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Net-Zero Townhomes Benefit From Solar Garden Roof

Green Team at Green Roof Technology, - Saturday, November 30, 2019
Net-Zero Townhomes Benefit From Vegetated PV Roofs
This suburban Washington, D.C., project proves there's no need to choose between a green roof or a photovoltaic roof



Developer-builders Jessica Pitts and John Miller of Flywheel Development had a goal and a problem with their Perry Street Townhouses project. Their goal was to build affordable net-zero townhomes in suburban Washington, D.C. Their problem was stormwater management: Rules in Prince George's County, Maryland, required them to detain the runoff from heavy rainstorms on-site, rather than divert it into municipal storm drains. The poorly draining site soils and the tight site precluded traditional ground-based stormwater best management practices, so they looked to a vegetated rain-detaining roof for a solution. But Pitts and Miller also had other plans for the roof: They needed solar power to meet their ambitious energy goals.

In the end, Pitts and Miller reached both of their objectives with an innovative combination: a vegetated roof whose growing medium captures significant amounts of rainfall, with solar arrays mixed in with the plants and supported by modular frameworks that are anchored and ballasted by the green-roof growing medium. Manufactured by German firm Optigrün, the PV array support system is imported from Germany, and the pair say this was the first time it had been deployed commercially in the United States. But Miller says the idea is a "no-brainer" financially: "Because the solar racking is ballasted by the green roof media and the plants that keep it from blowing away, that percentage of the green roof that is ballasting the panels is also eligible for the federal tax credit for PV." The roof is also effective as a stormwater management system.

"The solar green roof is designed to detain between 1.8 and 2.4 inches of rainfall," Pitts says. "There is little to no runoff from a small storm of about 1.2 inches or less, and runoff increases as the rainfall increases."

The process started during the design phase. Says Pitts, "This can go on any sort of deck. Our structures are wood framed. But you have to account for the load that you’re going to be carrying with the engineering, so it’s important if you do this, to have a mind to do it at the beginning."

"Wind uplift is a critical calculation on the solar," Pitts continues, "and the depth of the green roof media is determined by wind uplift calculations. We actually had a 3-foot parapet wall on three sides of the roof, and the PV system is down below that level and is protected from wind uplift on three sides, which reduced the depth of the green roof media that we needed to install."

The green roof media would help to protect the building's EPDM roof from sunlight and weather. But the green roof and solar would also impede any needed repairs or maintenance down the road. So Pitts and Miller decided to install a leak detection system before laying down the roofing.

"We thought it was prudent to install a leak detection layer—it's a metal mesh that goes underneath the roof membrane," says Pitts. "What that allows you to do is that if you ever get a leak, you can identify the exact location of it."

The thin stainless steel mesh comes in rolls and is installed directly to the roof deck before protection board and roofing are installed. "It looks like chicken wire," says Pitts. "There are two leads that you can run up the side of your parapet wall and hang out at the top. And you can test even before you put the green roof on. We had the people come out and test the membrane as soon as it was in place. They wet down the roof and apply an electrical charge and they look for places where you get a connection."

Miller explains that the leak testing crew uses a detector that looks like a push broom with metal bristles. "They found five or six little pinprick holes that you never would have noticed, and we patched them," he says. "All you have to have is a roofer maybe bends over and maybe one of the metal brads on their jeans pokes a hole in the roof, or they drop their utility knife, and you would never know. The leak detection crew will circle this spot with a Sharpie, and you’re like, 'Wait a minute, that’s a hole?' But this way you know on day one that your roof is leak-free. And if you have a future problem, then you can find it."

Next comes the layers of the green roof, which are integrated into the high-density plastic bases for the solar array racks. "You have your plastic protection layer, which keeps the roots from growing down into the actual roof itself," Pitts says. "Then you have a protection mat, which is kind of like a felt material. That’s for protecting the roof membrane from the roughness of the growing medium. Then you have a geotextile mesh, and the mesh that we were using has large holes in it—it’s a loose weave—and that goes on top of the bases that the green roof ballasts down."

