) -
    Share your greenroof project with us!  We can all learn from each other and it's encouraging to see what school is doing what to promote greenroof architecture.  Our readers want to see what you're researching or you've done, from the initial design process through construction to project completion.  Tell us about struggles and lessons learned - and maybe what you would do differently next time.

  • Student Guest Articles - Read our articles about projects, research, ideas, experiences and more submitted by students from around the world, as well as our own Student Editor.  Submit your article, too!

  • Book Reviews - Read or submit book, magazine, or article reviews about sustainable design in general or greenroofs.

  • Student NewsLinks - Read about students and their projects in the news.  Submit newslinks to us for posting.

  • ResearchLinks - Not just for students, of course, but make sure to visit to see what everyone is up to.

Great Research Resource:  Green Roofs for Healthy Cities - Research Committee
The goal of the Green Roofs for Healthy Cities Research Committee is to improve the quality and quantity of green roof research at the product, building, and community scales and to help select and peer review Research Track papers for the annual conference.
They have compiled a great bibliographical resource of researchers in various fields, offering an overview of current and planned research, lists contact information for greenroof researchers, and more.

See the BIBLIOGRAPHY OF GREEN ROOF ARTICLES IN ENGLISH (PDF updated 4-16-06), which contains peer reviewed scientific journal articles, books, proceedings from meetings, and other reports.

January 2013

students on green roofs

Question: What’s holding us back?
By Christine Thuring, Student Editor

By now, it’s common knowledge that the promotion of ecosystem services to cities and towns is key to a healthy future on this urbanising planet.  Happily, this future is being realised as we speak, as remarkable projects around the world are continually demonstrating what is possible.  Finally, decades’ of research, demonstration and development of green technologies have brought us to a point in time where we’re living within our own progress: the stage is set for our transformation from the industrial to the ecological age.

Question, then.  With all the knowledge, experience and conviction of how important living architecture and green infrastructure are, why are so many of the projects that do get built still novel and exceptional... >>>MORE

October 2011

students on green roofs

Virtual Conferencing: WOW, it’s NOW!
By Christine Thuring, Student Editor

My newsletters lately have tended to ruminate on the life, values and challenges of being a green professional.  I suppose this is because the future seems very tangible and near.

Perturbation about attending international conferences has been especially troublesome to my eco-morale.  In particular, I’ve been unsure how to reconcile the pros of attending international conferences (in the interest of improving the world) versus the cons of travel and associated footprints... >>>MORE

December 2009

students on green roofs

A Drop in the Bucket
By Christine Thuring, Student Editor (Download as a PDF)

Christine atop the Vancouver Public Library Green Roof in summer, 2007

Over Thanksgiving this year, I found myself in a discussion about the choices we make on behalf of the environment and planet.  It started before dinner over a beautiful glass of wine, when an uncle asked why I choose not to eat meat.  Keen on learning more about his organic garden and wishing to keep the conversation pleasant and simple, I opted for the simplest answer: “I just don’t like it.”  It seemed like he’d accepted this answer, but before I could launch into my curiosities he queried, “So you’re not one of those people who abstain from meat on behalf of the environment?”  Ach.

His take was that many of the environmental choices we make are personal sacrifices that will never be sufficient to effect the intended change.  “If you really want to effect change,” he said, “you need to target the big players: governments and policy, corporations and multi-nationals.  Until they change their ways, your choices are just a drop in the bucket that will never amount to anything.”

In genuine contemplation, I raised the point: if it weren’t for individual drops to fill it, what’s the bucket for in the first place?  As Lao Tzu put it in 6th century China, a vessel is a vessel because it is empty.  The empty space which defines its form also defines its usefulness.

Since I would travel to the World Green Roof Infrastructure Congress (Cities Alive!) in Toronto after Thanksgiving, the discussion got me thinking about the challenges associated with being a passionate “green professional.”  On the one hand, being part of the green professional community is exciting and inspiring: inter-disciplinary engagement with innovation, involvement in a growing community and market, and witnessing policy changes and adoptions of green practices can fuel great optimism for a bright future.  Yet in spite of all the positive aspects, “green” contributions are also rightly subjected to criticism and doubt, from both internal and external sources.

