Friday, April 29, 2011

Florida Green Roof Photos, MetroVerde, Jacksonville

Shown here are a few photos of the various field trial green roofs at MetroVerde and a few from a LEED Platinum project we are installing now.  As April leaves and May approaches we reflect back on and extremely dry, desiccating spring.  During this climatic condition we were pleasantly surprised to see the more cost-effective economy green roofs out-preform the more expensive built in place and tray systems.  

Florida Green Roof, Cow Peas, Mustards gone to seeds, Allium and Portulaca

Florida Extensive (25mm soil media) Economy Green Roof with Food Plants

Florida Green Roof, Cuban Sweet & Thai Chili Peppers

Florida Green Roof, Rooftop Permaculture, Wild Cherry Tomatoes & Luffa Gourds
Breaking Ground Contracting Green Roof Jacksonville

Breaking Ground Contracting Green Roof Jacksonville

Thursday, April 28, 2011

Green Roofs and Hurricanes

The Eastern Pacific Hurricane season begins in about two weeks, on May 15th and the Atlantic Hurricane season follows shortly thereafter.

Hurricane design is an important consideration for green roofs.  If a green roof is to be built in areas subject to hurricane or cyclone impacts then a few simple guidelines will help make the design more resilient against wind and storm damage.

At a minimum, we recommend;

  1. No large trees on a roof.
    1. Small shrubs and small trees may be used successfully depending upon the final design.  This may seem like a common-sense guideline but people try to put all types of tall, large trees on patio or garden roofs.  During a 130 mph cyclone, the tree will probably be blown over and may cause damage from the fall against the structure or to the street below.  It may also become airborne if the winds are strong enough.
  2. Anything and everything on a roof should be permanently attached.  
    1. Walkways should be constructed from a permanently attached TPO, EDPM or other mat and permanently affixed to the roof.
    2. No loose chairs, tables or other items should be present.  If you wish to have a chair and table stay on a roof during a cyclone, they must be permanently attached.
    3. All green roof components must be permanently attached to the structure.
    4. Any trays, plastics, pots, containers or other green roof components must be permanently attached to the building structure.  Florida Building Code does not allow for loose items to be installed on a roof - they must be attached.
    5. Green Roof Irrigation components must be permanently attached to the roof.
  3. Make sure all tools and gardening utensils are picked up and put away.
    1. It is very easy to forget the pair of shears, scissors or pliers on a roof.  Remember what you were using and where you liad them.
  4. Plant selection should be focused on those species that have historically survived cyclone and hurricane incidents.  There are several good books available at most bookstores here in Florida on proper cyclone resistent landscaping and many resources on the web, such as the Brevard County Landscaping Guide for Hurricane Areas.
  5. Check on the NOAA National Hurricane Center website daily.  The NHC webpage is a wonderful resource, full of links to climatic data.
Always use a green roof design or green roof system already proven in actual field trials with hurricane simulation testing.  Watching a green roof blow off during a storm is an avoidable event.  Due diligence upfront and preparedness is important for green roofs in hurricane prone and cyclone impacted areas.

Tuesday, April 26, 2011

Green Roof Irrigation, Where are the April Showers?

Much of Florida has a unique climate, one needing to be understood for successful green roof design.

April is supposed to bring rainfall so we can have May flowers, right?  Maybe it is due to cyclical weather patterns or maybe to climate change, but over the past ten years or so excluding tropical storms and hurricanes the state has been in a drought.

Much of the Southeastern US and the Caribbean has experienced similar rainfall shortages.

In areas where irrigation is restricted to certain days or prohibited all together this can mean serious potential damage to green roof and living wall plantings.

Unfortunately, without expensive treatment systems, grey water cannot be used for irrigation purposes in Florida by state mandate.  Therefore keeping green roofs and living walls irrigated can be problematic at times.
Capturing HVAC condensate for Green Roof Irrigation

Rainfall deficits aside, daily water vapor is typically quite high during these periods of drought.  High air water vapor has advantages and disadvantages though.  On a positive note, HVAC condensate can be captured and used for irrigation purposes as shown in the above photo ( the five gallon bucket is used to illustrate how much condensate accumulates).  Ten liters per day per 1000 SF, 92 SM.
Air Conditioning Condensate to be captured and reused
Though it is good to reuse condensate water from HVAC systems, always make sure there is no biocide added.

