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Creating Biodiversity on a Green Roof

Green Team at Green Roof Technology, - Monday, June 04, 2012

By Kat Harrold


Photo by ~ Jorg Breuning

Creating biodiversity on a green roof or green wall is significantly different than restoring it on ground level.  On a rooftop there is no preexisting ecology to enhance; everything is from scratch.  In most cases the growing media is drastically different from the soil down below which in turn dictates what ecology can be supported.  Accessibility, high winds, and proximity to the sun can also be challenging issues for organisms.

Studies show that plant selection and depth of growing media have a greater influence on the biodiversity of a green roof than height.  In the translation of research covering the biodiversity of green roofs, “Where the Beetles are Crawling and the Honeybees are Humming,” the biodiversity found on green roofs as tall as 400 feet were comparable to that of lower green roofs.

Tray or modular green roof systems create the visual impression of a green roof by placing a series of planters close together.   The history of German trays, introduced in 1978, show that in most cases the performance of pre-planted boxes fail to meet performance and maintenance expectations.  The composition of a modular system simply does not provide the right set-up to reliably enjoy the 30 to 50 year lifespan expected from a built up equivalent system.  Additionally there tends to be incredible amounts of species die back during the first 5 years creating a sparsely vegetated monoculture setting.  These factors create a very poor and unreliable environment for biodiversity to take place.

Visit us next week for more information on bio-diverse intensive green roofs!



Engaging the Senses

Green Team at Green Roof Technology, - Thursday, May 31, 2012
By Kat Harrold


Photos by ~ Green Roof Technology

When designing green roofs which encourage human interaction it is important to keep in mind the 5 senses, taste, touch, smell, sight, and sound.  

Taste – While the a green roof may be a tough environment for some vegetation to grow, there are still several edible herbs that can provide delicious accents to a meal or tea.  Mint, chives, parsley, cilantro, thyme, oregano and rosemary are just a few edible herbs that thrive on extensive to semi-intensive green roofs. 







Touch – Flowing grasses with prickly seed heads and the fuzzy leaves of Hieracium create a dynamic contrast to the lush springy texture of succulents and sedum.  Small berms can be used to integrate ornamental grass areas into extensive green roofs while keeping weight restrictions in check.








Smell – Closely related to taste, many culinary herbs can also employ a richly scented environment.  Other fragrant options for green roofs are lavender, polyantha rose “the Fairy”, sage, and Echinacea Daydream.







Sight – One of the many beautiful things about a green roof is there are a multitude of drought tolerant plants which provide year round interest.  Late winter and spring welcome a blast of color from crocus, Sedum hybridum “Czar’s Gold,” Dianthus, and Allium.  Summer brings forth a variety of extended bloomers including Sedum kamtschaticum, Hieracium, and Telinum.  Fall offers a variety of color from Aster Purple Dome, Snowcap Shasta Daisy as well as a red and gold glow from the foliage of several sedums.  Winter blankets the roof in festive greens and reds.  Sedums kamtschaticum, ‘Czar’s Gold,’ ‘Blue Spruce,’ and spurium ‘John Creech’ maintain their green foliage while Sedum spurium ‘Fuldaglut,’ moranense, album ‘Coral Carpet,’ and rupestre ‘Angelina’ brighten the season with displays of red and gold.



Sound – Green roofs have the to power to not only clean rain and air pollution but sound pollution as well.  When designing a green roof to function as a patio space, consider using plants which rustle in the wind such as grasses.  The tall reeds create white noise which helps mask the sound of a busy street.   








Begining of a Green Generation at the Episcopal Academy

Green Team at Green Roof Technology, - Thursday, May 17, 2012

By Kat Harrold


The Episcopal Academy -  Photo courtesy of

The Episcopal Academy has long been known for leading the way in academic excellence.  Adding to this commitment to enhance the mind, body, and spirit of it's pupils the academy will be installing a series of green roofs on their academic buildings under the guidance of Green Roof Technology.

The green roofs will feature an extensive greenroof set up composed mainly of sedum plants and hardy herbs.  The green roofs will be used to promote local ecology, aesthetic appeal, in addition to being an interactive learning tool.  Visible from high traffic areas in the building, these green roofs will be an ever present and key tool in promoting the latest in sustainable practice and design.




Green Power for NYC

Green Team at Green Roof Technology, - Monday, May 14, 2012

By Jorg Breuning

Sun Root with solar panel at the NYC Dept. of Parks and Rec, Randall's Island ~ Photos by Jorg Breuning

Big things are happening in New York!

