GRP, is our
(2005). He writes an occasional architectural
column entitled "A
View from the Sky Trenches," where he
selects and discusses pertinent greenroof industry
Patrick has a
degree in architecture and lives in Seattle,
Washington, principal of
hadj design, a green roof design-build
company. Patrick is also director of the
Northwest EcoBuilding Guild's Green Roof Project.
PKC is also a trainer for the Green Roofs for
Healthy Cities Green Roof 101, 201, 301,
& 401 Courses.
A View from the Sky Trenches
A Guide to Phytoremediation:
A Symbiotic Relationship with Plants, Water & Living Architecture
By Patrick Carey, the Architecture Editor
Not only do we kill life under the footprints of our buildings. But the processes that produce our building materials, and in other ways support our existence, also produce a toll on the environment. This waste takes the form of air, water, and land pollution. There are other effects as well.
For example, due to the acceleration of Himalayan glacier reduction three major water courses, the Ganges, Mekong, and Yangzi rivers, are providing less and less potable and irrigation water for one of the most, if not the most, densely populated areas on earth. Mark Twain once said, “Whiskey is for drinking. Water is for fighting over.”
The last time I heard many of the countries in this region are having armed conflicts and also several of them have nuclear arsenals. In Europe a similar problem is developing with Alpine glacier reduction. In the U.S. the Ogallala Reservoir system is being increasingly stressed. This is the major source of subsurface water between Montana and Texas. Think Dust Bowl.
Our ability to reuse the water we pull up from wells, melt from glaciers, and collect from precipitation will be critical in avoiding untold misery heading our way. By reducing the extent to which we ship our gray water to salinated water bodies and by increasing our ability to reuse this water, we can start stemming this tide of waste.
I first became curious about this subject when I was trying to figure out a way to put green roofs on structures that were burdened by a large cooling load. Most hot areas are short on water. So, irrigation water for green roofs had to come from some source other than potable sources. Ahah! Gray water! I had heard of plants cleaning grey water from wetland and bio-swale research. In the course of my readings I ran across some phytoremediation literature. This was followed up by an encounter with a Phytoremediation conference I attended almost by accident.
I found out that there are annual conferences, peer reviewed journals, and a growing body of research literature and field studies on the subject. This seemed like a natural fit for the world of green roofs and living walls. The first two things I learned was that it was a new and interdisciplinary field and that this was a complex topic.
The term phytoremediation was first coined in 1995. This shows how new a field of study this is. It is the study of the remediation effects of plants and their immediate environs. Over the past 40 or so years there have been a number of attempts to use plants to clean up our messes. One of the earliest of studies was NASA in trying to find a way to clean up air pollution on space vehicles¹. NASA came up with a list of plants that targeted certain pollutants such as volatile organic compounds, formaldehyde, benzene, etc. NASA also carried out experiments in plants cleaning up NASA sites on earth. When compared to the expense and energy embodiment of manufactured filtration equipment, plants were shown to be more efficient.
The Army Corps of Engineers have been using plants to clean up munitions ranges by planting plants that target pollutants like toluene and heavy metals.
Experimental environments like the Bio Dome/Bioshere project, Earthship, etc., have long been sources of research and speculation.
There are four free downloadable publications on the subject.
1. Low Impact Development, Technical Guidance Manual for Puget Sound offered through Washington State University Pierce County Extension Service. Appendices 5 and 6 offer an introduction to the subject (www.pierce.wsu.edu).
2. Introduction to Phytoremediation through the National Risk Assessment Research Laboratory, Office of R & D, U.S. E.P.A. (EPA/600/R-99/107)
3. Phytoremediation Technical and Regulatory Guidance and Decision Trees, Revised Interstate Technology & Regulatory Council, Phytotechnologies Team.
4. Handbook of Phytoremediation (Environmental Science, Engineering, and Technology), Ivan A. Golubev, Nova Science Pub.
5. I highly recommend carefully going through the suggested readings, sources of information, and footnotes of these publications. There is another book I recommend that relates to this subject and also to some other subjects in planned articles: Soil Microbiology, Ecology, and Biochemistry Ed. By Eldor A Paul through Academic Press.
If read in sequence, these offer a good introduction to the subject. Green roofs, living walls, and other planted elements are being used to serve phytoremediation functions.
There are also a number of journals that feature related topics.
1. Bioremediation Journal
2. International Journal of Phytoremediation
3. Environmental Forensics
4. European Journal of Phycology
5. Journal of Plant Interactions
6. Plant Ecology & Diversity
7. Plant Biosystems
8. The EPA has a number of very informative publications on brownfield site remediation and other topics related to plants cleaning up after us.
The International Phytoremediation Society holds annual conferences. The Interstate Technology and Regulatory Council offers a short course on Phytoremediation.
A simple Google search will point out a host of more sources of information on this
As we learn more about phytoremediation mechanisms, we have spotted previous errors in our assumptions and conclusions of these processes. For one thing, there are several forms of phytoremediation. For example, if the process takes place in the rhizosphere, it is called “rhizo,” if in the plant tissue it is called phyto…
Another distinction is the phytoremediation process itself. There is sequestration, hyper-accumulation, volatilization, extraction, filtration, and stabilization that have been identified so far.
Degradation, comprised of rhizodegradation, phytodegradation, and phytovolatilization, molecularly transforms the contaminant. In the rhizosphere (in the area bordered by 1 inch distant from the root hairs) fungi, bacteria, microbes, plant enzymes, and soil chemistry combine to break down contaminants such as petroleum hydrocarbons, PCP, perchlorate, pesticides, PCB’s, and other organic compounds. In the plant tissue, through phytodegradation, organic compounds such as chlorinated solvents, methyl bromide, DDT, PCB’s, phenols, nitriles, and nutrients are chemically transformed. In the leaf area through phytovolatilization plants aerate and dilute pollutants such as arsenic, tritium, mercury, and chlorinated solvents. This process also finishes the job of phytoremediation started by other such processes that partially work on the pollutants before reaching this stage.
Extraction, comprised of phytoextraction/phytomining, rhizofiltration, and phytovolatilization, is a process whereby plants extract contaminants from soils.
Through phytoextraction, metals, perchlorate, and organic chemicals are taken up and concentrated in plant tissues. Through rhizofiltration, fungi, algae, and bacteria bind metals, nitrate, ammonium, phosphate, and pathogens. Through phytovolatilization contaminants such as Se, tritium, Hg, chlorobenzene, and other chlorinated solvents are diluted and dispersed in the air and soils in lower concentrations for further exposure to all the above processes.
Contaminant Immobilization, comprised of phytostabilization and rhizofiltration, prevents contaminant movement, or leaching. Through phytostabilization and rhizofiltration contaminants such as metals, phenols, phosphates are trapped and concentrated.
Graphic Source: Pilons-Smits.Annu.Rev. Plant Biol 2005, 56:15-39
Other processes such as sequestration, hyperaccumulation have also been used to describe various processes. Fundamentally, plants and their immediate environs of the rhizosphere and the air around the foliage and stems serve to molecularly alter, concentrate and render inactive, or dilute for further processing many contaminants. Researchers at Penn State University have worked with the potential of plants cleaning grey water. Phyto-active living walls are in use cleaning indoor air pollution.