On a negative note, hot days with high humidity encourage plasmodial and fungus growth.  Though native plant species thrive with certain plasmodial and fungal interactions, other non-native landscape plants can turn to mush and die overnight (many sedum species are prone to hot weather Southern Blight effect here in Florida).

Ultimately, in areas where long periods of dry, hot , windy weather potential exists, especially during long daylight hours, the chance green roof plants will suffer are greatly increased.

Remembering photosynthesis processes in plants during design - right plant, right place - mitigates potential desiccation and drought damage.  Take advantage of all site climatic conditions during design.

Plants survive long, hot summers on their own.  As green roof designers we need to understand all aspects of light, wind, precipitation and other eco-variable conditions the green roof will be exposed to.

Monday, April 25, 2011

Biodiversity and Florida Green Roofs, Urban Core Wildlife

I have always seen wildlife come in droves once green is restored to the Urban Core.  Before our present-day horizontal green (lawns in a concrete jungle) the lands were covered in towering trees and lush vegetation, wildlife flourished and stormwater was treated naturally.  As plants and trees were cut and paved over wildlife disappeared.
As I mentioned, I have always seen wildlife return to the site quickly once roofs and walls were planted.

Breaking Ground Roof supports Biodiversity
Friday was Earth Day 2011 and Mary, Catherine and I planted a Grancy Grey Beard as the first green roof plant on the Breaking Ground Contracting Green Roof.

IT room HVAC Condensate to be used for irrigation

As Mary and Catherine were leaving, walking down the observation platform to the stairs, Mary pointed out an avian visitor.

Grancy Grey Beard on Breaking Ground Green Roof
This week will bring about the installation of many food and native plants on the roof.  We invite the wildlife to a big biodiversity party in the Urban Core of Jacksonville.

Friday, April 22, 2011

Green Roofs Florida, Earth Day Significance - Chionanthus virginicus Planted

Today we celebrate Earth Day here in Jacksonville by planting a Grancy Grey Beard, or Old Man's Beard, Chionanthus virginicus, on the Breaking Ground Contracting living roof.

Chionanthus virginicus ready for planting on the BGC Green Roof today, Earth Day 2011

To me, the tree and the project are very special.  Before moving to Jacksonville we owned a beautiful parcel of land on the Gulf Coast of Florida, one filled with pine flatwoods and cypress swamps.   Chionanthus virginicus grew wild there, along with her evergreen cousin the American olive, Osmanthus americanus, both being members of the Oleaceae family.  The olive is a beautiful evergreen shrub or small tree while the Grancy Grey Beard is deciduous.

In the early spring, along with Carolina jessamine, Chionanthus is one of the first blooms one comes across in Florida's nature and the sight is stunning.  Beautiful white, fringe-like flowers fill the shrub and call to wildlife.
Breaking Ground Green Roof Planting Beds, Solar Panels in the background
Planting a Grancy Grey Beard on the Breaking Ground Contracting's living roof is symbolic of Earth Day's true intent as Breaking Ground's staff are focused on sustainable construction, leading the way for their neighborhood renovation and creating a facility not only serving as an office but as an educational outreach resource for sustainability, to all.

As we celebrate Earth Day in many ways around the world, Green and Living Roofs stand side by side with other sustainability measures, cleaning stormwater, creating wildlife habitat for supporting biodiversity, sequestering carbon, cleaning the air we breath with fresh oxygen, offering educational, economic and social opportunities in the Urban Core and more.

Hope all have a wonderful and sustainable Earth Day 2011.

Thursday, April 21, 2011

Green Roof System Installed, Ready for Soil Media

Friday is Earth Day and we'll plant the first plant on the Breaking Ground Contracting green roof.  Yesterday Sterling Roofing installed the green roof system.  Today I'll be starting adding soil media and we'll be laying a patterned, anti-slip TPO walkway around the rooftop garden.

Below are a few photos of Jimmy's crew doing the install.  Pictured is the mat, edging and final assembly.

More photos over the next couple days as the green roof grows!

Florida Green Roof MetroVerde Design

Florida Green Roof MetroVerde Design

Florida Green Roof MetroVerde Design

Florida Green Roof MetroVerde Design

Tuesday, April 19, 2011

Green Roof Plants - C4 Plant List

We refer to green roofs plants possessing the C4 photosynthesis processes frequently here in the Green Roof blog and people often ask the question "Where can I find what plants are classified as having C4 photosynthesis processes?"