Green professionals whose career decisions are driven by personal determination may be challenged by demons who question the purpose or effectiveness of our choices.  On good days, all is well because we’re doing what we believe in. On bad days the demons remind us of the insurmountable scale of the challenge, allowing disenchantment to seep  in. We’ve chosen our work and engagements, which is empowering and liberating, but we may still doubt the efficacy of our contributions.

Do you ever find it difficult to keep your morale up, given that the system in which we continue to function is dinosaurian by design?  I’ve long wondered how best to protect the happy feelings associated with small accomplishments, especially in face of soul-sucking counterweights like the Tar Sands or runaway climate change.  Are personal contributions like boycotting industrial meat, composting organic waste or helping to advance green roof technology valuable, really, or are we deluding

Holding to the analogy, then, I was one droplet in a small watershed of professionals from all corners of the earth which united in Toronto to celebrate green roof potential and progress (at Canada’s biggest-ever green roof party).  Hurrah!  But hey, what about the negative impacts from such an international meeting?  Booh!  To reconcile this conflict for myself, I put the “drop in the bucket” analogy to test, with the hopes of finding a place where optimism is a protected gem and criticism is constructive and never defeating.

Seeking out opportunities for minimizing my personal environmental impacts related to the gathering, I found that making mindful choices was an empowering way to ease my sense of conflict.  Simply by paying attention to food and beverage and taking only what I needed, for example, I was able to create a personally holistic sense of place within the gathering as a whole.

Consumption of food and drink is a simple way to express choice for content and quality, as well as packaging and waste. Emissions aside, on international flights most (if not all) passengers will use at least one set of plastic cutlery and at least one cup.  For my travel to and from Toronto, I opted out of this system by using as little from the carrier as possible.  Before boarding the plane, I filled my travel mug (with my favourite tea) and replenished my water bottle.  On the plane, I took only what I wanted and left untouched as much plastic stuff as possible.

The important thing here is that these efforts were personal choices: they made me feel happy even if the landfill could care less.  I’ve come to recognize that likening one’s contributions to large-scale change is painful.  The few plastic cups that I didn’t use were trash from the moment they were created, simply by their design of disposability.  By contrast, I love my travel mug.  If anything, our self-centered choices represent (part of) the change we hope for; by acting upon them we are demonstrating our commitments both to ourselves and to others. And however miniscule the impacts from these choices, our experiences with them can help us better understand the barriers and limits for large-scale change.

As Thanksgiving dinner began to emerge from the warm oven, my uncle and I found a satisfying consensus.  Further to the need for “big-player” reformation (i.e. corporate and political), we agreed on the importance of every individual person doing their best.  In this case, this would include making mindful choices which challenge and reward, living within our means, and being compassionate for those with less.

I’m still experimenting with this, but now whenever I feel the unhappy uselessness of being a tiny drop in a giant bucket, whether in my work, beliefs or perceptions, I go through a quick series of corrections.  First I allow the feeling of smallness to soothe me.  I imagine my tiny form floating on a calm, gigantic blue ocean.  It’s very relaxing to feel unimportant.  Then, if it appears that the root of my conflict is derived from external sources (e.g. anxiety about climate change), I try not to let the gravity of the situation shut me down, but allow it rather to engage me in an immediate task (e.g. writing a letter).

Fundamentally, we gain the most when we do things without seeking approval or reward, not expecting anything from anyone else, and when we hold true to our values and challenge our limits.  When faced with disenchantment and personal conflict, we can find respite, rather than anxiety, from our smallness.  In a similar light, isn’t it also soothing to recall that we don’t actually know everything?  With my out-breath, I know that I cannot know what the future holds, and that the past is finished and done. With the in-breath, I know that all I know is now, and that now is good.

I’d love your feedback!  Please email me any thoughts, ideas, comments, or questions that this column might inspire, or consider posting them on the Forums page!

Kind regards,

Christine Thuring
MSc Horticulture (2005), Penn State Centre for Green Roof Research

Publisher's Note:  If you wish to get on Christine's mailing list, send her an email: christine (a) .  Read more from the Student Editor under Christine's Ramblings.