The first Green Roof & Solar Panel Installation by Green Roof Technology is now powered-up. A few weeks ago Green Roof Technology and the New York City Department of Parks and Recreation installed the first non-roof-penetrative PV-Green Roof combination in Northern America.  The installation took place at the New York City Department of Parks and Recreation building on Randall's Island as an addition to their already extensive green roof system collection

The Sun-Root system - promoted by Green Roof Technology - is the most advanced system solution that considers enhanced water storage for the plants and optimized evaporative cooling for solar panels at the same time.  Drought tolerant succulents were graciously donated by Mother Plants and the growing media was provided by Rooflite. This green roof system is truly unparalleled.  The project is accessible by appointment. Please contact

Learn more about the amazing Sun-Root™ System.  (YouTube Video) Click on the picture for more information on the marvels of combining solar and green roofs on our webpage. 







Sun Roots soaking up the sun after installation at NYC Dept.
Parks and Rec Building ~ Photo by Jorg Breuning


The NYC Department of Buildings oversees the property tax abatement's for the installation of solar and or green roofs in New York City. To find  out more about application deadlines and tax abatement's click on the NYC buildings logo above.

Green Roof & Solar Panel Installation in NYC  NYC Buildings

The Dirt on Urban Farming

Green Team at Green Roof Technology, - Tuesday, May 08, 2012

By Kat Harrold

Photo by - Jorg Breuning

For some the dream of farming on the roof is a mere extension of window box gardening while for others it can literally mean bringing the farm to the roof.  For those DIY farmers out there here are a few things to consider for your garden in the sky.

Whether you are creating an extensive or intensive green roof, always check to make sure the roof is strong enough for whatever weight load you might be adding to it.  The last thing you want is to wake up one morning feeling like a freshly planted spud.

Speaking of spuds, for the adventurous rooftop farmer looking to plant more than just a few herbs or the occasional tomato, consider creating raised planting beds.  When it comes to the health and safety of your green roof one of the most important things to keep in mind is proper drainage.    The organic material that is so good for your crops is a death sentence to the drainage system.  When the organic particles break down they get lodged in the filter fabric which can cause standing water and even bigger problems in the winter when it freezes.  To keep your roof happy and healthy, create a separate area, such as a planting bed with a bottom or container, for plants requiring deep rich soil like carrots and potatoes.  

Building raised planters can be advantageous for plant and farmer.  By having a set up allowing for the farmer to tend to the plants without crawling around the vegetation you protect the plants from accidental damage and compacting the soil.

Roof to Fork Menu

    Ratatouille (recipe courtesy of

    (all vegetative ingredients can be grown in a regular semi-intensive green roof set up with no additional organic matter needed)

        1 onion, sliced thin
        2 garlic cloves, minced
        5 tablespoons olive oil
        ¾ lb eggplant, cut into ½  inch pieces (about 3 cups)
        1 small zucchini, scrubbed, quartered lengthwise, and cut into thin slices
        ¾ lbs small ripe tomatoes, chopped coarse (about 1 ¼ cups)
        ¼ teaspoon dried oregano, crumbled
        ¼ teaspoon dried thyme, crumbled
        ¼ fennel seeds
        ¾ teaspoon salt

        ½ cup shredded fresh basil leaves

In a large skillet cook the onion and the garlic in 2 tablespoons of the oil over moderately low heat, stirring occasionally, until the onion is softened. Add the remaining 3 tablespoons oil and heat it over moderately high heat until it is hot but not smoking. Add the eggplant and cook the mixture, stirring occasionally, for 8 minutes, or until the eggplant is softened. Stir in the zucchini and the bell pepper and cook the mixture over the moderate heat, stirring occasionally, for 12 minutes. Stir in the tomatoes and cook the mixture, stirring occasionally, for 5 to 7 minutes, or until the vegetables are tender. Stir in the oregano, the thyme, the coriander, the fennel seeds, the salt, and pepper to taste and cook the mixture, stirring, for 1 minute. Stir in the basil and combine the mixture well. The ratatouille may be made 1 day in advance, kept covered and chilled, and reheated before serving.




Good News for EPDM Roofs!

Green Team at Green Roof Technology, - Thursday, May 03, 2012

By Kat Harrold

Photo courtesy of

Good News!  EPDM (ethylene propylene diene monomer) is a synthetic rubber waterproofing commonly used on roofs.  Once thought to be incompatible with (electric field vector mapping system), due to too much black carbon interference, now has compatible grey and white versions!  

What does this mean?  It means that if you want to use EPDM waterproofing under your green roof you can also have the piece of mind by having one of the most accurate leak detection systems installed as well!  In many cases the leak detection system is cheaper than the waterproofing warranty as well.

ABC Carpet Green Roof Environmental Monitoring

Green Team at Green Roof Technology, - Monday, April 30, 2012

By Andrew Yanders

Photo By Kat Harrold  -   Featuring Jorg Breuning (left) and Andrew Yanders (right) at ABC Carpet and Home

In 2010, the Bronx Overall Economic Development Corporation (BOEDC), in partnership with the Bronx Borough President’s Office, submitted a proposal to the Bronx River Watershed Initiative to fund a 10,000 square foot green roof on the ABC Carpet Bronx Outlet building at 1055 Bronx River Avenue, Bronx, NY.  Green Roof Technology worked with the BOEDC to manage the project, beginning with the design all the way through training and supervising a local workforce to install the green roof.  The installation at ABC Carpet was completed in early November of last year.