Below is a list of many plants know to have multi-cellular photosynthetic processes and drought resistant qualities.  The list is part of a University of California at Santa Cruz paper entitled "C4 Photosynthesis, Atmospheric CO2, and Climate", by Ehleringer, Cerling, Helliker (1997).  Though the paper is well over ten years old, the data is very useful.

Photosynthesis process are just one of many variables we use in modeling green roof plant placement and performance, however a very important one.

An interesting note is - of all the dicots, Asteraceae, Chenopodiaceae, and Amaranthaceae contain the most genera of C4 plants, while within the monocots you see many C4 plants within the Poaceae and Cyperaceae genera.

Considering shade, light availability, wind, temperatures and other factors along with the plants mentioned in the below list will assist in 'Right Plant, Right Place' determination.

Hope the list is useful.

Dicotyledonae (subclass)
Caryophyllanae (superorder)
Caryophylles (order)

Aizoaceae (Family) -      Cypselea, Gisekia, Trianthema, Zalaeya

Amaranthaceae (Family) -  Acanthochiton, Aerva, Alteranthera, Amaranthus, Brayulinea,
Froelichia, Gomphrena, Gossypianthus, Lithophila, Tidestromia

Caryophyllaceae (Family) - Polycarpaea

Chenopodiacea (Family) -  Anabis, Aellenia, Arthrophytum, Atriplex, Bassia, Bienerta, Camphorosma, Chenolea, Climacoptera, Comulaca, Cytobasis, Echinopsilon, Gamanthus, Girgensohnia, Ha-
lanthium, Halimocnemis, Halocharis, Halogeton, Halostigmaria, Haloxylon, Hammada,
Horaninovia, Hypocyclix, Kochia, Londesia, Noaea, Panderia, Petrosimonia, Salsola,
Seidlitzia, Suaeda, Theleophyton, Traganum

Molluginaceae (Family) -  Glinis, Mollugo

Nyctaginaceae (Family) - Allionia, Boerhaavia, Okenia

Portulaceae  (Family) - Portulaca

Theanae (superorder)
Polygonales (order)

Polygonaceae (Family) - Calligonum

Malvanae (superorder)
Euphorbiales (order)

Euphorbiaceae  (Family) - Chamaesyce, Euphorbia

Violanae (superorder)
Brassicales (order)

Capparaceae  (Family) - Gynandropsis

Geranianae (superorder)
Linales (order)

Zygophyllaceae (Family) - Kallstroemia, Tribulus, Zygophyllum

Asteranae (superorder)
Asterales (order)

Asteraceae (Family) - Flaveria, Glossocordia, Glossogyne, Isostigma, Pectis

Solananae (superorder)
Solanales (order)

Boraginaceae (Family) - Heliotropium

Convolvulaceae (Family) - Evolvulus

Gentiananae (superorder)
Scrophulariales (order)

Acanthaceae (Family) - Blepharis

Scrophulariaceae  (Family) - Anticharis

Monocotyledonae (subclass)
Commelinanae (superorder)
Juncales (order)

Cyperaceae (Family) - Ascolepis, Bulbostylis, Crosslandia, Cyperus, Eleocharis, Fimbristylis, Kyllinga, Lipocarpha, Mariscus, Pycreus, Rhynchospora

Poales (order)

Poaceae  (Family) - Alloteropsis, Andropogon, Arundinella, Bouteloua, Cynodon, Echinochloa,

Leptochloa, Microstegium, Panicum, Paspalum, Setaria, Sorghum, Spartina,
Sporobolus, Zea (many more genera)

Monday, April 18, 2011

Wind and Green Roof Plants

Included here are two photos of the same black-eye pea plants.  One is on a wind protected green roof, the other is on a wind exposed green roof.  Note the wind burn on the wind exposed roof plants.

Both looked the same prior to the 48 hour wind storm just leaving (killed 40 persons in the southeast US during tornados).

We recorded between 10 and 20 Km/Hr winds on a continual basis for the 48 hours with almost non-existent water vapor or air humidity.
Florida Green Roof, Wind Protected Green Roof Plants

Florida Green Roof, Wind Exposed Green Roof Plants

Wind can burn or kill green roof plants quickly, taking an otherwise beautiful planting and turning into a brown mess within a matter of days.  Even with more than adequate irrigation water applied - simply because the vascular system of the plants cannot keep up with the demand for water in the leaves.