April 2008

students on green roofs

By Christine Thuring, Student Editor (Download as a PDF)

Hello green roof enthusiasts!

If you’re coming to Baltimore, for the 6th annual Greening Rooftops for Sustainable Communities Conference, Awards and Trade Show, please stop by the booth (#108) to say hello! In the meantime, I’d like to share with you a little bit about what I’ve been up to and what this conference holds.

I’ve been very busy the last few months organizing North American’s first green roof tours to Europe: Green Roof Safari! This 6 day tour runs from Frankfurt to Zürich and features a diversity of green roof projects and conversations with local policy-makers, designers and researchers. Offered from Sept. 8 – 13 and Sept. 21 – 28th, the tours sandwich the World Green Roof Congress (Sept. 17 – 18) in London UK. Visit

Left: Municipal, residential, commercial, industrial, institutional green roofs; Right:  Vetsch Earth Houses; Hundertwasser, living roofs: Big and small, we will visit them all!

At the GRHC trade show, you can find postcards and brochures about Green Roof Safari at the booth (#108). My colleague and co-founder of the tours, Jörg Breuning, can tell you more, too, at the Green Roof Service booth (#318).

Since coming to Vancouver in 2006, I’ve been intrigued by the extensive moss communities that dominate this bioregion. The mossy roofscape seems to me to embody everything that extensive green roofs are meant to be. Resilient, regenerative, and self sustaining, these spontaneous communities do not require human inputs, remaining green and functional year round.

If we relieve ourselves of aesthetic conditioning (i.e. “unwanted plants are weeds”), might these moss roofs have lessons for us? Do they express a genius loci – spirit of the place – in a way that we’ve never considered? From a plant ecological perspective, what can we take from the patterns of colonization, the conditions for establishment, and the processes of natural succession? From an economic point of view, what place do mosses truly hold within the chronology of roof degradation? Do these diminutive organisms (which lack roots and vascular tissue) really cause roofing products to deteriorate? Or are mosses just indicators that the roof is degrading, as they take advantage of pre-existing puddles and cracks?

The old tar & gravel roofs of Granville Island are extensively covered with moss, as seen from the Granville St. Bridge (Fig. 3). With a couple roofs in mind, I tracked down the property manager and was granted access for a vegetation survey. With the help of a maintenance personnel (and a scissor lift) and bryologist colleagues (people who know their mosses), two inventories of 3 roofs were conducted in 2007 and 2008.

Granville Island greenroof; photo courtesy Christine ThuringLicorice fern; photo courtesy Christine Thuring

Left: If Granville Island’s green roofscape were intentional, this part of Vancouver could rival European cities for surface area covered by green roofs. Right: Licorice fern (Polypodium glycerrhiza) is a native fern which occurs in protected corners of mossy communities, whether the crotch of a tree or the protected corner of a roof.

The diversity on some of the roofs we surveyed was variable, depending on location, microclimate or other factors we are attempting to determine. For example, the roof of Waterfront Theatre supports 3 species (2 mosses and one grass), while the roof of the Parking Garage supports over 30 species, including both native and non-native grasses, ferns, herbs and Sedums.

As Granville Island begins a major renovation project for its infrastructure and many of the buildings, green roofs will likely be included in the plans. When initially approached, the property manager wondered if it would be possible to transplant these well-established moss communities onto “intentional” green roofs. Hurrah! This could represent the next phase for this study.

If you have any thoughts, ideas or opinion, please email me.

Hope to see you in Baltimore!




September 2007

students on green roofs

By Christine Thuring, Student Editor (Download as a PDF)

Christine Thuring

Like the Spring 2007 Students on Green Roofs Ramble, this one again contemplates how the green roof industry can stay ahead of the curve. Having a sense that this theme will persist, I’ve made this concept an entity of its own, “GREEN ROOFS ON THE CURVE.” I’d love to know your thoughts, ideas and comments on any of the content discussed; email me!