Different plants have different processes and targets. Their effectiveness can be greatly enhanced by our controlling what goes into the gray water in the first place. It can also be enhanced by some simple filtration and aeration mechanisms to prepare the pollutants for processing by the plants and their allies.
Some examples of plants of interest:
Dealing with Aromatic Contaminants (like benzene, toluene, xylene, formaldehyde, volatile organic compounds):
Alpine pennycress (Noccaea fendleri)
Dandelions (Taraxacum officinale)
Grasses (like Rye (Secale cereale), Fescue (Festuca), Bermuda (Cynodon dactylon), Sorghum)
Indian Mustard (Brassica juncea)
Nettle (Agastache urticifolia)
Phreatophyte trees (e.g. Poplar (Liriodendron), Willow (Salix), Cottonwood (Populus), Aspen (Populus))
Rapeseed (Brassica napus)
Dealing with Wood Preservatives (like arsenic and PAH’s):
Brake fern (Pteris L.)
Indian mustard (Brassica juncea)
Fibrous rooted grasses as listed above
Phreatophyte trees as listed above
Dealing with Leachates (like PCB’s, pesticides, herbicides):
Grasses, as above
Legumes (such as Clover (Trifolium), Alfalfa (Medicago), Cowpea (Vigna)
Osage Orange (Maclura pomifera)
Trees, as above
Dealing with Radiation:
Indian Mustard (Brassica juncea)
Pigweed (Amaranthus L.)
Dealing with Petroleum:
Alfalfa (Medicago sativa L.)
Grasses, as above
Hybrid Poplar (Liriodendron)
Indian Mustard (Brassica juncea)
Dealing with Nitrates:
Grasses, as above
Legumes, as above
Trees, as above
Bulrush (Blysmus Panzer)
Cattail (Typha L.)
Pondweed (Potamogeton L.)
Arrowroot (Maranta arundinacea L.)
Duckweed (Lemna L.)
Parrotfeather Treefern (Cyathea andina)
Eurasian water milfoil (Myriophyllum spicatum
Sweet flag (Acorus americanus)
Water Hyacinth (Eichhornia Kunth)
Water Lilies (Nymphaea)
Other plants used in various air phytoremediation functions:
Prayer Plant (Maranta leuconeura)
Peace Lily (Spathiphyllum)
Snake Tongue (Sansevieria)
English Ivy (Hedera helix)
Spider Plant (Chlorophytum comosum)
Fragrant Dracaena (Dracaena fragrans)
Seifriz’s Chamaedorea (Chamaedorea seifrizii)
Plants used in Water and Soil Phytoremediation:
Western Wheatgrass (Agropyron smithii) - (hydro-carbons, TPH, and PAH’s through rhizodegradation)
Blue Grama (Bouteloua gracilis) - (hydro-carbons, TPH, and PAH’s through rhizodegradation)
Bermudagrass (Cynodon dactylon) - (hydro-carbons, TPH, and PAH’s through rhizodegradation)
Parrotfeather Watermilfoil (Myriophyllum aquaticum)
Canada Wildrye (Elymus Canadensis) - (hydro-carbons, TPH, and PAH’s through rhizodegradation)
Perennial Ryegrass (Lolium perene) - (hydro-carbons and PAH’s through rhizodegradation)
Tall Fescue (Festuca arundinacea) - (pyrene and PAH’s through rhizodegradation)
Red Fescue (Festuca rubra) - (hydro-carbons through rhizodegradation)
Bird's Foot Trefoil (Lotus corniculatus) - (hydro-carbons through rhizodegradation)
Yellow Sweet Clover (Melilotus officinalis) - (hydro-carbons and TPH through rhizodegradation)
Switchgrass (Panicum virgatum) - (PAH’s through rhizodegradation)
St. Augustine Grass (Stenotaphinam secundatum) - (TPH and PAH’s through rhizodegradation)
Red Clover (Trifolium pratense) (TPH through rhizodegradation)
White Clover (Trifolium repens) (PAH’s through rhizodegradation, PCB’s though nitrogen fixing and metabolization)
Common Sunflower (Heleanthus annus) (PAH’s through rhizodegradation)
Buck's Horn Groundsel (Senecia glaucus) (organic contaminants and PCB 77 through phytodegradation)
Dwarf Rose (Rosa spp: R.gymnocarpa)
Buffalo Grass (Buchloe dactyloides)
False Indigo Bush (Amorpha fruticosa) - (Accumulates lead)
Feathered Mosquito Fern (Azolla pinnata) - (Biosorbs metals)
Water Thyme (Hydrilla verticillata) - (hyperaccumulates metals)
Field Chickweed (Cerastium arvense) - (accumulates Cadmium)
Miner's Lettuce (Claytonia perfoliata) - (accumulates Cadmium)
Bentgrass (Agrostis castellana) - (hyperaccumulates As, Pb, Zn, Mn, and Al)
Vicia spp. (uptakes metals-e.g. Al, also nitrogen, phosphorus, and potassium)
Common Sunflower (Helianthus annus) - (extracts Pb, Ur, Sr, Cs, Cr, Cd, Cu, Mn, Ni, and Zn)
Alpine Pennycress (Thlaspi caerulescens) - (hyperaccumulates Nickel, Zinc, and Cadmium)
Violet (Viola spp.) - (phytoextraction and hyperaccumulation of a wide variety of metals)
Willow (Salix spp.) - (Phytodegradation and rhizodegradation of perchlorate, Phytoextraction of metals)
Each of these species has specific targets, carries out its phytoremediation activities with one or more specific phytoremediational process, which may or may not include a number of regions of activity, from the rhizosphere to the air sheath adjacent to the leaf and stem structure.
In providing a proper habitat and ecology for these plants designers have to consider the impact of plant metabolic rates on the effectiveness of the phytoremediation process chosen. A plant in dormancy has a very low metabolic rate. This effects transpiration rated as well as the speed of biochemical activities. This has direct bearing on how much cleaning takes place. Another factor is what I call the “second hand of green roof design.” The first hand is finding plants that work well on a particular roof. The second hand is designing one’s roof so certain plants are happy.
Good green roof design does both at once. This is especially true once we depart from the “as light as we possibly can and as drought tolerant as possible” and approach the realm of the multifunctional green roof, the truly working roof.
This is a very knew area of scientific inquiry and we are just scratching the surface. However, enough successful work has been done that compels us to start incorporating these tactics and strategies in our built environment as partners in progress. Our green standards are abysmally too low for any serious self-congratulations. By using grey water as green roof and living wall irrigation now, we can start evaluating the phytoremediation effects as we go. After mechanical filtration and phytoremediation, along with control of the contaminants we introduce into our environment, I see no reason why we can’t start using green water for a wide array of uses from laundry to washing food to washing ourselves, to irrigating food crops, to irrigating green roofs and living walls in areas short on potable water.
Think of the possibilities:
The Active Phytoremediation Wall System;
Graphic by: CASE and SOM via Inhabitat
In addition to the free literature mentioned above, there will be two discussion panels on this subject in the Greenroofs & Walls of the World™ Virtual Summit 2013, starting yesterday, February 12 through March 13, 2013 held by Greenroofs.com, in association with the World Green Infrastructure Network (WGIN).
The beauty of a virtual conference is that you never have to miss events that are scheduled live. You can always return to a virtual venue later and see everything on demand at your convenience.