CAM plants and those plants with stomata remaining closed or closing under lack of water conditions must be used as perimeter wind break plants on green roofs with out parapets or other wind protection if the green roof is not otherwise sheltered.

Understand the different types of photosynthesis green roof plants have.  For a primer, check out the many articles we have posted before on CAM, C4 and C3 plants.

Other helpful sites are included here;

Great Irish Gardening blog article on wind damage in Ireland to garden plants.

North Carolina State University has another brief yet informative note on wind desiccation of plants.

Very interesting and informative Permaculture Wind Break Site.

Remember, your green roof site may receive plenty or precipitation or irrigation water, but if it is constantly exposed to desiccating winds the plants will experience the effects of wind damage.

Sunday, April 17, 2011

Storing Rainwater for Green Roof Irrigation, Florida Green Roofs and Water Conservation

We built a really cool bioswale and rainwater storage system to collect not only rainwater runoff from the green roof, but also to collect any irrigation water seeping from our terra cotta pots and the water we use to wash off shoes and our feet after working in the nursery or with the animals.

MetroVerde Bioswale
We looked at many designs before settling on the final.  There are some nice looking California designed wetlands in a box ( and those designed in northern states ) and we reviewed these products in detail.  Unfortunately, though we get 60 inches average, 154 CM, per year rainfall, most comes only in a few summer months and a nine to ten week drought with little or no rain is not uncommon.

Most 'wetlands in a box' design are for those areas where rainfall occurs every afternoon or every other day where there is a constant water input.   They just won't keep the plants alive during Jacksonville's long, hot droughts.

Florida Bioswale plants, Mentha spicata and Equisetum hyemale
For a modular wetland to work in Florida the design would have to be based around Florida climate and environment.  We are very hot in the summers, cool to cold in the winters, extremely humid in the summers,  subject to 20", 50CM rainfall events during a tropical storm,  prone to weeks without water and have high-speed desiccating winds.

So we thought if we could find an ecological system similar to what we wanted we could study the component parts and duplicate the wetland.  There are many wetlands in Florida to study but the problem is they all possess native hydrology where as the area under our green roofs and the area where we wanted the bioswale to be built was not an original wetland nor did it have any native hydrology.

Stormwater ponds were another resource to consider.  If we could find a small stormwater pond that was originally constructed in an upland area with no native hydrology and no additional irrigation, then we believed we could use the design.

It worked!  We found a system created in an upland now having developed into a nice Florida ecological system we could model our bioswale after.  Our reference wetland is a superb example of a long-term functioning wetland.  The system is located on the University of Florida campus in Gainesville and was designed by Dr. Mark Clark.
Water is stored for reuse within the bioswale system
We began construction in 2008 on our system and are very pleases with the performance.  The system allows for pedestrian access, provides a crisp appearance, allows for collection of rainwater and wash-off water and then reuse of the water through a pump and hose.  Interestingly, the design serves to capture even the smallest amount of rainwater and feeds the adjacent plants through wick action.  The design include multi staging and bay implementation yet the materials are readily available and cost-effective.  If fact, the most expensive component were the rock.  A sharp sand could easily replace the rock for additional value engineering without blinding or otherwise impacting performance of the system.

The functional components are structurally rated for H-20 loadings and one could easily drive a vehicle across the system if appropriate design measures were taken.

The horsetail spreads through rhizomes under the rock (as does the more invasive mint - a must have for iced tea or mojitos) and contributes to the stabilization (horsetail is native in Florida).

Well into it's fourth year of service, the bioswale has become an integral part of extensive green roof design and function.  For a look at another similar bioswale system we've installed here and is functioning well into its second/third year click here.

Thursday, April 14, 2011

Florida Green Roof Good Morning Photos

Photos from a few of the rooftops this am!
Florida Green Roof Peas and Allium

Florida Green Roof Tomatoes and Chives

Florida Green Roof - Matt's Wild Cherry Tomatoes

Florida Green Roof - Dew on the Chives

Florida Green Roof - More Food for Jax Urban Farm

Another Interesting Green Roof Factoid

We had a very hot day yesterday and a cold night last night. Yesterday's temperatures of the roof under the asphalt shingles soared near 130F, 55C in the bright Florida sunlight, then dipped into the low 40's F, 4C this morning.