Have you heard the term “Peak Oil” lately? A ground-breaking model, the Hubbert Peak Theory, gained wide acceptance in its time, then died down in the societal cycling of ideas. This ramble will revisit the theory and attempt to draw connections between Peak Oil and green roofs, as a way of presenting challenges for the green roof community to stay ahead of the curve. By weaving lessons from the past into our current endeavours, through dialogue and practice, we can each contribute towards the realization of a healthy vision of the future.

The Hubbert Peak Theory refers to a singular event in history: the peak of the entire planet's oil production. After Peak Oil, the rate of oil production on Earth will enter a terminal decline. Without getting into the details of the model, I’ll defer to George W. Bush’s January 2006 State of the Union address, in which he admitted to “a serious problem: America is addicted to oil.”

What does this mean for the green roof industry? Just as Peak Oil will be a major test for our society, it also represents a challenge for the green roof industry. As individuals and “dirty” industries begin to ask themselves how they can reduce their dependence on oil, the green roof industry, too, should examine its relationship to fossil fuels.

First of all, green roofs must become better known for the many solutions they offer. A major barrier to green roof implementation and acceptance is that they are poorly understood. I recently saw “Escape from Suburbia,” which featured many great people and projects engaged with their understanding of Peak Oil. The importance of food security received considerable air time, but not a single mention was made of rooftop gardens. Were green roofs absent from the discussion on urban agriculture because the film-makers weren’t aware of them, or did they simply not make the cut?

In addition to better representation in the media, the benefits of rooftop greening need to be more fully explored. For example, is it valid to think about green roofs as significant carbon sinks? Will the roofs we’re designing and building today support our cities in bumpy times of oil shortage? Do they truly support the triple-bottom line of local economies in their function? Do their embodied energies vindicate their value? And beyond their environmental benefits, will green roofs help to lead the way towards urban resilience? If so, how will this collaborative role be established and managed?

On the topic of urban agriculture, some developments require a certain percentage of built space to be offset with garden plots. In Vancouver, the new Olympic Village for the 2010 Games will allot 30% of the surface area to garden plots. The Vancouver Green Strategy, due in the near future, is also anticipated to devote a certain percentage to urban agriculture.

As far as economic value goes, we know that rooftops can generate revenue by growing herbs for restaurants, but what about growing cash crops, like cut flowers? If oil really becomes scarce and expensive, then at least the infrastructure would be in place for food production. In the meantime, locally grown flowers would be nice! Certainly the design would be dramatically different from that of an extensive Sedum roof, but many of the benefits could still be maintained and measures taken to deal with anticipated issues, like fertilizer and water use.

Ecologically, if we decide to re-instate ecosystem services and functions to our urban areas, wet roofs could not only close the loop on building water use, but also create valuable habitat and improve the urban climate through greater cooling benefits. Keep your eyes open for the next issue of Green Roofs for Healthy Cities’ “Green Roof Infrastructure Monitor” for an article about wet roofscapes. Whatever the system or design on top, connecting a building to its immediate environment through biofiltration can dramatically reduce its ecological footprint.

Peak oil is well underway, and prices will likely continue to rise. The extraction that continues today has a very low ‘energy return on energy investment,’ and represents the greed of annihilist petrol giants suffering from social and environmental myopia. The green roof community can take the higher path. By integrating sustainability principles into the practical needs of this emerging industry, we can reduce urban dependency on oil. With intent and collaborative genius, green roofs can contribute to a prosperous and secure future for all.

Please email me with any ideas, comments, concerns or questions that this column inspires, or post them on the Forums page!


Spring 2007

students on green roofs

By Christine Thuring, Student Editor (Download as a PDF)

Climate change is recognized as the biggest threat facing humanity, and the green roof community can stay ahead of the curve.  First let’s work together and with other disciplines to develop meaningful practices and policies: strive for designs that support ecosystem functions, biodiversity and health; roofscapes that help to improve local conditions; buildings that provide comfort and resilience in face of an uncertain future.

We can also align ourselves with the anticipated evolution of market responses to climate change.  Carbon has become a hot currency item, for example, and green roofs can serve as partial solutions for cutting carbon emissions in several ways.  In some cases research is ongoing; in others we might consider investigation.  In all cases, let’s collaborate and contribute some meaningful ideas to a healthy future on our planet!