B.C Wolverton, Anne Johnson and Keith Bounds, “Interior Landscape Plants for Indoor Air Pollution Abatement, Final Report –September 15, 1989.” Stennis Space Center, Mississippi, MS 39529-6000.
Publisher's Notes: We are extremely fortunate to have Patrick participating in a live Q & A Session regarding this article on February 13 at 4:00 pm EST plus leading our two Panel Sessions on Phytoremediation. Don't miss:
Friday, February 15 at 1:00 pm EST Panel Session: “Environmental Healing through Phytoremediation – Chapter One“ with Patrick Carey (Moderator), Dr. Alan Darlington, Dr. Paul Mankiewicz, and Dr. Clayton Rugh:
Tuesday, February 19 at 4:00 pm EST Panel Session: “Theory & Field Studies: An Interview with Dr. Ian Balcom from Lyndon State College of Vermont & Dr. Robert Cameron from Penn State - Phytoremediation Chapter 2“ with Patrick Carey (Moderator)
Credits: Dr. Ian Balcom and Dr. Bob Cameron
Not registered yet? Do so here. As a reader of Greenroofs.com, use discount code GCOM to only pay $39 (only $29 if you're a student/faculty or government employee).
Patrick Carey, principal of hadj design
How to Survive
on Planet Earth:
Changing Our Relationship with the Botanical World
By Patrick Carey
November 30, 2010
extol the virtues of nature and the botanical world in our work
and the work of others we encourage. What the hell, it’s
our business. If we weren’t pushing plants, we would have
to find something else to push. Any junkie in Needle Park
will extol the virtues of the poppy. Piles of expended
Bic lighters under alley fire escapes will attest to the popularity
of coca. Where would Lucrecia Borgia have been were it
not for a working knowledge of plant derived poisons?
Where would ADM
and Staley be in their agribusiness ventures were it not for
the malleability of corn and soy beans? Just imagine all
those diabetics so thankful for the ubiquitous presence of corn
syrup in our prepared food! The bloodbath we call Juarez
is all about plants, and a few other things. At different
times of year many of us suffer from airborne plant products
and use other plant products to alleviate the symptoms.
So, hurray for
plants! I say this not to condemn plants but to illustrate
that there is no universal ethic going on here. As living
entities, we are all striving for advantage and increasingly
competing for dwindling resources. The blessing in disguise
is that we are mutually dependent. Now, like no other
time in human history, we are in a position to connect dots.
Through the rapid
increase in shared data and increasing sophistication of our
means of inquiry we can start to see the connections between
water use and drought, between slash and burn agriculture and
build up of Co2, between ocean temperatures and jet stream variations
and changing weather patterns. We are starting to see
how some global functions are better given to the plants and
not machine replacements.
Besides the global
corporations and the national governments there is the natural
world which is becoming a new economic heavy weight on the scene.
The context of environmental goods and services is an economic
principle that transcends both capitalism and socialism.
Adam Smith’s Wealth
of Nations refers to an economic model that assumes growth based
on increasingly advantageous specialization. It was written
at a time when the world appeared to be infinitely abundant,
at a time when growth had no limits. Two hundred and thirty
some years later we have found that this is not the case.
As our increasing specializations have revealed, fuel, arable
land, and other natural resources can be stressed and even depleted
as populations and their per capita needs increase.
Past wars were
over oil. Very possibly the next ones will be over water.
Mark Twain had an interesting idea when he said “Whiskey is
for drinking. Water is for fighting over.” We are
beginning to discover the limits of technological solutions
in that they too frequently assume the same infinite abundance
that Mr. Smith did.
There are those
who would say that we have nurtured a belief in the afterlife
because we cannot bear to accept the finality of death.
There are those who have clung to the belief that a sacred text
endows man with the care taking responsibilities of our earth.
Unfortunately, the owner’s manual was not provided.
There are those
who have nurtured a belief in growth because we cannot bear
to accept restraint. This is Smith’s Achilles Heel. After
a long history of capital accumulation in pursuit of this illusion
you can imagine how difficult it is to steer this Titanic away
from the iceberg. It is the very self-interest that is
the bedrock of Smith’s theory that is its undoing. It
is blind to the likelihood that we, along with other natural
forces, have set into motion the engine of our own extinction.
The iceberg cometh.
Flawed but beautiful,
and poetic in its irony.
To me plants are
like next door neighbors who invite you to their BBQ, but whose
teenage son might slit your tires, the productive co-worker
who is a racist but keeps it outside the work place, or the
too friendly acquaintance you try to keep at bay. We strike
Faustian bargains with our botanical brethren, and they with
us. Bargains not unlike the ones we struck with the Cherokee.
A look at a possible
Sequence 1: An unpleasant aftermath.
We know too little
about the natural world to realistically consider ourselves
to be enlightened. We have not fully shared. So
now there are stark disparities that fuel highly focused myopias
like fundamentalism, reformulations of imperialism, and defensive
reformulations of our histories and even the nature of the world.
Sequence 2: Earth
Mouth! What the hell does this have to do with green roofs?”
you say. My reply is that we should not expect our approach
to green roofs and living walls to be any less flawed than our
past approaches to anything else. For instance, if we
need a living building element to perform certain functions
our Faustian bargain is that we have to acknowledge it is alive
and not some inert building part. This is a problem I
call “The Bauhaus Syndrome.” It is the conviction that
one can construct our built environment out of Legos that can
be manufactured with cheap labor and uniformly distributed anywhere
on earth for use.
For instance, if
we truly believe that green roofs are good for us, and not just
a reason to increase market share of our product or service,
we should determine where the roof surface is and pursue a strategy
to cover it. This is not being done.
Au contraire, green
roofs are most likely put on buildings that represent less than
1/5th of the roof surface. Why? Because it is looked
upon as an extension of existing business models and not as
a particularly green solution. It is a way of selling
more of what we already were selling, only with a green twist
because green sells.
We produce research
based on what research can be funded. So, when a particular
research topic becomes hot (fundable) an inordinate number of
research papers come out on the subject. An example of this
is the plethora of storm water retention research that has come
out in the past 10 years. The publications serve to keep
some academics employed. For some, it starts further publications
and book tours. This becomes a closed circle when other,
competing; research information becomes available - anecdotal
research dealing with unfunded topics.
For instance, design
professionals who need to expand their reputations by claiming
design credit for projects they did not design. By “design”
here I mean the selection and placement of all green roof or
living wall elements. Once a project has been properly
publicized it is frequently forgotten by the designer of record
and left to the maintenance staff to either correct the designer’s
mistakes or left to evolve on its own. The “designer”
of a green roof who relies on a single source provider is like
the car purchaser who claims to be an auto mechanic, yet design
credit is usually most zealously guarded by those with the least
understanding of waterproof membranes, geotextiles performance,
growth media composition, botany, and maintenance requirements.
Sequence 3: She's
Some green roof
design books have been authored by people who have never designed
a green roof. Arranging “where the plants go” is a very
small part of this design process. Yet this aspect gets
the biggest attention because it is the most obvious.
One prism we can
apply to history is our relationship with plants and landscape.
We scraped away topsoil for high impact development, drilled
wells, redirected watercourses, and started incinerating fuels.