Interestingly, the uninsulated roof decking under the asphalt shingles followed the outside air temperature and quickly fell below the decking under the green roofs. In fact, early this morning there was a 15 degree F difference between the green roofs and the asphalt shingle roof with the asphalt shingle decking being considerably colder than the decking under the green roofs.

The green roofs stored the solar heat yesterday, during the mid-day and slowly released the heat during the night as the outside air temperatures plummeted.

The more data collected the more we see just how green roofs moderate temperature swings.

Tuesday, April 12, 2011

Awesome Video - New York Rooftop Permaculture Gardens

New York Farm City from Petrina TV on Vimeo.

Florida Green Roofs, Biodiversity and A. carolinesis's fly

MetroVerde Florida Green Roof, Extensive, Rooftop Permaculture
Ever thought about helping save the planet's wildlife from extinction? Installing a green roof or living wall can help. Many species are dependent on the amount of greenery growing up above the ground for survival.

Species like the green Florida anole, Anolis carolinensis are being pushed towards extinction by newcomer lizard species to Florida, such as the Cuban anole, Anolis sagrei. However, the Cuban anole prefers lower, bushy plants and tree trunk areas for habitat while the Florida green anole likes taller greenery and vegetation.
Green Roof Biodiversity Anolis carolinesis's throat fan

So by adding what we call 'Volumetric Green' to your urban yard, you are providing the Florida green anole with a place to escape predators and live.

The photo sequence here starts with the recently constructed MetroVerde pea and tomato extensive food livign roof and shows the Florida anole resting on the palmetto frond siding attracting flies (and female anoles) with his 'dew lap' or 'throat fan'.
Green Roofs support integrated pest management

Green Roofs and Florida Anole

The fly, soon lands, the anole grabs and chews the fly and nature has just provided integrated pest management as a result of a green roof and volumetric green installation.

We have seen over and over how the addition of a small green roof can help increase the population of the green anoles, a species otherwise doomed to extinction in the asphalt and concrete jungle.  For a great website on this interesting species see the Discover Life website -   and for a great video of a green anole who loves riding wind turbines - click here.   

Installation of a green roof and living wall will not only offer the benefits of cleaning stormwater, providing habitat (saving a species) and creating beauty - when you install your MetroVerde green roof you are creating a permanent and effective method of Pest Control!  Anoles love to eat mosquitoes, termites and roaches!  Check out the you-tube video appropriately labeled "Crunch!"  

Sunday, April 10, 2011

Florida Green Roof Temperature Trending

Clearly the pattern of green roof temperature moderation, especially on south facing roofs continues.

We will resume our normal technical green roof posts tomorrow and switch over the temperature graphs to a page within the blog.

In the meantime - you may want to check out the great contest for green roof photos on GreenRoofs facebook page by clicking here.

Temperature Difference Green Roofs and Asphalt Shingles

Saturday, April 9, 2011

More Green Roof Temperature Comparisons

Daily trends are beginning to define themselves.

Asphalt shingles heat up very quickly during the day, much hotter than green roofs, then cool down much faster at night.

However, green roofs moderate daytime solar gain and do not heat the roof to the high temperatures seen on asphalt shingles.  Green roofs really help keep roofs cool - and make a great place to grow vegetables!
Green Roof Comparison Chart - Temperatures - Click to Enlarge
Green Roof Mustards

Friday, April 8, 2011

Green Roof Temperature Comparisons to Asphalt Shingles, Florida Green Roofs

Yesterday's data completed the first full set of every two hour temperature readings across the green roof decking and the decking under the asphalt shingles.

We still have a few bugs to work out with the data logger and then how to present the data on the blog, but here is the chart (in degrees F - note Celsius is coming soon) for the first full day, April 7 - April 8th.

What is interesting is the magnitude of difference.  The decking under the asphalt shingles heats up much more quickly during the day than the decking under the green roof. The inverse is true at night.  Though at night the decking temperatures become much closer in range, during the day the spread is significant.

Yesterday was partly cloudy with times of full sun.  Outside air temperatures ranged from the upper 50's F for lows to high 70's for the high temperature.

As you can see all three green roofs used for data collection produced the same basic temperature profile curve, though the shed was slightly lower (due to the presence of some shade).

We will be refining the data presentation as time permits.  Be sure to check back to see how these profiles develop over the late spring, summer and then into the fall and winter.