The mesh wraps under and around metal edging at the roof perimeter, and it runs over the PV rack bases. An L-shaped metal bar is installed into each of those bases, and then the rack is accepted into those metal L bars, according to Pitts. Each grouping of panels is also tied together. "We had four individual systems on top of each of the four individual homes," Pitts says. "So each panel grouping becomes linked together, and then they all become linked together through the geotextile mesh."

Next it was time to place the growing medium. "It’s very common to have drainage trays and things of that nature to help reduce the depth of green roofs, but we wanted it to be thicker because we are using the weight of it to hold down the solar," Pitts explains. "We had a green roof media company (Mulch Solutions of Falls Church, Va.) come and blow the media up onto the roof with its blower truck."



There were two types of media: a larger, heavier drainage medium as a base layer, then a layer of growing medium on top of that, separated by a layer of fabric. The entire placement with the blower truck took less than a day. Besides the efficiency, says Pitts, another advantage to the blower truck is that it avoids creating point loads on the roof during the application of the growing medium.

"And then the plants arrived," says Pitts. "There are two different types of green roof plants. There are ones that grow in sun, and there are ones that grow in shade. So we had to demarcate the locations behind and beneath the panels, and allocate the shade plants to those locations; and the sun plants went everywhere else. And then we got all the PV equipment, and the PV panels came up last."

The Perry Street Townhouses were completed in spring 2017, and the plants on the roof are spreading nicely over the growing surface. "Green roofs really require a lot of care and feeding in their first couple of years to get them to establishment," Miller says.

Flywheel Development is currently working on two more affordable net-zero developments in Washington, D.C., Stack Eight and Cycle House, slated for delivery in 2020 and 2021, respectively.





Mineral Wool in Green Roofs – From Zero to Hero?

Green Team at Green Roof Technology, - Saturday, April 13, 2019

 Mineral Wool in Green Roofs – From Zero to Hero?

The use of Mineral Wool in Green Roof applications is an increasing trend in North America and in countries where such industry is still young or focused on fast profits rather than on longevity.

 

One selling benefit of Green Roofs is the extended lifetime of the underlying water proofing because the Green Roof protects the roofing against the elements. Can Mineral Wool stand up to this?

Against any semi scientific promotional material from Mineral Wool applicators, the market share of mineral wool in the German Green Roof construction industry is around 0.1% or out of 100 million square foot new green roof construction every year (Germany) it is only around 100,000 sf/year.

The reasons for this marginal market share are simple:

  • Mineral Wool has shown a drastic loss in performance after 5-7 years.
  • Mineral Wool is engineered for nurseries and for only one growing cycle.
  • Mineral Wool fibers are considered “hazard” in Europe.
  • On extensive Green Roofs the water retention and water-air ratio is unsuitable for succulents.
  • Mineral Wool expands and contracts in wet-dry cycles.
  • Mineral Wool is hydrophobic and can dry out the traditional overlaying growth media faster.
  • Mineral Wool growth media boards require ballast.
  • Green Roofs with Mineral Wool are difficult to repair, replant or recover.
  • Mineral Wool interrupts natural soil profiles (unnatural soil profile).
  • Mineral Wool is an additional installation step and related to higher costs.
  • Some Mineral Wool products compress under the load of ballast (soil).
  • Some Mineral Wool products contain Phenol resin or Phenol-Urea-Formaldehyde resin as binder and these products can hardly be recycled. Ecose technology is environmentally better but it doesn’t eliminate other problems mentioned here.
  • Reuse of all types of Mineral Wool for the same purpose is only possible after a (non-existing) difficult remanufacturing process.

 

An inexperienced green roof installer might like the idea of an obvious simple installation. However, what looks nice in a brochure doesn’t necessarily reflect the reality. Ballast on the Mineral Wool boards is still required and this requires different equipment. The setup costs for additional equipment are the same whether small or larger amounts of ballast ( or ballast reduces the setup costs).

Engineers might like the tremendous amount of water retention of Mineral Wool. However, they forget that plants (vegetation) have a very specific need for a balanced air-water ratio. If engineers plan the use of succulents (like Sedums) such air-water ratio is even more important (emphasis on air). Engineers are not horticulturalists.