There is no lack of research topics for green roofs but if we root our attention to the perspective of climate change speculations we might tackle region-specific items like:

Thermal performance.  A number of research institutes have quantified the heat flux mitigation of various green roof types and measured the amount of energy conserved in different seasons.  Inevitably, such data will be required for any climatic region where green roofs are to be considered a strategy for achieving this benefit.

Carbon sequestration:  As with ground-level planting projects, green roofs don’t qualify for ‘Gold Standard’ carbon offsets but, official certifications and currency exchange aside, what is the carbon balance of a green roof?  How do shallow Sedum roofs compare with more diversely planted roofs?  What about nutrient cycles?

Sustainability:  Further to Life Cycle Analyses of green roofs, what are the ecological footprints of the individual green roof components/ materials?  What constitutes their manufacture; can they be locally produced?  Are different regions developing their own sustainable green roof infrastructure?

These just off the top of my head.  If you have any thoughts, please consider posting them to the Forums page!  See you in Minneapolis!


October 2007

students on green roofs

By Christine Thuring, Student Editor

Hi there,

Instead of the traditional Students on Green Roofs newsletter, this quarter I’m circulating a document that was prepared for the May 2006 Green Roofs for Healthy Cities (GRHC) Research Committee meeting.  The "Research Summary based on GRHC Bibliography" document summarizes the English-published green roof literature as listed in the GRHC Bibliography, with the intent of illuminating areas of missing information and knowledge gaps.

It's as comprehensive as the english-language bibliography permits, which has since been updated, so take it for what it's worth.

All the best,


Spring 2006

students on green roofs

By Christine Thuring, Student Editor

(Download as a PDF)

Hello hello!

Isn’t spring such an optimistic time? Not only because the days are getting longer, but also because of the exciting developments of late. Malcolm Gladwell’s 2001 bestseller, The Tipping Point: How Little Things Can Make a Big Difference, sets the tone of this newsletter, and current events on greenroof progress supply the optimism.

In case you haven’t read it yet, The Tipping Point examines social epidemics, or how ideas, behaviour, messages and products sometimes behave like outbreaks of infectious disease. Moving away from the epidemiological meaning, the tipping point represents the point at which the line on a graph starts shooting straight upwards. It's the critical mass, the boiling point, at which small ideas become epidemic and, eventually, the norm.

In our case of interest, the gradual awakening of common sense may be enough to tip greenroofs into contemporary application. For example, ever more American companies are following German suit by including greenroofs on their buildings, which could change the appearance of the commercial/ industrial landscape forever. In 2003, Ford included a green roof in the renovation of its legendary Rouge centre, and this summer the world’s largest retailer, Wal-Mart, will open its first U.S. store with a green roof, in a western suburb of Chicago.

Hurrah hurrah!! But hey… isn’t it about time?! In 2001, Wal-Mart Stores Inc. settled with the U.S. EPA for its many violations (at 17 locations) to the Clean Water Act, all of them due to construction impacts on nearby streams and watersheds. The settlement included a hefty fine as well as a financial commitment to develop environmental management plans focusing on storm water management. Enter greenroofs, naturally!

Green roofs are entering more and more municipal policy plans, too. In the early months of 2006, the City of Toronto approved a green roof strategy, which commits to the installation of green roofs on new and existing City buildings. A North American survey from 2005 estimated that 15 local governments are engaged in establishing policies specific to green roof investment, and that another 62 local, state and federal governments are implementing the USGBC’s LEED™ green building standard, which provides further support for green roof investment (15 possible points, hello!).

Still, these are only first steps. Little things can make a big difference, and the tipping point can tip the other way as well. When low bids compromise quality, for instance, poor standards will create a haze of distrust around greenroofs, and could bring the entire market crashing down before its full potential is realized. As R. Buckminster Fuller once stated, “If humanity does not opt for integrity we are through completely.” On a smaller scale, this assertion applies to all emerging green roof markets.