Thursday, April 7, 2011

Green Roof Temperature Comparisons

Today we are adding a temperature comparison chart to the blog.  The presentation will evolve over the next couple weeks until we work out the bugs, improving the quality of the graphics to make them more readable, however the intent is to make available temperature comparison data of green roofs and their moderating effects on solar radiation.

The diagram below depicts some of the green roofs scattered across the MetroVerde nursery and urban farm.

Green Roof Temperature Monitoring Locations
We will also be posting the temperatures of the decking under non-green roofs, such as asphalt shingles for benchmarking.

Location D is a the decking under a south facing sloped asphalt shingle roof exposed to full sun during the day.  Location C is the decking under a 3" extensive vegetated roof, south facing as is D and exposed to full sun.  These two face the most brutal of solar gain conditions.

Other locations include F, a north facing sloped green roof, and G the underside of a 2" extensive green roof on the feed storage shed (flat roof and under partial shade).

The below temperatures were taken at random times.  We will implement a standard routine and include Celsius values soon.

At first glance it appears the decking temperatures under the green roof follow the outside air temperatures, moderated significantly from the temperatures shown on from the decking under the exposed asphalt shingles.  More data soon, and we will set up the temperature spreadsheet as a separate page on the blog here.

Temperature Comparisons, Green Roof v Asphalt Shingles

Wednesday, April 6, 2011

Video - Florida Green Roofs, Winds and Storms - Does the Mulch Blow Away?

Enjoy the short video clip here of a recently planted rooftop garden mulched with pine straw and oak leaves being buffeted by a typical Florida violent thunderstorm.

We were under a tornado watch for several hours.

The video is dark at first however as it was shot just before dawn it soon lightens.

Tuesday, April 5, 2011

Intent on Using Sedum on Florida Green Roofs? Try Blue Spruce Sedum

Sedum are popular across the world to use as green roof plants.  This is because of their ability to withstand temperature variations as well being drought tolerant.

Blue Spruce Sedum on a Green Roof, Gainesville, Florida

In Florida, most do not do well.  There are a few advantages sedum brings to a green roof, including;

  • Extreme drought tolerance once established
  • Unique color and texture
  • Spread via rhizome and stem rooting, and others
There is an interesting discussion of sedum and biodiversity support found on the website, where they encourage mixing sedum with wildflowers.  The article does state sedum may have value to bees during the early summer months.

Yet as mentioned in the blog article, Sedums for Florida Green Roofs sedum can have a difficult time in Florida - especially because of Southern Blight and other fungal diseases.

Some say Florida's issues with sedum stem from high heat and humidity.  However this is only partly true.  High heat and humidity provide a platform for the real sedum killer, Southern Blight Fungus.

Southern Blight is transmitted primarily by spores in contaminated nursery soil or plants and becomes a rampant problem during Florida's long, hot, humid summers.

Though a sterile soil mixture may be used on a green roof, the fungus may still develop across the roof via means of birds carrying debris or vegetated material from the ground below.  It is practically impossible to keep Southern Blight at bay once the hot, humid summer months arrive.

But if you are intent on trying sedums on a Florida Green Roof...try the Blue Spruce variety.

Sedum reflexum - Blue Spruce Sedum  is one of the toughest I've seen, growing in Florida.  S. reflexum can grow in the poorest nutrient containing well drained soil.  

I've seen it on non-irrigated roofs in Gainesville - and last through brutal summers of hot sun exposure.  Sedum possesses C4 photosynthesis processes, keeping the stomata closed during most of the day to avoid desiccation and evaporation of water crucial to the Calvin Cycle.  Moreover, sedum possess specialized internal vacuoles to slow down water loss when temperatures soar and the sun shines.

I've seen it thrive in well-drained soils even during the wet season.

The downside to this plant is on hot, harsh roofs it is very slow growing and produces almost no root system, making it a candidate for easy blow-off during high winds.

So it won't spread quickly and fill in your green roof here in Florida.

But it should survive the 7 H's of Florida's Green Roofing Ecology and provide a small area of interesting color and texture.

Happy Green Roofing, Kevin

Monday, April 4, 2011

Green Roof Plants, Heliotropism, Diaheliotropism and Paraheliotropism

Understanding photosynthesis processes in green roof plants is crucial to the green roof designer and we have discussed the difference between C3, C4 and CAM photosynthesis processes in prior notes, including;
Yet nature is complicated and does not limit herself in resisting environmental stressor conditions to just the above three types of photosynthesis processes.