After a time we got dope-slapped into seeing at least some of
what we had done and also seeing some possible solutions that
could be provided by plants. Neighborhood garden plots,
urban reforestation, green roofs, living walls - both exterior
and interior - all started to contribute to the replanting of
the built environment.
Sequence 4: The natural
environment is reclaimed.
There is a media
series that speculates what will happen on earth after man’s
departure. We get inklings of this from viewing overgrown
Mayan, Aztec, Buddhist, temples and monuments. The plants
return. Like barbarians at the gates of Rome they stand
triumphant in their “chaos” before our “ordered environment.”
We have the hubris to place them lower than us on the phylum
scale. But, after all, it is OUR phylum scale. In
introducing serious vegetation back into the build environment
as a partner instead of a servant, we must learn to follow as
well as lead. Too few of us have tried to do this.
Buddhist ruin returning
The idea I am laboring
at is the need to create some distance between our individual
needs for revenue, fame, quick solutions, etc., and to pay attention.
We are flawed in so many ways. Our understanding is insufficiently
informed. Our logic is easily corrupted by our needs, desires,
and weaknesses. Our psychological needs are many times too complex
or opaque to analyze.
To reach a point
of harmony with our environment – the idea of “green” right?
- will require us to step down and back from our “Sheppard”
status or “top of the phylum scale” status and get down there
with our botanical neighbors who we currently treat like vassals
or worse. This is a huge evolutionary step to take for us. We
are still at the point where we cannot tell the difference between
religion and science.
just came out with a book that suggests that God did not create
the universe. This is getting flack from a few quarters. I find
it ironic that ancient religious shrines and temples are overgrown
with plants, their walls gradually being opened by protruding
roots, their images being obscured by foliage reaching for water
It tells me we
have a very long way to go in a world whose extinction we are
The natural world
is a survivor, and the plants will return.
GRP, has a degree in architecture and lives in Seattle,
WA, and also has backgrounds in Philosophy and Professional
Theatre. Director of the Northwest EcoBuilding Guild's
Green Roof Project since 2000, Patrick is also principal
hadj design, a green roof design-build company.
hadj has designed and installed over 75 green roofs that
range in size from chicken coops to complete houses to commercial
installations. hadj design has pioneered the cross-training
of its crews in all aspects of green roof installation and
has taken on the challenge of getting green roofs of all
scales up and running.
also a trainer for the Green Roofs for Healthy Cities Green
Roof 101, 201, 301, & 401 Courses.
A Bio-Regional Greenroof Research Call
By Patrick Carey
I have never ceased
to be surprised at the ingenuity and zeal of people determined
to discover a solution to a problem. With green roofs,
living walls, and other biophilic building elements, some of
the biggest challenges are the collecting and analyzing of data.
Every approach has its shortcomings. If a manufacturer
of a product or provider of a service offers research data,
there is always the possibility of conflict of interest.
If an academic institution offers research data, the implications
of the results may be highly limited to the micro-climates of
the test apparatus. If a layman does research, there is
always the possibility of lack of scientific rigor in designing
the experiment, collecting the data, and analyzing it.
On a recent trip to complete a green roof project I was told
there were several others in the area. I ran into 25.
Some were on sheds. Some were on houses. Some were
on barns. And I don't think a single one of them made
it to a design magazine, was studied for its behavior, or even
listed on any web site. (Publisher's Note:
The Greenroof Projects Database, a free international online
resource, lists projects of all shapes and sizes, so
submit away!) I also have run into people
who want to put up a test green roof in order to evaluate its
performance, but are not members of a study or academic institution.
My point is that there is a rich source of information out there
and plenty of people willing to get it.
So, I came up with the idea of the "Minions Project."
The minions are those who follow up on the ground-breaking,
earth shattering, Nobel Prize winning achievements of primary
researchers and replicate their work in other bio-regions, this
making it more useful information. This is much less glamorous
work, but, in my opinion, equally valuable.
How do we pay for it? However we can. The point
is to not use grant funding as a necessary condition to do the
work. This is where the academic researchers frequently
get held up. Ben Franklin, Edison, and Da Vinci rarely
used grants as the necessary starting point for their work.
The caveat is that contributors must subject themselves to scientific
rigor. Partnering up with local schools or NGO's is a
great idea. Perhaps in your locale you can enlist the
help of government sources, labor, and materials suppliers.
Perhaps you can establish a dialog with researchers in the field
and in the academy for guidelines on procedure and analysis.
Leave your ego at the door of the lab or test site and go about
the work as a search for truth versus a proof that you are right.
The topics? Any and all. For example, you have a
green roof on your chicken coop. No you don't, you have
a research test panel on your chicken coop! Here is how
you might start out: List the latitude, longitude, and elevation
(borrow someone's GPS) of the roof.
What is its slope(s)? Which direction does it face?
How deep is the media? How accurately can you define and
measure the components of the growth media? Are there
any micro-climatic influences on the roof like shade/leaf drop
for a tree, wind patterns, sun or wind blocked or focused by
adjacent structures? Now you know what you have.
Get a two dollar plastic rain gauge and put it in the middle
of your green roof and point it straight up. Collect the
rain runoff in a 55 gallon rain barrel and record the water
levels of the rain gauge and the barrel at regular intervals.
When either of them is filled up, empty them both (or disconnect
the barrel from the downspout) and start again. This data
would not pass muster for a scientific paper. But, when
added to the data of others, it starts to create a body of evidence
that can be substantial. And, you can always get more
precise. For instance, you can take more readings during
rain events and create a graph of roof behavior. You can send
water samples to a lab for analysis (call your local municipality
for a possible free test).
The beauty of a laboratory is that you can isolate the variables
you want to study and see how they behave. The drawback
here is that these same results might not be obtainable in the
real world. The drawback with a do-it-yourselfer researcher
is that they can have so many independent variables in their
study that any scientific inferences will be weak at best.
But even institutional researchers argue over the proper protocols
to use and whose produces better and more useable data.
So, you would not be alone, and there is strength in numbers!
If you want to fashion an experiment, we should be able to get
the help of researchers in the field who might be willing to
help with the design of it. On a smaller scale, there
are a number of successful (and very sturdy) tabletop green
roof trial gardens out there which we can replicate in any region,
and we can give you a materials list and simple details for
you to construct. These can be conventional built-in-place
models or modular system tabletop models. Below
are two examples in the metro Atlanta, Georgia, area:
you can assemble pre-made kits for more realistic structures,
such as storage sheds. For example, build two Tuff-Sheds
like the kind sold at Home Depot, as shown below from an installation
that the North West EcoBuilding Guild volunteers and I constructed
Phinney School Ecoroof
waiting for the green stuff. Photo by Linda
S. Velazquez, July 2004.
by Northwest EcoBuilding Guild volunteers. Photo
by Patrick Carey.
the interior space as your storage, but use the pitch area under
the roof (the 'crawl space") for testing. You might be
able to borrow some acoustical sensing equipment and see how
much sound makes it through the green roof across which frequency
ranges, and which don't. Use one Tuff-Shed as a neutral
for comparison - the control roof. You might even be able
to design the roof of your test shed to fit various, moveable
assemblies for testing. All this is relatively cheap and
at the same time is potentially useable for other practical,
non-research functions. The issue is rigor.
Experiments that evaluate the organic needs of growth media
based on plants, depth and bio-region are still in their infancy.