This past Friday, Jorg, Kat and Andrew traveled to the Bronx to check on the health of the green roof and to construct 4 environmental monitoring stations.  All 4 stations are approximately 1 m tall with a 1 m x 1 m x 0.15 m box integrated on top.  Two of of the top-mounted boxes are filled with an extensive green roof system and the other two are only lined with a waterproof membrane.  Each box is equipped with 3 temperature probes and a tipping bucket.  In the coming weeks, a stand alone weather station will be installed on the roof to monitor wind speed, relative humidity, air temperature, and sun intensity.  

Over the last decade Green Roof Technology has worked with numerous organizations and academic institutions to design and set up their green roof monitoring programs.  Beginning in the late 1990’s, GRT helped establish the first FLL green roof media testing laboratory at Pennsylvania State University and advised their leading researchers on how to set up their own green roof research center.  Since those early days in North American green roof research, Green Roof Technology has had the pleasure of establishing research programs at Carnegie Mellon University, Swarthmore College, the City Hall in Chicago, and Villanova University.  In 2007, Green Roof Technology worked with the BOEDC to design and install green roof research stations at the Bronx County Court House.  These stations were the first green roof boxes to be tested in North American according to the strict FLL guideline and the FLL’s standardized testing procedures.





What to Know When Working With TPO

Green Team at Green Roof Technology, - Thursday, April 26, 2012

By Kat Harrold


Photo - Jorg Breuning

Working with green roofs for quite some time we have come to appreciate the compatibility of the TPO waterproofing with the Electric Field Vector Mapping System (EFVM).  Something important to consider however is the relation between the insulation and the waterproofing in determining the type of EFVM system.  

A project using waterproofing adhered to the insulation requires a metal mesh EFVM system in between the waterproofing and insulation whereas the system that has the waterproofing mechanically fastened to the insulation requires only a wire perimeter on top of the waterproofing.   Aside from being more labor intensive to install and modify, some roofing manufacturers would not warrantee their TPO with the metal grid between their waterproofing and insulation.  Proceed with caution when roofers site incompatibilities with their TPO and an EFVM system.  You may want to consider another manufacturer. 

ASLA Tour Lancaster Green Roofs

Green Team at Green Roof Technology, - Monday, April 23, 2012

By Kat Harrold

Franklin and Marshall Schader Hall  -By Kat Harrold

This past Friday, our very own resident green roof guru, Jorg Breuning, acted as an impromptu green roof tour guide in the city of Lancaster, Pennsylvania.  They city was host to American Society of Landscape Architects’ Pennsylvania-Delaware chapter’s annual meeting.  The city of Lancaster boasts many thriving extensive green roofs and has recently announced its commitment to becoming a national role model for urban green infrastructure through its LIVE Green program.  Green Roof Technology has had the pleasure of designing several green roofs in Lancaster City.  Jorg led a group of 30 landscape architects around the city explaining the different green roof systems on display.  The tour group visited two green roof designed by our firm, located at Franklin & Marshall University and Tellus 360



Swarthmore's David Kemp Hall Reaches Tenure

Green Team at Green Roof Technology, - Wednesday, April 18, 2012
By Kat Harrold

Photo ~ By Green Roof Technology

For some, green roofs may seem a novel addition to a green minded institution but to Swarthmore College it was an essential and strategic move.  In 2008 when the college needed to add a dormitory to accommodate its growing student body, there were concerns about the increased run off from the new construction.  Sustainable architecture through green roofs offered a solution that minimized the building foot print making construction of the new dorm possible.  The green roof was spear headed by a few brave faculty, dedicated alumni and students, and Green Roof Technology.  To stay on budget the school chose to invest in a green roof instead of the costly LEED certificate while still building to LEED standards.  This dorm was recognized in 2010 with the American Institute of Architects Housing Award.

The 8,600 sf green roof is the home to many plant species including sedum album murale, sedum spurieum roseum, delosperma nubigerum, and some indigenous plantings.  The green roof also features a raised planting bed for experimental vegetation such as cacti.

The profile of the green roof is a shallow extensive system and has a total profile of 3.5 inches with the growing media depth composed of 2 inches.  While Swarthmore may have a reputation for having the best maintained green roofs in the area, the maintenance required on the roof is blissfully minimal.  To maintain its pristine state Gardener Lars Rasmussen weeds occasionally as needed and irrigates only when drought conditions exceed two weeks.  The roof is minimally fertilized and occasionally cutting back of the overly aggressive plants takes place to encourage more diversity on the roof.

Since its installation the green roof has reduced run off, air pollution, and saved energy on the top floor of the building by as much as 25%.  While the green roof is not available for students to congregate it is open for guided tours and classes and is visible to all from the third floor.

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