Mineral Wool is widely used in nurseries for one-season vegetables. After this growing season the Mineral Wool (often combined with plastic) ends up on landfills. In 2008 it was around 200,000 tons of hazard waste in Netherland alone. Further, nurseries are growing their crops under highly computer controlled conditions for nutrients and air-water ratio in green houses. Who wants to sell a nursery to a building owner with roof under the sky?

In general shouldn’t we like Mineral Wool in Green Roofs? Mineral Wool gives us lucrative additional jobs in the future for repair or replacement (job security…).

 

 Photo: Repair, Reuse - impossible

I am a lifelong green roof professional and I stand up to my principals with the promise that a green roof should last as long as the building – and that the materials can be reused for the same purpose after that and without processing (there are many fancy names in advertising for it, like cradle-to-cradle etc.).

Like me many people don’t care about fancy word creation and they stand for and what the American Green Roof industry should stand for uncompromised quality and doing things right. Quick profits, instant gratification or senseless warranties don’t promote the trade of professional Green Roofers and it is certainly not my philosophy.

Mineral Wool is: From hero to zero.

 

I appreciate reading my opinion, based on 4 decades of Green Roof experience from all Green Roof friendly places in the world.

101 Common Sense of Intensive Green Walls

Green Team at Green Roof Technology, - Monday, September 24, 2018

People like to make statements – environmentally friendly statements. For such statements, Intensive Green Walls are often utilized.  Intensive Green Walls are systems where the roots of plants are in vegetation carrier that is mounted to a vertical surface. Because of gravity it takes some technical efforts to supply the plants with their essential needs like nutrients, water, air, and light.

 

Picture: Schöner Wohnen

All these systems have bits, parts and materials that are man made and that wouldn’t be required on a natural horizontal area (e.g. Green Roofs). These materials are often made with a high input of natural resources.

The amount of man-made materials and the time needed for the installation makes intensive Green Walls rather expensive. They might start at around $90.00 per square foot but can go up to $150.00 or even more per square foot. An extensive Green Wall (with climbers) is somewhere between $1.00 - $20.00 per square foot. Extensive Green Walls only need a portion of natural resources and patience (what most people don’t have).

More impressive  are the operational costs of intensive Green Walls (“average fuel consumption”):

Water: Daily consumption between 1- 1.5 gal of water per 10sf and per day.  Pump:  1 kWh/day/10sf

Nutrients: Specially manufactured liquid nutrients per fertigation system $0.05-$0.10 per 10sf/day plus 200Wh/day

Light (if indoors without outside light): Approximately 2 kWh per day and 10 square foot  – assuming light duration 14 hours a day.

Plants: Indoor greenery typically doesn’t have native plants (where are all these native plants advocates?) and require subtropical conditions that require certain room temperatures (energy) and can cause corrosion with HVAC systems and ducts, besides spores and mildew.  

Maintenance: 1 man hour per two weeks per 10 square feet.

I understand that every intensive Green Wall supplier has great arguments and technology to lower operational costs (likely increases the setup costs and failure). Whether by using rain water, grey water or Solar/Wind energy, or even an industrial byproduct for fertilizers, everything is related to the use of natural resources that could be – potentially – used for other and more important purposes than just making a statement or showing (fake?) environmental cautiousness. Intensive Green Walls are a piece of art. Being an artist and working with living plants is not automatically being environmentally friendly nor it means being an environmentalist.

Even so intensive Green Walls likely create environmental awareness to a broad audience; it is still on the back of using natural resources - ineffectively. So you have to decide for you own and keep in mind that replacing an intensive Green Wall (because of operational costs) likely helps to fill landfills.

Picture: BuGG

For me (in my opinion). Intensive Green Walls are a wrong signal because it could be done much more efficient and with the patience of a true gardener who is in harmony with nature.

Jörg Breuning

Celebration 20 years of Integrated Green Infrastructure

Green Team at Green Roof Technology, - Thursday, July 12, 2018
Integrated Green Infrastructure That Last

Celebrating two projects with 20 years of integrated Green Infrastructure.

It is now 20 years after Jorg Breuning managed the Green Roof installation at the Zeppelin-Carrée (left)

and 1999 Kronen-Carrée (right) in Stuttgart.