Thermal and acoustical information is still highly specific
to particular test facilities. Depth of media and plant
species that work should be replicated by as many people as
possible to discover the applicable limits of scientific conclusions.
I would even include the anecdotal types of reports to a certain
extent, as a way to target more rigorous experiments.
If this idea interests anyone, I will work to get a coordinated
body of information out to the "minions." This information
will be shared by the minions here on Greenroofs.com until we
have enough information to be substantial. Let's say,
we work on projects and come up with a list of potential work
between now and March 21, 2008. Figure we can check in
at the equinoxes and solstices, or every fiscal quarter.
This information need not all come from experiments. I
am including a piece below by an independent researcher, Stephan
Elliott, of October 19, 2007 who is examining the embodied energy
of growth media components; some greenroofs are greener than
others. Stephan’s work helps to focus on part of this
With this Minion Greenroof Project Call for Research,
I see a community of academics and independent field researchers
getting more information out and with less cost than is now
the case. So, who is up?
~ Patrick Carey
Read the research paper "Embodied
Energy Comparisons - Light Weight Aggregates and Pumice," by
Stephen Elliott of October 19, 2007
has a degree in architecture and lives in Seattle, WA, and also
has backgrounds in Philosophy and Professional Theatre.
Director of the Northwest EcoBuilding Guild's Green Roof Project
since 2000, Patrick is also principal of
hadj design, a green roof design-build company. hadj
has designed and installed over 75 green roofs that range in
size from chicken coops to complete houses to commercial installations.
hadj design has pioneered the cross-training of its crews in
all aspects of green roof installation and has taken on the
challenge of getting green roofs of all scales up and running.
Patrick is the Architecture Editor
here at Greenroofs.com and welcomes your comments. Contact
him at ArchitectureEditor@greenroofs.com
The opinions expressed by our
Contributing Editors may not necessarily reflect the beliefs
of Greenroofs.com, and are offered to our readers to simply
present individual views and experiences and
open a dialogue of further
discussion, debate and research. Enjoy, and if you have
a particular comment, please contact the author or send us an
email to: email@example.com.
Roof Activism or
We are All Bozos on This Bus. Firesign Theatre
By Patrick Carey
All Photos Courtesy Patrick Carey unless otherwise noted.
the one hand green roofs are the fastest growing segment of
the roofing market. On the other they are microscopic
in terms of public familiarity and widespread use. We
wait. We wait for the definitive book that will describe
exactly how to design and build one that is perfect, tell us
exactly how much it will cost, and exactly how it will behave
over the 40-60+ year life span. We wait for the studies to come
out on storm water, thermal performance, etc. We wait
for our neighbor down the street to get one first. We
wait for enough of them to be built so that we can take tours
of all of them and see for ourselves what the pictures and words
are all about. We wait while the Germans and Japanese
make it a standard of construction. We wait while the
trades in other countries learn to actually talk to each other.
We wait for the incentive programs and the grants. We
wait to overcome our unspoken fears.
This garage decided
not to wait for humans, grants, or incentives -
just the perfect set of climatic conditions, etc.,
and it developed its own green roof. Moss grew spontaneously
on this roof -completely the result of neglect.
The implication being
that green roofs are going to happen with or without
us so we might as well help out the process. Examining
these kinds of things closely can teach you a great
deal about how green roofs operate.
I can’t help but wonder if there
isn’t some psycho-pathology at work. This roofing approach
has been around since ancient Iraq. The modern evolution
of it has been around since the late 1970’s. At some mysterious
point enough adventurous people will just spontaneously start
building green roofs and that will be the beginning of the sea
of change. This hasn’t happened yet.
But there are signs. D.C.
Greenworks in Washington, D.C., Northwest EcoBuilding Guild
in Seattle, Ecoroofs Everywhere in Portland, OR, and other experimenters
and advocates in Chicago, Minneapolis, New York, Vancouver,
B.C., and Austin, Texas are throwing up green roofs. Some
leak, some have all the plants die, some work beautifully, some
would make a green roof designer cringe or a roofer shake his/her
head. But they are going up. When they screw up,
the next ones are better. When they work, they are replicated.
When there is no money, they make them small. When there
is money, they get larger.
It’s all happening now and accelerating.
So here are some examples and ideas to jump-start a green roof
movement in your area. You might look at it this way:
how bad a failure can you tolerate? And then operate within
those limits. I 'm not talking about installing your home or
business with a green roof on the first go. Start small
and go from there.
Example # 1: Tom Liptan in Portland, Oregon, now known to very
many people as a green roof resource and advocate, shoveled
some backyard dirt on his garage metal roof over a sheet of
visqueen, threw some seeds on it, watered it and then measured
and observed it over a 9 year period. No cost, no grant,
no public incentive, not even a particularly great design.
But from that experiment sprung a green roof movement in Portland.
Example #2: Jon Alexander, a member
of the NW EcoBuilding Guild in Seattle, volunteered an old garage.
A bunch of fellow members volunteered to do some research on
the net. They got a few donations of free materials from
companies who either wanted to get some cheap market development
or advertising, and they gave it a shot. Now they have
20 green roofs up and running on structures from chicken coops
to complete single-family residences.
The Alexander garage.
Photo by LSV.
Publisher's Note: Read more about the NW EcoBuilding
Guild in Patrick's 2003 Guest Feature Article
here. Read about
Seattle greenroof activity in Linda's Aug/Sep 2004
Sky Gardens column
Example #3: In Chicago, with a
mayor touting the benefits of green roofs, a small group started
exploring the possibility of green roofs by starting out with
models shown to some landscape people, and then built some small
structures with green roofs.
Example #4: In Victoria, British Columbia two fellows with dreams
of a small landscape business attended a green roof conference
in Portland, worked with a green roof design/build business
for a few projects, and helped them with a few workshops.
Adam Weir and Liam Hall of Paradise CityScapes took what they
learned to design and build small greenroofs on accessory structures
Left: Adam Weir and
Liam Hall starting out a multi-level cathouse with
green roof. Right: Josh Powers demonstrating EPDM
membrane application for a doghouse.
Example #5: In our nation's capitol,
D.C. Greenworks uses training on green roofs and other activities
as a way to help people get job skills. Because greenroofs
involve a wide variety of skills form landscaping to carpentry
to roofing to metal work, to (and this is the important part)
making them all work together, trainees come out of this program
with a wide range of skills. As they work in the community,
they bring with them the skill and understanding of green roofs
that private house project people tap into.
Read about 1425 K
Street above in
The Greenroof Projects Database. Photo Courtesy
D.C Greenworks. Publisher's Note: Read
about D.C Greenworks in director Dawn Gifford's
August 2003 Guest Feature Article
Example #6: In Austin, Texas,
a homeowner read about green roofs and thought he might try
one on his property. Auten imitated the scrub pine and cactus
landscape surrounding his house, made a small roof and put it
at the entrance to his property.
Example #7 Ecoroofs Everywhere in Portland got volunteers together,
hooked up with some grants and some skilled roofers and started
putting up green roofs. They have about 10 up so far.
came up with this inexpensive drainage detail. One
of many ways to drain a green roof. Illustration
by Steve Cowden/The Oregonian. Publisher's
Note: Read about Ecoroofs Everywhere in founding
member Anthony Roy's November 2003 Guest Feature
here. See the Hawthorne Hostel ecoroof
The Greenroof Projects Database.