Cowpeas and other plants for example possess the ability to adjust their leaves position to either increase or decrease the amount of leaf surface area receiving direct sunlight.
Under Intense Sunlight Leaves Fold to Prevent Desiccation

Under optimal Sunlight C3 Leaves Open Widely

Under Optimal Sunlight Conditions C3 Leaves Open Widely
Heliotropoism is the term used to describe a plant's actions when it orients leaves to receive more sunlight and thereby increasing photosynthesis capabilities, i.e. - more CO2 fixation.

Diaheliotropoism describes a plant whose leaves actually track the sun'd path, maximizing solar contact.

Paraheliotroposim denotes a plants actions similar to the above photographs.  During parahelioproposim, plants may fold or move their leaves to either;

  • Minimize solar contact, or
  • Minimize total leaf surface area,
either way reducing water loss and preventing desiccation.

Though C3 plants such as the beans - and most other of the world's food plants except the grasses, maize, and sorghum - do not possess as complicated a multi-cellular Calvin Cycle as C4 plants and are more susceptible to drought, they - through Heliotropism biomechanisms they do possess their own unique desiccation prevention mechanisms.

Sunday, April 3, 2011

Florida Green Roofs & Rooftop Permaculture in Arid and Cyclone Prone Areas

Recently, one of the original field trial green roofs was temporarily removed to allow for installation of a solar hot water system piping.  The roof's slope was approximately 7/12 and originally the lightweight extensive mat system was installed over the existing asphalt shingles (with a root barrier/waterproofing liner).  The green roof system used a soil media comprised of primary organic mixtures, had a variety of sedum, succulents and native Allium species planted (A. canadense and others).
Florida Green Roof, MetroVerde Extensive Mat System

The sedum and original Aptenia struggled over time, eventually giving way to the A. canadense, primarily due to fungal attacks during the steamy hot, humid summer months (not necessarily rainy just high water vapor months).

Once removed the underlying roof appeared to look the same as the day the green roof was installed seven years ago, free of water damage and quite nicely preserved.

The green roof system was a simple.ost-effective system defying all odds and wagging-tongues - (don't use high organic soil media, the roof is too sloped, can't put a green roof over asphalt shingles, a nature-irrigated green roof will not survive, etc...).   The system easily survived several tropical cyclones, one rainfall event where we had eighteen inches of water in over two days (Tropical Storm Fay), extended periods of brutal drought and more).  The roof never had additional soil or plants added to it.

 Once the solar piping was in place the intent was to  add a recycled section of old, heavy duty chain link fence to the wall under the roof and plant and grow luffa gourds in the gutter, allowing them to cascade down over the guter edge across the chain link living wall fencing. I can hear the wagging tongues now - growing plants in gutter!
Florida Green Roof, Luffa Gourds in Gutters

Importantly, over the years of watching the roof preform the plants adsorbed and drank most of the rainfall events - especially any rain less than one inch (most of our afternoon rainstorms here are les than one inch) rendering the gutter useless.  The gutter was useless in the eighteen inch plus rainfall event too.  Though I would not do this on a commercial application, we do push the limits at the nursery to see what systems can do.  I am confident the green roof system we've replaced on the roof will handle any and all precipitation events, even with the luffa planted in the gutter, and just as the organic matter did not clog and wash out or decompose as predicted or the roof wash off during tropical cyclones, the luffa planted gutter - filled with a fast draining soil media will pleasantly surprise us.

The luffa is deciduous and will allow winter sun to hit our masonry walls, adding heat in the cooler months yet shading out summer solar radiation.

So with skyrocketing food prices in the grocery markets, a food based schema was designed for plantings.  The original mat, removed during the solar renovation process was replaced, adhered using a low VOC roofing glue.
Florida Extensive Green MetroVerde Green Roof, Mat installed
Once the mat was in place and inspected the soil media was added.   This is the process where the greatest leap of faith occurs for me.
Florida MetroVerde Extensive Green Roof Soil Media
A leap of faith because placing soil on a quite steep roof surface seems to be a futile approach, one probably washing off during the first rain storm, covering outside walls with a muddy mess.  Of course we watch the weather predictions as would any roofer and don't start if rain is predicted for a couple days.