 

Over 500,000 sf of green roofs nicely visible on Google Earth. Probably the first Solar Garden Roof on Earth.

Experience pays back on the first day!

 

#greenroofs #biophylilla #stormwater #greenrooftechnology #greeninfrastructure #optigreen #solargardenroof

Power Plant and Green Roof

Green Team at Green Roof Technology, - Tuesday, July 10, 2018
Green Roofs and Green Walls

Since 1991 the Waste to Energy Power Plant in Stuttgart, Germany utilizes solid "old school" living green technology that the building almost visually disappears from the street level.

Old school living green technology is rather based on the long experience of horticultural experts and professional gardeners than on innovative, complicated technology that requires more maintenance than the vegetation. This drastically lowers costs, maximized resilience and increases diversity.

Old school living green technology has very long tradition in Europe, it is inherited over generation and continuously improved with man-made materials that often come from the waste stream of urban developments. 

 

Fluent Transition from Green Roof to Green Wall

Green Team at Green Roof Technology, - Friday, April 06, 2018

Fluent Transition from Green Roof to Green Wall for 23 Years



Multimedia artist André Heller created a world of wonder to celebrate Swarovski’s hundredth anniversary in 1995. Heller’s thematic centerpiece for Swarovski Crystal Worlds was the shape of the Giant. He developed the story of a Giant who set out to experience the world and all of its treasures and wonders. With this knowledge, the Giant settled down in Wattens/Tyrol, where he has watched over his Chambers of Wonder ever since.

So far, 14 million visitors from around the world have experienced the magic!

The original principle of these Chambers of Wonder is based on the historical chamber of wonders in the castle of Ambras, which was a sixteenth-century attempt to assemble a universal collection of all knowledge known at the time. In the Chambers of Wonder at Swarovski Crystal Worlds, internationally and nationally recognized artists, designers, and architects have interpreted crystal in their own unique ways. They create concepts of space and experience from the sparkling material.

Welcome to the magical world that unfolds whenever you step through the head of the Giant into Swarovski Crystal Worlds…

Visit the worlds of wonders covered under a Green Roof and protected by the Green Giant:

The subterranean world of the Giant begins in the Blue Hall, the first Chamber of Wonder in Swarovski Kristallwelten (Swarovski Crystal Worlds). Its slanted walls, painted in the color “International Klein Blue,” a shade developed by the artist Yves Klein, suggest the inside of a cave.
#greeninfrastructure #greenroofs #greenwalls #svarovski #stormwater #oldschoolgreening #sustainable #museeum

Rooftop Vineyard

Green Team at Green Roof Technology, - Tuesday, April 03, 2018

Rooftop Vineyard

Rooftop farming for educational and recreational purposes seems a fancy trend in North America.
In 2002 Dipl.-Ing Markus Wittling was planning to elevate an entire vineyard on top of the Wine Museum in Cologne, Germany. The sloped green roof spans over the entire museum building of almost 20,000 square feet. It is likely the first vineyard on a roof and the first sloped rooftop farm in the world.

In the middle ages Cologne was the most important wine trading town north of the Alps. The "Weinmuseum Köln e.V." is honoring this fact with a museum and with astonishing and educational exhibits about wine.
The green roof displays 40 of the most important grape species from around the world situated onto 720 vine stocks.
The soil layer (growing media) including granular drainage is 27 inches deep and consists of a blend of porous volcano material like Lava rock and Pumice - materials in which grapes develop their unique taste. Over 15 years of high performance.

This rooftop vineyard is a prime example of old school green roof technology and is ideal for educational purposes. If you have a chance to visit Cologne, the Wine Museum is a must on your Green Roof Safari and your effort will be rewarded with amazing wine tasting!

#greenroofs #stormwater #vineyard

Sustainability, Resilience:

Green Team at Green Roof Technology, - Friday, February 09, 2018
Celebrating two projects with 20 years of integrated Green Infrastructure.



20 years after managing the Green Roof installation in 1997 Zeppelin-Carrée (left)
and 1999 Kronen-Carrée (right).
Both buildings are covered with over 500,000 sf of multiple types of green roofs.

It is likely the world's first Solar Garden Roof.