There are many examples I have
not listed here. There are design-build classed offered
by Colleges and Junior colleges that have taken classes out
and built green roofs; classes offering green roof education
are common in Japan. A s soon as the right mixture of skill
sets is reached and coordinated, a green roof skill-building
workshop can take place. There are more than enough literature
and information sources about this subject right now.
Here are some ideas:
Jeff Jaramillo demonstrating
Get on any of the green roof websites
(those not selling products or services might be more objective)
and study up on assemblies. Advertise on craigslist.org
for free building materials like plywood, pond liner, framing
lumber, single ply roofing membrane scraps (or contact local
commercial roofing companies or go to commercial roofing construction
sites). I had a friend who would always counsel me on
“ the best “ stereo equipment, another example of the high-tech
world of computer software/hardware, cell phones and services.
His theory was to wait because some really huge improvement
was just around the corner. His passion to get the ultra-first
of its kind-prototype-future-advanced-totally up-to-date thing
prevented him from actually getting anything and then moving
on from there. I f anyone puts aside 30 days and reads the four
major publications on green roofs, the three CD’s of the past
three Green Roof conferences in the U.S., and goes through two
or three good green roof websites, you will know as much as
90% of all the green roof experts and practitioners around.
Most of the people and companies who promote themselves as experts
are expert in usually only one or two aspects of a green roof
and leave the rest to consultants they hire.
Student trying her
hand at EPDM membrane application.
MAKE FRIENDS WITH A ROOFER! (Someone
who is familiar with single ply membranes.) They do not
have to know a plant from a car. If you can’t, then get
a single piece big enough so you don’t have to cut or seam it.
You don’t have to be a non-profit or an institution or anything
else just someone who wants to build a green roof. You
can get an old dog house, a bird house, a cat house, anything
with a plywood roof and build it up to make a shallow trough
and then line it with pond liner from Home Depot, or visqueen.
Next, get few small piles (¼ cubic yard – sized piles) of growth
medium ingredients like pumice, lava rock, compost, coco fiber,
(experiment and get to about 10% organic to 90% mineral in the
mix). If it works, you can be one of the growing numbers
of people who make their recipes secret. Y ou can come up with
exotic names like “ Roof Dirt 257.“
Go to a construction site where
they are doing foundation work and get some sub-surface drain
mat. Now make a roof with some plywood 2x framing on the
edges for a shallow planter, line it with your pond liner, or
roofing scraps, lay down the drain mat, fill it about 4-6 inches
with your “Roof Dirt 257,“ throw some seeds on it and you have
a green roof. That is it! Will it be the best green
roof, the most advanced, the longer lasting, the only one of
its kind? No. It might even leak or fall down. All the
plants might die. “What if it rains too much?” “What if
I don’t have the right plants?” “What if the stock market
crashes again?” “What happens if the bird flu reaches
the U.S.?” "What happens if the Cubans invade Florida?”
LIGHTEN UP!!! This will not make you a green roof expert.
But it will put you in the game. Once you have a few of
these up, they will be your teachers.
by Northwest EcoBuilding Guild volunteers.
Going to a Home Depot or Lowe's
or other big box store might get you a donated Tuff-Shed, or
other prefabricated small, low liability structure like dog
houses, kiddie play houses, bird houses, etc. There are tons
of plans for building these things yourself on the web.
Now that you have your act together, map out your city and figure
where you can replicate this process so that many different
kinds of people get to see them. What is the worst thing
that could happen if you make one and put it in front of City
Hall – take a bunch of photos, of course. How about a
homeless encampment? How about a tool shed for a public
garden? A bus stop? Anything that can benefit from
a roof or a canopy can get a green roof. If you are nervous
about the structure, make a small one and replicate it.
Get someone with an official stamp to pass on it.
Monitoring: showing how they work can be of public benefit –
think of the educational angle. All you need is a science
class, a playground with a small green roof, a $2.00 rain gauge
and a 5-gallon bucket or 55 gallon rain barrel with a closed
top attached to a downspout. You now have a storm water
monitoring station. City and county governments love this
type of information because it can set storm water policy.
A college engineering/architecture class doing acoustical tests
on it, a local roofers union doing an apprentice training on
single ply membrane application, a local horticultural group
doing some plant and growth media experiments, and you have
Fashioning some drainage.
Green roofing is not rocket science
at first. It is simple as dirt at first. After your
first experience with it the nuances and subtleties will come
into play. But these will be in the form of improvements,
not in the form of being able to do it at all. A defining
quality of an activist is to be active. Sartre spoke of
having to destroy the world in order to act in it. I took
him to mean that the point at which one takes action is the
like jumping off a diving board. To act means to ignore
all that you know, stop letting the way things are now and the
security you feel in they’re never changing in unknown ways;
hold back the impulse to create. The worst thing that
can happen is, God forbid, you make a mistake!
Example of what you might hear from a conservative: "For
heaven’s sake! Don’t try this at home!!!" illustrating the hesitancy
to experiment on the type of ultra-unsophisticated green
roof model prototype that I am talking about.
A small kiosk built
during a workshop.
Now imagine a group of previously
green roof-ignorant people who have made the leap. They
tried and failed about 3-4 times. But the fifth
time was a charm and they actually got that green roofed doghouse
to look like something. The skills they learned in carpentry,
roofing, horticulture, and green roofing in general now are
grounded in the homework they have done with the literature
in the field. Now they are players. They can
ask more insightful questions, the skills they learn are now
more sophisticated and focused, the people they go to for help
are familiar with their projects. They do a few presentations
to a few groups around the town, explaining green roofs in general
and showing the experiments they have done. All of a sudden
somebody wants them to do a workshop at their house and in the
process build them a green roof. They become green roof
guerillas and do things like put a 4’ x 8’ green roof panel
on the roof of a local office building, a school, and a park.
The more they do, the more they learn, the sharper their skills
are honed, etc. Now they teach others and plan a possible
start up business. Voila! Green Roof Activism.
Left: A green roof
retrofit on a straw bale structure; Right: A green
roofed chicken coop. Egg production was documented
as a 23% increase. (This is a lie.)
Some words of good or bad advice,
as much as you should summon up courage for tackling the unknown,
you should fear yourself as much. In the 6 years I have
been green roofing I have witnessed in some, usually those who
are the most distanced from actual green roof projects, a kind
of turf mentality. Those people claim credit for the work
of others, claim expertise they do not have, and seek to take
advantage of a field that is still new and relatively rare.
They come in all forms, the plant nursery worker who attended
one workshop and now knows everything needed to consult on green
roofs, the academic who is in love with his or her research
technique or theory, the green roof system sales person who
is pushing the product of his/her company, the landscape architect
who assumes that his/her training alone is all that is needed
to claim expertise, the architect who visited the actual site
twice – first to introduce the green roof installers to the
client and second to photograph the result and is now giving
lectures on green roofs as though he/she had done any serious
homework, the do-it-yourselfer who has stopped exploring beyond
his/her project and figures he/she can now stop learning.
I have seen a lot of attitude-copping, even in the mirror, and
I deplore it. It gets in the way.