The soil media is a fine material, free of aggregate - important when designing in a cyclone prone area.  Our soil media specifications call for microscopic sharp, geometric edges capable of locking together and when roots are added to the blend a highly stable, well-drained monolithic system is created.  The trick lies in initially adding fast growing C3 plants to bind all together then incorporating a purposeful evolution to a blend of more C4 and CAM plants to allow for drought tolerance and wind resilience.
Florida Extensive Green Roof, Matt's Wild Cherry Tomatoes

Since I love Wild Cherry Tomatoes and cannot get enough of them I decided on Matt's Wild Cherry Tomatoes to accompany the luffa's.  This wild breed produces more delicious cherry tomatoes than any other variety I have seen.  I am expecting thousands and thousands of cherry tomatoes this year.
Florida Green Roof, Food Roof, Rooftop Permaculture by MetroVerde

Cherry tomatoes are ramblers and will cascade down alongside the luffas, down the living wall so I won't have to actually climb the roof to fetch the round red scrumptious fruits.
Florida Green Roof - Rooftop Permaculture
Expect update photos as the luffa's and tomatoes grow and fill in the living wall, cascading down from above, providing us and countless hungry insects, birds and other Urban Jax Core wildlife with fresh organic nectar, food and beauty.

I'll add a video clip of a hard rain too, to show how well the drainage actually works.

Friday, April 1, 2011

Cradle to Cradle Biodiversity, Green Roofs, Rooftop Permaculture

Cradle to Cradle is a popular term in Green Building circles, encompassing the concept of recycling, reuse and elimination of unnecessary waste.  Many times though, the 'Cradle to Cradle' concept is forgotten about and simply over-looked with respect to site landscaping.  Although certainly an integral part of any site development or redevelopment project, landscaping is typically not considered a part of a building and as such is often ignored when building sustainability is discussed.
Biodiversity efforts include saving existing plant material
The other day I received an email from Catherine Burkee, Breaking Ground Contracting's Education Director discussing the green roof component of the project.  Catherine used the term 'plant rescue' in a conversation about site biodiversity preservation and the living walls and green roof.  A portion of the BGC green roof project would serve to house a representative sample of the existing flora on the site, affording the site's original plant genetic material an opportunity to continue growing, existing into the future rather than being destroyed during new landscape preparations.

The continuance and preservation of original site biodiversity may be more critical than most first think.  The most humble appearing plant may provide a critical function to the health of our world.  The Breaking Ground green roof project looks to greatly improve site biodiversity, encouraging all plants - food, native wildflowers and Florida friendly landscaping plants, an opportunity to thrive.  Importantly the team has recognized the ecological value of existing plants.  Through plant harvesting and replanting on the green roof, the area wildlife (insects and other pollinators) will not be loosing specific plant types they have come to expect and be dependent on across the lot.

Recall the small Taraxacum plant and the honey bee post of last week.  The specific plant mentioned in the post was harvested and replanted for use in the green roof.  Ideally, site plant material should be harvested for preservation during the dormant season or during a rainy period to reduce plant stress.

Jacksonville has received the first significant rainfall of 2011 this past week and the soil was wet from the precipitation.  Site plant's vascular systems were saturated with water and photosynthesis processes going strong when we went to the site to collect the specimens to be relocated.

Collections were made of all the herbaceous plants we identified during our site bio-assessment plus an additional  eight species.  Specimens were dug using a shovel, tagged and placed into a bag for transport tot he nursery.  Once in then nursery they were potted up into shallow containers to acclimate them to green roof living.

Certainly the plants collected are considered by many to be simply 'weeds', not readily available for purchase at the local nursery or even native plant nurseries.  Many are those plants who are routinely saturated with herbicides and other poisons because they do not fit the definition of a culturally accepted landscape plant.

Yet if we are to take cradle to cradle concepts seriously we must look at our site's existing plants with new perspective.

Benefits of site plant material preservation and adaptation into a small section of the green roof are many.  The overall number of site species will be increased.  Native seed source will be preserved.  Nectar and pollen sources will remain and supplement those additional and new nectar sources brought to the site with the new green roof, living wall and landscape plants.

Biodiversity increases exponentially with increased plant diversity.

In keeping with the 'Cradle to Cradle' sustainability model, the Breaking Ground Project incorporates a continuance of native plant genetic material into the building's living roof.  True sustainability looks beyond just the building structure.   Harvesting site flora for reuse and 'plant rescue' is an excellent example of comprehensive 'Cradle to Cradle' sustainability put to action.