Moving to the scale of the Student Forum, each of us can influence the tipping point by ensuring integrity of information through our studies, research and how we share our information. As you know, is attempting to compile a comprehensive body of Global Greenroof Projects. Since this is a time-consuming undertaking, we are currently exploring ways to get students involved with the growing Database, especially in compiling and verifying greenroof projects from all over the world. Interested?

If you have any thoughts with regards to these ramblings, please drop me a line! For sustained optimism, take a look at some of the references and links below.

All the best, happy spring, see you soon?


N.B. The “NewsLinks” page on offers updated news pertaining to green roofs. It’s a great way to stay on top of things without having to do the searching yourself!

City of Toronto. 2006. Green roofs. 16 March, 2006. <>

Dean, T. 2006. Wal-Mart on schedule, should open this summer. 8 February, 2006

Friend, G. 2006. Sustainability - At the Tipping Point? 5 March, 2006. <>

Gladwell, M. 2002. The tipping point: how little things can make a big difference. 2nd ed. Malcolm Gladwell, U.S.A.

Peck, S. and D. Goucher. 2005. Overview of North American policy development and the policy development process. Proc. 3rd Int. Green Roof Conf.: Greening rooftops for sustainable communities 3:8-31.

United States Environmental Protection Agency. 2001. U.S. reaches water pollution settlement with Wal-Mart: Retailer to pay $1 million fine, establish environmental management plan. 14 January, 2005.$1M.htm

October 18, 2005

students on green roofs

Publisher's Note: This response was posed to Christine after she wrote her October 2005  Newsletter.  Christine sends out the "Students on Green Roofs" Newsletter to students, faculty and others interested in The Student Forum.

A reader in Maryland writes: I know biodiversity is good; however, honestly, I do not actually want critters abiding above my abode (or office). About the best I can get myself to co-exist with on a daily basis in the buildings I have owned and/or maintained would be bats (they eat mostly flying insects not grubs and hibernate in winter) and bees (if there were sufficient trees in the area, I would love to see rooftop apiaries sustaining honey and pollen production.) (Eventually decaying) logs and the circles of life they would support make me dizzy just thinking about the possibilities.

Christine:  I can see your point. Owners who permit green roofs for biodiversity on their own buildings would ideally be into that idea, and may rejoice in the very aspects that make others cringe!! That would be their choice of design. Unless, of course, such designs were mandated by law, for example the regenerating construction zones of London which harbour protected species. The only choice those owners have is either include a living roof or forget building!

The rooftop is a surface that a building has encroached upon the natural world, right?  If this elevated surface is not being used for anything, isn't it only fair to offer it to misplaced critters? They have no voices, and we might be impoverishing our own existence by ignoring them. You never know.

If the green roof, and the habitat it could potentially harbour, is a sealed surface that is related to the building interior no differently than a ground-level parkette, then is this distant co-existence still disquieting? More flying insects will undoubtedly pass by the windows, but the earth-bound critters wouldn't move too far from their habitat.

I'm glad for your feedback! Being an ecologist makes me insensitive to items that may cause repugnance in others, and responses like yours get me thinking. I do believe that more contact with nature would improve the human condition. Doesn't the sight of a butterfly up close take you to another place, even if only for a split second?

And to contemplate that there is a much bigger, more complex world out there than any of us is capable of being truly aware is a mind-boggling, earth-connecting experience. The ever-urbanizing populace has few chances for encountering nature, and so few reasons to think about it or to know and appreciate the magic that exists on our special planet.

All the best, keep in touch!! Christine :-)

contact the student editor

We welcome all your comments, suggestions and input!  Send me an email if you would like to be on my Student Newsletter list.  Please contact:

Christine Thuring
christine (a), The Student Forum

Christine Thuring graduated in Spring 2005 as a MSc student in Penn State's Department of Horticulture's Centre for Green Roof Research.  Her project studied the effect of different medium depths on plant performance, seeking a balance between depth and effective green roof function (stormwater retention, persistent plant community).  Read her January 2005 Student Forum Editorial and her June 2004 Student Guest Feature.  Read more about her here, and:

Past Christine's Ramblings.
Past Exclusives.

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