 

It is now on Goggle Earth.

#greenroofs #biophylilla #stormwater #greenrooftechnology #greeninfrastructure #optigreen #solargardenroof

Health Care and Green Infrastructure

Green Team at Green Roof Technology, - Tuesday, February 06, 2018

State of the Art Health Care and Green Infrastructure

BG Hospital Tübingen A hospital with LEED certification might be far away from State-of-the-Art. That it can be done differently and with commons sense shows the featured project. It has been upgraded constantly over the last 5 decades, always with Green Infrastructure in mind as a central element to reduce the footprint of the building and the increase the well-being of the patients.
 

This project likely increases LEED Platinum by 30%, but no Dollar or Cent was wasted for any certification. All money was directly invested in measurements to improve the environmental foot print and to increase the patients experience, that they can leave the hospital as soon as possible.

American Hospitals typically want to shine with their LEED points and assume that patients like this idea. Unfortunately this doesn't help in their healing process, actually keeps them longer in hospital - what helps the hospitals having more occupied beds and more income. The patients pay for the ego of the hospitals likely twice (not State-of-the-Art!).
BG Hospital Tübingen: The BG Hospital Tübingen is one of the largest trauma centers in Germany. 

Initially designed as follow-up clinic, it has been working closely with the neighboring Eberhard Karls University of Tübingen and its university hospital. 
In 1987, the collaboration became contractual: within the scope of the “Tübinger Modell”, the clinic takes care of the treatment of patients, as well as of research and teaching in the fields of trauma, hand, plastic and burn surgery. In 2006, this very successful model was expanded to the fields of oral, jaw and facial surgery, which have since been integrated into the BG hospital. The Siegfried Weller Institute for Traumatological Surgery at the BG hospital Tübingen works on a wide range of innovative projects. The work done by interdisciplinary teams focuses on bone metabolism diseases and stem cell research.

Germany has a universal multi-payer health care system with two main types of health insurance: "Statutory Health Insurance" (Gesetzliche Krankenversicherung) known as sickness funds (Krankenkassen) and "Private Health Insurance" (Private Krankenversicherung). Germany's state healthcare system is the oldest in Europe, dating back to the 1880s. Citizens pay into one of the 300 statutory state sickness funds through their payroll or bank. According to the Euro health consumer index, which placed it in 7th position in its 2015 survey, Germany has long had the most restriction-free and consumer-oriented healthcare system in Europe. Patients are allowed to seek almost any type of care they wish whenever they want it.
Please find a larger picture here: Jorg Breuning www.greenrooftechnology.com

Garden Bridge Orlando Florida - The First

Green Team at Green Roof Technology, - Sunday, February 04, 2018
Modern Green Roof technology combined with a Blue Roof to minimize artificial irrigation, to maximize water retention and enable visitors to cross a busy four-lane highway without leaving the lush greening of a park.

Picture: Jorg Breuning 2018

The Garden Bridge at Universal Studios in Orlando is the first of its kind in Florida. Designed by Miles Architecture Group Inc., Libra Design Group and Green Roof Service LLC, the green bridge creates an innovative connection of Universal City developments. Selected ground covers, shrubs and trees escort pedestrians almost without notice that they are crossing over a busy highway. The distinctive landmark project is engineered with people in mind.

The Garden Bridge at Universal Studios Orlando project is approximately 3,000 sf (145' x between 18 and 25' wide). The bridge is designed to pond water in the granular drainage area to increase the water retention (a blue-green roof combination, Patent hold by Optigreen - 1978 and the first time introduced to North America by Jorg Breuning in 2001).



Unique projects require unique solutions. Keeping the costs for the structure low, the trees are located above the bridge's pillars. The walkway gently winds up to the bridge and over and is easy accessible for the handicapped or service carts.

The project was possible with an outstanding waterproofing solution by ALT Global. ALT Global meets the FLL requirements for root resistance.


This innovative green roof project is a master piece of teamwork between architects, structural engineers, landscape architects and green roof professionals with an open mind, environmental leadership and common sense.

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  1. Net-Zero Townhomes Benefit From Solar Garden Roof Green Team at Green Roof Technology, 30-Nov-2019
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