There is a kind of greed out there, and green roofs are the
next item on the menu. There is notoriety, publication,
media interviews; press coverage, grants and awards given out
that can all conspire to force you to miss the point: The
roof is the expert, not you. I would trust people
who have both dirt under their fingernails and a well-worn pair
of reading glasses over those who appear with various mantles
of expertise. THERE ARE NO GREEN ROOF EXPERTS! There are
only those who have a disciplined passion for the subject and
those whose appetite for notoriety and future business exceeds
their ability and knowledge.
~ Patrick Carey
August Reader Email to the Architecture
Subject: Green Roof & Snow Load Question
Perhaps you can answer a question
raised by a Public Works Director interested in installing a
green roof on a municipal highway garage. A green roof reportedly
provides an insulating effect. The question: In climates with
a heavy snow load, does this mean that snow will not melt as
quickly as it might from a black-top roof? Will snow load increase?
We would appreciate any help you can provide. Thank you.
What causes snow to melt on a roof either heat leaking up through
the building assembly, a rise in ambient air temperature above
the thawing temperature, or reflected heat from adjacent surfaces,
or any of these in combination. If you want to get more exact,
a rise in atmospheric pressure, heat from a mechanical system
equipment, or the introduction of a black body radiator on the
roof would also contribute to this effect. Once snow is on a
roof in sufficient depth to be completely white to the sky,
it will convert very little light to heat. If the snow becomes
dirty, it will convert more light to heat. So, what does this
all have to do with a black top roof? As long as the snow is
shallow enough to show some of the black of a black top roof
to the sky, the black top will absorb light and convert it to
heat and possibly melt the snow adjacent to the black areas
of the roof. In some conditions, the snow adjacent to the black
will melt and then refreeze in the form of ice on a cooler part
of the roof. Fluffy, dry snow - because it traps air in pockets
- is an insulator. Wet snow - because it has more water which
has a specific heat of one - transfers more heat.
As more and more of a green roof is revealed by melting snow
or snow that has drifted to thick and shallow areas, there will
be some conversion of light to heat with a snow melting effect.
It will not be as extreme an effect as would happen with a black
roof. So, in this case the snow would last longer. In the case
of very low temperatures, a black roof might contribute to more
ice on the roof due to more rapid thawing (due to the black
body) and then rapid freezing (due to the melt moving to a cooler
part of the roof). A Boston winter may well have any of these
conditions. The big issue here is not whether one type of roof
will melt snow more rapidly, but rather how frequently do various
conditions occur, and is that frequency significant? A building
with bad insulation will melt more snow than either of these
roof types in general. A black roof covered with snow is no
longer a black roof. A green roof covered with snow is also
a white roof to the sky. Once the sun goes down, the advantage
of black body radiation is eliminated.
I realize that this is not a simple answer to your question.
However, roof behavior is frequently context-dependent.
If the Only Tool You Have is
a Hammer, Every Problem Looks Like a Nail
Every Tool is a
By Patrick Carey
marketing of green roofs is on the rise. One of the elements
that fuels this phenomenon is the belief that there is a way
to create green roof components that can be shipped to broad
markets, thus taking advantage of manufacturing efficiencies.
So we now have sedum blankets manufactured in Japan being shipped
to the U.S., pre-grown green roof container boxes of metal or
plastic being shipped from the Midwest to the coasts, German
drain mats and Swedish EPDM membranes being shipped to the U.S.
The common assumption in all this is that a particular component,
sub-system, or system is the “be all” and “end all” of its kind
and, hence, worth the trouble and expense of shipping.
International trade is not new. What is interesting to
me is the marriage of biology and manufacturing, of ecology
with the sharp-elbowed world of the corporate search for profit,
and the belief that a manufacturing process that strives to
serve an international market can also supply biological components
that are viewed less as elements of a natural environment but
more as products of manufacture.
Way back when green roofers were using tarred reeds and melted
lead or birch bark and pitch for their waterproof membranes,
they looked around near them to find the plant and substrate
candidates for the biological component of their assemblies.
Some worked, some didn’t. And an evolution of thought
and experience from experimentation with their local natural
resources developed into what we now call green roofs.
When large waterproof membrane companies saw the potential to
sell more product with the growing popularity of green roofs,
they started to introduce their marketing strategies into this
arena as well. Their products could be manufactured and
stored for long periods of time. Their products could
serve a wide array of needs and environmental situations.
One could create a waterproof membrane and geotextile system
for tropical, arid, temperate, or polar climates. One
could set up manufacturing plants and a distribution system
to more efficiently serve growing markets. These components,
whether drain mats, membranes, root barriers, or separation
components, were very convenient for the manufacturing sector
to produce. Manufacturers could subcontract out components
of their systems, as is done in many in many other manufacturing
processes. A subcontractor who found that his/her product
could also be used, with or without adaptation, for a new market
would become very excited.
So drain mats that were originally designed and used for sub-surface
foundation applications were now “ green roof system components.”
Professionals and contractors with any remote association with
any aspect of green roofing felt emboldened to declare a new
expertise, with or without the requisite qualifications.
Small manufacturers complying with the vendor’s specifications
produce many components for green roof systems. Various
specialists compete for these contracts and so can change from
fiscal cycle to fiscal cycle depending on the bidding competition.
This can result in changes in component design, cost, and general
ability of those components to integrate with the system for
which they are designed. So, for instance, companies like
Tremco, Green Grid, Garland, Firestone, Carlisle, etc., produce
green roof systems defined by the manufacturing specialty of
the primary corporate owner or product name. What I find interesting
about all this is that these companies and more describe their
product as a green roof “system” while actually they are principally
selling one component, whether that is a membrane or a planter
box, or some other single product of a manufacturing process.
I fear that the elements that actually make a waterproof membrane
roof a green roof, specifically the growth media and plants,
are getting the short end of the stick.
Let us assume that a green roof is defined by the whole assembly
of elements that go from a deck with the appropriate slope and
strength to the mature and balanced ecology of a plant population.
It seems to me that a vendor of such a system should be able
to speak with authority on any of these components and not just
the one that they manufacture. However, this is generally not
An alternative title to this article might be “If the Only
Answer You Can Provide is a Manufactured Component, Every Roof
is a Parking Spot for It,” or “ Every Green Roof is Just Your
Component.” By not recognizing the interconnected
nature of many of these green roof components, installers have
frequently blown it. For example, the plants of the Oakland
Museum intensive roof garden, built in the 1960's, failed as
the medium was designed using nursery trade assumptions, and
not designed for long term use. Little medium components
remained in the mix after a few years except fine sand; the
organics washed out or blew away. Moisture retention dropped
and the plants lost so much volume in the substrate (slumping)
that aeration and drainage were severely affected. Other
elements deteriorated to create plugged drainage. This
is a good example of a failure because it covers several mistakes,
bad growth media composition and the flawed theory that created
it as well as filtration materials that deteriorated and led
to drainage problems.
As wonderful as the Gap headquarters was as an idea and as much
applause as it received, the majority of the plants on it still
died. After the Seattle Justice Center green roof became
a beacon for green roof enthusiasts, the plants had to be replaced,
twice. At Seattle’s King County Airport the plants got
in trouble as well – possibly because the landscape architect
specified potting soil as a growth medium. After Portland’s
EcoTrust Building’s green roof helped establish Portland as
one of the leaders in the green roof race, it developed a sick
plant syndrome where the drought tolerant plants started to
drown and the water tolerant plants started to starve for lack
For example, architects frequently specify a slope that is the
same slope that they always specify for “flat” roofs (around
¼”: 1’-0” or 2%) and therefore, insufficient drainage is generated
because the architects didn’t talk to the plant people - who,
of course, were never contacted by the “system” provider because
the “system” provider makes their money from membrane or drainage
sales, not plant sales. This same scenario can be generated
for any green roof system that is simply composed of a bunch
of separate manufacturing units whose providers are in poor
communication with each other and lack understanding of the
interrelationships of all the components. The component
manufacturer with the deepest pockets dictates the system; in
most cases this is the waterproof membrane manufacturer.
Manufactures of systems like the ones I’ve mentioned would,
of course, point to those elements they manufacture and say
how well they kept water out of the building. Clients
of these manufacturers would return for more business, despite
the failure of the green roof system, because the manufacturer
emphasized the benefits of their manufactured elements.
However, the green roof still failed and would most likely fail
again without an in-depth review of the green roof design
as a whole living system.
The issue here has to do with the inherently corrupting influence
of justifying large inventory expenditure. Once a company commits
to the tooling up, manufacture, and stocking of their particular
“ hammer “ or solution to the green roof design problem, their
investment is then a self-justifying solution. The investors
and those responsible to them must then commit to that inventory
and the decisions that lead to it or else face losses.
So we wind up with solutions that are championed, not necessarily
because they are the best or most appropriate, but because there
is so much riding on their success.
The real faith should be placed not on the inventory but on
the intelligence of the decisions. Intelligence, however,
is not a marketable quantity. A green roof system is difficult
to duplicate on a mass scale as it is usually regionally or
project-specific. It is a tool that does not fit in a tool chest.
Most honest adults will admit that their learning curve flattens
out once they have to start generating money, profit, or revenue.
Green roofs are still a niche market. Because of that no one
is yet ready to lay heavy bets on it. It might be a fad. No
earth-shattering profits have been realized yet. The subject
is too inter-disciplinary for a boilerplate solution for all
customers for all regions. In my opinion, no system has been
designed and manufactured yet that is worth copying. In this
climate, money is cautious. In this climate that still shows
so much promise, there is a hunger for a silver bullet, or …a
I fear the green roof movement will get a black eye for the
rushed and failed attempts to grab headlines and the market’s
imagination. For now, failures from the living and natural
components of projects like the GAP Headquarters building, the
King County Airport, the Seattle Justice Center, the Eco-Trust
Building, and the Oakland Museum will be relegated to the same
status as the retraction page of a newspaper. But if a
critical body of failures develops, then it becomes a story
in its own right. If this happens, the bright promise
of green roofs to provide so many benefits to our quality of
life may produce a dismissive response from the market and those
who shape it. And it might take much longer to recover
than a poorly chosen plant in a bad growth medium on a slope
that is too flat.
So let’s make sure that we design holistically as an integrated
inter-disciplinary green roof design team who actually interact
with each other, perhaps by using as our tutors the very ecosystems,
we in our hubris, claim to master.
and A View from the Sky Trenches Inaugural Column, April 2005
Night All Cows are Black
In the Land of the Blind the One-Eyed
Man is King
introduction to the upcoming
"A View from the Sky Trenches,"
By Patrick Carey
of these titles allude to the current states of flux within
the green roof world, competing theories, phony experts, lack
of good public education, and cultural conflicts of various
kinds that impede clear thought and progressive action.
Every month we will try to tackle an issue we think is central
to the spread of green roofs, and the first topic to be discussed
next month will be residential/commercial. Commentary,
adverse or complimentary, is welcomed.
Who am I?
I promote the idea of green roofs as well as design and install
them. My green roof philosophy is that they represent
an ecological model that should be reflected in the methods
and organization required to realize them. By that I mean
that the roofers have to be comfortable with horticulture and
the horticulturists must be comfortable with roofing.
Green roofs should be the result of an interdisciplinary approach,
not a result of a series of specialists who never talk to each
other. The best green roofs are not the result of one
specialist with a lot of expertise, back inventory of product
to move, or business agreement with a few other element producers.
The best green
roofs are a result of the breaking down of knowledge and skill
barriers, of market share greed, and of outmoded thought and
methodology. There are no green roof experts. Those
who claim this mantle are either misguided or frauds.
However, those who are humble and passionate enough can make
wonderful things happen at the border between building and sky.
By showing success in this approach, other barriers to enlightened
design and construction can be called into question, and perhaps
even remove barriers to leading lives in balance with all of
our neighbors, human and non-human.
Six years ago
I knew nothing about green roofs. Thanks to web sites
like this I was able to start researching without the market
driven perspectives of sales representatives of various products.
I started where I could, doing Google searches, doing library
journal searches, setting up email correspondence, and acquiring
as much free technical and product information I could from
any company that remotely related to the design and installation
of green roofs.
With the help of research committees within the Northwest EcoBuilding
Guild we compiled boxes and boxes of documents and samples.
(Publisher's note: Please read more about
Patrick and the Northwest EcoBuilding Guild
here.) Not being certified roofing applicators
or a vendor of a warranted product, we asked for Guild members
to offer their roofs to us for experimentation while waving
the warranty considerations. The Guild is composed of building
contractors, architects, engineers, permaculturists, and others
new or in the construction industry and trades. Drawing
from their experience we started our first experiments.
First we started to mimic commercial systems. Later we
broke free and started mixing and matching green roof elements,
exploring different growth media, plant types, etc. Twenty
roofs later we have a body of research and field experience
that gave us the confidence to feel semi-literate about green
roofs as a subject of discussion. What sets this effort
apart is that it did not originate with an industry like the
waterproof membrane, geotextile, or horticultural industries,
finding another market for its respective product in green roofs.
We started with the ecological impulse from the beginning.
The advantage of this approach is that it liberated us from
concerns about moving inventory of product that was not originally
designed for green roofs. We came to the perspective that,
like our habit of sending cars overseas with the steering wheels
on the wrong side or - God forbid, going metric - our
industrial sector is focused less on the specific needs of a
new market than moving product and increasing market share.
One of the best ways we had of gathering information was to
get manufacturers to talk about the competition's product.
If a green roof system vendor was originally a waterproof membrane
manufacturer, we would skip questions about membranes and ask
them questions about soil structure or soil biology or plant
adaptability to test how into green roofs they really were or
if they were just trying to "sell more steak knives."
We found that
academics also can suffer from myopia and produce work that
is divorced from the interdisciplinary culture of ecology.
So, we proceeded with a skeptical perspective so we could stay
closer to what we deemed the truth. Even after six years
and 30 roofs later, I still find myself humbled by the knowledge
base and expertise of vendors, academics, and trades-men in
the field. The bargain I try to make with myself is that I should
never try to take myself as seriously as the least serious "expert"
on green roofs.
If you catch me screwing up, let me know. This column
is intended to be an inquiry into the green roof industry and
practices. My perspective is one of many. So let's
put on our clown noses and inflatable shoes and dive right in.
The worst thing that can happen is that I can be mistaken.
In which case someone, I am sure, will enlighten me and we will
all be better off.
expressed by our Guest Feature writers and editors may not necessarily
reflect the beliefs of Greenroofs.com, and are offered to our
readers to simply present individual views and experiences and
open a dialogue of further discussion, debate and research.
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